Field

The present invention relates to an actuator assembly and methods of assembling an actuator assembly, such as an actuator assembly for a camera.

Background

Many electronic devices comprise a movable electronic component which must be electrically connected to one or more other components in the device which do not move with the movable component. Such an electrical connection may be for the purposes of data and/or power transfer. Therefore, an electrical interconnect between the movable component and the non-moving component is required which does not hinder movement of the movable component.

An example of a device in which such an interconnect may be required is a camera. In a camera, various degrees of movement of a movable component may be required for example for the purposes of optical image stabilisation (OIS) and/or autofocus. The movable component in a camera may be, for example an image sensor or a module comprising the image sensor.

In a camera, the purpose of OIS is to compensate for camera shake, that is vibration of the camera, typically caused by user hand movement, which degrades the quality of the image captured by the image sensor. OIS typically involves detecting the vibration by a vibration sensor such as a gyroscope sensor, and controlling, on the basis of the detected vibration, an actuator arrangement that adjusts the camera apparatus to compensate for the vibration. Several techniques for adjusting the camera apparatus are known.

In one type of OIS, a camera unit comprising an image sensor and a lens assembly for focussing an image on the image sensor is at least tilted relative to a support component around two notional axes that are perpendicular to each other and parallel to the light-sensitive region of the image sensor (when untilted). WO-2010/029316 and WO-2011/104518, which are incorporated herein by reference, each disclose actuator assemblies of this type in which a plurality of shape memory alloy (SMA) actuator wires are arranged to drive tilting of the camera unit.

In another type of OIS, a lens assembly is moved orthogonally to the optical axis thereof.

WO-2013/175197 and WO-2014/083318, both incorporated herein by reference, each disclose actuator assemblies of this type in which a plurality of SMA actuator wires are arranged to drive movement of the lens assembly.

WO-2017/072525, which is incorporated herein by reference, discloses an image sensor mounted on a carrier that is suspended on a support component by a bearing that allows movement of the carrier and the image sensor relative to a support component in any direction laterally to the light-sensitive region of the image sensor. An actuator arrangement comprising plural shape memory alloy wires is arranged to move the carrier and the image sensor relative to the support component for providing OIS of the image captured by the image sensor. In other examples, the image sensor may be moved along the optical axis, for example for the purpose of autofocus. This may be combined with OIS sensor-shift or may be used without OIS.

The components in such actuator arrangements can sometimes be defective. This is particularly the case for small or miniaturised devices, where the components of the actuator arrangement may be more fragile. It is therefore typical in a manufacturing process to produce a number of defective actuator assembly units. As the actuator assembly incorporates an electronic component such as an image sensor, the cost of these defective units is high.

Summary

According to a first aspect of the present invention, there is provided a method of assembling an actuator assembly including an electronic component. The method comprises: providing an initial assembly comprising a support component, an intermediate component, an actuator arrangement comprising shape memory alloy elements arranged to move the intermediate component relative to the support component, and an electrical interconnect arrangement comprising conductive elements extending from the support component to the intermediate component for providing an electrical connection to the electronic component; testing the actuator arrangement of the initial assembly; and then attaching the electronic component to the intermediate component and making electrical contact with electrical interconnect arrangement, thereby forming the actuator assembly.

In such a method, an electrical interconnect arrangement is integrated into the assembly prior to attachment of the electronic component. This allows the actuator arrangement of the assembly to be tested in a state that is representative of the final product, because the electrical interconnections are present, but without attaching the expensive electronic component. If the testing reveals a defect, the initial assembly can be disposed of, recycled, or corrected, without wasting the electronic component. Thus the method provides for reduced cost in the manufacturing of an actuator assembly. In some embodiments, the conductive elements of the electrical interconnect arrangement are flexures made of conductive material. In some embodiments the electrical interconnect arrangement comprises a flexible printed circuit and the conductive elements of the electrical interconnect arrangement are conductive tracks of the flexible printed circuit. In some embodiments, the electrical interconnect arrangement comprises (e.g. metallic) flexures and the conductive elements of the electrical interconnect arrangement are conductive tracks on the flexures.

According to a second aspect of the invention there is provided an actuator assembly comprising: a support component; an intermediate component; an actuator arrangement comprising shape memory alloy elements arranged to move the intermediate component relative to the support component; an electronic component attached to the intermediate component; and an electrical interconnect arrangement comprising conductive elements extending from the support component to the intermediate component and in contact with the electronic component.

According to a third aspect of the invention there is provided a method of attaching an electronic component in an aligned manner to an intermediate component of an actuator assembly that further comprises a support component, an actuator arrangement comprising shape memory alloy elements arranged to move the intermediate component relative to the support component, and an electrical interconnect arrangement comprising conductive elements extending from the support component to the intermediate component for providing an electrical connection to the electronic component, wherein one of the electronic component and conductive elements of the electrical interconnect arrangement comprises plural contacts and the other of the electronic component and the conductive elements of the electrical interconnect arrangement comprises plural flexible connectors, the method comprising: initially positioning the electronic component on the intermediate component with the flexible connectors in contact with the contacts of said one of the electronic component and the conductive elements of the electrical interconnect arrangement; aligning the electronic component with respect to the support component while maintaining the flexible connectors in contact with the contacts of said one of the electronic component and the conductive elements of the electrical interconnect arrangement by flexing the flexible connector; and attaching the electronic component to the structural component.

As discussed above, it is beneficial to attach an electrical interconnect arrangement to an initial assembly and test the initial assembly, prior to attachment of an electrical component. However, by integrating the interconnect into the actuator, the process of latterly attaching the electrical device can be made more difficult, potentially resulting in yield loss if using a conventional method e.g. soldering. This is especially true for devices which have many small electrical contacts. The method according to the third aspect provides a flexible connection between the electronic component and the initial apparatus, making the attachment process simpler and more tolerant to dimensional and alignment errors, therefore reducing the yield loss of the attachment process.

