TECHNICAL FIELD

The disclosure relates to a haptic feedback arrangement comprising a chamber enclosing a propagation medium, a wall of the chamber being formed by an elastic membrane configured to provide haptic feedback to a user in response to propagation of a shear wave in the propagation medium.

BACKGROUND

Haptic or tactile feedback is widely used in electronic apparatuses, even in apparatuses used for creating a simulated or virtual environment, for providing cues alerting a user of specific events or to provide realistic feedback sensations to create a greater sensory experience. In order to generate such haptic effects, different types of actuators can be utilized to stimulate the skin at a specific place of contact with a device interaction surface. Actuators are used to generate haptic effects by means of specifically shaped surface oscillation, pattern of signals, or interference of multiple signals in a specific way to integrate them effectively and efficiently in a particular contact location or to dynamically cancel haptic feedback in certain areas of the interaction surface.

For regular consumer-grade electronic apparatuses, multiple signal interference may be achieved by mapping the propagation of vibration signals in a given range of the haptic spectrum. However, when neglecting the effect of mechanical energy propagation, from the actuator to specific receptors the magnitude of tactile signals is attenuated, making the tactile signals weak and less informative than expected.

Furthermore, the skin at the fingertip has been shown to experience a nonlinear increase in stiffness when pressure is applied against a contact surface, until a maximum skin indentation of approximately 3 mm. Gentle and sophisticated tactile signals are therefore useless when the fingertip contacts a flat rigid surface such as a touchscreen. Hence, it is difficult, if not impossible, to provide effective and efficient stimulation of skin receptors by transmitting mechanical signals in a wide range of frequencies through a stiff display. Therefore, designers have attempted to improve the conditions for mechanical energy propagation of the stimuli to the skin receptors, and to develop elastic skin-compliant overlays for interaction surfaces as a mediator of tactile signals. For example, deformable transparent display overlays have been designed to detect the pressure and the position of the user's fingertip on an otherwise stiff display.

Other solutions comprise a reservoir filled with a liquid. At least one side of the reservoir comprises a flexible membrane, and the haptic output device also comprises actuators in physical contact with the reservoir and configured to impart pressure waves to the liquid. The pressure waves interact with the flexible membrane to supply a haptic effect to a user.

Liquid media such as gel, oil, or synthetic fluids, when used within the interface, introduce the problem of haptic signal distortion due to seismic shear waves being easily generated in the liquid media. Liquid media such as electro-rheological and magneto-rheological fluids have at least theoretically been considered useful to dynamically adjust the properties of the fluid to control wave propagation. Nevertheless, this would be a power-consuming solution that is not ready to be applied for portable devices such as smartphones, tablets, or wearables.

Hence, there is a need for providing an improved haptic feedback arrangement that is suitable for portable electronic apparatuses.

SUMMARY

It is an object to provide an improved haptic feedback arrangement. The foregoing and other objects are achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description, and the figures.

According to a first aspect, there is provided a haptic feedback arrangement comprising a chamber enclosing a two-phase propagation medium, the propagation medium comprising a plurality of first phase inclusions being dispersed in a second fluid phase, the first phase and the second phase of the propagation medium being configured to allow propagation of at least one shear wave within the chamber along a first axis, a wall of the chamber being formed by an elastic membrane, the elastic membrane being configured to provide haptic feedback to a user in response to propagation of the shear wave(s). A first actuator is operably connected to the chamber and configured to generate a first shear wave in the propagation medium. A restricting element is arranged within the chamber and configured to control microdisplacement and/or oscillation of the first phase inclusions, and a second actuator is operably connected to the restricting element. The second actuator is configured to move the restricting element from a first position to a second position along a second axis, the second axis extending perpendicular to the first axis. The restricting element is configured to, when in the first position, allow microdisplacement and/or oscillation of the first phase inclusions in directions parallel to the second axis and/or in directions parallel to the first axis within the second phase, hence allowing propagation of the shear wave(s) along the first axis. The restricting element is also configured to, when in the second position, at least partially prevent microdisplacement and/or oscillation of the first phase inclusions within the second phase, hence diminishing propagation of the shear wave(s) along the first axis. Hence, the movement of the restricting element between the first position and the second position controls the haptic feedback provided to the user.

