The present techniques generally relate to apparatus and methods for providing haptic feedback in electrical and electronic products, and in particular, relate to apparatus for providing haptic feedback which com prise a shape m em ory alloy (SMA) actuator.

Consumer electronics devices, such as laptops and smartphones, m ay em ploy different types of controls to give users of the devices some feedback indicating that they have successfully pressed a button on the device. This is generally known as haptic feedback, and haptic buttons or controls on a device may provide a tactile sensation to the user to confirm that the they have successfully pressed the button/control/switch . A haptic button may be provided as a module or assembly for incorporation within an electronic device by a device manufacturer. However, space within mobile and portable consumer electronic devices is typically at a prem ium . Haptic buttons are typically located along or near edges of a smartphone or a portable com puting device, for exam ple, so that the display screen m ay be m axim ised. The ever-decreasing thickness of portable computing devices, and the increasing display screen size, means that there is relatively little free space within a smartphone for haptic buttons. It is therefore, advantageous to produce a haptic button having a low profile, e.g. having a low/sm all height such that the button is able to be incorporated into the free space along an edge of a portable computing device. However, a low profile button is, by design , not able to m ove/travel within the com puting device as m uch as ordinary buttons, and therefore, may not be able to provide a satisfying tactile response or sensation to the user.

The present applicant has identified the need for an im proved haptic button assembly for electronic devices.

I n a first approach of the present techniques, there is provided a haptic button assem bly com prising : a housing comprising a cavity; a button provided within the cavity and moveable along a first axis within the cavity; at least one intermediate elem ent provided within the cavity in contact with the button and moveable in a plane defined by the first axis and a second axis, the second axis being perpendicular to the first axis, and arranged to drive movement of the button along the first axis; and at least one shape-memory alloy (SMA) wire coupled to the at least one interm ediate m oveable elem ent and arranged to, on contraction, m ove the interm ediate moveable elem ent in the plane.

I n a second approach of the present techniques, there is provided a haptic button assem bly com prising : a housing com prising a cavity; a button provided within the cavity and m oveable along a first axis within the cavity; at least one intermediate moveable elem ent provided within the cavity in contact with the button and rotatable about a second axis that is parallel to the first axis, and arranged to drive m ovem ent of the button along the first axis; and at least one shape memory alloy (SMA) actuator wire coupled to the at least one interm ediate moveable element and arranged to, on contraction, rotate the intermediate moveable element about the second axis.

I n a third approach of the present techniques, there is provided a haptic assembly com prising : a rotatable button arranged to rotate about a first axis; at least one interm ediate m oveable element rotatable about the first axis, and arranged to drive rotation of the rotatable button ; and at least one shape memory alloy (SMA) actuator wire arranged along a second axis, the second axis being perpendicular to the first axis, the at least one SMA actuator wire being coupled to the at least one intermediate moveable element and arranged to, on contraction, rotate the intermediate m oveable element about the first axis.

I n a fourth approach of the present techniques, there is provided an apparatus com prising : a moveable com ponent; a static com ponent; at least one haptic assem bly arranged to move the moveable component, the haptic assembly comprising: at least one intermediate m oveable element arranged to drive movement of the moveable component; and at least one shape mem ory alloy (SMA) actuator wire coupled to the at least one intermediate m oveable element and arranged to, on contraction, drive movem ent of the interm ediate m oveable component.

I n a fifth approach of the present techniques, there is provided an apparatus comprising any of the haptic button assemblies described herein for delivering a haptic sensation to a user of the apparatus.

The apparatus may be any one of: a smartphone, a protective cover or case for a smartphone, a functional cover or case for a sm artphone or electronic device, a cam era, a foldable smartphone, a foldable im age capture device, a foldable smartphone camera, a foldable consumer electronics device, a camera with folded optics, an image capture device, an array cam era, a 3D sensing device or system , a servom otor, a consumer electronic device (including domestic appliances such as vacuum cleaners, washing machines and lawnmowers) , a m obile or portable computing device, a m obile or portable electronic device, a laptop, a tablet computing device, an e-reader (also known as an e-book reader or e-book device) , a com puting accessory or computing peripheral device (e.g. m ouse, keyboard, headphones, earphones, earbuds, etc.) , an audio device (e.g. headphones, headset, earphones, etc.) , a security system , a gam ing system , a gam ing accessory (e.g. controller, headset, a wearable controller, joystick, etc.) , a robot or robotics device, a m edical device (e.g. an endoscope) , an augmented reality system , an augmented reality device, a virtual reality system , a virtual reality device, a wearable device (e.g. a watch, a smartwatch, a fitness tracker, etc.) , an autonom ous vehicle (e.g. a driverless car) , a vehicle, a tool, a surgical tool, a remote controller (e.g. for a drone or a consum er electronics device) , clothing (e.g. a garment, shoes, etc.) , a switch, dial or button (e.g. a light switch, a thermostat dial, etc.) , a display screen, a touchscreen, a flexible surface, and a wireless com m unication device (e.g. near-field com m unication (NFC) device) . It will be understood that this is a non-exhaustive list of possible apparatus.

I n a further approach of the present techniques, there is provided a method for providing a haptic sensation to a user using any haptic button assembly described herein, the m ethod comprising: receiving data from a sensor indicating that the button has been pressed; and sending a signal to drive the at least one SMA actuator wire.

Preferred features are set out in the appended dependent claims.

I m plementations of the present techniques will now be described, by way of example only, with reference to the accompanying drawings, in which :

Figure 1 shows a cross-sectional view of a first arrangement of a haptic button assem bly;

Figure 2 shows a cross-sectional view of a second arrangement of a haptic button assem bly;

Figure 3 shows a cross-sectional view of a third arrangem ent of a haptic button assem bly;

Figure 4 shows a cross-sectional view of a fourth arrangement of a haptic button assem bly; Figure 5 shows a cross-sectional view of a fifth arrangem ent of a haptic button assem bly and a sealing m echanism ;

Figure 6 shows a cross-sectional view of a sixth arrangem ent of a haptic button assem bly and a sealing m echanism ;

Figure 7 shows a cross-sectional view of a seventh arrangem ent of a haptic button assem bly;

Figure 8 shows a cross-sectional view of an eighth arrangem ent of a haptic button assem bly;

Figure 9A shows a cross-sectional view of a ninth arrangement of a haptic button assem bly;

Figures 9B, 9C and 9D show various arrangements of SMA actuator wire;

Figure 10A shows a cross-sectional view of a tenth arrangem ent of a haptic button assem bly and a sealing mechanism , and Figure 10B shows a zoomed-in view of a portion on the tenth arrangem ent;

Figures 1 1 A and 1 1 B respectively show a plan view and a cross-sectional view of a sealing m echanism for sealing a haptic button assem bly, and Figure 1 1 C shows a cross-sectional view of a modified sealing mechanism ;

Figures 1 2A to 12C show cross-sectional views of three mechanisms for sealing a haptic button assem bly;

Figures 1 3A and 13B show cross-sectional views of two further mechanism s for sealing a haptic button assem bly;

Figure 14 shows a cross-sectional view of a further mechanism for sealing a haptic button assem bly;

Figure 1 5 shows a cross-sectional view of an eleventh haptic button assembly and a sealing mechanism ;

Figure 16 shows a cross-sectional view of a twelfth haptic button assembly and a sealing mechanism ;

Figure 16A shows a cross-sectional view of a further haptic button assembly;

Figure 1 7 shows a cross-sectional view of a thirteenth haptic button assembly;

Figures 18A and 1 8B respectively show cross-sectional views of a fourteenth haptic button assembly in an equilibrium state and in an activated state;

Figure 19 shows a plan view of a fifteenth haptic button assem bly; Figure 20 shows a cross-sectional view of a sixteenth haptic button assembly;

Figures 21 A and 21 B respectively show cross-sectional views of a gapless haptic assembly in an equilibrium state and in an activated state;

Figure 22 shows a cross-sectional view of a further arrangement of a haptic button assembly;

Figure 23A shows a cross-sectional view of a gapless haptic assembly;

Figures 23B to G show cross-sectional views of a flexible portion of the gapless haptic assembly of Figure 23A;

Figure 24 shows a cross-sectional view of a partly gapless haptic assembly;

Figure 25 shows a cross-sectional view of a gapless haptic assembly;

Figure 26 shows schematic diagrams of gapless and partly gapless haptic assemblies;

Figure 27A shows a schematic perspective view of a smartphone, Figure 27B shows a schematic view of an edge of the smartphone of Figure 27A, and Figures 27C-E show schematic views of the profile of a button portion of the smartphone of Figure 27A;

Figure 28A shows a schematic cross-sectional view of a gapless haptic assembly comprising magnets, and Figure 28B shows an alternative arrangement of the magnets in Figure 28A;

Figure 29A shows a cross-sectional view of a gapless haptic assembly comprising a material under compression, and Figure 29B shows a cross-sectional view of the haptic assembly of Figure 29A with a gap;

Figure 29C shows a cross-sectional view of a gapless haptic assembly comprising a piston, Figure 29D shows an alternative arrangement of the gapless haptic assembly of Figure 29C, and Figure 29E shows a cross-sectional view of the haptic assembly of Figure 29D with a gap;

Figures 30A and 30B show schematic plan views of a smartphone comprising a partly gapless haptic assembly in the equilibrium (inactive) and active states respectively;

Figures 31 A and 31 B show schematic plan views of a smartphone comprising an alternative partly gapless haptic assembly in the equilibrium (inactive) and active states respectively; Figure 32 shows a schem atic plan view of a smartphone com prising a further alternative partly gapless haptic assem bly in the active state; and

Figure 33A shows a plan view of a button of a further haptic button assembly, Figure 33B shows a plan view of the further haptic button assem bly and Figure 33C shows a cross-sectional view of the further haptic button assembly.

Broadly speaking, em bodiments of the present techniques provide haptic button assem blies in which the haptic button has a low profile while still providing a satisfying tactile response or sensation to a user. Advantageously, the haptic button assemblies m ay have a profile that, for exam ple, enables the assem bly to be incorporated into the free space along an edge of a portable computing device. The haptic assemblies may, for example, be arranged to move the button perpendicularly with respect to the edge of the device (instead of laterally along the edge of the device) .

I t is possible to generate a haptic sensation from a button or movable portion by m oving the button in a lateral direction with respect to the contact by the user - see, for exam ple, WO201 8/046937 and GB2551657. Flowever, it may be preferable that a haptic button m oves in a direction that is norm al to the surface of the button and the surface of a device in which the button is incorporated. This is because a disadvantage of a haptic button that moves laterally is that it requires a large gap between the moving button and the edges of the housing which houses the button to allow lateral motion of the button, but the large gap m eans it is more difficult to make the haptic button water proof and dust proof in an energy efficient m anner. Thus, a haptic button which is easier to make water and dust proof is desirable. It is also desirable to provide a haptic button which does not have a large visible gap (e.g. of the order of 250pm for a laterally moving button) between the button and the housing, as a sm aller gap (e.g. of the order of 50pm or less) is more aesthetically pleasing.

Furthermore, due to the pressures on size and layout associated with many consumer electronics devices such as wearables, watches and m obile phones, it is also desirable that the haptic button assembly has a low profile.

The present techniques provide haptic button assem blies which have both a low profile (such that they m ay be more readily incorporated into consum er electronics devices such as smartphones) , and may be water and dust proof. Furthermore, the present techniques provide a local haptic sensation caused by a direct impulse, rather than through inertial effects. For exam ple, smartphones comprise inertial haptic actuators - a m ass is moved when a haptic effect is required. Movem ent of the m ass causes the whole sm artphone to shake or vibrate. Thus, the haptic effect is general and is not localised. The present techniques provide a localised haptic feedback. Further still, the haptic feedback provided by the present techniques may be custom isable by a user by m odifying software parameters. This allows different types of haptic feedback to be provided for different purposes or to suit different users.

The term“bearing” is used interchangeably herein with the term s“sliding bearing”, “plain bearing”, “rolling bearing”, “ball bearing”, “flexure”, and“roller bearing”. The term “bearing” is used herein to generally mean any element or combination of elem ents that functions to constrain m otion to only the desired motion and reduce friction between m oving parts. The term“sliding bearing” is used to mean a bearing in which a bearing element slides on a bearing surface, and includes a“plain bearing”. The term “rolling bearing” is used to m ean a bearing in which a rolling bearing element, for example a ball or roller, rolls on a bearing surface. The bearing m ay be provided on, or may comprise, non-linear bearing surfaces. I n some embodim ents of the present techniques, more than one type of bearing elem ent may be used in com bination to provide the bearing functionality. Accordingly, the term “bearing” used herein includes any combination of, for example, plain bearings, ball bearings, roller bearings and flexures. I n em bodiments, a suspension system may be used to suspend the intermediate m oveable elem ent and/or the button within the haptic button assembly and to constrain motion to only the desired m otion. For example, a suspension system of the type described in WO201 1 / 104518 may be used. Thus, it will be understood that the term“bearing” used herein also m eans“suspension system”. The bearing m ay be formed from any suitable m aterial, e.g. ceram ic, a metal, a metal alloy, steel, stainless steel, m ild steel, bearing bronze, phosphor bronze, plastic, and polytetrafluoroethylene ( PTFE) . The bearing m ay be coated with a friction-reducing or low-friction coating such as a lubricant, a dry film lubricant, a diam ond-like coating ( DLC) , a vapour-deposited coating, and hard chrom e. The bearing, or a surface that contacts the bearing, m ay be polished. Each of the haptic button assem blies described herein m ay be incorporated into any device in which it m ay be useful to provide a user of the device with haptic feedback. For exam ple, the haptic button assemblies may be incorporated into an electronic device or a consum er electronics device, such as a com puter, laptop, portable com puting device, sm artphone, computer keyboard, gam ing system , portable gam ing device, gam ing equipment/accessory (e.g. controllers, wearable controllers, etc.) , m edical device, user input device, etc. It will be understood that this is a non- lim iting, non-exhaustive list of possible devices, which m ay incorporate any of the haptic button assemblies described herein. The haptic button assem blies described herein may be, for exam ple, incorporated into or otherwise provided along an edge of a sm artphone or on a surface of a smartphone. I n embodiments, the haptic button assemblies described herein may be provided as standalone modules that m ay be incorporated into an electronic device during manufacture, and may be adapted to suit the device specifications such that it fits into a casing or external surface of the electronic device. I n alternative embodim ents, some or all of the com ponents of the haptic button assemblies described herein m ay be integrally formed in an electronic device. For example, the housing, button and/or seal of each haptic button assembly may be part of the electronic device itself. Each haptic button assem bly m ay comprise electrical connections, which m ay couple the assem bly to the device’s processor(s) , chip(s) , m otherboard, etc., such that the action of the button of the assembly being pressed m ay be processed by the device and so that the haptic feedback can be provided.

Various haptic button assemblies are now described with respect to the Figures. It will be understood that elem ents or features described with respect to one particular Figure or haptic button assem bly may equally apply to any of the Figures or haptic button assemblies described herein. For exam ple, the techniques for sealing a haptic button assembly or the different possible SMA actuator wire arrangements described with respect to particular Figures, may apply equally to any or all of the haptic button assem blies described herein

The I nterm ediate Moveable Elem ent

Figure 1 shows a cross-sectional view of a first arrangem ent of a haptic button assem bly 100. The haptic button assembly 100 com prises a button 102. The button 102 may be pressed by a user to perform a particular operation, such as m aking a selection, turning a device on/off, entering data (e.g. typing on a keyboard) , scrolling, turning a function of the device in which the assembly 100 is located on/off or adj usting the function (e.g. adj usting volum e of audio output from the device) , etc. Pressing or unpressing (depressing) the button 102 m ay cause haptic feedback or a haptic sensation to be delivered to the user, so that the user is provided with some sensory feedback (particularly touch-based feedback) to indicate that the operation has been perform ed.

I n m any of the arrangem ents and embodiments described herein, the button 102 m ay be a surface feature on a device/ apparatus that incorporates the haptic button assembly. I n this case, the haptic button 102 may not be pressed by a user but may still be able to provide haptic feedback. I nstead of a button press triggering haptic feedback, the haptic feedback m ay be triggered by software in response to another event. For exam ple, if a user m akes a selection on a screen of their sm artphone, the selection m ay cause haptic feedback to be triggered, where the feedback is provided by the button or surface feature. (Software-triggered haptic feedback may occur in particular applications, such as in gam ing and/or virtual/augm ented reality devices) . Thus, in m any of the arrangements and em bodiments described herein, direct pressing of the haptic button 102 m ay not be required in order for haptic feedback to be delivered. However, in each case, the m echanism to deliver the haptic feedback is broadly the same whether or not button itself is pressed.

I n embodim ents, such as that shown in Figure 1 , the haptic button assem bly 100 may com prise a housing 104 (also referred to herein as“support”,“chassis”, “casework”, and“casing”) . The housing 104 may comprise a cavity or recess 1 12. The button 102 may be provided within the cavity 1 12 of the housing 104. The button 102 com prises a contact surface 106 (also referred to herein as an outer surface, external surface or upper surface) . I n em bodiments, the button 102 may be arranged within the cavity 1 12 such that the contact surface 106 is substantially level with/flush with an external surface 108 of the housing 104. However, in em bodiments, the button 102 m ay protrude from the external surface 108 of the housing 1 04. It will be understood that the housing 104 surrounds and encases the button 102, such that only the contact surface 106 of the button is visible/ contactable by a user. The haptic button assembly 100 may comprise an intermediate, movable element 110 , which may be provided within the cavity 112 below the button 102. Button 102 may be arranged to move (when pressed/depressed by a user) in a first direction. The first direction may be a direction that is perpendicular to the external surface 108 of housing 104, as indicated by arrow 116 in Figure 1. In other words, contact of a user’s finger with the contact surface 106 of button 102, for example, may cause the button 102 to move into the housing 104 or further into cavity 112. In particular embodiments, the button 102 may move into the cavity 112 by 100pm. The haptic button assembly 100 may comprise a sensor (not shown) in the housing 104 below the button and intermediate moveable element 110. The sensor may be a force sensor, for example. Generally speaking, the sensor may be any suitable sensor or mechanism for detecting depression of the button 102 by a user (i.e. detecting that a user has pressed the button 102). The movement of the button 102 into the cavity 112 (as a result of the user pressing the button 102) causes a force to be exerted on the sensor. The sensor may be coupled to control circuitry (not shown), and the sensor may be configured to communicate with the control circuity when the force on the sensor changes, or when the force on the sensor has been applied for a minimum duration. The detection by the sensor of a user pressing the button causes the haptic feedback to be generated and applied by haptic button assembly 100.