The actuator assembly may be an actuator assembly according to any embodiment of the second aspect, or may be an actuator assembly assembled using the method of any embodiment of the first aspect.

In some embodiments, the step of aligning the electronic component with respect to the support component comprises providing power to the electronic component and/or receiving signals from the electronic component through the contacts and the flexible connectors, and aligning the image sensor on the basis of the signals received from the electronic component. For example, the electronic component may comprise an image sensor and the signals received from the electronic component may represent an image captured on the image sensor.

It may be necessary to provide power to the electronic device and/or receive signals from the electronic device to determine if it is correctly aligned, and to continue to do so as the electronic component is moved around to its aligned position. Conventionally this might be achieved for example using a separate connection with e.g. many small pins, which can be a complicated arrangement. However, the flexible interconnect arrangement of the present invention can provide the power and/or receive the signals to align the electronic component, thus simplifying the alignment equipment interface.

In accordance with a fourth aspect of the invention there is provided a actuator assembly comprising: a support component; an intermediate component; an actuator arrangement comprising shape memory alloy elements arranged to move the intermediate component relative to the support component; an electronic component attached to the intermediate component; an electrical interconnect arrangement comprising conductive elements extending from the support component to the intermediate component, wherein one of the electronic component and conductive elements of the electrical interconnect arrangement comprises plural contacts and the other of the electronic component and the conductive elements of the electrical interconnect arrangement comprises plural flexible connectors attached to, and in contact with, the contacts of the one of the electronic component and the conductive elements of the electrical interconnect arrangement.

In the third and fourth aspects, the plural contacts may themselves comprise flexible connectors. Brief Description of the Drawings

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, which show the following.

Fig. 1 is a schematic representation of an actuator assembly;

Fig. 2 illustrates an alternative view of part of the actuator assembly of Fig. 1;

Fig. 3 illustrates an electrical interconnect arrangement comprising a flexible PCB;

Fig. 4 illustrates a method of assembling an actuator assembly;

Figs. 5a and 5b illustrate components of an initial assembly for use in the method of Fig. 4;

Figs. 6a and 6b illustrate components of an alternative initial assembly for use in the method of Fig. 4;

Fig. 6c illustrates an actuator assembly formed from the initial assembly of Figs. 6a and 6b;

Fig. 7 illustrates a method of attaching an electronic component in an actuator assembly;

Fig. 8 illustrates a conventional approach for attaching an electronic component;

Fig. 9a illustrates an example of attaching an electronic component in accordance with the method of Fig. 7;

Fig. 9b shows the actuator assembly of Fig. 9a in a maximally misaligned position;

Fig. 9b shows the actuator assembly of Fig. 9a in a minimally misaligned position; and

Fig. 10 is a schematic representation of a camera apparatus incorporating an actuator assembly.

Detailed Description

Figs. 1 and 2 illustrate an actuator assembly 2. Fig. 1 is a side view of the actuator assembly 2. Fig. 2 is an underside view of components of the actuator assembly 2. The actuator assembly allows movement of an electronic component 12. In the illustrated example the electronic device 12 is an image sensor with a photosensitive region 7.

The actuator assembly comprise a support component 4. Optionally, the support component 4 comprises a support plate 5 which may be formed from sheet material, which may be a metal for example steel such as stainless steel or copper or a copper alloy. Although the support component 4 comprises a single support plate 5 in this example, optionally the support component 4 may comprise other layers which may be attached to or laminated with the support plate 5.

In the illustrated example, the support structure 4 comprises a printed circuit board (PCB) 10 supported on the support plate 5. The underside of the PCB 10 is shown in Fig. 2. For clarity, Fig. 2 does not show the support plate 5 on which the PCB 10 rests. The support structure 4 may be electrically connected to an apparatus into which the actuator assembly 2 is incorporated. For example the PCB 10 may comprise connections for receiving power from the apparatus.

The actuator assembly 2 further comprises an intermediate component 30. The intermediate component 30 is moveable with respect to the support component 4 by an SMA actuator 40, described further below. The intermediate component may for example be or comprise a plate, ring of material, or PCB capable of supporting an electronic component 12.

An electronic component 12 is attached to the intermediate component 30. The electronic component 12 is fixed to and moves with the intermediate component 30. In particular examples, the electronic component 12 is an image sensor, for example a CCD (charge-coupled device) or a CMOS (complementary metal-oxide-semiconductor) device. In such examples, the actuator apparatus may be incorporated into a camera apparatus 1. A camera apparatus 1 is illustrated in Fig. 10, and is discussed further below.

In the illustrated example the electronic component 12 comprises a printed circuit board 9. The PCB 9 may be attached to the intermediate component 30 for attaching the electronic component 12 thereto. The PCB 9 may also comprise electrical contacts for receiving and transmitting data signals from the electronic component 12, and/or for receiving electrical power. As discussed below, the movable electronic component 12 is electrically connected to the support component 4 by an electrical interconnect arrangement 50.

The actuator assembly 2 further comprises an actuator arrangement 40 arranged to move the intermediate component 30 (and hence the electronic component 12) relative to the support component 4. The actuator arrangement 40 comprises shape memory alloy (SMA) wires 41. The SMA wires 41 are connected to both the support component 4 and the intermediate component 30. In the illustrated example, the intermediate component 12 comprises crimp portions 42 and the support component 4 comprises crimp portions 43 for connecting the SMA wires 41 to the respective components.