Such a solution allows attenuating undesired seismic signals while providing more accurate and adaptable haptic stimuli to a user, enhancing the response of human skin to vibrational stimulation. The solution is responsive and efficient in terms of power consumption.

In a possible implementation form of the first aspect, the control of microdisplacement and/or oscillation of the first phase inclusions comprise the restricting element physically engaging and disengaging the first phase inclusions, providing a simple, reliable, and adaptable way of controlling seismic wave(s) propagation.

In a further possible implementation form of the first aspect, the first axis, a main plane of the elastic membrane, and a main plane of the restricting element extend in parallel, facilitating an as thin arrangement as possible.

In a further possible implementation form of the first aspect, the elastic membrane forms a first main barrier surface of the chamber and wherein the restricting element is arranged adjacent a second main barrier surface when the restricting element is in the first position, the second main barrier surface extending parallel to the first main barrier surface, facilitating an as thin arrangement as possible. In a further possible implementation form of the first aspect, the elastic membrane provides haptic feedback by being in tactile contact with a user, facilitating a simple and effective way of providing stimuli to a user’ s skin.

In a further possible implementation form of the first aspect, the haptic feedback arrangement further comprises a third actuator operably connected to the chamber and configured to generate a second shear wave in the propagation medium, the first actuator and the third actuator being operably connected to opposite ends of the chamber, the first shear wave and the second shear wave propagating in opposite directions along the first axis. The provision of two actuators allows the creation of constructive wave interference along the length of the chamber.

In a further possible implementation form of the first aspect, the third actuator is configured to generate the second shear wave independently of, or simultaneously with, the generation of the first shear wave, providing maximum flexibility to the arrangement.

In a further possible implementation form of the first aspect, the first shear wave and the second shear wave interfering constructively when generated simultaneously, enhancing the effectiveness of the arrangement.

In a further possible implementation form of the first aspect, the first phase is at least partially interlocked between the elastic membrane and the restricting element when the restricting element is in the second position, providing a simple and reliable solution for controlling the microdisplacement and/or oscillation-of the first phase inclusions and, as the result, seismic wave(s) propagation.

In a further possible implementation form of the first aspect, the first phase is configured to oscillate freely within the second phase when the restricting element is in the first position, allowing free propagation of shear waves in the propagation medium.

In a further possible implementation form of the first aspect, the first phase has a density which is lower than the density of the second phase, allowing the first phase inclusions to naturally gather closer to the elastic membrane and hence increasing the responsiveness of the arrangement. In a further possible implementation form of the first aspect, the first phase being closer to the first main barrier surface of the chamber than the second main barrier surface of the chamber when the restricting element is in the first position due to the lower density.

In a further possible implementation form of the first aspect, the first phase comprises a plurality of solid particles and the second phase comprises a fluid, facilitating maximum propagation of shear waves as well as simple and immediate stoppage of the propagation.

In a further possible implementation form of the first aspect, the fluid is incompressible and has a linear stress-to-strain response within the pressure range of the first actuator, facilitating adequate transmission of seismic waves.

In a further possible implementation form of the first aspect, the fluid is a liquid, a gel, or an oil.

In a further possible implementation form of the first aspect, the fluid is an electrostatic fluid.

In a further possible implementation form of the first aspect, each inclusion comprises at least one curved surface, such that the inclusion has minimum impact on seismic shear wave propagation when freely displaceable while creating turbulence, hence attenuating the seismic shear waves, when displacement is prevented.

In a further possible implementation form of the first aspect, the inclusions have identical shapes, the shape preferably being one of spherical, cylindrical, conical, ellipsoidal, or freeform, facilitating both propagation and attenuation of shear waves.