Moveable element 110 may be able to move in a second direction within the cavity 112. The second direction is different to the first direction. The second direction may be a direction that is substantially parallel to the external surface 108 of casing 104, as indicated by arrow 118 in Figure 1. That is, moveable element 110 may move in a sideways (or lateral) direction within the housing 104 (or within the recess 112 of the housing 104). Thus, the first direction and the second direction may be orthogonal. Movement of the intermediate moveable element 110 in the second direction may cause movement of the button 102 in the first direction. That is, movement of the intermediate moveable element 110 may cause the button 102 to be moved in such a way that a haptic effect/sensation is delivered to a user touching the button 102. The concept of moving intermediate moveable element 110 in one direction to cause movement of button 102 in another direction may be implemented in a number of ways. For example, in embodiments such as that shown in Figure 1, both the button 102 and the moveable element 110 may be wedge-shaped, and arranged within the cavity 112 such that a wider end of the wedge-shaped button 102 is in proximity to a narrower end of the wedge-shaped moveable element 110. Thus, a narrower end of the wedge-shaped button 102 is in proximity to a wider end of the wedge-shaped moveable element 110. This arrangement of the wedge- shaped button 102 and moveable element 110 means that when the moveable element 110 is caused to move within the casing 104 in the second direction 118, the button 102 will be forced to move in the first direction 116. In this embodiment, the intermediate moveable element 110 is a‘single wedge’, as only one surface of the element is sloped/inclined.

The movement of moveable element 110 is now described. The haptic button assembly 100 may comprise at least one shape memory alloy (SMA) actuator wire 120. The at least one SMA actuator wire 120 may be provided within a further cavity 112a in housing 104. The further cavity 112a may be smaller than the cavity 112 but may be large enough for the intermediate moveable element 110 to at least partly fit into. The SMA actuator wire 120 may be coupled at one end 122 to the housing 104 (and specifically to the further cavity 112a) and at another end 124 to the intermediate moveable element 110. Thus, in embodiments, the intermediate movable element 110 may be formed of a material that is suitable for coupling to (e.g. crimping) an SMA actuator wire, such as a suitable metallic material. Alternatively, the intermediate moveable element 110 may be formed of any material, and crimp components may be fixedly attached to the intermediate moveable element 110, to crimp an end of the SMA actuator wire. Generally speaking, a coupling element may be used to couple each SMA actuator wire 120 to the housing 104 (i.e. the static component) and to the intermediate moveable element 110. The coupling element may provide a permanent (i.e. fixed) connection between the SMA wires and the static component or the moveable component. The coupling element may be a crimp connector, a welded component that is welded to each SMA actuator wire to form a weld, or other similar connectors. A coupling element (e.g. crimp connector or welded component) may hold multiple SMA actuator wires or may hold a single SMA actuator wire, as described in United Kindgom Patent Application No. GB1820042.8 to the present applicant. Thus, each SMA actuator wire may be coupled to the at least one intermediate moveable element via a coupling element. The coupling element may be a crimp connector, a welded component, or a non-fixed connector.

As an alternative to crimping, the ends of each SMA actuator wire 120 may be connected in place using welding (e.g. arc welding, welding using a weld bar, laser/heat-based welding, etc.). During the welding process, care needs to be taken to control the welding so that damage to the SMA actuator wire, e.g. melting or loss of material, is minimised.

The coupling element may alternatively comprise a connector which provides a non-fixed connection between the SMA actuator wire and the intermediate moveable component or static component. Such a non-fixed connector may be in the form of a protruding element such as a hook, dowel pin or similar element around which the SMA wires are looped or similarly held in place. For example, a length of SMA actuator wire may wrap around/be provided around a dowel pin (see e.g. Figure 9D) on the intermediate moveable element, and the ends of the SMA actuator wire may be attached to the housing via crimps. Alternatively, a length of SMA actuator wire may be attached to the intermediate moveable element and wrap around a pin-like feature or dowel on the static portion/housing.

When a button press is detected by the sensor, this detection is communicated to control circuitry (not shown). The control circuitry may be arranged to control power delivered to the at least one SMA actuator wire 120. Power may be delivered to the at least one SMA actuator wire. When the SMA actuator wire 120 is powered, it becomes hot and contracts. The contraction of the SMA actuator wire 120 causes the intermediate moveable element 110 to move laterally/sideways within the cavity 112, and towards (and in embodiments, at least partly into) the further cavity 112a. In the illustrated arrangement, the intermediate moveable element 110 moves towards the left of the Figure. As the intermediate moveable element 110 moves sideways towards/into the further cavity 112a, the wedge-shape of the moveable element 110 forces the button 102 to move within cavity 112. I n the illustrated arrangement, the button 102 moves upwards in/towards the top of the Figure. The intermediate moveable element 110 may cause the button 102to move by, for example, between 20 pm to0.5mm. In embodiments, the button 102 may move by up to 1mm. Generally speaking, it will be understood that the button 102 and intermediate moveable elem ent 1 10 could be shaped such that the button m oves into the cavity 1 12 when the SMA actuator wire 120 is powered and caused to contract. Thus, in each em bodiment described herein, the button 102 may move into the cavity in order to deliver haptic feedback. (The types of haptic feedback deliverable when the button m oves into the cavity may be the sam e as or different to the types of feedback deliverable when the button m oves outwards of the cavity) .

The haptic button assembly 100 m ay comprise an element which opposes the force of the at least one SMA actuator wire 1 20. For exam ple, the haptic button assem bly 100 m ay comprise a return spring 126. The return spring 126 may be provided within the further cavity 1 12a and may be coupled at one end to the housing 104 and at another end to the interm ediate m oveable elem ent 1 10. The return spring 1 26 m ay be arranged to oppose the contraction of the at least one SMA actuator wire 120 (which caused the m oveable element 1 10 to move in one direction) , and thereby m ove the interm ediate moveable element 1 10 in an opposite direction, i.e. away from the further cavity 1 12a. I n the Figure, the return spring 126 m ay cause the interm ediate moveable elem ent 1 10 to move to the right when the wire is not being powered and is not being actively heated (i.e. is cooling) . The elem ent which opposes the force of the at least one SMA actuator wire 120 m ay be any suitable resilient biasing elem ent, and it will be understood that the return spring is only one non-lim iting example. I n embodiments, a further SMA actuator wire may be used to oppose the force of the SMA actuator wire 120. This may be arranged to, on contraction, pull the interm ediate m oveable elem ent in the opposite direction to the m ovement caused by the SMA actuator wire 120. The further SMA actuator wire may be provided between the housing 104 and the opposite side of the intermediate moveable elem ent 1 10 (opposite to the side to which SMA actuator wire 120 is attached) . I n this embodiment, the at least one SMA actuator wire 120 and the return spring 126 may be considered to form an actuator which causes movem ent of the intermediate moveable elem ent 1 10 (also referred to herein as a“moving portion”) in the housing 104 (also referred to herein as a“static portion”) .

I n alternative embodiments, a return spring or further SMA actuator wire may not be used. I nstead, the force of a user’s finger on the button 102 may be sufficient to oppose the contraction of the at least one SMA actuator wire 120 and thereby move the intermediate moveable element away from the further cavity 112a.

In embodiments, a system of opposing SMA actuator wires may be used to customise the haptic feedback delivered when a user presses the button 102. For example, the system of opposing wires may allow different types of haptic feedback to be provided depending on what the sensor of the assembly 100 detects/ senses. For example, where the sensor is a force sensor, the haptic feedback may be customised based on the magnitude of the force detected by the sensor - a high contact force may cause a particular type of haptic feedback to be delivered while a low contact force may cause a different type of haptic feedback to be delivered. The feedback delivered may be adjusted by having an arrangement of opposing SMA actuator wires that allows the movement (e.g. speed, direction, etc.) of the intermediate moveable element 110 to be finely controlled. In embodiments, the SMA actuator wire(s) may themselves be part of the sensor mechanism of the assembly, by measuring the resistance of the SMA actuator wires to determine e.g. the contact force.

The haptic button assembly 100 may comprise one or more bearings to reduce friction between the moving parts of the assembly. For example, the haptic button assembly 100 may comprise a first bearing 130 between the button 102 and the intermediate moveable element 110. The first bearing 130 may comprise one or more ball bearings 128 that are provided between surface 134 of the button 102 and surface 136 of the intermediate moveable element 110. Surfaces 134 and 136 are ramped (inclined) so that when the SMA actuator wire 120 contracts and moves the moveable element laterally, the button 102 is forced to move within cavity 112 (i.e. orthogonaltothe movement of the moveable element 110). Surfaces 134 and 136 are inclined by the same angle and in the same direction. Specifically, the direction in which the surfaces 134, 136 are inclined is chosen so that movement of the intermediate moveable element 110 towards the further cavity 112a pushes the button 102 upwards in the cavity 112, i.e. such that contact surface 106 may protrude from the housing 104 (and may not be flush with surface 108 of the housing 104). First bearing 130 may comprise the inclined (ramped) mating surfaces 134 and 136 and one or more ball bearings 128. For example, bearing 130 may comprise three ball bearings 128, but this is a non- limiting example. The haptic button assembly 100 may comprise a second bearing 132 between the intermediate moveable element 110 and a surface of the housing 104 (i.e. a surface of the cavity 112). The second bearing 132 may comprise one or more ball bearings 128 provided between surface 138 of the intermediate moveable element 110 and surface 140 of the housing 104 (i.e. a surface of the cavity 112), which may facilitate the lateral movement of the movable element 110. The horizontal movement of the movable element 110 causes the button 102 to move up and down (as indicated by the double-headed arrows) to provide the tactile effect to the user’s finger.

The haptic button assembly 100 may comprise an endstop 114 in cavity 112. The endstop 114 may be formed as part of the housing 104 or cavity 112, or may be a separate element that is provided in cavity 112. The endstop 114 may be provided at a location in the cavity 112 to restrict movement of the intermediate moveable element 110. Generally speaking, if SMA actuator wire is stretched too far (i.e. a certain tension is exceeded), the SMA actuator wire may weaken or become damaged, or even break. The force of the return spring 126 on the intermediate moveable element 110 may cause the SMA actuator wire 120 to become overstretched. Therefore, the endstop 114 may restrict the movement of the intermediate moveable element 110 so that the at least one SMA actuator wire 120 does not overstretch. Similarly, a force applied to the button surface by the user’s finger may cause the wire to overstretch if there is no endstop.

Accordingly, the present techniques provide a haptic button assembly comprising: a housing comprising a cavity; a button provided within the cavity and moveable along a first axis within the cavity; at least one intermediate moveable element provided within the cavity in contact with the button and moveable in a plane defined by the first axis and a second axis, the second axis being perpendicular to the first axis, and arranged to drive movement of the button along the first axis; and at least one shape memory alloy (SMA) actuator wire coupled to the at least one intermediate moveable element and arranged to, on contraction, move the intermediate moveable element in the plane.

Figure 2 shows a cross-sectional view of a second arrangement of a haptic button assembly 200. The haptic button assembly 200 in Figure 2 is similar to the arrangement shown in Figure 1, and therefore, for the sake of conciseness, like features are not described. In haptic button assembly 100, both the button 102 and the intermediate moveable element 1 10 are wedge-shaped. Specifically, the m ating surfaces 134 and 136 are inclined (ramped) . I n haptic button assembly 200, surfaces 234 and 236 are not inclined/ram ped. I n this em bodiment, the intermediate m oveable elem ent 210 is a‘single wedge’, as only one surface of the elem ent is sloped/ inclined. The haptic assembly 200 may comprise a first bearing 230 between the button and the intermediate moveable element. The first bearing 230 m ay comprise one or more ball bearings that are provided between the surfaces 234 and 236 of the button and interm ediate moveable elem ent respectively. For example, the first bearing 230 may comprise three ball bearings, but this is a non-lim iting example.

I n haptic button assembly 1 00, surfaces 138 and 140 of the intermediate moveable element 1 10 and the housing 104 respectively are substantially flat (i.e. are not inclined or ramped) . I n haptic button assem bly 200, surface 238 of the intermediate moveable element is ramped/inclined, and surface 240 of the housing/cavity is also ramped/inclined. The surfaces 238 and 240 are inclined by the same angle and in the sam e direction, such that the moveable element m ay, when actuated, slide or m ove along the surface 240 and in doing so, push the button upwards in the cavity such that the contact surface of the button protrudes from the housing. As m entioned earlier, in embodim ents, the button may move into the cavity when delivering haptic feedback - in this case, the direction of the ramps/inclined surfaces m ay be reversed. The haptic button assem bly 200 m ay comprise a second bearing 232 between the interm ediate moveable elem ent and a surface of the housing/surface of the cavity. The second bearing 232 may comprise one or m ore ball bearings provided between surface 238 of the intermediate m oveable elem ent and surface 240 of the housing/cavity, which may facilitate the m ovem ent of the interm ediate moveable element. The bearing 232 may comprise three ball bearings, for example. The second bearing 232 m ay comprise the ram ped/inclined surfaces 238, 240. I n this arrangement, when the at least one SMA actuator wire contracts (as described above with reference to Figure 1 ) , the interm ediate m oveable element may move laterally (e.g. in the direction of the force exerted by the at least one SMA actuator wire on the moveable element) and in a substantially perpendicular or orthogonal direction. As the moveable element m oves along the ram p provided by surface 240 of the cavity, the moveable element causes the button to m ove within the cavity (as indicated by arrow 216) .

Figure 3 shows a cross-sectional view of a third arrangem ent of a haptic button assem bly 300. The haptic button assembly 300 in Figure 1 is sim ilar to the arrangement shown in Figure 1 and therefore, for the sake of conciseness, like features are not described. The haptic button assembly 300 com bines features of assemblies 100 and 200. Specifically, both the button and the interm ediate moveable elem ent are wedge-shaped in haptic button assem bly 300. The haptic button assem bly 300 m ay comprise one or more bearings to reduce friction between the moving parts of the assembly. For exam ple, the haptic button assembly 300 m ay com prise a first bearing 330 between the button and the intermediate moveable elem ent. The first bearing 330 may comprise one or more ball bearings that are provided between surface 334 of the button and surface 336 of the interm ediate m oveable elem ent. Surfaces 334 and 336 are ramped/inclined so that when the SMA actuator wire contracts and moves the m oveable element in the direction of the force applied by the SMA actuator wire, the button is forced to move within the cavity (i.e. substantially orthogonal to the m ovement of the moveable elem ent) . Surfaces 334 and 336 are inclined by the sam e angle and in the same direction. Specifically, the direction in which the surfaces 334 and 336 are inclined is chosen so that m ovement of the interm ediate m oveable elem ent towards the further cavity 1 12a pushes the button upwards in the cavity, such that the contact surface of the button m ay protrude from the housing . Thus, this is an example of the intermediate m oveable element being a‘double wedge’, as two surfaces of the element are sloped/inclined.

The haptic button assembly 300 m ay com prise a second bearing 332. I n haptic button assembly 300, surface 338 of the intermediate m oveable element is ramped/inclined, and surface 340 of the housing/cavity is also ramped/inclined. The surfaces 338, 340 are inclined by the sam e angle and in the same direction, such that the moveable element may, when actuated, slide or move along the surface 340 and in doing so, push the button upwards in the cavity such that the contact surface of the button protrudes from the housing. The second bearing 332 of the assembly 300 may be provided between the interm ediate moveable element and a surface of the housing/cavity. The second bearing 332 m ay comprise one or m ore ball bearings provided between surface 338 of the intermediate m oveable elem ent and surface 340 of the housing/cavity, which m ay facilitate the m ovem ent of the interm ediate m oveable elem ent. The second bearing 332 may com prise three ball bearings, for example. The second bearing 332 may com prise the inclined/ram ped surfaces 338, 340. The direction in which surfaces 334, 336 are inclined is opposite to the direction in which surfaces 338, 340 are inclined. The angles or gradients of the pairs of inclined surfaces 334, 336 and 338, 340 may be the sam e or different - however, the angles/gradients of the surfaces in a pair of inclined surfaces need to be the sam e. The gradients of the pairs of inclined surfaces /the bearing surfaces may be linear or non-linear. I n other words, the bearing surfaces may have a constant gradient or a non-linear gradient. Thus, in em bodiments, the at least one ramp/bearing surface m ay have a constant gradient, or may have a variable, non-constant gradient (which follows any non-linear equation) . Thus, in this arrangem ent, when the at least one SMA actuator wire contracts (as described above with reference to Figure 1 ) , the moveable elem ent may move laterally - causing the button to m ove upwards as in Figure 1 - and in a substantially perpendicular or orthogonal direction - causing the button to m ove upwards as in Figure 2. Thus, the arrangement of Figure 3 combines two techniques to m ove the button and deliver a haptic sensation.

Figure 4 shows a cross-sectional view of a fourth arrangem ent of a haptic button assem bly 400. The haptic button assembly 400 in Figure 4 is sim ilar to the arrangement shown in Figure 1 and therefore, for the sake of conciseness, like features are not described. I n haptic button assembly 100, both the button 102 and the interm ediate m oveable element 1 10 are wedge-shaped. Specifically, the mating surfaces 134 and 136 are inclined/ramped. I n haptic button assem bly 400, surfaces 434 and 436 are not entirely inclined/ram ped across their full extent. I nstead, surfaces 434 and 436 are locally ramped. Surface 434 of the button comprises one or m ore localised ram ps 442 (as shown m ore clearly in the inset close-up view of the assem bly) . Surface 436 of the interm ediate m oveable element com prises one or more localised ramps 444 (as shown m ore clearly in the inset close-up view of the assem bly) . The localised ram ps 442 and 444 are co located in pairs. I n other words, a localised ram p 442 of the button is in close proxim ity to a corresponding localised ramp 444 of the interm ediate moveable element. The localised ram ps 442 and 444 are inclined by the sam e angle and in the sam e direction. Where there is m ore than one pair of localised ram ps, all of the ram ps m ay be inclined by the same angle and in the sam e direction. The direction in which the localised ramps 442 and 444 are inclined is chosen so that the movement of the interm ediate moveable elem ent towards the further cavity pushes the button upwards in the cavity, i.e. such that the contact surface of the button may protrude from the housing. ( It can be seen that the direction of the localised ramps is the same as the direction of the inclined surfaces 134, 136 in Figure 1 ) . I n the illustrated example, there are three pairs of localised ram ps, but it will be understood that this is a non-lim iting exam ple. An advantage of the localised ramps 442, 444 is that they may enable the overall height of the haptic button assem bly to be reduced relative to, for exam ple, the arrangem ent shown in Figure 1 , as the surfaces 434, 436 are not ram ped across their whole length . I n this embodiment, the interm ediate m oveable elem ent may be considered a ‘single wedge’, as only one surface of the elem ent comprises the localised ramps.