In use, each of the SMA wires 41 is held in tension, thereby applying a force between the support component 4 and the intermediate component 30. The actuator assembly 40 is arranged to move, on selective driving of the SMA wires 41, the intermediate component relative to the support component in a plane defined by the electronic component 12. In examples where the electronic component 12 is an image sensor, the actuator assembly 40 may be arranged to move the image sensor relative to the support component 4 in any direction laterally to a light-sensitive region 7 of the image sensor and/or of rotating the electronic component about an axis orthogonal to the light-sensitive region 7. The SMA wires 41 may be perpendicular to the optical axis O (or generally an axis orthogonal to a plane defined by the electronic component 12) so that the force applied to the intermediate component 30 is lateral to the light-sensitive region 7/plane. Alternatively, the SMA wires 41 may be inclined at a small angle to the light-sensitive region 7/plane so that the force applied to the intermediate component 30 includes a component lateral to the light-sensitive region 7 and a component along the optical axis O (or generally axis that is orthogonal to the plane of motion) that acts as a biasing force that biases the intermediate component 30 against a bearing arrangement. The bearing arrangement may for example be a ball bearing arrangement. Thus, the SMA wires 41 may act as a biasing arrangement.

SMA material has the property that on heating it undergoes a solid-state phase change which causes the SMA material to contract. At low temperatures, the SMA material enters the Martensite phase. At high temperatures, the SMA enters the Austenite phase which induces a deformation causing the SMA material to contract. The phase change occurs over a range of temperature due to the statistical spread of transition temperature in the SMA crystal structure. Thus heating of the SMA wires 41 causes them to decrease in length.

The SMA wires 41 may be made of any suitable SMA material, for example Nitinol or another Titanium- alloy SMA material. Advantageously, the material composition and pre-treatment of the SMA wires 41 is chosen to provide phase change over a range of temperature that is above the expected ambient temperature during normal operation and as wide as possible to maximise the degree of positional control.

On heating of one of the SMA wires 41, the stress therein increases and it contracts, causing movement of the intermediate component 30 (and hence of the electrical component 12). A range of movement occurs as the temperature of the SMA increases over the range of temperature in which there occurs the transition of the SMA material from the Martensite phase to the Austenite phase. Conversely, on cooling of one of the SMA wires 41 so that the stress therein decreases, it expands under the force from opposing ones of the SMA wires 41. This causes the intermediate component 30 to move in the opposite direction.

The actuator arrangement 40 may for example take the form of any of the SMA arrangements described in WO-2014/083318, which is incorporated herein by reference in its entirety.

The actuator arrangement 40 illustrated in Fig. 1 provides for lateral movement of the electronic component 12 in a plane defined by the electronic component 12, and rotation of the electronic component around an axis orthogonal to the plane. In some embodiments, however, the intermediate component 30 and/or electronic component 12 may be supported on the support component 4 in a manner allowing movement of the electronic component 12 relative to the support component 4 in alternative or additional directions, for example movement along the said axis and/or rotation about one or more axes parallel to the said plane. An appropriate actuator for driving such movement may be used. An example of such an actuator mechanism is disclosed in W02011/104518A1, which is incorporated herein by reference in its entirety.

Although not illustrated in the figures, the actuator assembly 2 may further comprise a bearing arrangement for supporting the intermediate component 30 in a manner allowing the movement discussed above. The bearing arrangement may for example comprise any example of the plain bearings discussed in WO-2017/072525, which is incorporated herein by reference. Such a plain bearing comprises two bearing surfaces that bear on each other, permitting relative sliding motion. Such a plain bearing may be compact and facilitate heat transfer between the electronic component 12 and the support component 4.

In order to provide an electrical connection to the movable electronic component 12, the actuator apparatus 2 further comprises an electrical interconnect arrangement 50. The electrical interconnect arrangement comprises conductive elements 51 extending from the support component 4 to the intermediate component 30 and in contact with the electronic component 12. The electrical connection provided by the electrical interconnect arrangement 50 may be for connecting the electronic component 12 to an apparatus into which the actuator assembly 2 is incorporated, such as a camera, a mobile telephone, or a tablet computer. The electrical connection may be for providing power to the electrical component 12, for example from the apparatus. The electrical connection may be for allowing transfer of data such as image data from the electrical component. The electrical connection may be for other purposes, for example providing control signals for autofocus and/or optical image stabilisation in a camera.

The actuator apparatus 2 may comprise a plurality of electrical connections between support structure 4 and the electronic component 12, which may each be facilitated by separate conductive elements 51 of the electrical interconnect arrangement 50. Such connections may provide for multiple signal input and outputs to the electronic device 12, for example. In some examples the electrical interconnect component comprises 5 or more, or 10 or more, or 15 or more, or 20 or more conductive elements 51.

An example electrical interconnect arrangement 50 is illustrated in Fig. 2. Fig. 2 is a plan view of one side (either the underside or the top side) of the PCB 10 of the support component 4 and the PCB 9 of the electronic component 12. Fig. 2 may be a view of the actuator assembly 2 shown in Figure 2 with the support plate 5 removed.

As shown in Fig. 2, the electrical interconnect arrangement 50 comprises a plurality of conductive elements 51. For clarity only one group of conductive elements 51 are labelled in the figure. The conductive elements 51 are configured to electrically connect the support component 4 to the electronic component 12. For example, when PCBs are present, the conductive elements 51 may be configured to electrically connect the PCB 10 of the support component 4 to the PCB 9 of the electronic component 12. The conductive elements 51 may be configured to transfer data between the support component 4 and the electronic component 12. For example, image data acquired by an image sensor may be transferred from the PCB 9 to the PCB 10 via the conductive elements 51. The conductive elements 51 may alternatively or are configured to supply power for the electronic component 12 from the PCB 10 to the PCB 9. In general, the electrical interconnectors 51 are configured to transfer electrical signals such as power and data in either direction between the support component 4 and the movable part. The electrical interconnectors 51 may also be configured to transfer (or provide a common return path for) signals for driving the SMA wires 40 from the support component 4 to the movable part.

