Actuator assembly

Abstract

An actuator assembly (14) comprises a first portion (4) and a second portion (15) movable relative to the first portion (4) in a first plane (16). The actuator assembly (14) further comprises a first set of one or more shape memory alloy wires (19) configured to move the second portion (15) relative to the first portion (4) in a first plane (16). The first set of shape memory alloy wires (19) is arranged such that a movement of the second portion (15) is amplified relative to a corresponding change in length of the first set of shape memory alloy wires (19). The actuator assembly (14) further comprises a third portion (17) movable relative to the second portion (15) in a second plane (18). The second plane (18) is parallel or coplanar with the first plane (16). The actuator assembly (14) also includes a second set of one or more shape memory alloy wires (22) configured to move the third portion (17) relative to the second portion (15) in a second plane (18). The second set of shape memory alloy wires (22) is arranged such that the movement of the third portion (17) is amplified relative to a corresponding change in length of the second set of shape memory alloy wires (22).

Description

field

[0001] The present application relates to actuator assemblies, and in particular to actuator assemblies including a plurality of segments of shape memory alloy (SMA) wire. background

[0002] Such an actuator assembly may, for example, be used in a camera to move a lens assembly in a direction perpendicular to the optical axis in order to provide optical image stabilization (OIS). Where such a camera is to be incorporated into a portable electronic device such as a mobile phone, miniaturization may be important.

[0003] WO 2019 / 086855 A1 describes a camera with an actuator assembly, which includes a supporting platform, a moving platform supporting a lens assembly, an SMA wire connected to the supporting platform and the moving platform, a support member supporting the moving platform on the supporting platform, and two arms extending between the supporting platform and the moving platform. Overview

[0004] According to a first aspect of the present invention, an actuator assembly is provided, the actuator assembly comprising a first part and a second part movable in a first plane relative to the first part. The actuator assembly also includes a first group of one or more shape memory alloy wires, which are configured to move the second part relative to the first part in the first plane. The first group of shape memory alloy wires is arranged so that the movement of the second part is amplified relative to the corresponding length change of the first group of shape memory alloy wires. The actuator assembly also includes a third part movable relative to the second part in a second plane. The second plane is parallel or coplanar with the first plane. The actuator assembly also includes a second group of one or more shape memory alloy wires, which are configured to move the third part relative to the second part in the second plane. The second group of shape memory alloy wires is arranged so that the movement of the third part is amplified relative to the corresponding length change of the second group of shape memory alloy wires.

[0005] Thus, movement of the third part relative to the first part is a combination of movement of the second part relative to the first part and movement of the third part relative to the second part.

[0006] The second portion may be coupled to the first portion via a first set of shape memory alloy wires, and the third portion may be coupled to the second portion via a second set of shape memory alloy wires.

[0007] The second portion may be constrained to move within a first plane. The second portion may be movable within the first plane parallel to the first axis and the second non-parallel axis. The first axis and the second axis may be orthogonal directions within the first plane. The third portion may be constrained to move within the second plane. The third portion may be movable in a pair of orthogonal directions within the second plane.

[0008] The actuator assembly may include a first support device between the first portion and the second portion. The first support device may be configured to constrain movement of the second portion relative to the first portion to a first plane. The actuator assembly may include a second support device between the third portion and the second portion. Alternatively, the actuator assembly may include a second support device between the third portion and the first portion. In either case, the second support device may be configured to constrain movement of the third portion relative to the second portion and / or relative to the first portion to a second plane.

[0009] By constraining the second / third part so that it cannot move directly in the contraction direction of the shape memory alloy wire in the corresponding first group / second group, the movement of the corresponding second / third part can be amplified relative to the corresponding length change of the shape memory alloy wire. The constraint that causes amplification can be provided by one or more other shape memory alloy wires in the corresponding first group / second group. The constraint that causes amplification can be provided by one or more elastic elements. The elastic element can include a spring or take the form of a spring. The elastic element can include a flexure or take the form of a flexure. The constraint that causes amplification can be provided by one or more supports. The constraint that causes amplification can be provided by a combination of two or more, one or more elastic elements, one or more springs, one or more flexures and one or more supports in other shape memory alloy wires in the corresponding first group / second group.