The haptic button assem bly 400 may comprise a first bearing 430 between the button and the intermediate m oveable elem ent. The first bearing 430 m ay comprise one or m ore ball bearings 128 that are provided between surface 434 of the button and surface 436 of the intermediate m oveable elem ent. At least one ball bearing 128 may be provided between the or each pair of localised ramps 442, 444. As shown in Figure 4, a ball bearing 128 is provided between each of the three pairs of localised ramps. Flowever, it will be understood that m ore than one ball bearing 128 m ay be provided on each ramp. For example, in em bodiments there m ay be three ball bearings on each localised ramp 442, 444. The number of ball bearings per localised ramp may depend on whether there are other ways of contraining the motion of the interm ediate moveable elem ent and the button (e.g. additional wall contacts or end stops) . The first bearing 430 m ay comprise one or more localised ramps 442, 444, and one or more ball bearings 128.

The haptic button assem bly 400 m ay comprise a second bearing 432 between the intermediate moveable element and a surface of the housing/cavity. The second bearing 432 may com prise one or m ore ball bearings provided between surface 438 of the intermediate moveable element and surface 440 of the housing (i.e. a surface of the cavity) , which may facilitate the lateral movement of the m ovable element. It will be understood that the localised ram ps shown in Figure 4 could be incorporated into any of the arrangem ents shown in Figures 1 to 3 , or indeed, any of the embodiments described herein . Generally speaking, the localised ramps may be provided between the button and the interm ediate moveable elem ent, and/or between the intermediate m oveable elem ent and the housing. This may amplify the am ount by which the button is m oved when the intermediate moveable elem ent is actuated. The direction and inclination angle of the localised ramps may be chosen to suit each arrangement.

Figure 22 shows a cross-sectional view of an alternative arrangem ent of a haptic button assem bly 2200. The haptic button assembly 2200 is sim ilar to the arrangement shown in Figure 4 and therefore, for the sake of conciseness, like features are not described. I n Figure 22, the location of the localised ramps is changed relative to Figure 4. I n Figure 4, surfaces 434 and 436 are locally ramped. I n com parison, in Figure 22, surfaces 438 and 440 are locally ram ped and surfaces 434 and 436 are not. Surface 438 of the interm ediate moveable element comprises one or m ore localised ram ps 442’ (as shown m ore clearly in the inset close-up view of the assem bly) . Surface 440 of the housing (i.e. a surface of the cavity) , com prises one or m ore localised ramps 444’ (as shown more clearly in the inset close-up view of the assem bly) . The localised ramps 442’ and 444’ are co-located in pairs. I n other words, a localised ram p 442’ of the intermediate moveable element is in close proxim ity to a corresponding localised ramp 444’ of the housing. The localised ram ps 442’ and 444’ are inclined by the sam e angle and in the same direction. Where there is more than one pair of localised ram ps, all of the ram ps m ay be inclined by the same angle and in the sam e direction. The direction in which the localised ramps 442’ and 444’ are inclined is chosen so that the movem ent of the intermediate m oveable element towards the further cavity pushes the button upwards in the cavity, i.e. such that the contact surface of the button m ay protrude from the housing. . Flowever, it will be understood that if the direction of incline of the localised ram ps are reversed, the button could move into the cavity/housing. I n the illustrated example, there are three pairs of localised ram ps, but it will be understood that this is a non-lim iting exam ple. An advantage of the localised ramps 442’, 444’ is that they m ay enable the overall height of the haptic button assembly to be reduced relative to, for exam ple, the arrangem ent shown in Figure 1 , as the surfaces 438, 440 are not ram ped across their whole length. I n this em bodim ent, the intermediate moveable element may be considered a‘single wedge’, as only one surface of the element comprises the localised ramps.

An advantage of this embodiment relative to that shown in Figure 4 is simplified manufacturing. I n the case of sm artphones, typically the button may be manufactured and inserted into a sm artphone handset by one m anufacturer, and the haptic button assembly m ay be inserted into the smartphone handset by another manufacturer. I n the em bodim ents shown in Figures 1 , 3, and 4 to 6, for example, the button m ay need to be specially designed, shaped or m illed, either to have inclined surfaces or localised ramps. Flowever, the embodim ent shown in Figure 22 may sim plify the m anufacturing process as the button does not need to be specially designed. I nstead, the intermediate m oveable element and the housing are shaped to comprise the localised ram ps, but these are typically manufactured by the sam e manufacturer. This m ay m ean that any button can be used alongside the haptic button assembly 2200, which simplifies the design of the haptic button assem bly and removes any requirem ent for the manufacturer of the smartphone handset to shape the handset in a particular way or provide a particular type of button.

Figure 22 shows a haptic button assem bly 2200 in which there is a gap between the button and the housing. I n this case, as described herein, it m ay be necessary to incorporate a sealing m echanism to prevent or m inim ise liquid and/or dirt ingress into the assembly via the gap. Flowever, it will be understood that the haptic button assembly 2200 m ay be arranged as a gapless haptic assembly, i.e. one in which there is no gap between the button and the housing. For exam ple, the button (i.e. the element which is used to deliver haptic feedback) may be integrated into the housing, as shown in Figure 25.

The haptic button assembly 2200 m ay com prise a first bearing 430’ between the button and the intermediate moveable element. The first bearing 430’ may com prise one or more ball bearings 128 that are provided between surface 434 of the button and surface 436 of the interm ediate moveable element, which m ay facilitate the lateral m ovem ent of the m ovable elem ent.

The haptic button assembly 2200 may comprise a second bearing 432’ between the intermediate moveable element and a surface of the housing/cavity. The second bearing 432’ may com prise one or more ball bearings 128 that are provided between surface 438 of the intermediate m oveable elem ent and surface 440 of the housing (i.e. a surface of the cavity) . A ball bearing 128 may be provided between the or each pair of localised ramps 442’, 444’. As shown in Figure 22, a ball bearing 128 is provided between between each of the three pairs of localised ramps. The second bearing 432’ may com prise one or more localised ramps 442’, 444’, and one or more ball bearings 128.

It will be understood that the localised ram ps shown in Figure 22 could be incorporated into any of the arrangem ents shown in Figures 1 to 3, or indeed, any of the embodim ents described herein. Furthermore, the localised ramps shown in Figure 22 could be used in addition to or instead of the localised ram ps of the arrangements of Figures 4 to 6. Generally speaking, the localised ramps m ay be provided between the button and the interm ediate m oveable elem ent, and/or between the intermediate m oveable elem ent and the housing. This m ay am plify the am ount by which the button is moved when the interm ediate m oveable element is actuated. The direction and inclination angle of the localised ram ps may be chosen to suit each arrangem ent.

Thus, in em bodim ents, the haptic button assembly may further com prise a bearing provided between the interm ediate m oveable elem ent and a base of the cavity and arranged to bear movem ent of the intermediate m oveable element along the second axis. The second bearing of the haptic button assembly may comprise at least one ram p and at least one ball bearing arranged to roll along the at least one ramp. The at least one ram p may be provided by an inclined surface of the intermediate moveable elem ent and/or a base surface of the cavity. The at least one ram p may be a localised ramp provided on a surface of the intermediate moveable elem ent and/or on the base surface of the cavity.

Turning now to Figure 7, this shows a cross-sectional view of a seventh arrangement of a haptic button assembly 700. The haptic button assem bly 700 is sim ilar to the arrangement shown in Figure 1 and therefore, for the sake of conciseness, like features are not described. I n haptic button assem bly 700, button 702 is wedge-shaped and interm ediate moveable element 710 is also wedge-shaped. The button 702 and interm ediate m oveable element 71 0 are arranged within the cavity such that a wider end of the wedge-shaped button 702 is in proxim ity to a narrower end of the wedge-shaped moveable element 710, and a narrower end of the wedge-shaped button 702 is in proxim ity to a wider end of the wedge-shaped moveable element 710. I n Figure 1 , movement of the intermediate m oveable elem ent 710 towards/into the further cavity 1 12a caused the button 102 to be pushed upwards in the cavity 1 12 such that the button 102 may protrude from the housing 108. I n contrast, the haptic button assembly causes the button 702 to m ove downwards, i.e. further down into the cavity when the moveable element 710 moves into/towards the further cavity. This is achieved by changing (reversing) the direction of the inclined surfaces relative to the arrangement of Figure 1 . Specifically, surface 734 of the button 702 and surface 736 of the interm ediate m oveable elem ent 710 are inclined in the opposite direction to surfaces 134 and 136 of Figure 1 . Thus, movem ent of the intermediate moveable element 710 towards the further cavity enables the button 702 to drop or move downwards in the cavity (i.e. m ove towards a base of the cavity) . I n this embodiment, the interm ediate m oveable elem ent 710 m ay be considered a‘single wedge’, as only one surface of the element is inclined/sloped.

An advantage of the arrangement of Figure 7 m ay be that the m otion of the button 702 into the cavity is assisted by any pressure that a user applies to the button 702 (rather than resisting the m otion when the button moves upwards) . Furthermore, the effect of the button dropping away from a user’s finger m ay be another type of haptic feedback. It also m eans that if the button is prevented from moving, the wire will not reach very high tensions and so run the risk of being damaged. For example, in Figure 1 , if the button 102 were prevented from moving upwards/vertically/out of the cavity (by e.g. a user pushing down on the button with excessive force) , the SMA actuator wire will not be able to contract even though it is being powered - this may cause the SMA actuator wire to reach a high tension that m ay lead to dam age. Flowever, in Figure 7, if the button 702 were prevented from moving, the interm ediate moveable element 710 is still able to move as the SMA actuator wire contracts, thereby avoiding potential dam age to the wire.

It will be understood that the“reverse wedge” arrangem ent shown in Figure 7 m ay be com bined with any of the techniques described with reference to any of the preceding arrangements of Figures 1 to 6.

Figure 8 shows a cross-sectional view of an eighth arrangem ent of a haptic button assem bly 800. The haptic button assembly 800 is sim ilar to the arrangement shown in Figures 1 and 6 and therefore, for the sake of conciseness, like features are not described. The haptic button assembly comprises a button 802 and an intermediate moveable element 810. The button 802 is similar to button 602 in Figure 6. Button 802 comprises a protrusion 846 which forms the contact point or contact surface of button 802. As per Figure 6, here there is a large gap between the button 802 and protective seal 842, which may enable the protective seal 842 to flex/bend in such a way that the seal does not restrict the motion of the button 802. The button 802 comprises one or more localised ramps along surface 834 (i.e. the surface which comes into contact with the intermediate moveable element 810). Thus, the intermediate moveable element 810 may be considered a‘single wedge’, as only one surface of the element comprises the localised ramps.

The intermediate moveable element 810 may be formed from a sheet of material which may be etched to form one or more localised ramps. The or each localised ramp may be formed by etching a tab-like element in the sheet of material and folding the tab by the required angle and in the required direction to create a ramp. In the illustrated arrangement, the intermediate moveable element 810 comprises two localised ramps 810b, 810c formed from two tabs in the sheet of material, but this is a non-limiting example. Two opposite ends of the sheet of material may be folded in the same direction to form edges 810a and 81 Od of the intermediate moveable element 810. Edge 810a is coupled to the at least one SMA actuator wire and, if present, may be coupled to a return spring (or similar component). Edge 810d may, in combination with endstop 814, function to limit the range of motion of the intermediate moveable element 810. The button 802 and intermediate moveable element 810 may comprise the same number of localised ramps. The localised ramps of the button 802 and intermediate moveable element 810 may be co-located in pairs. In other words, a localised ramp of the button may be in close proximity to a corresponding localised ramp of the intermediate moveable element 810. The intermediate moveable element 810 may, in embodiments, be formed from a thin sheet of metal which may be relatively rigid (such that, in use, the localised ramps do not flex or bend). For example, the intermediate moveable element 810 may be formed from a sheet of phosphor bronze. In embodiments, the tab-like elements may be formed by plastic deformation of the sheet of material into a well or pocket, to thereby improve the rigidity of the sheet of metal which forms the intermediate moveable element. I n em bodim ents, rib-like features m ay be provided on the interm ediate m oveable element 810 to further stiffen the metal sheet where required.

The haptic button assem bly 800 may comprise a first bearing 830 between the button 802 and the interm ediate moveable element 810. The first bearing 830 m ay com prise one or more ball bearings 128 that are provided between surface 834 of the button and surface 836 of the interm ediate moveable element. At least one ball bearing 128 may be provided between the or each pair of localised ramps. The first bearing 830 m ay com prise one or more localised ramps and one or more ball bearings. It will be understood that more than one ball bearing 128 may be provided between each pair of localised ramps. For example, in em bodiments there m ay be three ball bearings on each localised ram p.

The haptic button assem bly 800 m ay comprise a second bearing 832 between the intermediate moveable elem ent 810 and a surface of the housing/cavity. The second bearing 832 m ay com prise one or more ball bearings provided between surface 838 of the interm ediate moveable element and surface 840 of the housing (i.e. a surface of the cavity) , which m ay facilitate the lateral movement of the m oveable element.

The button 802 may com prise a clearance nick or cut 838 at a corner of the button which interacts with edge 81 Od of the interm ediate moveable elem ent 810. The clearance cut 838 m ay be provided so that edge 81 Od m ay be able move freely when the intermediate m oveable element 810 is actuated.

The overall height of the intermediate moveable elem ent 810 m ay be sim ilar to the height of the moveable elem ent in, for example Figure 6, or may be lower. Furthermore, less m aterial may be used to form the interm ediate moveable element 810 compared to, for example, Figure 6. Therefore, the arrangement of Figure 8 may advantageously enable a lower height /smaller size haptic button assembly to be provided and/or m ay provide a lower cost assembly (as less material is used) .

Figure 9A shows a cross-sectional view of a ninth arrangem ent of a haptic button assem bly 900. The haptic button assembly 900 is sim ilar to the arrangement shown in Figure 1 and therefore, for the sake of conciseness, like features are not described. Button 902 of the haptic button assembly 900 m ay comprise a lip 916 that protrudes from a side or along at least a part of the button 902 (providing a‘local’ endstop) . The lip 91 6 m ay be provided all the way around the button if the lip also acts as a sealing m echanism . The housing 904 may comprise a corresponding ledge or groove 914, and the lip 916 of the button m ay engage with the ledge 914 of the housing 904. The ledge 914 m ay, for exam ple, restrict the movement of the button 902 into the cavity of the housing 904. The lip 916 therefore functions as an endstop to restrict the motion of the button 902 in one direction. I f the button 902 is pressed with excessive force, the lip 916 comes into contact with the ledge 914, and the force is transm itted into the housing 904 through this contact, instead of passing through the bearings which could potentially cause damage to the bearings. Furtherm ore, the lip 916 may perform a sealing function when the button is pressed. For exam ple, if the lip 916 of the button 902 has the form of an O-ring, the lip 916 may provide sealing of the assem bly 900 against water and dust ingress when the button is in its equilibrium position.

Figure 10A shows a cross-sectional view of a tenth arrangem ent of a haptic button assembly 1000, and Figure 1 0B shows a zoomed-in view of a portion on the tenth arrangement. Generally speaking, it m ay be useful to constrain the motion of the button within the cavity of a haptic button assem bly such that it only m oves up and down within the cavity (i.e. along a first axis A) and not side- to-side/laterally ( i.e. not along a second axis B) . I n embodiments, a bearing may be provided between the button and the cavity/housing to restrict the m otion along the second axis B. Alternatively, if the assem bly comprises one or more flexures, the flexures m ay restrict the m otion of the button along the second axis B. The intermediate moveable element m oves along the second axis B and may in some em bodim ents also m ove along the first axis A. The motion of the button along axis B m ay be restricted in a variety of ways. For exam ple, a surface of the button and a surface of the housing ( i.e. an inner surface of the cavity) may be in contact such that they operate as a plain bearing. Alternatively, one or more ball bearings may be provided between the button and the cavity, and/or one or m ore flexures may be provided between the button and the cavity/housing to constrain lateral motion of the button ( i.e. motion along axis A) . I n embodim ents, the protective mem brane (described above) may act as a flexure that constrains the lateral motion of the button. The protective m em brane/flexure is stiff and able to absorb the m oment induced in it by the interm ediate moveable element. The haptic button assembly 1000 is similar to the arrangement shown in Figure 8 and therefore, for the sake of conciseness, like features are not described. Haptic button assembly 1000 comprises at least one ball bearing 1028 provided between button 1002 and housing 1004 (i.e. an inner surface of the cavity of the housing), which may accept/absorb any sideways/lateral force that is transferred from intermediate moveable element 1012tothebutton 1002. The ball bearing(s) between the button 1002 and the housing 1004 may be sufficient to restrict motion of the button 1002 along axis B.

Additionally or alternatively, the haptic button assembly 1000 may comprise means for restricting the amount of lateral motion of intermediate moveable element 1012. By restricting the extent of lateral motion that the intermediate moveable element 1012 can undergo (i.e. motion along axis B), the lateral motion of the button 1002 may also be restricted. The means for restricting the lateral motion of intermediate moveable element 1012 may be or comprise a spacing component 1050, provided between the intermediate moveable element 1012 and the housing 1004. The spacing component 1050 may be formed of a sheet or layer of material. The spacing component 1050 may comprise one or more holes 1054. Each hole 1054 may be a through-hole or a blind hole. The intermediate moveable element 1012 may comprise one or more localised ramps 1056, which correspond to the localised ramp(s) of the button 1002, as described above with reference to Figure 8. The or each localised ramp 1056 may be arranged to sit within (locate within) the holes 1054 in the spacing component 1050. The spacing component 1050 may therefore restrict the motion of the intermediate moveable element 1012 because the hole 1054 constrains the motion of the localised ramp 1056 that is located in the hole.