In the illustrated example, the conductive elements 51 extend across a portion of the intermediate component 30 to contacts 52 through which the electronic component 12 makes electrical contact with the conductive elements 51 of the electrical interconnect arrangement. For clarity only one group of contacts 52 are labelled in the figure. The contacts may be on the electronic device 12, providing a direct connection to the electronic device 12. In some examples, the contacts are at a far edge of the intermediate component. In particular examples, as illustrated in Fig. 2, the conductive elements 51 extend across a portion of the intermediate component 30 and protrudes beyond the intermediate portion 30 to the contacts. This means that the conductive elements 51 can be connected directly to the electronic component 12. This helps to keep the electrical path resistance to a minimum.

Optionally, the support component 4 has a first aperture 8. At least part of the intermediate component 30 is inside the first aperture. As illustrated in Fig. 2, the first aperture 8 may an aperture in the PCB 10 of the support component 4. Further, the intermediate component 30 may have a second aperture 31. The electrical interconnect arrangement 50 may then extend from the support component 4 into the first aperture 8 and across the portion of the intermediate component 30 and protrude into the second aperture 31 to the contacts. The second aperture 31 can be seen most clearly in Fig. 5B, discussed further below. In some examples the electrical interconnect arrangement 50 is arranged to allow and/or guide movement of the intermediate component 30 relative to the support component 4 in a plane (e.g. the plane of the light sensitive region 7), and the actuator arrangement 40 is arranged to move the intermediate component 30 relative to the support component in the plane. Thus in addition to providing the electrical connection, the electrical interconnect arrangement 50 may help movement of the intermediate component 30 and electronic component 12.

In the example illustrated in Fig. 2, the conductive elements 51 are flexures made of conductive material, such as a metal. The flexures may be etched strips. The flexures allow movement between the support component 4 and the intermediate component 30, ensuring an electrical connection even when the intermediate component 30 is moved. The conductive elements 51 may each be formed as a single piece.

Optionally a plurality of groups of electrical interconnectors 51 are provided. For example, Fig. 2 shows four groups of electrical interconnectors 51. Each group of electrical interconnectors 51 is generally for providing electrical connection between the support component 4 and a respective side or corner of the electronic component 12. The number of groups of electrical interconnectors 51 may alternatively be one, two, three, or more than four, for example. For example, in an alternative arrangement the PCB 10 of the support component 12 may extend around only two sides of the electronic component 12. In such an arrangement, there may be only two groups of electrical interconnectors 51.

Although the electrical interconnect arrangement 50 is shown as comprising multiple flexures in Fig. 2, in general any electrical interconnect which allows for movement of the intermediate component 30 may be used. For example, conductive tracks may be provided on the flexures, e.g. separated from the flexure by an insulated layer. In this case, there may be fewer flexures and each flexure may carry multiple tracks. As another example, Fig. 3 illustrates an alternative electrical interconnect arrangement 50 in which the electrical interconnect arrangement 50 comprises a flexible printed circuit (FPC) 52. The conductive elements 51 of the electrical interconnect arrangement are conductive tracks on the flexible printed circuit (not illustrated in Fig. 3).

Fig. 3 is an underside view of such an FPC electrical interconnector arrangement 50, (i.e. looking along the optical axis O where the electrical component 12 is an image detector). The interconnect arrangement 50 comprises a flexible printed circuit (FPC) 50a. The FPC 50a may be a section of FPC tape. The FPC 50a may have a conventional construction, for example it may comprise a flexible substrate made of a suitable material, for example a plastic such as polyimide, PEEK or polyester with copper tracks. The FPC 50a may comprise a single layer of tracks or more than one layer of copper tracks (for example two, three, four or more), with each layer of tracks separated by an insulator e.g. polyimide. Such tracks may be used as the conductive elements 51 of the electrical interconnect arrangement 50.

The FPC 50a comprises a first end 53 attached to the intermediate component 30, and a second end 54 attached to the support component 4. An arm 55 extends between the first end 53 and the second end 54 in a loop around the intermediate component 30. In some examples the flexible printed circuit 50a extends along a side of the intermediate component 30 and includes plural contacts spaced along the side of the intermediate component 30.

In particular examples, as shown in Fig. 3, portions of the FPC 50a are planar. In the embodiment shown in Figure 3, the FPC 50 comprises a first planar arm portion 55a, a second planar arm portion 55b, a third planar arm portion 55c and a fourth planar arm portion 55d. Each of the first, second, third and fourth planar arm portions lie in a first plane. The FPC also comprises a first bend between the first and second planar arm portions 55a, 55b; a second bend between the second and third planar portions 55b, 55c; and third bend between the third and fourth planar portions 55c, 55d. Each of the bends 61, 62 and 63 also lies in the first plane.

The FPC 50 also comprises a fifth planar arm portion 55e; and a fourth bend; a sixth planar portion 55f and a fifth bend. The fourth bend is between the fourth planar arm portion 55d and the fifth arm planar portion 55e and the fifth bend is between the fifth planar arm portion 55e and the sixth planar arm portion 55f.

The electronic component 12, or part of it such as PCB 9, also lies in the first plane. The planar arrangement of the FPC 50a is advantageous for a number of reasons. Firstly, the FPC 50a does not add any additional height (or adds minimal height) in the direction along the optical axis because it is coplanar with at least a portion of the electronic component 12 (for example the PCB 9). This may be particularly useful in devices in which z height is limited.

Further, the FPC 50a also has a small footprint in the plane of movement, thus taking up only limited space in that plane. A further advantage is that the material for manufacturing the FPC 50a can be used more efficiently compared to FPCs that require large patterns of FPC tape which then must be folded into shape. The manufacturing itself is also simplified in comparison to FPCs which require folding because the folding step(s) are avoided.