In a further possible implementation form of the first aspect, a center axis of a cylindrical inclusion or a conical inclusion extends parallel to the second axis, facilitating an as thin arrangement as possible.

In a further possible implementation form of the first aspect, the inclusions are arranged in at least one layer extending parallel to the elastic membrane and the restricting element. In a further possible implementation form of the first aspect, the restricting element is one of a solid plate, a mesh element, and a membrane.

In a further possible implementation form of the first aspect, the restricting element is less elastic than the elastic membrane, facilitating secure interlocking of inclusions.

In a further possible implementation form of the first aspect, the restricting element is configured to divide the chamber into a first sub-volume and a second sub-volume, the first phase of the propagation medium being arranged in the first sub-volume only and the second phase of the propagation medium being arranged in at least the first sub-volume, the first sub volume having a first size when the restricting element is in the first position and a second size when the restricting element is in the second position, the second size being smaller than the first size.

In a further possible implementation form of the first aspect, the restricting element comprises a plurality of recesses, each recess being configured to engage one inclusion when the restricting element is in the second position, the engagement limiting or preventing microdisplacement or/and oscillations of the inclusions along the first axis and/or the second axis. This facilitates an increase in the range and accuracy of the inclusion microdisplacement.

In a further possible implementation form of the first aspect, a predefined inclusion engages a predefined recess, providing additional and/or adaptable interlocking of the inclusions.

In a further possible implementation form of the first aspect, the haptic feedback arrangement further comprises a first driver configured to drive the first actuator, a second driver configured to drive the second actuator, and optionally a third driver configured to drive the third actuator.

In a further possible implementation form of the first aspect, the first actuator, the second actuator, and optionally the third actuator is one of a piezoelectric actuator, an ultrasonic actuator, an electrostatic actuator, an electromagnetic actuator, a thermal actuator, and a pneumatic actuator.

In a further possible implementation form of the first aspect, at least one of the restricting element, the first phase of the propagation medium, and the second phase of the propagation medium comprises an electroactive material, a photoactive material, a temperature active material, and a magnetoactive material.

In a further possible implementation form of the first aspect, at least one of the restricting element, the first phase of the propagation medium, and the second phase of the propagation medium comprises magnetoactive material, and the second actuator is a voice coil actuator, allowing the arrangement to be operated without mechanical linkage being necessary.

In a further possible implementation form of the first aspect, the first actuator and optionally the third actuator is a linear actuator configured to actuate along the first axis, and the second actuator is a linear actuator configured to actuate along the second axis.

In a further possible implementation form of the first aspect, the haptic feedback arrangement further comprises at least one sensor element configured to detect haptic feedback provided by the elastic membrane to a user in response to propagation of the shear wave(s), improving the responsiveness of the arrangement.

According to a second aspect, there is provided a tactile apparatus comprising the haptic feedback arrangement according to the above, the elastic membrane of the haptic feedback arrangement forming a tactile interface configured to be in direct physical contact with a user. This solution allows for more accurate and adaptable stimuli to be provided to a user, enhancing the response of human skin to vibrational stimulation. The solution is responsive and efficient in terms of power consumption.

In a possible implementation form of the second aspect, the haptic feedback arrangement is one of part of a display panel of the apparatus and a cover layer applied onto a display panel of the apparatus, reducing the number of components required at final assembly.

These and other aspects will be apparent from the embodiment s) described below.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following detailed portion of the present disclosure, the aspects, embodiments, and implementations will be explained in more detail with reference to the example embodiments shown in the drawings, in which: Fig. 1 shows a schematic view of a tactile apparatus comprising a haptic feedback arrangement in accordance with an example of the embodiments of the disclosure;

Fig. 2 shows a schematic view of a tactile apparatus comprising a haptic feedback arrangement in accordance with an example of the embodiments of the disclosure;

Fig. 3 shows a schematic view of a tactile apparatus comprising a haptic feedback arrangement in accordance with an example of the embodiments of the disclosure;

Fig. 4a shows a schematic view of a tactile apparatus comprising a haptic feedback arrangement in accordance with an example of the embodiments of the disclosure;

Fig. 4b shows a schematic top view of the restricting element of the haptic feedback arrangement shown in Fig. 4a.