Where the intermediate moveable element 1012 comprises multiple localised ramps 1056, at least one ball bearing may be provided between the ramps 1056 to reduce friction between the unramped portions of the intermediate movable element 1012 and the spacing component 1050. In the embodiment shown in Figure 10B, the intermediate moveable element 1012 comprises two localised ramps 1056. Ball bearing 1028’ is provided between the unramped portion of the intermediate movable element 1012 and the housing 1004. Ball bearing 1028’ is located in a hole 1054 in the spacing component 1050 to keep this ball in the correct location. As mentioned earlier with reference to Figure 1 , each haptic button assembly may com prise a sensor to detect when a user is pressing the button. Figures 10A and 10B show a sensor 1052 for detecting when a user is pressing the button 1002. The sensor 1052 is provided between the spacing com ponent 1050 and the housing 1004. The sensor 1052 m ay be a contact sensor and may comprise a deformable surface 1058. Thus, when button 1002 is pressed, the downward force on the button is transferred to the intermediate m oveable elem ent 1012 and the spacing component 1050, which causes the deform able surface 1058 to deform and make an electrical contact with conductive surface 1060 of the sensor 1052. This type of sensor may be provided in any of the haptic button assemblies described above with reference to Figures 1 to 9C. An example mechanism to detect a press of a button is described in GB2551657, which is hereby incorporated by reference in its entirety.

Figure 16 shows a cross-sectional view of a thirteenth haptic button assembly 1600. The haptic button assem bly 1600 comprises a button 1602 and a housing 1604. I n this case, the button 1602 is part of the housing 1604. The housing 1604 may comprise at least a portion which is flexible and pressable and therefore provides the button 1602 of the assem bly 1600. Advantageously, by form ing the button 1602 as part of the housing 1 604, there is no gap between the button and the housing and therefore, a sealing m echanism is not required. This may also provide a cheaper and sim pler assem bly to manufacture.

The assem bly 1600 com prises an interm ediate m oveable element 1606, which takes the form of a lever arm . The interm ediate m oveable elem ent 1606 may be coupled to a first SMA actuator wire 1608 to m ove the lever arm in a first direction, and may be coupled to a second SMA actuator wire 1610 to m ove the lever arm in a second direction. Alternatively, one of the actuator wires 1 608, 1610 m ay be replaced by a return spring or sim ilar resilient element. Further alternatively, the flexible portion of the housing 1604 may itself be stiff enough to provide a return force - in this case, a return spring or second SMA actuator wire may not be required. Movement of the interm ediate m oveable elem ent 1606 may cause the button portion 1 602 of the housing 1604 to flex. Thus, the housing 1604 may be formed of a flexible m aterial such that when the intermediate moveable elem ent 1606 is actuated, the button portion 1602 flexes and provides a haptic sensation. Alternatively, the housing 1604 m ay be form ed of a m aterial which is not generally flexible unless it is provided as a thin layer. Thus, the button 1602 may be thinner than the rest of the housing 1604 such that the button portion is flexible. For exam ple, at least the button 1604 m ay be formed from a thin layer of m etal, e.g. a 50pm thick layer of alum inium .

Figure 16A shows a cross-sectional view of a further haptic button assem bly 1650 com prising a lever arm 1656. The haptic button assembly 1650 com prises a button or button portion 1652 and a housing 1654. I n this case, the button 1652 is part of the housing 1654. The housing 1604 may comprise at least a portion which is flexible and pressable and therefore provides the button 1652 of the assem bly 1650. Advantageously, by form ing the button 1652 as part of the housing 1654, there is no gap between the button and the housing and therefore, a sealing m echanism is not required. This may also provide a cheaper and simpler assembly to manufacture. Flowever, it will be understood that the haptic button assembly 1650 m ay be arranged such that there is a gap between the button 1652 and the housing 1654 (e.g. as shown in Figure 24) , or such that there is a separate button com ponent which is not part of the housing (e.g. as shown in Figure 1 ) .

The assem bly 1650 comprises an interm ediate moveable elem ent 1656, which takes the form of a lever arm . The interm ediate m oveable elem ent 1656 may be coupled to at least one SMA actuator wire 1658 to m ove the lever arm in a first direction. The intermediate m oveable element 1656 m oves about pivot 1660. I n em bodiments, the lever arm 1 656 may be coupled to another SMA actuator wire (not shown) to move the lever arm in a second direction. Alternatively, one of the actuator wires may be replaced by a return spring or sim ilar resilient element. Further alternatively, the flexible portion of the housing 1654 m ay itself be stiff enough to provide a return force - in this case, a return spring or second SMA actuator wire may not be required. I n som e cases, the force of a user’s finger may be sufficient to provide a return force, such that an SMA actuator wire or return spring is not required to return the button to an equilibrium position. Movement of the intermediate m oveable elem ent 1656 m ay cause the button portion 1652 of the housing 1654 to flex. Thus, the housing 1654 m ay be form ed of a flexible m aterial such that when the interm ediate moveable elem ent 1656 is actuated, the button portion 1652 flexes and provides a haptic sensation. Alternatively, the housing 1654 may be formed of a material which is not generally flexible unless it is provided as a thin layer. Thus, the button 1652 m ay be thinner than the rest of the housing 1654 such that the button portion is flexible. For example, at least the button 1654 may be formed from a locally-thinned section of the housing, e.g. a 30pm thick layer of alum inium .

Thus, in em bodim ents, the intermediate moveable elem ent m ay be a lever arm arranged to drive m ovem ent of the button along the first axis.

Figure 17 shows a cross-sectional view of a fourteenth haptic button assembly 1700. As m entioned above with respect to Figure 1 , each haptic button assembly described here m ay comprise a sensor in the housing below the button and interm ediate m oveable element. The sensor m ay be a force sensor, for example. Generally speaking, the sensor m ay be any suitable sensor or mechanism for detecting depression of the button by a user (i.e. detecting that a user has pressed the button) . The movement of the button into the cavity (as a result of the user pressing the button) causes a force to be exerted on the sensor. The sensor m ay be coupled to control circuitry, and the sensor may be configured to com m unicate with the control circuity when the force on the sensor changes, or when the force on the sensor has been applied for a m inim um duration. The detection by the sensor of a user pressing the button causes the haptic feedback to be generated and applied by haptic button assem bly. The haptic button assembly 1700 shown in Figure 17 comprises an alternative arrangem ent of the sensor, which may advantageously reduce the overall size/height of the assem bly.

The haptic button assembly comprises a button 1702 and an intermediate moveable element 1706, both provided in housing 1704. The assembly com prises at least one SMA actuator wire 1708, which is coupled at one end to the intermediate m oveable elem ent 1706, and another end to the housing 1704. A resilient biasing elem ent 1710 may be coupled to the intermediate m oveable element 1706 and the housing 1704. The biasing element 171 0 may be a weak spring, and m ay be weaker than a return spring because the force applied to the button by a user may be advantageously used to stretch out the SMA actuator wire 1708. Thus, in em bodiments, the force applied by a user can be utilised to provide the‘return force’ against the SMA actuator wire, such that only a weak spring is required (or the spring may be rem oved com pletely) . When a press of button 1702 is detected, the SMA actuator wire 1 708 is driven, which causes the wire 1708 to contract. The contraction of the wire 1708 causes the intermediate moveable elem ents 1706 to m ove into the further cavity of the housing (as described with reference to e.g. Figure 1 ) , which causes the button 1702 to move upwards (i.e. out of the cavity) . The biasing elem ent 1 710 m ay enable the button 1702 to return to the equilibrium state as the SMA actuator wire 1708 cools.

The haptic button assem bly 1700 m ay com prise an endstop 1 712 in the cavity. The endstop 1712 m ay be form ed as part of the housing 1704 or cavity, or may be a separate element that is provided in the cavity. The endstop 1712 may be provided at a location in the cavity to restrict m ovem ent of the intermediate moveable element 1706. As explained above with reference to Figure 1 , if SMA actuator wire is stretched too far (i.e. a certain tension is exceeded) , the SMA actuator wire may weaken or becom e damaged, or even break. The force of the biasing elem ent 1710 on the interm ediate m oveable element 1706 may cause the SMA actuator wire 1 708 to becom e overstretched. Therefore, the endstop 1712 may restrict the movement of the intermediate moveable elem ent 1706 so that the at least one SMA actuator wire 1708 does not overstretch. Sim ilarly, a force applied to the button 1702 by a user’s finger may cause the wire to overstretch if there is no endstop, because when the button is pushed downwards (i.e. into the cavity) , the intermediate moveable element 1706 moves towards the left in the Figure, such that the SMA actuator wire 1708 is stretched.

The fact that the interm ediate m oveable elem ent 1706 m oves towards the endstop 1712 when the button is pressed 1702 is used to provide the alternative arrangement of the sensor. I n assembly 1 700, a sensor 1714 is provided on the endstop 1712. The sensor 1712 m ay be a contact sensor or a force sensor, and a conductive element 171 6 may be provided on the interm ediate m oveable element 1706. When the button 1702 is pressed, the downward force on the button causes the interm ediate moveable elem ent 1706 to m ove towards, and make contact with, the endstop 1712. When the interm ediate m oveable elem ent 1706 and endstop 1712 are in contact, the contact sensor 1712 and the conductive element 1716 m ake an electrical connection , which indicates that the button 1702 has been pressed and that haptic feedback should be delivered.

Figures 18A and 18B respectively show cross-sectional views of a fifteenth haptic button assem bly 1800 in an equilibrium state and in an activated state. The haptic button assem bly 1800 comprises a button 1802, a housing 1804 and an interm ediate moveable element 1806. The intermediate m oveable elem ent 1806 is a flat flexure, which is attached at one end 1808 to the housing 1804. The other end 1810 of the flexure 1 806 is not attached to the housing 1804 and is free to translate along the flexure’s longitudinal direction. The button 1802 is coupled to (e.g. attached to) the flexure 1806. The assembly 1800 comprises an SMA actuator wire 1812 which is coupled at one end to the free end 1810 of f lexure 1806 and at another end to the housing 1804. The SMA actuator wire 1812 m ay be arranged such that when the wire contracts (on heating) , the wire forces an out-of-plane deflection of the flexure 1806, which forces the button 1802 to move upwards, i.e. to move out of the cavity of the housing 1 804, as shown in Figure 18B. When the wire is cooled, the flexure 1806 returns to its equilibrium state (i.e. is substantially flat) , which causes the button 1802 to move downwards within the cavity of the housing 1 804, as shown in Figure 18A. Advantageously, the flexure 1806 m eans that an additional bias spring is not required to oppose the effect of the SMA actuator wire 1 812. Thus, the assem bly m ay be sim pler and cheaper to m anufacture and operate. Furthermore, com pared to the em bodiments which com prise a wedge-shaped button and/or interm ediate moveable element (e.g. Figures 1 to 3) , the overall profile or size of the haptic button assem bly 1800 may be reduced by using a flexure as the intermediate moveable element.

I n embodim ents, the assembly 1800 may be adapted to allow vertically ‘downward’ m otion of the button 1802, i.e. to allow the button 1802 to move into the cavity. (As m entioned earlier, haptic feedback may be provided by the button moving upwards into a user’s finger, or by the button dropping away from the user’s finger) . I n this case, the assembly 1800 may comprise a well or further cavity in the housing 1804 below the flexure 1806. Thus, the flexure 1806 m ay be arranged to buckle or bend into the well/further cavity, and doing so causes the button 1802 to m ove further into the cavity.

Figure 19 shows a plan view of a fifteenth haptic button assembly 1900. (The button has been removed from the illustration for the sake of clarity) . Flere, intermediate moveable elem ent 1906 is able to rotate within housing 1904, rather than merely translate. As a result, the button (not shown) may also be able to rotate or tilt. This m ay be achieved by providing a series of ramps 1908 which are arranged such that the gradient of the ramps increases in the sam e direction along a helical (or substantially helical) path. I n this example, the assembly 1900 comprises four ram ps and ball bearings roll along the ramps in the same direction when the interm ediate m oveable element 1 906 is actuated (by SMA actuator wires 1902) such that the interm ediate moveable element rotates. I n some cases, a bearing layer may be provided between the button and the interm ediate moveable element to prevent the button from rotating - the bearing layer m ay de-couple the button from the rotating interm ediate moveable elem ent. Suitable mechanism s m ay be used to keep the ball bearings in place, e.g. the bearings may be located in tracks or grooves to constrain their m otion.

I n embodim ents, a single SMA actuator wire may be sufficient to drive motion of the intermediate m oveable element 1906. For example, as per Figure 17, the force of a user’s finger m ay be sufficient to provide a return force, such that an SMA actuator wire is not required to return the button to an equilibrium position. Alternatively, to maxim ise the force used to move the button, m ultiple SMA actuator wires m ay be used (e.g. m ultiple wires arranged to be mechanically in parallel) .

Turning to Figure 33A shows a plan view of a button of a further haptic button assem bly 3300, Figure 33B shows a plan view of the further haptic button assembly 3300 and Figure 33C shows a cross-sectional view of the further haptic button assem bly 3300. The haptic button assembly 3300 comprises a button 3302 which is able to rotate within housing 3304. The haptic button assem bly 3300 comprises an interm ediate moveable elem ent 3308 and at least one SMA actuator wire to m ove the intermediate moveable elem ent in one direction and a resilient element (e.g. a spring) to move the interm ediate m oveable elem ent in the opposite direction. I n the illustrated arrangement, the haptic button assem bly 3300 com prises two SMA actuator wires 3310a, 3310b which may be arranged as opposing wires (i.e. one of the SMA actuator wires acts as the resilient element that provides the restoring force) . I n other words, SMA actuator wire 3310a m ay move the interm ediate m oveable element 3308 in one direction, and SMA actuator wire 3310b may move the interm ediate m oveable elem ent 3308 in an opposite direction. The haptic button assembly 3300 comprises a central shaft or bearing 3306. The central bearing 3306 is coupled to the interm ediate m oveable element 3308 and to the button 3302. Movement of the interm ediate m oveable element 3308 in one direction causes the central bearing 3306 to rotate in one direction, which thereby causes the button 3302 to rotate relative to the housing 3304. Movem ent of the intermediate m oveable elem ent 3308 in the opposite direction causes the button 3302 to rotate in an opposite sense. The haptic button assembly 3300 may comprise a seal 3312, such as a flexible sealing membrane, to prevent any fluid and/or dirt which enters the haptic assem bly through the gap between the housing 3304 and the button 3302 from travelling any further into the haptic assem bly, or into the device in which the haptic assembly is incorporated. The haptic button assembly 3300 m ay com prise one or more bearings (e.g. ball bearings) 3314 which are provided between the housing 3304 and the intermediate m oveable component 3308. The ball bearings 3314 may provide a low friction surface on which the interm ediate moveable component 3308 is able to move.

Accordingly, the present techniques provide a haptic button assem bly comprising: a housing com prising a cavity; a button provided within the cavity and moveable along a first axis within the cavity; at least one interm ediate moveable elem ent provided within the cavity in contact with the button and rotatable about a second axis that is parallel to the first axis, and arranged to drive movement of the button along the first axis; and at least one shape m em ory alloy (SMA) actuator wire coupled to the at least one interm ediate m oveable element and arranged to, on contraction, rotate the interm ediate m oveable element about the second axis.

Figure 20 shows a cross-sectional view of a sixteenth haptic button assembly 2000. I n haptic button assembly 2000, button 2002 is chevron-shaped, i.e. the button 2002 comprises two slopes which are inclined in opposite directions at equal angles. The assem bly 2000 com prises two interm ediate m oveable elements 2004 and 2006 which are wedge-shaped. I n this embodim ent, the intermediate m oveable element m ay be considered to be or com prise two ‘opposing wedges’, as the two elem ents are wedges having slopes inclined in opposite directions. The gradient of the wedge-shaped moveable element 2004 corresponds to one slope of the chevron-shaped button 2002, and the gradient of the wedge-shaped moveable elem ent 2006 corresponds to the other slope of the chevron-shaped button 2002. I n em bodim ents, the angles or gradients of the slopes of the two m oveable elem ents 2004, 2006 are the same, to prevent the button 2002 from tilting when the SMA actuator wire 2008 is driven. However, in some embodim ents a tilt may be required and may be achieved by having differing slopes. It will be understood that the direction of the gradients or slopes of the two wedge-shaped m oveable elements may be reversed without loss of functionality (though the slopes of the button 2002 will also need to be reversed) . The two interm ediate m oveable elements 2004, 2006 are coupled together via an SMA actuator wire 2008.

A return spring 2010 is coupled to m oveable elem ent 2004 and the housing, and another return spring 2012 is coupled to moveable element 2006 and the housing. When a press of button 2002 is detected, the SMA actuator wire 2008 is driven, which causes the wire 2008 to contract. The contraction of the wire 2008 causes the intermediate moveable elem ents 2004 and 2006 to move towards each other, which causes the button 2002 to m ove upwards (i.e. out of the cavity) . The return springs 2010, 2012 m ay enable the button 2002 to return to the equilibrium state as the SMA actuator wire 2008 cools and a force is applied. I n em bodiments, the return springs m ay not be required as the force of the user’s finger on the button 2002 m ay be sufficient to return the button to the equilibrium state after the haptic sensation has been provided. The assembly may comprise two endstops 2010, 2012 to restrict the motion of the interm ediate m oveable elements 2004, 2006, respectively.

Thus, from the above-described embodim ents and arrangements, it will be understood that the interm ediate m oveable elem ent which causes the button to move‘vertically’ may be a single wedge-shaped elem ent (or elem ent comprising localised wedges/ramps) , m ay comprise two wedge-shaped elem ents (or elements com prising localised wedges/ram ps) , or may comprise opposing wedges. Alternatively, the intermediate moveable element may be a flexure (see e.g. Figure 18A) , or a lever arm (see e.g. Figure 16) . The interm ediate moveable element be arranged to drive m otion of the button (or button portion of the housing) into the housing or out of the housing (i.e. vertically ‘downwards’ or ‘upwards’) .

Sea li ng Mechan ism s

The haptic button assem blies may com prise a protective seal to prevent ingress of fluids and/or dirt/dust into the assem bly. The haptic button assem blies described herein m ay be incorporated into a variety of different devices, including smartphones and wearables. Smartphone and wearable devices m ay be required to meet a particular waterproofing standard. For example, such devices may be required to meet the standard necessary for an I ngress Protection ( I P) Rating of 67 or 68. An I P rating of 67 indicates the device has som e sort of protection that results in the device being dust tight and being waterproof when the device is im m ersed in up to 1 m of water, while an I P rating of 68 indicates the device has some sort of protection that results in the device being dust tight and being waterproof when the device is continuously im m ersed in more than 1 m of water. Accordingly, if the haptic button assem blies are to be incorporated into a smartphone or wearable device with an I P rating of 67 or 68, the haptic button assembly also needs to be water and dust proof to the same standard.