As shown in Fig. 3, the FPC 50a bends around the PCB 9. The FPC 50 extends from the end 53 connected to the intermediate component 30, and is then bent around bends (otherwise referred to as corners), extending to the other end 54 of the FPC 50a, where it is connected to the support component 4. For example the second end 54 of FPC 50a may connect to a PCB 10 of the support component 4.

As the FPC 50a is arranged bent around a number of corners, it accommodates the motion of the intermediate portion 30 relative to the support component 4 in any direction in the plane (including rotation about an axis orthogonal to the plane, such as the optical axis O). In particular, the FPC 50a will bend in a direction perpendicular to its length. Accordingly, the portions of the FPC 50a on sides A and C of the assembly (the first and third planar arm portions 55a and 55c) will accommodate motion in the y direction (see axis labels in Fig. 3) (although portions 55b and 55d will also flex to some extent). The portions of the FPC 50a on sides B and D (the second and fourth planar arm portions 55b and 55d) will accommodate motion in the x direction (although portions 55a and 55c will also flex to some extent). The FPC 50a can also accommodate motion along an axis orthogonal to the plane (e.g. along the optical axis, O), for example for the purposes of auto-focussing. The FPC 50a will give in the manner of a helical spring being extended. In such embodiments, the FPC 50a in Fig. 3 may be used in conjunction with an actuator providing for motion in the x, y and z directions. For example, the actuator described in W02011/104518A1 (incorporated herein by reference in its entirety) may be used.

The FPC 50a can also accommodate tilting e.g. about any axis in a plane parallel to the X-Y plane. As will be appreciated, the above-described features that enable the FPC 50a to accommodate e.g. translational motion in x, y and z directions also enable the FPC 50 to accommodate such tilting.

In the example shown in Fig. 3, the electrical interconnect arrangement 50 comprises one FPC 50a. However, more than one FPC 50a may be provided, for example, two, three or four may be provided. For example, and additional FPC 50a may extend around the exterior of the illustrated FPC 50a, providing a further independent connection between the intermediate component 30 and the support component 4. Further, any other suitable shape or arrangement of one or more FPCs may be used to provide the electrical interconnect arrangement 50.

Fig. 4 illustrates a method of assembling an actuator assembly 2 including an electronic component 12. The method may be used for example to assemble any of the examples of actuator assembly 2 discussed above.

The method comprises, at Al, providing an initial assembly 60. Figs. 5A and 5B illustrate an example of an initial assembly 60 that can be used to assemble the actuator assembly 2 illustrated in Fig. 2. Fig. 5A shows a side on view, similar to Fig. 1. Fig. 5B illustrates an underside view of the initial assembly 60, without the support plate 5. The initial assembly 60 comprises a support component 4, an intermediate component 30, an actuator arrangement 40 comprising shape memory alloy wires 41 arranged to move the intermediate component relative to the support component, and an electrical interconnect arrangement 50 comprising conductive elements 51 extending from the support component to the intermediate component for providing an electrical connection to the electronic component. Any of these components may take the form of any of the corresponding components discussed above in relation to Figs. 1-3. In particular, although illustrated in Figs. 5A and 5B as comprising flexures, in other examples the electrical interconnect arrangement 50 may comprise a flexible printed circuit, with the conductive elements 51 being conductive tracks on the flexible printed circuit, similar to the electrical interconnect arrangement 50 shown in Fig. 3.

Thus the initial assembly 60 comprises most or all of the features of the completed actuator assembly 2, with the exception of the electronic component 12. The initial assembly 60 is ready to receive an electronic component 12. For example the conductive elements 51 of the electrical interconnect arrangement 50 may extend across a portion of the intermediate component 30 to contacts through which the electronic component 12 will make electrical contact with the conductive elements 51 of the electrical interconnect arrangement. As illustrated in Fig. 5B, in some examples the electrical interconnect arrangement 50 extends across a portion of the intermediate component 30 and protrudes beyond the intermediate component to the contacts, facilitating future connection to the electronic component 12.

Returning to Fig. 4, the method proceeds to A2, wherein the actuator arrangement 40 of the initial assembly 50 is tested. Testing may comprise for example verifying reliable operation of the actuator arrangement 40 in one or more directions of movement. In addition, the electrical connections of the initial assembly 60 may be tested, such as the electrical interconnection arrangement.

The initial assembly 60 is representative of the final actuator assembly 2, albeit without the electronic component 12 attached. Testing the actuator arrangement 40 on the initial assembly 60 therefore approximates behaviour in the finished product. This allows any defects that previously would only have been noticed in the finished product to be identified before the electronic component 12 is attached. The electronic component 12 is likely the most expensive component of the actuator assembly 2, and so this approach reduces waste and costs associated with conventional assembly techniques.

Having tested the initial apparatus 60, the method of Fig. 4 proceeds to A3. At A3, the electronic component 12 is attached to the intermediate component 30, and electrical contact is made with the electrical interconnect arrangement 50, thereby forming the actuator assembly 2. The attachment may be achieved by any conventional technique, for example using adhesive and/or solder. In some examples the electronic component 12 is attached only if the test in A2 was successful. In some examples where the test at A2 is not successful, the initial assembly 60 is disposed of, or adjusted to correct the defect. Further testing may be carried out after the electronic component 12 has been attached.

Figs. 6a-6b illustrate application of the method of Fig. 4 to an actuator assembly 2 with a flexible PCB as the electrical interconnect arrangement 50. For example the flexible PCB may be of the form shown in Fig. 3. Figs. 6a-6b illustrate a cross-sectional view of only one side of an actuator assembly 2. As will be appreciated, the actuator assembly 2 may additional components attaching the other side of the intermediate component 30 to the support structure 4 via the actuator arrangement 40, for example as illustrated in Fig. 1.