[0010] The second part can be movable relative to the first part in a first plane parallel to the first axis and a different second axis. These first and second axes can be orthogonal. The movement of the second part parallel to the first axis can be amplified by a greater multiple than the movement of the second part parallel to the second axis. Therefore, the first group of shape memory alloy wires can provide an asymmetric stroke magnification in the first plane, so that the movement of the second part parallel to the first axis is amplified by a greater multiple than the movement of the second part parallel to the second axis. This allows the first group of shape memory alloy wires to preferentially move the second part along the first axis.

[0011] The third portion can be movable relative to the second portion in a second plane parallel to the first axis and the second axis. The movement of the third portion parallel to the second axis can be amplified by a greater multiple than the movement of the third portion parallel to the first axis. Therefore, the second set of shape memory alloy wires can provide asymmetric stroke amplification in the second plane, so that the movement of the third portion parallel to the second axis is amplified by a greater multiple than the movement of the third portion parallel to the first axis. This allows the second set of shape memory alloy wires to preferentially move the third portion along the second axis.

[0012] Thus, a first set of shape memory alloy wires may be arranged to preferentially magnify along a first axis, and a second set of shape memory alloy wires may be arranged to preferentially magnify along a second axis.

[0013] Alternatively, the third portion may be movable relative to the second portion in the second plane parallel to third and fourth non-parallel axes. The third and fourth axes may be non-parallel to either of the first and second axes. Movement of the third portion parallel to the third axis is amplified by a greater factor than movement of the third portion parallel to the fourth axis.

[0014] The actuator assembly may also include a controller configured to control the selective contraction of the shape memory alloy wires in the first group and the second group so that the third portion moves a first component parallel to the first axis and a second component parallel to the second axis relative to the first portion. In particular, the controller may control the drive signals supplied to the shape memory alloy wires in the first group and the second group.

[0015] The control of the movement of the second part relative to the first part can be achieved by controlling the drive signal supplied to the first group of shape memory alloy wires. The control of the movement of the third part relative to the second part can be achieved by controlling the drive signal supplied to the second group of shape memory alloy wires. The drive signal can be current controlled. The drive signal can be voltage controlled.

[0016] The controller may be configured (at least in the first mode) such that the first component corresponds to movement of the second part relative to the first part and the second component corresponds to movement of the third part relative to the second part.

[0017] The first component can be provided by controlling the selective contraction of the first group of shape memory alloy wires so that the second part moves along the first axis in the first plane relative to the first part. The second component can be provided by controlling the selective contraction of the second group of shape memory alloy wires so that the third part moves along the second axis in the second plane relative to the second part. Therefore, the movement of the third part along the first axis can be fully controlled using the shape memory alloy wires of the first group, and the movement of the third part along the second axis can be fully controlled using the shape memory alloy wires of the second group. The controller can be configured to (at least in the first mode) control the contraction of the shape memory alloy wires so that the second part does not move or has only a negligible movement parallel to the second axis relative to the first part, and the third part does not move or has only a negligible movement parallel to the first axis relative to the second part.

[0018] Alternatively or additionally, the controller may be configured (at least in the second mode) such that within the first movement envelope, the first component corresponds to movement of the second part relative to the first part, and the second component corresponds to movement of the third part relative to the second part. The controller may also be configured (at least in the second mode) such that outside the first movement envelope and within the second movement envelope, the first component and / or the second component corresponds to movement of the second part relative to the first part combined with movement of the third part relative to the second part.

[0019] In other words, the first movement envelope is enclosed within the second movement envelope.The movement envelope corresponds to a trajectory of points to which the second portion can be moved relative to the first portion using the first and second sets of shape memory alloy wires.

[0020] Within the first movement envelope, the first component may correspond exclusively to movement of the second portion relative to the first portion. Within the first movement envelope, the second component may correspond exclusively to movement of the third portion relative to the second portion. In other words, within the first trajectory, the controller may isolate movement of the second portion and the third portion such that the second portion and the first set of shape memory alloy wires provide movement along the first axis, while the third portion and the second set of shape memory alloy wires provide movement along the second axis.