As m entioned above, the haptic button assemblies described herein may be more readily, and m ore efficiently, sealed com pared to haptic button assem blies in which the button m oves laterally. There are a num ber of different possible sealing mechanism s, som e of which are described with reference to Figures 5, 6, 9A, 1 1 A-C, 12A-C, 13A- B, and 14 to 1 6. Before these specific sealing m echanisms are described, some general concepts associated with the sealing mechanism are described.

Generally speaking, the sealing mechanism may be non-structural ( i.e. it does not provide any intentional force on the button of the haptic button assembly) , or may be structural (i.e. it provides some force on the haptic button assembly to, for example, guide the m ovement of the button) .

I n cases where the sealing m echanism is substantially non-structural, additional bearings may be required to constrain the lateral (sideways) motion of the button within the cavity. For exam ple, a rolling bearing may be provided between the button and the cavity, on the sam e side of the button to which the SMA actuator wire is connected, such that when the SMA actuator wire contracts, the bearing prevents the button from m oving sideways or from tilting within the cavity (i.e. constrains the m otion of the button) . Alternatively, when the sealing mechanism is non-structural, no rolling bearing may be provided between the button and the cavity - in this case, the direct contact of the button with the cavity is a high friction, low efficiency sliding contact which acts to constrain the motion of the button. I n som e em bodiments, the sealing m echanism may be non- structural, and may be combined with a flexure to guide the m otion of the button ‘vertically’ in the cavity. I n this case, a rolling bearing between the cavity and button may not be required.

I n cases where the sealing mechanism is structural, the sealing m echanism provides both a sealing function and a bearing function, i.e. the sealing m echanism is able to guide the motion of the button within the cavity. I n this case, an additional bearing between the cavity and the button may not be required.

Alternatively, the sealing mechanism m ay be provided by housing itself - the button may be an integral part of the housing such that no additional sealing mechanism is required. This may be achieved by m aking the button part of the housing thinner than the rest of the housing, such that it is flexible. However, in this case, a further button that a user may press/ contact m ay be provided externally in order to protect the thin integrally-form ed button of the housing.

Regardless of whether the sealing mechanism is structural or non- structural, the sealing m echanism may function at all times or m ay only function when the button of the haptic button assembly is not in m otion.

Turning now to Figure 5, this shows a cross-sectional view of a fifth arrangement of a haptic button assem bly 500 com prising a sealing mechanism which is structural and functions at all times (i.e. both when the button is in m otion and is not in m otion) . The haptic button assembly 500 is sim ilar to the arrangement shown in Figure 4 and therefore, for the sake of conciseness, like features are not described. Compared to assem bly 400, haptic button assem bly 500 comprises a protective seal 542 (also referred to as a protective m em brane, film or cover) . The protective seal 542 m ay be a waterproofing and/or dust proofing seal to prevent water and/or dust ingress into the cavity. Generally speaking, a sm all gap m ay be provided between the button and the cavity, to avoid contact between a surface of the button with a surface of the cavity, which may increase friction and affect the perform ance of the assembly. However, the gap m ay then enable liquid and/or dirt to enter the cavity of the assembly, where it could affect the perform ance of the assembly. For exam ple, dirt could inhibit the m ovem ent of button, the bearings and/or the intermediate m oveable elem ent, while liquid could interfere with any electronic components/circuitry. Thus, the protective seal 542 may advantageously enable a waterproof/dustproof haptic button assem bly to be provided. The protective seal 542 may be provided across the entire area of the external surface of the housing (i.e. surface 108 in Figure 1 ) and the button (as shown in Figure 5) , or may be provided across the button and at least part of the area of this external surface. I n either case, the protective seal 542 may be form ed of a flexible m aterial, an elastic m aterial, or a m aterial which exhibits some flexibility/elasticity when it is provided as a thin layer, which enables the protective seal 542 to flex as the button m oves. ( I f the protective seal 542 were not made of a flexible/elastic m aterial, the protective seal may inhibit or lim it the m otion of the button, which may affect the haptic sensation delivered by the assembly) . The protective seal 542 may be formed of an elastom er, hard plastic, a composite material, a thin m etallic layer e.g. a thin alum inium or a thin stainless steel layer, for example. It will be understood that is a non-exhaustive, non-lim iting example list of m aterials. The protective seal 542 m ay be attached to the housing 504 by any suitable technique, such as adhesive, welding, or otherwise.

Optionally, when a haptic button assem bly comprises a protective seal, the housing of the assem bly m ay be modified to accom m odate the protective seal. As shown in Figure 5, the housing 504 com prises a cut-out or ledge 544 in the external surface of the housing, provided around the button. The cut-out or ledge 544 provides clearance or space between the button and the housing. The protective seal 542 m ay be able to bend/flex into the ledge 544 when the button moves in the cavity, such that a portion of the protective seal 542 which is able to move when the button m oves is increased. This m ay advantageously reduce the extent to which the protective seal 542 resists the m otion of the button.

It will be understood that the protective seal, and the optional cut-out, may be incorporated into any of the haptic button assemblies described herein.

Figure 6 shows a cross-sectional view of a sixth arrangem ent of a haptic button assem bly 600 com prising a sealing mechanism which is structural and functions at all tim es (i.e. both when the button is in motion and is not in m otion) . This m ay be considered to include a m ore extreme version of the cut-out shown in Figure 5. The haptic button assembly 600 is sim ilar to the arrangem ents shown in Figures 4 and 5 and therefore, for the sake of conciseness, like features are not described. Compared to assembly 500, haptic button assembly 600 com prises a reduced size (i.e. reduced height) button 602. The button 602 com prises a protrusion 646 which form s the contact point or contact surface of button 602. Thus, the area or size of the contact surface of button 602 is reduced relative to Figure 5. By reducing the height of the button 602 and providing the protrusion 646 as the contact surface, a large gap 644 is provided between the button 602 and protective seal 642. Accordingly, the extent to which the protective seal 642 resists the m otion of the button is further reduced. As explained above, the protective seal 642 may be form ed of an elastomer, hard plastic, a composite material, a thin m etallic layer e.g. a thin alum inium or a thin stainless steel layer, for example. It will be understood that is a non-exhaustive, non-lim iting example list of materials.

Returning briefly to Figure 8, in this em bodiment, the protective seal 842 acts as a flexure to guide the button to m ove in the first direction (vertically) . Thus, the sealing m echanism is structural and functions at all times (i.e. both when the button is in m otion and is not in m otion) .

Figures 1 1 A and 1 1 B respectively show a plan view and a cross-sectional view of a mechanism 1 100 for sealing a haptic button assembly, and Figure 1 1 C shows a cross-sectional view of a m odified m echanism 1 100’. The sealing mechanism shown in Figures 1 1 A to 1 1 C is structural and functions at all times (i.e. both when the button is in motion and is not in motion) . The sealing mechanism s 1 1 00, 1 1 00’ may provide an efficient mechanism for water- and dust proofing a haptic button assembly. The sealing m echanism 1 100 comprises a flexible skin or m em brane 1 102 and an external button 1 104. The flexible skin 1 102 may cover the cavity in the housing which houses the button 1 1 06, intermediate m oveable elem ent 1 108 and at least one SMA actuator wire 1 1 10, as described earlier, such that the flexible skin 1 102 effectively covers the cavity. The flexible skin 1 102 m ay be considered an impermeable barrier between the external environm ent and the cavity of the housing of a haptic button assem bly (i.e. the internal environm ent) . Thus, the term‘external button’ is used to mean that button 1 104 is provided at least partly outside of the cavity, i.e. at least partly on the external side of the barrier form ed by the flexible skin 1 102. The external button 1 104 m ay cooperate with the ( internal) button of the haptic button assemblies described earlier.

Figure 1 1 B shows an example internal button 1 106, which is provided on the internal side of the barrier formed by the flexible skin 1 102. The external button 1 104 m ay com prise a stem 1 1 12 that is arranged to cooperate with the internal button 1106. In the mechanism 1100 shown in Figure 11 B, the stem 1112 contacts the flexible skin 1102. When the external button 1104 is pressed by a user, the stem 1112 exerts a force on the flexible skin 1102, which causes the flexible skin 1102 to flex/bend. The force applied to the button 1104 is transferred via the stem 1112 to the internal button 1106, and a press of the internal button 1106 is detected as described earlier (e.g. via a sensor located within the cavity) .

Figure 11 C shows a sealing mechanism 1100’ having a flexible skin 1102’ which comprises a cut-out (not visible) to reduce the overall stiffness of the mechanism in the direction of motion. Thus, the stem 1112 of external button 1104 at least partly extends through the cut-out in the flexible skin 1102’. Thus, the stem 1112 may be able to directly contact the internal button 1106.

The flexible skin 1102, 1102’ may be made from any suitable material having an appropriate stiffness in the direction of motion. The flexible skin 1102, 1102’ is preferably an impermeable material, i.e. impermeable to liquids and dirt. The flexible skin 1102, 1102’ may be formed from a thin film polymer, for example. The flexible skin 1102, 1102’ may be formed of a material which is impermeable to liquid, such that the sealing mechanism protects the haptic button assembly against fluid ingress. The flexible skin may be, for example, a thin silicone film. The sealing mechanism 1100, 1100’ may comprise an adhesive or an adhesive element to fixedly attach the flexible skin 1102, 1102’ to the housing of the assembly. The flexible skin (also referred to as a thin membrane) may deflect sufficiently to enable the button 1106 to move within the haptic button assembly. The thin membrane 1102,1102’ may provide a return force to return the button 1106 to its default, rest state when the intermediate moveable element 1108 is not being actuated to deliver a haptic sensation.

Advantageously, the sealing mechanisms 1100, 1100’ secure the haptic button assembly against ingress of liquid and/or dirt or dust. The flexible skin may enable a water and dust proof haptic button assembly to be provided along a curved edge of a device. The sealing mechanisms 1100, 1100’ decouple the sealing mechanism from the button/external button - this may be advantageous as the external button may then be customisable without affecting the sealing mechanism or mechanics of the assembly. For example, the design and texture of the external button m ay be selected/custom ised without im pacting the sealing mechanism .

Figures 12A to 12C show cross-sectional views of three mechanism s for sealing a haptic button assem bly.

Figure 12A shows a portion of a haptic button assem bly 1200 comprising a sealing mechanism which is non-structural and functions only when the button is not in use, because when the button m oves upwards, the seal is broken . Flere, button 1202 of the haptic button assem bly performs two functions - it provides a contact surface which a user presses and it forms part of the sealing mechanism . The haptic button assembly 1200 comprises button 1202, interm ediate m oveable element 1206 and one or more ball bearings 1208, which are provided in a cavity of the housing 1204 of the assembly. The haptic button assembly shown here is sim ilar to that shown in Figure 4 and comprises localised ram ps on both the button 1202 and the moveable elem ent 1206. At least one ball bearing 1208 is provided between pairs of localised ram ps, as shown. The button 1202 com prises a lip 1212 that extends all the way around the button. The housing 1204 comprises a corresponding ledge or groove 121 0, and the lip 1212 of the button may engage with the ledge 1210 of the housing 1204. The ledge 1210 m ay, for exam ple, restrict the movement of the button 1202 into the cavity of the housing 1204, and thereby providing a sealing effect. The button 1202 m ay be formed of a thick flexible m aterial, such that the button 1202 flexes when the button is pressed and when the interm ediate moveable elem ent 1206 is actuated. The button 1202 may be m oulded from a flexible m aterial. The button 1202 may be form ed of a material which is impermeable to liquid, such that the sealing mechanism protects the haptic button assembly against fluid ingress. The button 1202 m ay be bonded to the housing 1204 - the lip 121 2 m ay be fixedly attached to the ledge 1210 of the housing 1204, thereby providing a seal. The sealing mechanism m ay comprise an adhesive or an adhesive elem ent to fixedly attach the button 1202 to the housing 1204. The button 1202 may deflect sufficiently to enable the button to m ove within the haptic button assembly. The button 1202 m ay provide a return force to return the button to its default, rest state when the intermediate m oveable element 1206 is not being actuated to deliver a haptic sensation.

Figure 12B shows a portion of a haptic button assembly 1220 comprising a sealing mechanism which is non-structural and functions only when the button is not in use, because when the button m oves upwards, the seal is broken . Here, button 1222 of the haptic button assem bly performs two functions - it provides a contact surface which a user presses, and it forms part of the sealing mechanism . The haptic button assembly 1220 comprises button 1222, interm ediate m oveable element 1226 and one or more ball bearings 1228, which are provided in a cavity of the housing 1224 of the assembly. Com pared to Figure 12A, the em bodiment shown in Figure 12B comprises one or more localised ram ps on one surface only, i.e. on the button 1222 or the interm ediate moveable element 1226. I n the arrangement shown in Figure 12B, the intermediate m oveable elem ent 1226 comprises at least one localised ram p. At least one ball bearing 1228 is provided between the ramp of the intermediate moveable element 1226 and the button 1222. The intermediate m oveable element 1226 may comprise one or m ore supports 1234 which extend towards and support the button 1222.

The button 1222 comprises a lip 1232 that extends all the way around the button. The housing 1224 comprises a corresponding ledge or groove 1230, and the lip 1232 of the button may engage with the ledge 1230 of the housing 1224. The ledge 1230 may, for example, restrict the m ovem ent of the button 1222 into the cavity of the housing 1224, and thereby providing a sealing effect. The button 1222 m ay be formed of a thin layer of m aterial, such that the button 1222 flexes when the button is pressed and when the intermediate m oveable elem ent 1226 is actuated. The button 1222 may be moulded from a flexible material, or may be form ed from a thin m etallic film or layer. The button 1222 may be formed of a material which is im permeable to liquid, such that the sealing mechanism protects the haptic button assembly against fluid ingress. The button 1222 may be bonded to the housing 1224 - the lip 1 232 m ay be fixedly attached to the ledge 1230 of the housing 1224, thereby providing a seal. The sealing m echanism m ay comprise an adhesive or an adhesive element to fixedly attach the button 1222 to the housing 1224. The button 1222 m ay deflect sufficiently to enable the button to move within the haptic button assembly. The button 1222 may provide a return force to return the button to its default, rest state when the interm ediate moveable element 1226 is not being actuated to deliver a haptic sensation.

Figure 12C shows a portion of a haptic button assembly 1240 comprising a sealing mechanism which is structural and functions at all tim es (i.e. both when the button is in m otion and is not in motion) . Here, button 1242 of the haptic button assembly performs two functions - it provides a contact surface which a user presses and it forms part of the sealing m echanism . The haptic button assembly 1240 comprises button 1242, interm ediate moveable element 1246 and one or more ball bearings 1248, which are provided in a cavity of the housing 1244 of the assembly. Com pared to Figure 12B, the em bodiment shown in Figure 12C com prises one or m ore localised ramps on one surface only, i.e. on the button 1242 or the intermediate moveable elem ent 1246. I n the arrangem ent shown in Figure 1 2C, the intermediate moveable elem ent 1246 comprises at least one localised ramp. At least one ball bearing 1248 is provided between the ramp of the interm ediate m oveable element 1246 and the button 1242. The button 1242 comprises a lip 1252 that extends all the way around the button. The housing 1244 com prises a corresponding ledge or groove 1250, and the lip 1252 of the button m ay engage with the ledge 1250 of the housing 1244, optionally via an CD- ring 1258. The O- ring 1248 is provided on ledge 1250 of the housing and between the ledge and the lip 1252 of the button. I n em bodim ents, the O-ring 1258 may be replaced by any suitable internal seal, that is able to prevent ingress of dirt and liquid into the housing of the button assembly. For example, internal seal 1 258 could be a flexible Y-shaped seal, flexible C-shaped seal, flexible hollow O-ring, etc. The ledge 1250 may, for example, restrict the m ovem ent of the button 1242 into the cavity of the housing 1244, and thereby providing a sealing effect. The button 1242 (or at least the contactable/pressable portion of the button) may be form ed of a thin layer of material, such that the button 1242 flexes when the button is pressed and when the interm ediate m oveable element 1246 is actuated. The button 1242 m ay be m oulded from a flexible material, or may be formed from a thin metallic film or layer. The button 1242 may be formed of a material which is im perm eable to liquid, such that the sealing mechanism protects the haptic button assembly against fluid ingress. The internal seal 1258 provides an additional barrier against dirt or fluid ingress.

The button assem bly 1240 may comprise a flexure 1252 or sim ilar flexible element provided below the button 1242. The flexure 1252 extends across the cavity of the button assembly below the button 1242, and is attached along its edge(s) to an internal surface of the housing 1244. Thus, flexure 1252 m ay function as a further barrier against dirt or fluid ingress. The flexure 1252 is flexible and is therefore able to flex when the button 1242 m oves in and out of the cavity of the housing 1244. A gap 1260 between the flexure 1252 and the housing 1244 may be provided to provide a space into which the flexure 1252 can flex/bend into when the button 1242 moves upwards. Accordingly, when a flexure 1252 is provided, ball bearing 1248 is provided between the ramp of the intermediate m oveable element 1246 and the flexure 1252 below the button 1242. The button 1242 m ay be bonded to the housing 1 244 - the lip 1252 may be fixedly attached to the ledge 1250 of the housing 1244, thereby providing a seal. The sealing mechanism m ay com prise an adhesive or an adhesive element to fixedly attach the button 1242 to the housing 1244. The button 1242 may deflect sufficiently to enable the button to move within the haptic button assem bly. The button 1242 m ay provide a return force to return the button to its default, rest state when the interm ediate m oveable elem ent 1246 is not being actuated to deliver a haptic sensation.

Figures 13A and 13B show cross-sectional views of two m echanisms for sealing a haptic button assem bly.