Figs. 6a and 6b illustrate providing an initial assembly 60, in accordance with Al of the method of Fig. 4. In Fig. 6a a first part is provided, comprising a support component 4, actuator arrangement 40, and intermediate component 30, similar to those discussed above. Separately, an electrical interconnect arrangement 50 formed of a flexible PCB is provided. In step 6b, the electrical interconnect arrangement 50 is attached to the intermediate component 30. In particular, the first end 53 of the flexible PCB may be attached to the intermediate component 30. Although not illustrated in the figure, a second end 54 of the flexible PCB is attached or electrically connected to the support component 4. The combination of the first part and the electrical interconnect arrangement 50 provides the initial apparatus 60. The initial apparatus 60 is tested as described above. Then, as shown in Fig. 6c, an electrical component 12 is attached to the initial apparatus 60. In the illustrated figure, the electrical component 12 is physically attached to the intermediate component 30 so that is supported by the intermediate component, and electrically connected to a contact 52 of the flexible PCB.

Attaching an electronic component

Fig. 7 illustrates a method of attaching an electronic component 12 in an aligned manner to an intermediate component 30 of an actuator assembly 2. The method may be used to attach the electronic component 12 in A3 of the method of Fig. 4. Alternatively the method of Fig. 7 may be used to attach an electronic component 12 for an actuator assembly 2 that is not produced using the method of Fig. 4.

Fig. 8 illustrates a conventional approach for attaching an electronic component 12 to an intermediate component 30 of an actuator assembly 2. Although not illustrated, the actuator assembly 2 further comprises a support structure 4 and an actuator assembly 40. Any of the electronic component 12, intermediate component 30, support structure 4, and actuator assembly 40 may take the form of any of the corresponding components described above in relation to Figs. 1-3, and in the referenced documents.

In the conventional approach illustrated in Fig. 8, the electronic component 12 comprises an electrical bridge component 14. The electrical bridge component 14 is a stiff component that is typically preattached to the electronic component 12. The electrical bridge component is intended to be soldered to an electrical contact 52 of the intermediate component 30, which in turn provides an electrical connection through to the support structure 4. An adhesive 16 is used to provide a physical attachment between the electrical component 12 and the intermediate component 30. Typically, the adhesive 16 is a UV curable adhesive. This allows the electronic component 30 to be manoeuvred into position before being fixed in place by the UV cure. This may be used to align the electronic component 30 as required for its function. For example, where the electronic component 12 is an image sensor, and the actuator assembly 2 is part of a camera apparatus, the electronic component 12 may require aligning with an optical axis of the camera apparatus. WO2018073585 Al, which is incorporated herein by reference, discloses such methods of attaching an electronic component 12.

To make a good electrical connection, the gap between the electrical bridge component 14 and the contact 52 of the intermediate component 30 should be minimised. In Fig. 8 this gap is represented by the double headed arrow. However, an alignment process such as that for an image sensor can require a height adjustment of 0.15mm or more at the electrical connection site. This means that a nominal clearance between the connection components of at least 0.15mm is required, which can increase to 0.3mm. In isolation, this depth of gap could be tolerated by a soldering process. However, in many cases the electronic component 12 will require plural electrical connections to the intermediate component 30. In the case of attaching an image sensor to an actuator interconnect there will be many more connections, and so the area of each contact and the gap between them is reduced, making the soldering process more difficult. Furthermore, the style of connection used in the conventional approaches is a corner joint which is not very space efficient. The lap joint illustrated in Fig. 8 is more space efficient but may not be as tolerant of component misalignment.

As discussed above, it is preferable to incorporate an electrical interconnect arrangement 50 into the actuator assembly 2 to allow testing prior to attachment of the electronic component 12. However, this can make the process of latterly attaching the electrical device more difficult, potentially causing yield loss if using the conventional soldering methods. This is especially true for devices which have many, small electrical contacts which would not normally be connected in this way. The method of Fig. 7 simplifies the electrical connection of the electronic component 50 to the electrical interconnect component 50 and makes it more tolerant to dimensional and alignment errors, therefore reducing the yield loss of the attachment process.

Fig. 9a illustrates an example of an actuator assembly 2 in which the electronic component 12 has been attached using the method of Fig. 7. As with the actuator assemblies 2 described above, the actuator assembly 2 comprises a support component 4 (not illustrated in Fig. 9a), an intermediate component 30, and an electronic component 12. An actuator arrangement 40 comprising shape memory alloy wires 41 (not illustrated in Fig. 9A) is arranged to move the intermediate component 30 relative to the support component 4. An electrical interconnect arrangement 50 comprising conductive elements 51 extend from the support component 4 to the intermediate component 30 for providing an electrical connection to the electronic component 12. Any of these components may take the form of any of the corresponding components discussed above in relation to Figs. 1-6. The actuator assembly 2 may be an actuator assembly according to any of the examples discussed above in relation to Figs. 1-6.

One of the electronic component 12 and conductive elements 51 of the electrical interconnect arrangement 50 comprises plural contacts 52 and the other of the electronic component 12 and the conductive elements of the electrical interconnect arrangement 50 comprises plural flexible connectors 54. In the example illustrated in Fig. 9a, the electrical interconnect arrangement 50 comprises plural contacts 52. The electrical component 12 comprises plural flexible connectors 54. For clarity only one contact 52 and flexible connector 54 is illustrated in Fig. 9a, but it is to be appreciated that there may be further contact-connector pairs at other positions on the electronic device 12, for example on multiple sides of the electronic device 12.