DETAILED DESCRIPTION

Fig. 1 shows a tactile apparatus 15, such as a smartphone, tablet, or wearable, comprising a haptic feedback arrangement 1 described in more detail further below. The haptic feedback arrangement 1 comprises an elastic membrane 5 forming a tactile interface configured to be in direct physical contact with a user U, such as an outer surface of a display panel. The haptic feedback arrangement 1 may be part of the display panel or be a separate cover layer applied onto the display panel.

The haptic feedback arrangement 1 comprises a chamber 2 enclosing a two-phase propagation medium, the propagation medium comprising a plurality of first phase 3 inclusions being dispersed in a second fluid phase 4. The first phase 3 and the second phase 4 of the propagation medium are configured to allow propagation of at least one shear wave S within chamber 2 along a first axis Al. A wall of the chamber 2 is formed by an elastic membrane 5, the elastic membrane 5 being configured to provide haptic feedback to a user U in response to propagation of the shear waves S. A first actuator 6 is operably connected to chamber 2 and configured to generate a first shear wave S in the propagation medium. A restricting element 7 is arranged within chamber 2 and configured to control microdisplacement and/or oscillation of the first phase 3 inclusions. A second actuator 8 is operably connected to the restricting element 7. The second actuator 8 is configured to move the restricting element 7 from a first position PI to a second position P2 along a second axis A2, the second axis A2 extending perpendicular to the first axis Al. The restricting element 7 is configured to, when in the first position PI, allow microdisplacement and/or oscillation of the first phase 3 inclusions in directions parallel to the second axis A2 and/or in directions parallel to the first axis Al within the second phase 4, hence allowing propagation of the shear waves S along the first axis Al. The restricting element 7 is also configured to, when in the second position P2, at least partially prevents microdisplacement and/or oscillation of the first phase 3 inclusions within the second phase 4, hence diminishing, i.e. attenuating or reducing, propagation of the shear waves S along the first axis Al. The movement of the restricting element 7 between the first position PI and the second position P2 controls the haptic feedback provided to the user U.

As shown in Figs. 1 to 4a, the haptic feedback arrangement 1 comprises a closed chamber 2, one wall, or side, of the chamber 2 being formed by an elastic membrane 5, described in more detail further below.

Chamber 2 is configured to enclose a two-phase propagation medium, the medium comprises material in a first phase 3, optionally a solid phase, and in a second phase 4, optionally a liquid phase. As shown in Figs. 1 to 4a, the propagation medium comprises a plurality of inclusions in a first phase 3 which are dispersed in a second phase 4 which is a fluid phase. The fluid may be a liquid, a gel, or an oil. Fluid 4 may be an electrostatic fluid.

The first phase 3 may comprise a plurality of inclusions such as solid particles. Each inclusion may comprise at least one curved surface. The inclusions may have identical shapes, the shape preferably being one of spherical, as shown in Figs. 1 and 2, cylindrical, as shown in Fig. 3, conical, as shown in Fig. 4a, ellipsoidal (not shown), or freeform (not shown). The curved shape has a minimum impact on seismic shear wave propagation when the inclusions can follow the shear waves S freely. However, when their microdisplacement and/or oscillation are controlled and/or prevented, the inclusions create turbulence behind them, attenuating the seismic shear waves S. Preferably, a center axis of a cylindrical inclusion or a conical inclusion extends parallel to the second axis A2. The inclusions may be arranged in at least one layer extending parallel to the elastic membrane 5 and with a restricting element 7 arranged within chamber 2.

The first phase 3 and the second phase 4 are preferably different phases. Optionally, the first phase 3 and the second phase 4 comprise different materials with different densities. The first phase 3 may have a density that is lower than the density of the second phase 4. The first phase 3 inclusions are dispersed evenly, or unevenly, throughout the second fluid phase 4.