Figure 13A shows a portion of a haptic button assem bly 1300 comprising a sealing mechanism which is non-structural and functions at all tim es ( i.e. both when the button is in motion and is not in motion) . The sealing mechanism comprises an O-ring type of seal 1310. The O-ring 131 0 is provided between button 1302 and housing 1304 of the haptic button assembly 1300. The cavity comprises button 1302, interm ediate m oveable elem ent 1306 and one or more ball bearings 1308. The haptic button assembly shown here is sim ilar to that shown in Figure 4 and comprises localised ramps on both the button 1302 and the moveable element 1306. I t will be understood however, that the localised ramp(s) could be m ore generally provided on one or both of the button 1302 and the moveable element 1 306 (see e.g. Figure 1 2C) . At least one ball bearing 1308 is provided between pairs of localised ramps, as shown. The O-ring 1310 constrains the edges of button 1302 within the housing 1304 of the button assem bly. The O-ring 1310 may perm it some movem ent or flexing of the button 1302 in and out of the housing 1304, but prevents or m inim ises lateral (sideways) movement of the button 1302 in the housing. The O-ring 1310 form s a tight seal between the button 1302 and the housing 1304 and thereby protects the haptic button assembly against fluid and dirt ingress. Figure 13B shows a portion of a haptic button assem bly 1350 com prising a sealing mechanism which is structural and functions at all tim es (i.e. both when the button is in m otion and is not in motion) . The sealing mechanism com prises an internal seal 1360. The internal seal 1360 is provided between button 1352 and housing 1354 of the haptic button assem bly 1350. The cavity comprises button 1352, intermediate m oveable element 1356 and one or m ore ball bearings 1358. The haptic button assem bly shown here is sim ilar to that shown in Figure 4 and com prises localised ram ps on both the button 1352 and the moveable element 1356. It will be understood however, that the localised ram p(s) could be more generally provided on one or both of the button 1352 and the m oveable element 1356 (see e.g. Figure 12C) . At least one ball bearing 1358 is provided between pairs of localised ram ps, as shown. The internal seal 1360 is provided across a portion of both the button 1352 and the cavity of the housing 1354. Specifically, the internal seal 1360 is provided where edges of the button 1352 and cavity meet. The internal seal 1360 is provided below the button 1352 and within the cavity such that it cannot be seen from the outside of the button assembly 1350. The internal seal 1360 m ay be ring shaped, for example. The internal seal 1360 may be attached to both the cavity and the button 1352 such that when button 1 352 moves within the cavity, the seal 1 360 prevents or m inim ises ingress of dirt and fluid into the cavity. The internal seal 1360 m ay be form ed of a flexible material to enable the button 1352 to move within the cavity to deliver a haptic sensation.

Figure 14 shows a cross-sectional view of a portion of an eleventh haptic button assem bly 1400 comprising a sealing mechanism which is structural and functions at all tim es (i.e. both when the button is in motion and is not in m otion) . The arrangement is sim ilar to that shown in Figure 12C. Flere, the O-ring type internal seal 1 310 shown in Figure 12C may be replaced with a Y-shaped flexible internal seal, C-shaped seal or hollow O-ring 1410. The haptic button assembly 1400 com prises button 1402, interm ediate moveable element 1406 and one or more ball bearings 1408, which are provided in a cavity of the housing 1404 of the assembly. The haptic button assembly shown here comprises localised ram ps on both the button 1402 and the moveable elem ent 1406. I t will be understood however, that the localised ramp(s) could be more generally provided on one or both of the button 1402 and the moveable elem ent 1406 (see e.g. Figure 12 B) . At least one ball bearing 1408 is provided between pairs of localised ram ps, as shown.

The button 1402 comprises a notch 1414 along one or m ore surfaces of the button which are within the cavity of the housing 1404. The notch 1414 may, for example, be a circumferential notch provided around a surface of the button 1402. The housing 1404 com prises a groove or notch 1412 in one or m ore surfaces of the cavity of the housing. The groove 1412 m ay be, for exam ple, a circumferential groove provided around a surface of the cavity. The Y-shaped flexible internal seal 1410 com prises a portion which extends into the notch 1414 of the button 1402, and a portion which extends into the groove 1412 of the cavity wall. I n the arrangement depicted in Figure 14, the stem portion of the Y-shaped seal is provided in the notch 1414 and the fork or V portion of the Y-shaped seal is provided in the groove 1412. ( It will be understood that, alternatively, the step portion m ay be provided in groove 1412 and the fork portion in the notch 1414) . The stem portion of the Y-shaped seal 1410 m ay be fixedly attached in notch 1414, and each end of the fork portion m ay be fixedly attached in groove 1412. The Y-shaped seal 1410 is formed of a flexible m aterial such that when the button 1402 m oves up and down in the cavity, the seal stretches and continues to prevent ingress of fluid and dirt into the cavity. The Y-shaped seal 1410 m ay also function as a spring or resilient element because when one of the prongs of the fork portion is compressed, the other prong is stretched and provides a return force.

Figure 15 shows a cross-sectional view of a portion of a twelfth haptic button assembly 1500 comprising a sealing mechanism which is structural and functions at all times ( i.e. both when the button is in motion and is not in motion) . The haptic button assem bly 1500 com prises a button 1502 and a housing 1504. I n this case, the button 1502 is part of the housing 1504. The housing 1504 m ay comprise at least a portion which is flexible and pressable and therefore provides the button 1502 of the assem bly 1500. The assembly comprises an intermediate moveable elem ent 1506 and one or more ball bearings 1508. The haptic button assembly com prises localised ram ps on both the button 1502 (i.e. the button portion of the housing 1504) and the m oveable elem ent 1 506. At least one ball bearing 1508 is provided between pairs of localised ram ps, as shown. Advantageously, by form ing the button 1502 as part of the housing 1504, there is no gap between the button and the housing and therefore, a sealing mechanism is not required. This may also provide a cheaper and sim pler assembly to manufacture. The housing 1504 may be formed of a flexible m aterial such that when the interm ediate moveable elem ent 1506 is actuated, the button portion 1502 flexes and provides a haptic sensation . Alternatively, the housing 1504 m ay be form ed of a material which is not generally flexible unless it is provided as a thin layer. Thus, the button 1502 may be thinner than the rest of the housing 1504 such that the button portion is flexible. For exam ple, at least the button 1504 m ay be form ed from a thin layer of metal, e.g. a 50pm thick layer of alum inium , or of stainless steel or of flexible/deform able glass.

Sim ilarly, returning briefly to Figure 1 6, the assembly 1600 comprises a sealing mechanism (i.e. the housing 1604) which is structural and functions at all tim es (i.e. both when the button is in m otion and is not in motion) .

It will be understood that any of the sealing m echanism s described herein may be used with any of the haptic button assemblies described herein. Many of the sealing mechanism s described above are independent of the curvature of surface/ edge of the device into which the haptic button assembly is incorporated.

SMA Actuator W ire Arrangem ents

As m entioned earlier, the haptic button assem blies described with reference to Figures 1 to 8 may com prise an SMA actuator wire and a return spring coupled to the same edge of the intermediate m oveable element, but this is a non-lim iting arrangement and other arrangements are possible. For example, the haptic button assemblies may comprise two or more SMA actuator wires. The SMA actuator wires may all be parallel to each other. The SMA actuator wires may all act in the sam e direction (i.e. they m ay, on contraction, cause the interm ediate moveable elem ent to move in the sam e direction) , which m ay advantageously increase the force applied to the intermediate moveable elem ent. Each wire of the two or m ore SMA actuator wires m ay be driven in unison or may be separately driveable. I f each wire is separately driveable, the force applied to the intermediate m oveable elem ent m ay be variable and thus, the haptic sensation delivered to a user may be varied (e.g. m ay be made softer or stronger) . Alternatively, one or m ore of the SMA actuator wires may act in the opposite direction to one or m ore of the remaining SMA actuator wires. I n this case, as mentioned earlier, SMA actuator wires m ay be used to provide a reversed or return force, and may thereby replace the return spring. The SMA actuator wire or wires may, in embodiments, run alongside the intermediate moveable element. That is, the SMA actuator wire(s) m ay be coupled to and extend across a side of the intermediate moveable elem ent, instead of being coupled to an edge and extending into the further cavity. Advantageously, such an arrangement of SMA actuator wires m ay reduce the width or length of the haptic button assembly, as the further cavity is no longer required.

Example arrangements of SMA actuator wires are described below with reference to Figures 9B to 9D. Figures 9B, 9C and 9D show various arrangements of SMA actuator wire in a haptic button assem bly 900’. Generally speaking, the force available to m ove the interm ediate moveable elem ent m ay be proportional to the num ber of SMA actuator wires provided in a mechanically parallel arrangement in the assem bly. Furtherm ore, the overall stroke of the actuation mechanism in the assem bly may depend on the length of the SMA actuator wire(s) - longer SMA actuator wires generally provide increased stroke. Generally, the wire arrangements may com prise parallel wires that are m echanically in parallel but electrically in series (e.g. wire loops) , parallel wires that are both mechanically and electrically in series/parallel, parallel wires that are m echanically in series but electrically in parallel, or independently driven opposing wires.

The haptic button assem bly 900’ is sim ilar to the arrangement shown in Figure 1 and therefore, for the sake of conciseness, like features are not described. I n the haptic button assem bly 900’, at least one SMA actuator wire 908 runs along at least one side of intermediate moveable element 906, instead of being coupled to an edge and extending into the further cavity (see Figure 9A, for exam ple) . Thus, compared to e.g. Figure 9A, the stroke of the actuation m echanism of Figures 9B- D is greater because the SMA actuator wire is longer. I n Figure 9B, the haptic button assembly 900’ com prises at least one SMA actuator wire 908, where the or each wire is coupled at one end to the interm ediate moveable element 906 via a connector or crimp 910b, and at another end to the housing 904 via a connector or crimp 910a. Thus, a large portion of the at least one SMA actuator wire 908 is parallel to a side of the intermediate moveable elem ent 906. A return spring 912 m ay be coupled between the intermediate m oveable element 906 and the housing 904. One or m ore ball bearings 918 m ay be provided between button 902 and the interm ediate moveable elem ent 906, and between the interm ediate m oveable element 906 and the housing 904, as described above with reference to any of Figures 1 to 8. This arrangem ent of SMA actuator wire(s) 908 may provide a more com pact haptic button assembly.

Figure 9C shows a plan view of a haptic assem bly com prising two parallel SMA actuator wires. As mentioned above, the haptic button assem bly 900’ may comprise at least one SMA actuator wire 908. I n Figure 9C, the haptic button assembly is shown to comprise two parallel SMA actuator wires 908a, 908b which are coupled to (and extend across) opposite sides of the interm ediate moveable element 906. The two SMA actuator wires 908a, 908b may act in the sam e direction ( i.e. m ay apply a force to the intermediate moveable element in the sam e direction) , or m ay act in opposite directions. I n the form er case, the two SMA actuator wires advantageously provide twice the force of a single wire, while in the latter case, the wires may rem ove the need for return spring 912. A first SMA actuator wire 908a is coupled at one end to the intermediate m oveable element 906 via a connector or crimp 910b, and at another end to the housing 904 via a connector or crimp 910a. A second SMA actuator wire 908b is coupled at one end to the intermediate moveable element 906 via a connector or crimp 91 Od, and at another end to the housing 904 via a connector or crim p 91 0c.

Figure 9D shows a variation of the assembly 900 depicted in Figure 9B. Flere, a single SMA actuator wire 908’ is hooked at its m idpoint over a hook 920 provided on a side of the intermediate moveable elem ent 906. The two halves of the SMA actuator wire 908’ mechanically act in parallel and therefore, the SMA actuator wire 908’ m ay provide twice the force of a single wire. This m ay be advantageous relative to Figure 9C because only one set of connectors/crim ps are required to couple the SMA actuator wire 908’ to the intermediate m oveable element 906 and housing 904. Further advantageously, both of the connectors 910a, 910b are provided on the housing 904. As the SMA actuator wire 908’ needs to be powered, the connectors 910a, 910b are electrical connectors (to connect the SMA actuator wire to a power supply) , and therefore, the arrangement of Figure 9D simplifies the connections and circuitry to power the wire 908’.

It will be understood that any of the haptic assemblies described herein may com prise SMA actuator wire(s) which is either under tension or which is slack. I n some cases, when a user presses the button, the force exerted by the user on the button may cause the SMA actuator wire(s) to be stretched. This may mean a required pre-load is applied to the SMA actuator wire(s) to achieve an optimal phase transformation when the SMA actuator wire(s) is powered. The force applied by the user may cause the SMA actuator wire to be stretched to its original length. When the user applies a force to the button, the intermediate moveable element may be forced to move laterally/horizontally such that the SMA actuator wire stretches. In some cases, the SMA actuator wire may be considered to be slack when the length of the SMA actuator wire between two coupling elements (e.g. crimp connector or welded component) is longer than the distance between the two coupling elements when no external load is applied to the button/intermediate moveable element by a user (e.g. the system is in equilibrium) at ambient temperature (which may, in some cases be, 25°C). More particularly, the SMA actuator wire may be considered to be slack when the length of the SMA actuator wire between two coupling elements is longer than the distance between the two coupling elements when the intermediate moveable element abuts against an endstop within the cavity.

In some cases, the SMA actuator wire(s) may be much longer than the distance between the two coupling elements when no external load is applied/the system is in equilibrium, at ambient temperature (which may, in some cases be, 25°C). In other words, the SMA actuator wire may not always be in tension.

In some cases, the SMA actuator wire(s) may be much shorter than the distance between the two coupling elements when no external load is applied/the system is in equilibrium, at ambient temperature (which may, in some cases be, 25°C). In other words, the SMA actuator wire may always be in tension.

In some cases, the SMA actuator wire(s) may have a precise amount of slack, at ambient temperature (which may, in some cases be, 25°C) . For example, the distance between the two coupling elements when no external load is applied/the system is in equilibrium may be 7.5mm, and the length of SMA actuator wire may be 7.5mm plus a precise amount of slack. The amount of slack may be between a few microns and no more than a few tens of microns.

Thus, in embodiments, the at least on SMA actuator wire may be slack.

The SMA actuator wire(s) used in any of the haptic assemblies described herein may be uncoated, or may be coated with an electrically insulating layer/ coating. In some cases, the SMA actuator wire may be coated with an electrically insulating layer of thickness in the range from 0.3pm to 10pm . The electrically insualting layer may coat the entire length of each SMA actuator wire or a part of the length of each SMA actuator wire. Techn iques for providing the coated SMA actuator wire are described in WO2015/036761 . Although WO2015/036761 describes the use of coated wire or partly-coated wire in m iniature cam eras, it will be understood that the techniques described therein may be utilised in other applications, such as haptics.

Gapless Desians

Various techniques for sealing a haptic assembly have been described above. Alternatively, haptic assemblies which are gapless (or partly gapless, or gapless when not in use) , are now described. The truly gapless haptic assemblies may not require any additional sealing mechanisms. The haptic assemblies which are partly gapless or gapless when not in use may require additional sealing mechanism s, such as those described above, in order to provide sealing.

The term “gapless” is used herein to generally mean any haptic assembly in which there is no gap between the button/m oveable component and the housing. The term“gapless” is used interchangeably herein with the term“truly gapless”.

The term“partly gapless” is used herein to mean a haptic assem bly in which there is no visible gap or which appears to be gapless, but in which there is actually a gap between the button/m oveable component and the housing. I n som e cases, the gap may only become visible when the button/moveable component is being actuated to deliver a haptic sensation. The term “partly gapless” is used interchangeably herein with the terms“gapless when not in use”,“near gapless”, “unibody”,“apparently gapless”, and“no visible gap”. I n some cases, a device such as a sm artphone may be formed from two or m ore pieces/ components to provide an apparently unibody or gapless device. As described below, a haptic assembly m ay be provided within a device such as the gap or join line between the pieces/ components of the device are used to provide a gap between the button/m oveable component and the housing of the haptic assembly.

Figures 21 A and 21 B respectively show cross-sectional views of a gapless haptic assem bly 2100 in an equilibrium state and in an activated state. The haptic assembly 2100 may be coupled to a flexible piece of material 2106. The flexible piece of material 21 06 m ay be, for exam ple, a flexible portion of a casing of a smartphone or of a housing of a consum er electronics device, or may be a flexible display screen or flexible surface. I t will be understood that these are merely exemplary. Alternatively, the flexible piece of material 2106 m ay be part of the haptic assembly 2100 itself. It will also be understood that the flexible piece of material may be replaced by a button of the type shown in Figure 1 , for example, such that the haptic assem bly is used to move the button. Thus, the haptic assembly 2100 may be gapless, apparently gapless or to have a visible gap, depending on other design criteria.

The haptic assembly 2100 comprises a first m oveable arm 21 02a which is fixedly connected at a first end 21 1 2 to the flexible piece of material 2106, and rotatably/m oveably connected at a second end via a hinge 21 10 (or sim ilar) to a first end of a second moveable arm 2102b. The second moveable arm 2102b is fixedly connected at a second end to a static component 2104. The haptic assembly 2100 com prises a third m oveable arm 2102c which is fixedly connected at a first end 21 12 to the flexible piece of m aterial 2106, and rotatably connected at a second end via a hinge 21 10 (or sim ilar) to a first end of a fourth moveable arm 2102d. The fourth moveable arm 2102d is fixedly connected at a second end to the static com ponent 2104. At least one SMA actuator wire 2108 is connected to the pins 21 10. The at least one SMA actuator wire 2108 is arranged such that when the wire(s) contract(s) (on heating) , the angle between the first m oveable arm 2102a and the second m oveable arm 2102b increases, and the angle between the third moveable arm 2102c and the second m oveable arm 2102d increases. I n other words, the ends of the first and second m oveable arms which are connected to the m oveable com ponent 2106 and static component 2104 m ove further apart, and the ends of the third and fourth moveable arm s which are connected to the moveable com ponent 2106 and static component 2104move further apart. As a result, the first m oveable arm 2102a and third moveable arm 21 02c pushes upwards against the flexible piece of m aterial 2106, causing the flexible piece of material 2106 to bend/deflect in the direction of arrow A, as shown in Figure 21 B. When the at least one SMA actuator wire 2108 is cooled, the m oveable arms 2102a-d return to their equilibrium state, which cuases the flexible piece of material to m ove downwards and return to being substantially flat, as shown in Figure 21 A. I n som e cases, the haptic assembly 2100 may com prise an additional resilient elem ent (e.g. a return spring or an opposing SMA actuator wire) to provide a return force. I n some cases, the force of a user’s finger may be sufficient to provide a return force, such that an SMA actuator wire or return spring is not required to return the m oveable com ponent 2106 to an equilibrium position.

It will be understood that at least one of the two pivot points (hinges 21 10) m ust be able to move in a direction parallel to the length of the SMA actuator wire 2108. If only one side is free to translate, the button will‘tilt’. Otherwise, it will move upwards sym m etrically about the line of sym m etry of the m echanism .

It will be understood that the first and second moveable arms m ay be a flexure, and the third and fourth moveable arms be another flexure.

If the flexible piece of m aterial 2106 is a part of the casing of a sm artphone, for example, the haptic assem bly 21 00 m ay be advantageous because the design may be configured to be gapless when compared to, for example, the em bodiments which com prise a wedge-shaped button and/or interm ediate moveable elem ent (e.g. Figures 1 to 3) . This means that the device containing the haptic assem bly 2100 may be substantially dust-proof and/or water-proof.