The flexible connector 54 replaces the rigid electrical bridge 14 shown in Fig. 8. The flexible connector provides a compliant electrical contact, and, for example, may be thinner than the electrical bridge 14. The flexible connector 54 may be made from a thin sheet of electrically conductive material, for example: copper, phosphor bronze, beryllium copper, copper nickel tin, copper titanium or steel. This flexible connector 54 may be plated with a very thin layer of gold or perhaps silver or tin. The length, thickness and/or material choice of the flexible connector 54 may be selected to allow it to deflect up to the range of misalignment without breaking. In the case of the image sensor discussed above this may be +/-0.15mm = 0.3mm. In other examples the flexible connectors 54 may allow deflection of 0.15mm or more, or 0.3mm or more, or 0.5mm or more, or 0.7mm or more, or 1mm or more. The width may be adjusted to increase the connection force to a suitable level. The flexible connectors 54 therefore allow movement of the electronic component 12, for example during an alignment process, reducing the risk of failures. The flexible connectors 54 may be separate components attached to the other of the electronic component 12 and conductive elements 51 prior to assembly of the actuator assembly 2. In the example illustrated in Fig. 9a, the flexible connectors 54 are attached to, and in contact with, contacts 18 of the electronic component 12. In other examples the flexible connectors 54 are attached to, and in contact with, contacts of the conductive elements 51 of the electrical interconnect arrangement 50.

Initially, the electronic component 12 is not attached to the rest of the actuator assembly 12. The method of Fig. 7 starts at Bl, comprising initially positioning the electronic component 12 on the intermediate component 30 with the flexible connectors 54 in contact with the contacts 52 of said one of the electronic component 12 and the conductive elements 51 of the electrical interconnect arrangement 50. Thus in the illustrated example, the electronic component 12 is initially positioned with the flexible connectors 54 in contact with the contacts 52 of the electrical interconnect arrangement 50.

During this initial positioning, an adhesive 16 may be placed attaching the electronic component 12 to the intermediate component 30. The adhesive 16 allows movement of the electronic component 12 during an alignment step, but subsequently fixes the electronic component 12 in place. For example the adhesive 16 may be a curable adhesive, such as a UV curable adhesive.

The method of Fig. 7 then proceeds to B2, comprising aligning the electronic component 12 with respect to the support component 4 while maintaining the flexible connectors 54 in contact with the contacts 52 of said one of the electronic component 12 and the conductive elements 51 of the electrical interconnect arrangement 50 by flexing the flexible connector 54.

Fig. 9a illustrates the electronic component 12 aligned in a nominal position. This may for example be an initial position attempted, as in Bl of the method. The same actuator assembly 2 is shown in Figs. 9b and 9c in alternative alignment positions. Fig. 9b shows an example of the electronic component 12 maximally misaligned with respect to the intermediate component 30. Fig. 9c shows the electronic component 12 with minimal misalignment with respect to the intermediate component 30.

In some examples, the flexible connectors 54 are biased towards the contacts 52, providing a loading that maintains an electrical connection between the contacts 52 and flexible connectors even as the electronic component 12 moves. In the illustrated example the flexible connector 54 is pressed against the contact 52 via a preload in the flexible connector 54. This preload may be created either by preforming the flexible connector 54, or by offsetting the flexible connector 54 from the contact 52. Then when the components are aligned, they interfere and deflection of the flexible connector 54 is created which imposes this internal pre-stress. In some examples, the contacts may themselves comprise flexible connectors.

In some examples, the alignment of the electronic component 12 may be based on a signal received from the electronic component 12 itself. For example, where the electronic component 12 is an image sensor, the signal may represent an image captured on the image sensor. This can be used for example to align the image sensor with an optical axis of a camera apparatus into which the actuator assembly 2 is incorporated. This may be an automated process, referred to as an automated alignment (AA) process. The signal received from the electronic component 12 may be output through the flexible connectors 54, avoiding the need for additional contacts during the alignment process. Further, power may be provided to the electronic device 12 through the flexible connectors 54, allowing the electronic device to be powered during an alignment process. Thus in some examples B2 of the method comprises providing power to the electronic component 12 and receiving signals from the electronic component 12 through the contacts 52 and the flexible connectors 54, and aligning the electronic component 12 on the basis of the signals received from the electronic component.

Once the electronic component 12 has been aligned, the method proceeds to B3, wherein the electronic component 12 is attached to the intermediate component 30. For example, this may comprise curing or otherwise setting the adhesive 16. Alternatively or additionally other attachment means may be used to attach the electronic component 12 to the intermediate component 30, such as mechanical arrangements.

In some examples, once the electronic device 12 has been aligned, the method further comprises applying solder to the contacts 52 and the flexible connectors 54, to secure the respective electrical connections. Solder may be applied either before or after attaching the electronic component 12 to the intermediate component 30 in B3. In other examples solder may not be used. For example, the biasing force of the flexible connectors 54 themselves may provide sufficient connection between the contacts 52 and flexible connectors 54.

In general, the process of initially positioning, aligning, and attaching the electronic device 12 may use any of the techniques discussed in WO2018073585 Al, which is incorporated herein by reference.

Applications

Although many of the above examples relate to use of the disclosed actuator assemblies 2 in a camera, the actuator assemblies 2 may equally be used in any application in which a movable electronic component 12 must be moved relative to a static component. For example, the actuator assemblies 2 could be used to connect an illumination source that is moved, for example for the purposes of 3D scanning or as part of a head-mounted display.

Camera apparatus

An example camera apparatus 1 that incorporates an actuator assembly 2 in accordance with any examples of the present disclosure is shown in Fig. 10. Fig. 10 is a cross-sectional view taken along the optical axis O. In the depicted example, the actuator assembly 2 is a sensor shift assembly. The camera apparatus 1 is to be incorporated in a portable electronic device such as a mobile telephone or tablet computer. Thus, miniaturisation is an important design criterion.