The first phase 3 inclusions may be configured to follow the shear waves S as long as their microdisplacement and/or oscillation are not limited by the sides of chamber 2 or the restricting element 7. The microdisplacement and/or oscillation of the first phase 3 inclusions may be limited due to high friction between the first phase 3 inclusions and the restricting element 7 and/or between the first phase 3 inclusions and the inner surface of the elastic membrane 5. This helps to immediately fixate or immobilize the first phase 3 inclusions at an end position along the second axis A2.

The first phase 3 and the second phase 4 of the propagation medium are configured to allow propagation of at least one shear wave S within chamber 2 along a first axis Al. A shear wave, also known as an S wave or a secondary wave, is an elastic wave moving through a body such as the two-phase propagation medium. S waves are transverse waves, i.e. the oscillations of the S wave's inclusions are perpendicular to the direction of wave propagation. In other words, the shear wave S propagates within chamber 2 along the first axis Al, and the shear wave S oscillates, i.e. has an amplitude as shown in Figs. 1 to 4a, along an axis A2 which is perpendicular to the first axis Al . The oscillations of the shear wave S can be detected by the user U as haptic feedback, intentionally or unintentionally.

A first actuator 6 is operably connected to chamber 2 and configured to generate a first shear wave S in the propagation medium. The second phase fluid 4 may be incompressible and have a linear stress-to-strain response within the pressure range of the first actuator 6.

A restricting element 7 is arranged within chamber 2 and configured to control microdisplacement and/or oscillation of the first phase 3 inclusions. The first axis Al, a main plane Ml of the elastic membrane 5, and a main plane M2 of the restricting element 7 may extend in parallel. The control of microdisplacement and/or oscillation of the first phase 3 inclusions may comprise the restricting element 7 physically, electrically, or magnetically engaging and disengaging the first phase 3 inclusions. The movement of the restricting element 7 between a first position PI and a second position P2, along the second axis A2 which extends perpendicular to the first axis Al, controls the haptic feedback provided to the user U.

A second actuator 8 is operably connected to the restricting element 7, and is configured to move the restricting element 7 between the first position PI and the second position P2 along the second axis A2, as shown in Figs. 1 to 4a. The second actuator 8 may be separate from the restricting element 7 or embedded in or fully integrated with the restricting element 7.

The restricting element 7 is configured to, when in the first position PI, allow microdisplacement and/or oscillation of the first phase 3 inclusions in directions parallel to the second axis A2 and/or in directions parallel to the first axis Al within the second phase 4, hence allowing propagation of the shear waves S along the first axis Al.

Furthermore, the restricting element 7 is configured to, when in the second position P2, at least partially prevent microdisplacement and/or oscillation of the first phase 3 inclusions within the second phase 4, hence diminishing i.e. attenuating or reducing, propagation of the shear waves S along the first axis Al.

A third actuator 10 may be operably connected to chamber 2, as shown in Fig. 2, and may be configured to generate a second shear wave S in the propagation medium, the first actuator 6 and the third actuator 10 being operably connected to opposite ends of the chamber 2, the first shear wave S and the second shear wave S propagating in opposite directions along the first axis Al. The third actuator 10 may be configured to generate the second shear wave S independently of, or simultaneously with, the generation of the first shear wave S. The first shear wave S and the second shear wave S may interfere constructively, as suggested in Fig. 2, when generated simultaneously.

The first actuator 6 and optionally the third actuator 10 may be a linear actuator configured to actuate along the first axis Al, and the second actuator 8 may be a linear actuator configured to actuate along the second axis A2. The first actuator 6 and the third actuator 10 may be arranged at opposite ends of chamber 2, actuating linearly in opposite directions along the first axis Al. The flexible elastic membrane 5 is configured to provide haptic feedback to the user U in response to the propagation of the shear waves S, when being in tactile contact with the user U. In other words, the elastic membrane 5 may deform to the shapes or patterns of seismic shear waves S that travel through the propagation medium from the first actuator 6 and optionally the third actuator 10 to the place of contact with the skin of the user U.