Figure 23A shows a cross-sectional view of a gapless haptic assembly 2300, and Figures 23B to E show cross-sectional views of a flexible portion of the gapless haptic assembly 2300 of Figure 23A. The haptic assembly 2300 may be incorporated into or otherwise provided along an edge of an electronic deviceor on a surface of an electronic device. The haptic assem bly 2300 m ay be arranged to move a flexible portion of a casing of a smartphone or of a housing of a consumer electronics device, for example. The haptic assembly 2300 may be provided as a standalone module that m ay be incorporated into an electronic device during manufacturer. Alternatively, som e or all of the components of the haptic assem bly 2300 may be integrally formed in an electronic device.

The haptic assem bly 2300 com prises a housing 2304. The housing 2304 is shaped (e.g. by form ing, etching, or otherwise) , to com prise a button portion 2302 and a flexible portion 2312. The flexible portion 2312 is connected to the button portion 2302 such that it surrounds the button portion 2302. The flexible portion may be form ed of thinner material than the button portion 2302 to provide the flexibility. The button portion 2302 comprises a contact surface 2306. I n em bodiments, the contact surface 2306 m ay be substantially level with/flush with an external surface 2308 of the housing 2304 when the haptic assembly is in an equilibrium state.

The haptic assembly 2300 com prises an intermediate m oveable elem ent 2310 sim ilar to that shown in Figure 22, and for the sake of sim plicity, the features and operation of the interm ediate moveable elem ent will not be described again . When the interm ediate moveable elem ent 2310 m oves, the button portion 2302 of the housing is caused to m ove within/relative to the housing 2304. The button portion 2302 is able to m ove because the flexible portion 2312 is flexible. The haptic assem bly 2300 is advantageous because the button portion 2302 is part of the housing 2304 such that there is no external gap between the button portion and the housing 2304 when the haptic assem bly 2300 is interegrated into devices such as a smartphone. Thus, the haptic assembly 2300 is substantially water proof and/or dust-proof.

As shown in Figures 23B to 23D the flexible portion 2312 m ay take on various form s. I n Figure 23B, the flexible portion 2312 is sim ply thinner than the button portion 2302. This m ay be useful as it may enable a smooth edge or surface to be provided when the haptic assembly 2300 is integrated into a device such as a smartphone. I n other words, this form of the flexible portion 2312 may be the m ost aesthetically-pleasing to a user. Flowever, as the flexible portion 2312 needs to flex to enable the button portion 2302 to move, it may be useful for the flexible portion 2312 to have a non-linear profile. I n other words, it m ay be useful for the flexible portion 2312 to be shaped in some way or to comprise one or more bends/curves, which provide the flexible portion 2312 with the structure to enable it to flex easily. Thus, in Figure 23C, the flexible portion 2312 is dom e-shaped, while in Figure 23D, the flexible portion is dim ple- or well-shaped. I n Figure 23 E, the flexible portion 2312 has a wavy or undulating form . I n Figure 23F, the flexible portion 2312 may comprise a point about which the flexible portion may bend/flex. I t may be advantageous to provide m ore than one flexible portion 2312 on either side of the button 2302, to further reduce stiffness/increase the flexibility of the flexible portion. For example, it m ay be useful to combine any of the the flexible portions 2312 shown in Figures 23B to 23F in a series combination on either side of the button 2302. An exam ple of this is shown in Figure 23G - here, two of the flexible portions 2312 shown in Figure 23F are combined to form a larger com bined flexible portion 231 2’. This larger com bined flexible portion 231 2’ may be provided on either side of the button 2302. It will be understood that different shaped flexible portions 2312 m ay be combined in series to form the com bined flexible portion 2312’.

Figure 24 shows a cross-sectional view of a partly gapless haptic assembly 2400. The haptic assem bly 2400 m ay be incorporated into or otherwise provided along an edge of an electronic device or on a surface of an electronic device. The haptic assem bly 2400 m ay be arranged to m ove a flexible portion of a casing of a smartphone or of a housing of a consumer electronics device, for exam ple. The haptic assem bly 2400 m ay be provided as a standalone m odule that may be incorporated into an electronic device during m anufacturer. Alternatively, som e or all of the components of haptic assem bly 2400 m ay be integrally formed in an electronic device.

The haptic assembly 2400 m ay comprise a housing 2404. I n this case, the haptic assem bly 2400 may be a m odule which is incorporated into an electronic device. Alternatively, the housing 2404 m ay be part of an electronic device (and not part of the haptic assembly) into which the com ponents of the haptic assem bly 2400 are incorporated. I n this case, the electronic device may be more aesthetically pleasing to a user because the edge or surface of the electronic device where the haptic assem bly 2400 is located may be substantially smooth and nearly gapless/ apparently gapless. This may allow an electronic device to be produced which has sm ooth edges/surfaces that do not have protruding buttons. I nstead of having a visible, protruding button, the haptic assem bly 2400 m ay provide haptic feedback when a user contacts (or is in the vicinity of) a‘non protruding button’ of the haptic assembly.

The housing 2404 (whether it is part of the haptic assem bly 2400 or otherwise) comprises a (non-protruding) button portion 2402. One or more edges of the button portion 2402 m ay be connected to the housing 2404. I n the em bodiment shown in Figure 24, at least one edge of the button portion 2402 is not connected to the housing 2404. This allows the button portion 2402 to move relative to the housing 2404 (as indicated by the arrow) when the haptic assembly 2400 is activated. The button portion 2402 m ay com prise a thinner hinge portion 2410. The hinge portion 241 0 of the button portion 2402 may be thinner than the rest of the button portion, such that the button portion 2402 is able to move/ flex about the hinge portion 2410. I n other words, the thinner hinge portion 2410 may provide the button portion 2402 with the flexibility to m ove relative to the housing 2402. The hinge portion 2410 may be provided by machining, form ing, etching or half-etching the button portion 2402 to remove material. The button portion 2402 comprises a contact surface. The contact surface may be substantially level with/flush with an external surface of the housing 2402 when the haptic assem bly is in an equilibrium state.

The haptic assembly 2400 comprises an interm ediate moveable element 2406 sim ilar to that shown in Figure 22, and for the sake of sim plicity, the features and operation of the interm ediate moveable element will not be described again . When the interm ediate moveable elem ent 2406 moves, the button portion 2402 of the housing is caused to m ove within/relative to the housing 2404. The button portion 2402 is able to move because the hinge portion 2410 provides some flexibility to the button portion . At least one bearing 2408 (e.g. a ball bearing - see also the definition above of the term‘bearing’) is disposed between the button portion 2402 and the intermediate m oveable element 2406. The at least one bearing 2408 may facilitate the lateral m ovem ent of the button portion 2402 when the interm ediate m oveable elem ent 2406 moves. The haptic assembly 2400 may be advantageous because the button portion 2402 is part of, and connected to the housing 2404 such that there is a reduced external gap between the button portion and the housing 2404 when the haptic assembly 2400 is integrated into a device such as a sm artphone. For example, if the button portion 2402 is connected to the housing 2404 by three of its four edges (such that only one edge of the button portion 2402 is free and unconnected to the housing) , the gap is m uch reduced compared to, for exam ple, the em bodim ent of Figure 1 . Furthermore, the gap may be m inimal (and potentially even difficult to see/not easily visible) when the haptic assembly 2400 is in an equilibrium state. When the haptic assembly 2400 is in an active state and the button portion 2402 is moving relative to the housing 2404, the gap m ay be larger and m ore visible. Thus, the haptic assem bly 2400 may reduce the possibility of dust and/or water ingress into the device at least when then haptic assembly is in the equilibrium state.

Figure 25 shows a cross-sectional view of a gapless haptic assembly 2500. The haptic assem bly 2500 m ay be incorporated into or otherwise provided along an edge of a smartphone or on a surface of a smartphone. The haptic assem bly 2500 may be a provided as a standalone m odule that may be incorporated into an electronic device during manufacture. Alternatively, some or all of the components of haptic assembly 2500 may be integrally form ed in an electronic device.

The haptic assembly 2500 m ay comprise a housing 2504. I n this case, the haptic assem bly 2500 may be a m odule which is incorporated into an electronic device. Alternatively, the housing 2504 may be part of an electronic device (and not part of the haptic assembly) into which the components of the haptic assembly 2500 are incorporated. I n this case, the electronic device may be more aesthetically pleasing to a user because the edge or surface of the electronic device where the haptic assem bly 2500 is located may be substantially smooth and gap-free. This m ay allow an electronic device to be produced which has smooth edges/surfaces that do not have protruding buttons. I nstead of having a visible, protruding button, the haptic assembly 2500 m ay provide haptic feedback when a user contacts (or is in the vicinity of) a‘non-protruding button’ of the haptic assem bly.

The housing 2504 (whether it is part of the haptic assembly 2500 or otherwise) com prises a (non-protruding) button portion 2502. All of the edges of the button portion 2502 m ay be connected to the housing 2504. However, the button portion 2502 is thinner than the rest of the housing 2504 - this allows the button portion 2502 to move relative to the housing 2504 (as indicated by the arrow) when the haptic assembly 2500 is activated. I n other words, the thickness of the button portion 2502 may provide the button portion 2502 with the flexibility to m ove relative to the housing 2502. The button portion 2502 may be provided by machining, stam ping, etching or half-etching the housing 2502 to rem ove material. The button portion 2502 comprises a contact surface. The contact surface may be substantially level with/flush with an external surface of the housing 2502 when the haptic assembly is in an equilibrium state.

The haptic assembly 2500 comprises an interm ediate moveable element 2506 sim ilar to that shown in Figure 22, and for the sake of sim plicity, the features and operation of the interm ediate moveable element will not be described again . When the interm ediate moveable elem ent 2506 m oves, the button portion 2502 of the housing is caused to move within/relative to the housing 2504. At least one bearing 2508 (e.g. a ball bearing or plain bearing) may be disposed between the button portion 2502 and the interm ediate m oveable element 2506. The at least one bearing 2508 may facilitate the lateral movement of the button portion 2502 when the interm ediate moveable element 2506 m oves. Alternatively, the bearing 2508 may be replaced by som e support m echanism to support the button portion on the actuator, as the button portion 2502 may be form ed of a thin piece of material (i.e. may be formed by locally-thinning the housing 2504) and may be easily dam aged or punctured if it is not supported. The haptic assembly 2500 may be advantageous because the button portion 2502 is part of the housing 2504 such that there is no gap between the button portion and the housing 2504 when the haptic assem bly 2500 is integrated into a device such as a smartphone. Thus, the haptic assem bly 2500 is substantially water-proof and/or dust-proof.

As m entioned above with reference to Figures 24 and 25, the button or moveable element of the haptic assem blies may be part of the housing itself. I n Figure 24, the button portion is connected along at least one edge to the housing, while in Figure 25, the button portion is com pletely connected to the housing. Turning to Figure 26, this shows schem atic diagrams of gapless and partly gapless haptic assem blies. Specifically, Figure 26 shows schematic plan views of the moveable element (or button or button portion) of five haptic assemblies 2600- 2614. I n haptic assem bly 2600, short edges 2604 of m oveable element 2602 are mechanically connected to the housing (not shown) of the haptic assembly (i.e. are m echanically constrained) , while long edges 2606 are m echanically constrained to be‘free’. When the haptic assem bly 2600 is in the equilibrium state, the haptic assembly 2600 m ay appear‘gapless’ and m ay be substantially water-proof and/or dust-proof. Flowever, when the haptic assembly 2600 is activated and the m oveable element 2602 moves, gaps between the moveable element 2602 and the housing may appear and therefore, the assembly may not be water- and/or dust-proof while the haptic assem bly 2600 is delivering haptic feedback.

I n haptic assem bly 2608, the moveable element 2602 com prises only one ‘free’ long edge 2606. I n haptic assembly 2610, the m oveable elem ent 2602 comprises no free edges, i.e. both the long edges and short edges are fixed. I n haptic assembly 2612, the short edges 2604 of the m oveable element 2602 are free while the long edges are fixed. I n haptic assem bly 2614, the moveable element 2602 com prises only one free short edge. Hapt ic assem bly 2610, which has four fixed edges, is the stiffest and provides the most resistance against deflection by the intermediate m oveable com ponent (not shown) , but is the only design which is water- and dust-proof in both the equilibrium and active states.

Figure 27A shows a schematic perspective view of a sm artphone 2700. The smartphone 2700 comprises one or m ore design features or functional features (such as antenna bands) provided around the smartphone. I n the illustrated example, the smartphone 2700 com prises at least two such design features (e.g. antenna bands) 2704, 2708, which are located near the top and bottom edges of the sm artphone (when held by a user in‘portrait m ode’) . The front and back faces of the sm artphone 2700 may be form ed from glass, while the sides/ edges of the smartphone 2700 m ay be formed from three pieces/ components 2702, 2706 and 2710 which m ay be moulded or otherwise formed as separate com ponents and which are connected together in the m anufacturing process. The three components 2702, 2706, and 2710 m ay be form ed of alum inium , stain less steel, plastic or flexible/deform able glass. It will be understood that these are merely example m aterials. The three com ponents are typically machined and then insert moulded into one piece, with the antenna bands provided between the sections. As shown, antenna band 2704 is located between components 2702 and 2706 (and m ay typically be moulded into com ponents 2702 and 2706) , and antenna band 2708 is located between components 2706 and 271 0 (and m ay be moulded into components 2706 and 2710) . I n some cases, there is no gap (or significant gap) between the three components 2702, 2706 and 2710 - there may be a seam less transition between the three com ponents such that it appears that the edges of the sm artphone (and possibly the entire sm artphone) are formed from a single piece of m aterial. I n this instance, the sm artphone m ay be gapless, particularly if there are no protruding mechanical buttons along the edges of the smartphone 2700. Accordingly, the sm artphone m ay achieve an I ngress Protection ( I P) Rating of 67 or 68 indicating the device is dust-proof and water proof to some standard. I n som e cases, there may be a small gap either side of each antenna band 2704, 2708 of up to 20pm for exam ple, and in this instance the smartphone is not gapless. Accordingly, additional sealing techniques may be required to provide the sm artphone with the required dust-proof and water-proof qualities, such as the sealing techniques described above.

Figure 27B shows a schematic plan view of an edge of the sm artphone of Figure 27A, and Figures 27C- E show schematic cross-sectional views of the profile of a button portion 2706 of the sm artphone of Figure 27A. The button portion 2706 may be used to deliver haptic feedback to a user of the sm artphone. The length of the button portion 2706 may be long - for exam ple, the button portion 2706 may be nearly as long as a long edge of the sm artphone 2700. A single haptic assembly/haptic actuator m ay not impart the required force to m ove the whole length of the button portion 2706 and thereby deliver an adequate haptic sensation to a user. Therefore, one or m ore haptic assem blies m ay be coupled to the button portion 2706 and arranged to deliver localised haptic feedback.

Figure 27C shows how the button portion 2706 m ay be shaped to form a cantilever 2712. The cantilever 271 2 is adjacent to antenna band 2704 and the gap between the button portion 2706 and com ponent 2702. Accordingly, when a force is applied to the cantilever 2712 by a haptic actuator (as indicated by the arrow) , the cantilever 2712 is able to move/tilt relative to the rest of the button portion 2706 and to the com ponent 2702. Accordingly, the haptic assembly makes use of an existing gap in the smartphone 2700 to enable movem ent of the cantilever 2712 to deliver a haptic sensation.

Figure 27D shows how the button portion 2706 may be shaped to form a first cantilever 2712 and a second cantilever 2714. The second cantilever 2714 is adjacent to antenna band 2708 and the gap between the button portion 2706 and component 2710. The first and second cantilevers 2712, 2714 m ay be separately actuated by individual haptic actuators to deliver haptic feedback at different positions along the button portion 2706. I n this way, localised haptic feedback may be delivered via button portion 2706.

Figure 27E shows how the button portion 2706 may be shaped to form a first cantilever 2712, a second cantilever 2714 and a thin flexible portion 2716. A further haptic actuator may be used to move the thin flexible portion 2716 to deliver haptic feedback at a point along the length of the button portion 2706. Thus, by shaping the cross-sectional profile of the button portion 2706 it is possible to deliver haptic feedback at different points along the button portion 2706. I t will be understood that the num ber of points of haptic feedback on the button portion 2706 may depend on the length of the button portion 2706.

Figure 28A shows a schematic cross-sectional view of a part of a gapless haptic assem bly 2800 which uses m agnets and m agnetic interaction to produce haptic feedback. The gapless haptic assem bly 2800 com prises a housing 2802, sim ilar to that shown in for example, Figures 23A and 25. The housing 2802 comprises a contact surface which a user may touch to receive haptic feedback. The gapless haptic assem bly 2800 comprises a first magnet or magnetic element 2806, which may be fixedly connected to an internal surface of the housing 2802, and specifically to an internally-located side of the contact surface. The first magnet 2806 may be a permanent m agnet. As shown in Figure 28A, the north pole of the first magnet 2806 may be closest to the internal surface of the housing 2802 and the south pole is further away from the internal surface of the housing, however it will be understood that this is m erely exem plary. The gapless haptic assembly 2800 comprises a second magnet 2804. The second m agnet 2804 is moveable relative to the housing 2802 and relative to the first m agnet 2806. The second m agnet 2804 m ay be a perm anent magnet. The second m agnet 2804 is arranged such that the south pole faces the south pole of the first magnet 2804. The second magnet 2804 is coupled to at least one SMA actuator wire 2808. The at least one SMA actuator wire 2808 is coupled at one end to a static component (e.g. the housing 2802 itself) , and at another end to the m oveable second magnet 2804. I n an equilibrium state, the second magnet 2804 is at a distance from the first magnet 2806 such that the magnetic interaction between the two m agnets is m inim al/insignificant. When the at least one SMA actuator wire 2808 is heated and caused to contract, the second magnet 2804 is moved closer to the first magnet 2806. As the like poles of the two magnets 2804, 2806 are brought closer together, the movement of the second magnet 2804 forces the first magnet 2806 to be repelled away from the second magnet 2804. This repulsion causes the movement of the housing 2802 (specifically the contact surface of the housing) , which thereby causes a haptic sensation to be delivered.

Figure 28B shows an alternative arrangement of the first m agnet in Figure 28A. Flere, the first magnet 2806’ m ay be arranged such that the poles of the magnet are at an angle to the internal surface of the housing 2802. This may help to reduce any undesired horizontal/sideways m otion of the first m agnet 2806’ when the second magnet 2804 is m oved into proxim ity with the first m agnet 2806’. Additionally or alternatively, one or m ore bearings (not shown) may be used to restrict the horizontal/sideways m otion of the first m agnet 2806, 2806’ within the housing. The haptic assemblies shown in Figures 28A and 28B m ay further com prise a bias spring or other com ponent (not shown) to oppose the effect of the at least one SMA actuator wire 2808. The haptic assem blies m ay further comprise one or more endstops (not shown) in the housing to restrict movem ent of the second magnet 2804 and first magnet 2806.