The camera apparatus 1 comprises a lens assembly 20 that is assembled with the actuator assembly 2 by being mounted to the support component 4. The actuator assembly 2 comprises an electronic component 12. In this case the electronic component 12 comprises an image sensor 6 attached to a PCB 9. The image sensor 6 has a light sensitive region 12.

The lens assembly 20 comprises a lens carriage 21 in the form of a cylindrical body that is mounted to the rim portion of the support component 4. The lens carriage 21 supports at least one lens arranged along the optical axis O. In general any number of one or more lenses may be provided. Without limitation to the invention, in this example the camera apparatus 1 is a miniature camera in which the at least one lens (i.e. each lens if plural lenses are provided) typically have a diameter of at most 10mm or 15mm or 20mm. The at least one lens of the lens assembly 20 is arranged to focus an image onto the image sensor.

In this example, at least one lens is supported on the lens carriage 21 in a manner in which at least one lens is movable along the optical axis O relative to the lens carriage 21, for example to provide focussing or zoom, although that is not essential. In particular, the at least one lens is fixed to a lens holder 23 which is movable along the optical axis O relative to the lens carriage 21. Where there are plural lenses, any or all of the lenses may be fixed to the lens holder 23 and/or one or more of the lenses may be fixed to the lens carriage 21 and so not movable along the optical axis O relative to the lens carriage 21.

An axial actuator arrangement 24 provided between the lens carriage 21 and the lens holder 23 is arranged to drive movement of the lens holder 21 and lenses along the optical axis O relative to the lens carriage 21. The axial actuator arrangement 24 may be any suitable type, for example being a voice coil motor (VCM) or an arrangement of SMA wires, such as is described in WO-2019/243849 which is incorporated herein by reference.

In addition, the camera apparatus 1 may comprise a can 15 fixed to the support component 4 and protruding forwardly therefrom to encase and protect the other components of the camera apparatus 1.

As discussed above, in operation the SMA wires 40 are selectively driven to move the image sensor assembly 12 in any direction laterally and/or to rotate the image sensor assembly 12 about an axis parallel to the optical axis O. This is used to provide optical image stabilisation (OIS), compensating for image movement of the camera apparatus 1, caused by for example hand shake.

Relative movement of the image sensor 6 relative to the support component 4 and hence also relative to the lens assembly 20 may be used to stabilise the image against tilting of the camera apparatus 1, i.e. rotation about axes extending laterally to the light-sensitive region 7. In addition, rotation of the image sensor 6 may be used to stabilise the image against rotation of the camera apparatus 1 around the optical axis O.

The SMA wires 40 are driven by the control circuit implemented in the IC chip 30. In particular, the control circuit generates drive signals for each of the SMA wires 40 and supplies the drive signals to the SMA wires 40.

The control circuit 30 receives the output signals of the gyroscope sensor 31 which acts as a vibration sensor. The gyroscope sensor 31 detects the vibrations that the camera apparatus 1 is experiencing and its output signals represent those vibrations, specifically as the angular velocity of the camera lens element 20 in three dimensions. More generally, larger numbers of gyroscopes or other types of vibration sensor could be used.

The drive signals are generated by the control circuit in response to the output signals of the gyroscope sensor 31 so as to drive movement of the image sensor assembly 12 to stabilise an image focused by the camera lens element 20 on the image sensor, thereby providing OIS. The drive signals may be generated using a resistance feedback control technique for example as disclosed in any of WO-2013/175197, WO- 2014/076463, WO 2012/066285, WO-2012/020212, WO-2011/104518, WO-2012/038703, WO 2010/089529 or WO-2010/029316, each of which is incorporated herein by reference.

The camera apparatus 1 may be incorporated into a portable electronic device, such as such as a mobile telephone or tablet computer. SMA

The above-described SMA actuator assemblies comprise at least one SMA element. The term 'shape memory alloy (SMA) element' may refer to any element comprising SMA. The SMA element may be described as an SMA wire. The SMA element may have any shape that is suitable for the purposes described herein. The SMA element may be elongate and may have a round cross section or any other shape cross section. The cross section may vary along the length of the SMA element. The SMA element might have a relatively complex shape such as a helical spring. It is also possible that the length of the SMA element (however defined) may be similar to one or more of its other dimensions. The SMA element may be sheet-like, and such a sheet may be planar or non-planar. The SMA element may be pliant or, in other words, flexible. In some examples, when connected in a straight line between two components, the SMA element can apply only a tensile force which urges the two components together. In other examples, the SMA element may be bent around a component and can apply a force to the component as the SMA element tends to straighten under tension. The SMA element may be beam-like or rigid and may be able to apply different (e.g. non-tensile) forces to elements. The SMA element may or may not include material(s) and/or component(s) that are not SMA. For example, the SMA element may comprise a core of SMA and a coating of non-SMA material. Unless the context requires otherwise, the term 'SMA element' may refer to any configuration of SMA material acting as a single actuating element which, for example, can be individually controlled to produce a force on an element. For example, the SMA element may comprise two or more portions of SMA material that are arranged mechanically in parallel and/or in series. In some arrangements, the SMA element may be part of a larger SMA element. Such a larger SMA element might comprise two or more parts that are individually controllable, thereby forming two or more SMA elements. The SMA element may comprise an SMA wire, SMA foil, SMA film or any other configuration of SMA material. The SMA element may be manufactured using any suitable method, for example by a method involving drawing, rolling or deposition and/or other forming process(es). The SMA element may exhibit any shape memory effect, e.g. a thermal shape memory effect or a magnetic shape memory effect, and may be controlled in any suitable way, e.g. by Joule heating, another heating technique or by applying a magnetic field.