The haptic feedback arrangement 1 may comprise at least one sensor element (not shown) configured to detect such haptic feedback provided by the elastic membrane 5 to the user U. The elastic membrane 5 may form a first main barrier surface of the chamber 2, and a second main barrier surface 9 may extend parallel to the first main barrier surface 5. The restricting element 7 may be arranged adjacent the second main barrier surface 9 when the restricting element 7 is in the first position PI, as shown in Figs. 1 to 3. The first phase 3 may be configured to oscillate freely within the second phase 4, along the first axis A1 and/or the second axis A2, when the restricting element 7 is in the first position PI. The first phase 3 may also extend closer to the elastic membrane/first main barrier surface 5 of chamber 2 than the second main barrier surface 9 of chamber 2 when the restricting element 7 is in the first position PI due to a lower density, as suggested in Figs. 1 to 3.

The restricting element 7 may be arranged more towards the elastic membrane/first main barrier surface 5 when the restricting element 7 is in the second position P2, as shown in Fig. 4a. The first phase 3 may be at least partially interlocked between the elastic membrane 5 and the restricting element 7 when the restricting element 7 is in the second position P2.

The restricting element 7 may be less elastic than the elastic membrane 5. The restricting element 7 may be one of a solid plate, a mesh element, and a membrane.

The restricting element 7 may be configured to divide chamber 2 into a first sub-volume and a second sub-volume, the first phase 3 of the propagation medium being arranged in the first sub volume only and the second phase 4 of the propagation medium being arranged in at least the first sub-volume. The first sub-volume has a first size when the restricting element 7 is in the first position PI and a second size when the restricting element 7 is in the second position P2, the second size being smaller than the first size. As shown in Fig. 4b, the restricting element 7 may comprise a plurality of recesses 11, each recess 11 being configured to engage one inclusion when the restricting element 7 is in the second position P2. The engagement limits or prevents microdisplacement or/and oscillations of the inclusions along the first axis A1 and/or the second axis A2. One predefined inclusion may be configured to engage one predefined recess 11. Preferably, the inclusion is a conical particle, the inclusion tapering along the second axis A2 in a direction towards the restricting element 7 and recess 11.

The haptic feedback arrangement 1 may further comprise a first driver 12 configured to drive the first actuator 6, a second driver 13 configured to drive the second actuator 8, and optionally a third driver 14 configured to drive the third actuator 10. The drivers may be controlled using synchronized signals, creating various haptic pattern envelopes with adjustable configurations of attacks and decays.

The first actuator 6, the second actuator 8, and optionally the third actuator 10 may be one of a piezoelectric actuator, an ultrasonic actuator, an electrostatic actuator, an electromagnetic actuator, a thermal actuator, and a pneumatic actuator.

At least one of the restricting element 7, the first phase 3 of the propagation medium, and the second phase 4 of the propagation medium may comprise an electroactive material, a photoactive material, a temperature active material, and a magnetoactive material. At least one of the restricting element 7, the first phase 3 of the propagation medium, and the second phase 4 of the propagation medium may comprise a magnetoactive material, the second actuator 8 being a voice coil actuator.

The various aspects and implementations have been described in conjunction with various embodiments herein. However, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed subject-matter, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. The reference signs used in the claims shall not be construed as limiting the scope. Unless otherwise indicated, the drawings are intended to be read (e.g., cross-hatching, arrangement of parts, proportion, degree, etc.) together with the specification, and are to be considered a portion of the entire written description of this disclosure. As used in the description, the terms “horizontal”, “vertical”, “left”, “right”, “up” and “down”, as well as adjectival and adverbial derivatives thereof (e.g., “horizontally”, “rightwardly”, “upwardly”, etc.), simply refer to the orientation of the illustrated structure as the particular drawing figure faces the reader. Similarly, the terms “inwardly” and “outwardly” generally refer to the orientation of a surface relative to its axis of elongation, or axis of rotation, as appropriate.