Many of the haptic assemblies described above use wedge-shaped components or inclined surfaces to transfer motion along one axis into motion along a second axis (e.g.‘horizontal’/lateral motion to‘vertical’ motion) . Figures 29A and 29B show two gapless haptic assemblies which use alternative mechanism s to deliver haptic feedback.

Figure 29A shows a cross-sectional view of a gapless haptic assembly 2900 comprising a material under compression . The haptic assem bly 2900 m ay be incorporated into or otherwise provided along an edge of a smartphone or on a surface of a smartphone. The haptic assem bly 2900 m ay be a provided as a standalone module that m ay be incorporated into an electronic device during manufacture. Alternatively, som e or all of the com ponents of haptic assembly 2900 m ay be integrally form ed in an electronic device.

The haptic assembly 2900 m ay com prise a housing 2906. I n this case, the haptic assem bly 2900 m ay be a module which is incorporated into an electronic device. Alternatively, the housing 2906 may be part of an electronic device (and not part of the haptic assembly) into which the com ponents of the haptic assem bly 2900 are incorporated. I n this case, the electronic device may be more aesthetically pleasing to a user because the edge or surface of the electronic device where the haptic assem bly 2900 is located may be substantially sm ooth and gap-free. This m ay allow an electronic device to be produced which has smooth edges/surfaces that do not have protruding buttons. I nstead of having a visible, protruding button, the haptic assembly 2900 may provide haptic feedback when a user contacts (or is in the vicinity of) a‘non-protruding button’ of the haptic assem bly.

The housing 2906 (whether it is part of the haptic assembly 2900 or otherwise) com prises a (non-protruding) button portion 2902. All of the edges of the button portion 2902 m ay be connected to the housing 2906. Flowever, the button portion 2902 may be thinner than the rest of the housing 2906 - this allows the button portion 2902 to m ove relative to the housing 2906 (as indicated by the arrow) when the haptic assem bly 2900 is activated. I n other words, the thickness of the button portion 2902 may provide the button portion 2902 with the flexibility to m ove relative to the housing 2902. The button portion 2902 may be provided by machining, etching or half-etching the housing 2902 to remove m aterial. The button portion 2902 com prises a contact surface. The contact surface m ay be substantially level with/flush with an external surface of the housing 2902 when the haptic assem bly is in an equilibrium state.

The haptic assembly 2900 comprises an interm ediate moveable element 2904. The interm ediate m oveable element 2904 is coupled to at least one SMA actuator wire. The or each SMA actuator wire is coupled at one end to the housing 2906 and at another end to the interm ediate m oveable element 2904. The haptic assembly 2900 may comprise a return spring/bias spring. The haptic assem bly 2900 com prises a com pliant or flexible m aterial 2908. The com pliant m aterial 2908 may be an elastom er, such as natural rubber, silicone rubber, thermoplastic polyurethane (TPU) , neoprene rubber and polyurethane. It will be understood that is a non-exhaustive, non-lim iting example list of m aterials. The com pliant material 2908 is in contact with the intermediate m oveable elem ent 2904 and the button portion 2902 of the housing 2906. When the haptic assem bly 2900 is in the equilibrium (inactive) state, the interm ediate moveable element 2904 exerts a force on the compliant material 2908. Generally speaking, when the compliant material 2908 is com pressed in one direction (e.g. by the interm ediate moveable element 2904) , the com pliant material 2908 expands in another direction. When the at least one SMA actuator wire is heated and contracts, the interm ediate moveable element 2904 moves and the force exerted by the intermediate moveable element 2904 on the com pliant m aterial 2908 is reduced. This enables the compliant material 2908 to expand in the lateral direction ( i.e. along the axis of movement of the intermediate m oveable elem ent 2904) .

The haptic assembly 2900 may function in a num ber of ways. For example, in one arrangem ent, in the equilibrium state, the com pliant m aterial 2908 m ay exert a force on the button portion 2902 which causes the button portion 2902 to bulge or be in a‘raised’ position. I n this case, when the haptic assembly 2900 is in the active state, the compliant m aterial 2908 is able to expand in the lateral direction (i.e. along the axis of movement of the intermediate m oveable elem ent 2904) . This causes the button portion 2902 to becom e‘unraised’, such that the button portion 2902 moves vertically‘downward’ when the haptic assembly 2900 is activated. I n an alternative arrangement, in the equilibrium state, the com pliant material 2908 may exert a force on the button portion 2902, and the button portion 2902 m ay exert an equal but opposite force on the compliant material 2908. I n this case, the button portion 2902 is substantially flush with/level with the housing 2906 in the equilibrium state. When the haptic assem bly 2900 is in the active state, the force on the com pliant material 2908 is reduced, but the force exerted by the button portion remains the same. Therefore, the button portion 2902 m ay form a dim ple-shape when the haptic assem bly is activated.

It will be understood that the arrangement of the intermediate m oveable element and the compliant material m ay be changed so that the button portion 2902 m oves vertically‘upward’ when the haptic assembly 2900 is activated.

The haptic assembly 2900 may be advantageous because the button portion 2902 is part of the housing 2906 such that there is no gap between the button portion and the housing 2906 when the haptic assem bly 2900 is integrated into device such as a smartphone. Thus, the haptic assem bly 2900 is substantially water-proof and/or dust-proof.

Like m any of the gapless haptic assemblies described herein, the haptic assembly 2900 may be m odified such that it is used to move a button (e.g. a button of the type shown in Figure 1 ) . Thus, the haptic assem bly 2900 may be gapless, apparently gapless or have a visible gap, depending on other design criteria. Figure 29B shows a cross-sectional view of the haptic assembly 2900 having a gap between the button 2902’ and the housing.

Figure 29C shows a cross-sectional view of a gapless haptic assem bly 2950 comprising a piston . The haptic assem bly 2950 may be incorporated into or otherwise provided along an edge of an electronic device or on a surface of a electronic device. The haptic assembly 2950 may be provided as a standalone module that may be incorporated into an electronic device during m anufacture. Alternatively, some or all of the com ponents of haptic assem bly 2950 may be integrally formed in an electronic device.

The haptic assembly 2950 m ay com prise a housing 2956. I n this case, the haptic assem bly 2950 may be a m odule which is incorporated into an electronic device. Alternatively, the housing 2956 may be part of an electronic device (and not part of the haptic assembly) into which the components of the haptic assem bly 2950 are incorporated. I n this case, the electronic device may be more aesthetically pleasing to a user because the edge or surface of the electronic device where the haptic assem bly 2950 is located may be substantially smooth and gap-free. This m ay allow an electronic device to be produced which has smooth edges/surfaces that do not have protruding buttons. I nstead of having a visible, protruding button, the haptic assembly 2950 m ay provide haptic feedback when a user contacts (or is in the vicinity of) a‘non-protruding button’ of the haptic assem bly.

The housing 2956 (whether it is part of the haptic assem bly 2950 or otherwise) com prises a (non-protruding) button portion 2952. All of the edges of the button portion 2952 m ay be connected to the housing 2956. However, the button portion 2952 m ay be thinner than the rest of the housing 2956 - this allows the button portion 2952 to m ove relative to the housing 2956 (as indicated by the arrow) when the haptic assembly 2950 is activated. I n other words, the thickness of the button portion 2952 may provide the button portion 2952 with the flexibility to m ove relative to the housing 2952. The button portion 2952 m ay be provided by machining, etching or half-etching the housing 2952 to remove material. The button portion 2952 comprises a contact surface. The contact surface may be substantially level with/flush with an external surface of the housing 2952 when the haptic assem bly is in an equilibrium state.

The haptic assem bly 2950 comprises an interm ediate moveable element 2954. The interm ediate m oveable element 2954 is coupled to at least one SMA actuator wire. The or each SMA actuator wire is coupled at one end to the housing 2956 and at another end to the interm ediate moveable element 2954. The haptic assembly 2900 may comprise a return spring/bias spring. The haptic assem bly 2950 comprises a piston 2960 and a fluid 2958. The fluid 2958 may be an oil, m ineral oil, silicone-based fluids, glycol-based fluids, water, gas, air, or an inert gas (e.g. nitrogen) . It will be understood that is a non-exhaustive, non-lim iting example list of materials. The piston 2960 is in contact with the button portion 2952 and the fluid 2958. The fluid 2958 is in contact with the piston 2960 and the interm ediate m oveable element 2954. When the haptic assem bly 2950 is in the equilibrium (inactive) state, the interm ediate moveable element 2954 exerts a force on the fluid 2958, which in turn exerts a force on the piston 2960. Thus, this haptic assembly 2950 uses a hydraulic m echanism to transfer the motion of the SMA actuator wire(s) to the button portion 2952. When the at least one SMA actuator wire is heated and contracts, the interm ediate moveable elem ent 2954 moves and the force exerted by the interm ediate moveable elem ent 2954 on the fluid 2958 is reduced. This enables the fluid 2958 to expand in the lateral direction (i.e. along the axis of movement of the intermediate m oveable element 2954) .

The haptic assembly 2950 m ay function in a number of ways. For exam ple, in one arrangement, in the equilibrium state, the fluid 2958 may exert a force on the piston 2960, which causes the button portion 2952 to bulge or be in a‘raised’ position. I n this case, when the haptic assem bly 2950 is in the active state, the fluid 2958 is able to expand in the lateral direction ( i.e. along the axis of m ovem ent of the intermediate m oveable elem ent 2954) . This causes the button portion 2952 to becom e ‘unraised’, such that the button portion 2952 moves vertically ‘downward’ when the haptic assem bly 2950 is activated. I n an alternative arrangement, in the equilibrium state, the fluid 2958 m ay exert a force on piston 2960, and the button portion 2952 m ay exert an equal but opposite force on the piston 2960. I n this case, the button portion 2952 is substantially flush with/level with the housing 2956 in the equilibrium state. When the haptic assem bly 2950 is in the active state, the force on the fluid 2958 and the piston 2960 is reduced, but the force exerted by the button portion 2952 remains the same. Therefore, the button portion 2952 may form a dimple-shape when the haptic assembly is activated.

Figure 29D shows an alternative arrangement of the gapless haptic assembly of Figure 29C, in which the direction of m ovem ent of the interm ediate moveable elem ent is reversed relative to the arrangement of Figure 29C. I n other words, when the SMA actuator wire is powered, the intermediate m oveable element exerts a higher force on the fluid 2958. I n this case, the button portion 2952 m oves vertically ‘upwards’ when the SMA actuator wire is powered and contracts.

The haptic assembly 2950 may be advantageous because the button portion 2952 is part of the housing 2956 such that there is no gap between the button portion and the housing 2956 when the haptic assem bly 2950 is integrated into device such as a smartphone. Thus, the haptic assem bly 2950 is substantially water-proof and/or dust-proof. Like many of the gapless haptic assemblies described herein, the haptic assembly 2950 may be modified such that it is used to move a button (e.g. a button of the type shown in Figure 1). Thus, the haptic assembly 2950 may be gapless, apparently gapless or have a visible gap, depending on other design criteria. Figure 29E shows a cross-sectional view of the haptic assembly 2950 having a gap between the button 2952’ and the housing.

Thus, in embodiments of the haptic button assembly, the button and the housing may be integrally formed.

The button may comprise at least one free edge.

The button may be formed by etching or half-etching the housing.

The button may comprise at least one cantilever and the at least one intermediate moveable element is arranged to drive movement of the cantilever along the first axis.

The haptic button assembly may comprise a first magnetic element fixedly connected to the button, and wherein the intermediate moveable element may comprise a second magnetic element.

The haptic button assembly may comprise a compliant material provided between the button and the intermediate moveable element, wherein the intermediate moveable element may be arranged to drive movement of the compliant material along the first axis, and the movement of the compliant material drives movement of the button along the first axis.

The haptic button assembly may comprise a fluid and a moveable component, wherein the intermediate moveable element is arranged to drive movement of the fluid, the fluid is arranged to drive movement of the moveable component, and the moveable component drives movement of the button along the first axis.

In embodiments, the at least one intermediate moveable element may comprise: a first moveable arm fixedly connected at a first end to the button; a second moveable arm rotatably connected at a first end to a second end of the first moveable arm via a first hinge, and fixedly connected at a second end to the static component; a third moveable arm fixedly connected at a first end to the button; a fourth moveable arm rotatably connected at a first end to a second end of the third moveable arm via a second hinge, and fixedly connected at a second end to the static component; wherein the at least one SMA actuator wire is connected to the first and second hinges and arranged to drive movement of the intermediate m oveable elem ent in a first plane, thereby driving m ovement of the button in the first plane.

Figures 30A and 30B show schematic plan views of a device 3000 comprising a partly gapless haptic assembly in the equilibrium (inactive) and active states respectively. As m entioned above with reference to Figures 27A to 27E, it m ay be possible to take advantage of existing gaps and design features within a smartphone or other consumer electronic device, for exam ple, when designing and integrating a haptic assem bly into the device. Figures 30A and 30B show how a haptic assembly m ay be used to slide existing design features of a device 3000, and thereby create a haptic sensation. The haptic assem bly in this case m ay not convert horizontal/lateral m otion into vertical m otion - instead, the haptic assem bly may simply be used to m ove a component of the device 3000 laterally.

The device 3000 com prises at least one m oveable component which may be moved by a haptic assembly to deliver haptic feedback. I n the illustrated example, the device 3000 comprises a first moveable component 3002 and a second moveable component 3004. The device 3000 com prises one or more haptic assem blies (not shown) , where each haptic assembly is used to m ove an individual moveable com ponent. I n the equilibrium state, the first and second moveable components 3002, 3004 are flush against other com ponents of the device 3000, such that there is no discernible gap 3006, 3008 and the device m ay be water- and/or dust-proof. I n the active state, a haptic assembly may slide one of the m oveable com ponents 3002, 3004 back and forth to generate haptic feedback. Flowever, this causes a visible gap 3006, 3008 to be form ed while the moveable component is in motion. Thus, while the device 3000 is delivering haptic feedback, the device 3000 m ay not be water- and/or dust-proof. To provide water- and/or dust-proofing, the device 3000 may com prise an additional sealing mechanism , such as those described in I nternational Patent Application No. PCT/GB2018/052923.

Figures 31 A and 31 B show schematic plan views of a device 3100 comprising an alternative partly gapless haptic assem bly in the equilibrium (inactive) and active states respectively. As mentioned above with reference to Figures 27A to 27E, it m ay be possible to take advantage of existing gaps and design features within a smartphone or other consum er electronic device, for example, when designing and integrating a haptic assembly into the device. Figures 31 A and 31 B show how a haptic assembly m ay be used to slide existing design features of a device 3100, and thereby create a haptic sensation. The haptic assembly in this case may not convert horizontal/ lateral m otion into vertical motion - instead, the haptic assem bly may sim ply be used to m ove a com ponent of the device 3100 laterally.

The device 3100 com prises at least one m oveable component which may be moved by a haptic assembly to deliver haptic feedback. I n the illustrated example, the device 3100 comprises a first moveable component 3102 and a second moveable component 3104. The device 3100 com prises one or m ore haptic assem blies (not shown) , where each haptic assembly is used to m ove an individual moveable com ponent. I n the equilibrium state, the first and second moveable com ponents 3102, 3104 are flush against each other, such that there is no discernible gap between the two components and the device 3100 may be water- and/or dust-proof. I n the active state, a haptic assem bly m ay slide one of the moveable components 3102, 3104 back and forth to generate haptic feedback. Flowever, this causes a gap 3106 to be formed between the two moveable components while the or each moveable com ponent is in m otion. Thus, while the device 3100 is delivering haptic feedback, the device 3100 may not be water- and/or dust-proof. To provide water- and/or dust-proofing, the device 3000 m ay comprise an additional sealing m echanism , such as those described in I nternational Patent Application No. PCT/GB2018/052923.

Thus, in em bodim ents, the at least one SMA actuator wire m ay be arranged to drive m ovem ent of the intermediate moveable com ponent along an axis parallel to the axis of the at least one SMA actuator wire; and the at least one intermediate moveable element may be arranged to drive movement of the m oveable component along an axis parallel to the axis of the at least one SMA actuator wire. I n other words, the intermediate m oveable com ponent and the m oveable component m ay m ove in the sam e direction as the contraction and expansion of the at least one SMA actuator wire (horizontally/ laterally) . Figure 32 shows a schem atic plan view of a device 3200 comprising a further alternative partly gapless haptic assem bly in the active state. Here, a whole side or edge of the device 3200 m ay be a moveable com ponent 3202 which is moveable to deliver haptic feedback. I n this case, a visible gap may only appear when the m oveable com ponent 3202 is being moved to deliver haptic feedback. One or more haptic assemblies may be provided to move the moveable component 3202 vertically upwards.

I n each of the embodiments shown in Figures 30 to 32, additional sealing mechanism s m ay be provided to ensure the device is water-proof and/or dust- proof in use. For exam ple, seals between the moveable com ponent and the haptic assembly m ay be provided to prevent fluid and/or dust ingress into the body of the device. Thus, even if fluid/dust gets into the gap while the haptic assembly is active, it m ay not be able to move any further into the body of the device.

While the importance of providing a dust- and/or water-proof device has been discussed, it will be understood that there are a num ber of applications where this is not required. For exam ple, while compliance with the I ngress Protection ( I P) Rating of 67 or 68 m ay be important for sm artphones, smartwatches and some other wearable devices, it m ay not be im portant for gam ing controllers, dom estic applicances and within vehicles, for example. Therefore, in some cases, it m ay not be necessary for the haptic assembly to be gapless or fully sealed both in an equilibrium and active state.

It will be understood that any of the gapless haptic assem blies described above m ay be modified such that it they can be used to m ove a button (e.g. a button of the type shown in Figure 1 ) . That is, the gapless haptic assemblies may be modified to be apparently gapless or have a visible gap.

Those skilled in the art will appreciate that while the foregoing has described what is considered to be the best mode and where appropriate other modes of perform ing present techniques, the present techniques should not be lim ited to the specific configurations and methods disclosed in this description of the preferred embodim ent. Those skilled in the art will recognise that present techniques have a broad range of applications, and that the em bodiments may take a wide range of modifications without departing from any inventive concept as defined in the appended claims.