[0021] Outside the first movement envelope and within the second movement envelope, the first component may correspond to a superposition of movement of the second portion relative to the first portion and movement of the third portion relative to the second portion. Outside the first movement envelope and within the second movement envelope, the second component may correspond to a superposition of movement of the second portion relative to the first portion and movement of the third portion relative to the second portion. In other words, the drive circuit may be configured to extend the range of motion of the third portion (relative to the first portion) beyond the first movement envelope by combining movement of both the second portion and the third portion along the same axis.

[0022] For example, the first group of shape memory alloy wires can be configured to move the second portion (relative to the first portion) parallel to the first (x) axis and the second (y) axis. The first group of shape memory alloy wires can be configured to amplify the movement of the second portion parallel to the x axis rather than parallel to the y axis. The second group of shape memory alloy wires can also be configured to move the third portion (relative to the second portion) parallel to the x axis and the y axis. However, the second group of shape memory alloy wires can be configured to amplify the movement of the third portion parallel to the y axis rather than parallel to the x axis. In such an example, the first movement envelope can correspond to the position to which the third portion can be moved by moving the second portion only parallel to the x axis and moving the third portion only parallel to the y axis. The second movement envelope can correspond to the additional movement that can be obtained by adding the range of motion of the third portion parallel to the x axis (due to the second group of shape memory alloy wires) to the range of motion of the second portion parallel to the x axis and adding the range of motion of the second portion parallel to the y axis (due to the first group of shape memory alloy wires) to the range of motion of the third portion parallel to the y axis.

[0023] Additionally or alternatively, the controller may be configured (at least in the third mode) such that the first component includes or selectively is one of: i) a first movement of the second portion relative to the first portion parallel to the first axis, and ii) a second movement of the third portion relative to the second portion parallel to the first axis, the second movement being less than the first movement. The controller may also be configured (at least in the third mode) such that the second component includes or selectively is one of: i) a third movement of the third portion relative to the second portion parallel to the second axis, and ii) a fourth movement of the second portion relative to the first portion parallel to the second axis, the fourth movement being less than the third movement.

[0024] In this way, the controller can use the maximum amplification movement of the second and third parts, respectively, to provide relatively coarse movement, and use the less amplification movement of the second and third parts, respectively, to provide relatively fine movement, thereby moving the third part to a position relative to the first part. The controller can use both the maximum amplification movement and the less amplification movement in combination, for example to allow both high-travel movement (with maximum amplification movement) and fine control / precision movement.

[0025] Alternatively or additionally, the controller may selectively use either of the maximum amplification movement and the lesser amplification movement, for example depending on whether a relatively large movement or a relatively small movement is required. The controller may control the first component by controlling the first group of shape memory alloy wires when a relatively large movement along the first axis is required or by controlling the second group of shape memory alloy wires when a relatively small movement along the first axis is required. Similarly, the controller may control the second component by controlling the first group of shape memory alloy wires when a relatively small movement along the second axis is required or by controlling the second group of shape memory alloy wires when a relatively large movement along the second axis is required.

[0026] The controller may be configured to be switchable between at least two modes of a first mode, a second mode, and a third mode.

[0027] The actuator assembly can be arranged so that the contraction of each shape memory alloy wire in the first group is opposed by one or more other shape memory alloy wires in the first group, and / or the contraction of each shape memory alloy wire in the second group is opposed by one or more other shape memory alloy wires in the second group. The controller can control the tension in the shape memory alloy wires in the first group and / or the second group. Compared with the arrangement of springs or other elastic elements opposing the shape memory alloy wires, this allows more precise and reliable movement control.

[0028] Alternatively, the contraction of each shape memory alloy wire in the first group can be opposed by one or more elastic elements (such as a spring coupling the first portion to the second portion). The contraction of each shape memory alloy wire in the second group can be opposed by one or more elastic elements (such as a spring coupling the third portion to the second portion). The elastic element (opposing any SMA wire) can take the form of a coil spring, a flat spring, a leaf spring, a flexure, an element formed of an elastomeric material, etc.

[0029] The first set of shape memory alloy wires may include four shape memory alloy wires in an arrangement wherein none of the shape memory alloy wires are co-linear. The second set of shape memory alloy wires may include four shape memory alloy wires in an arrangement wherein none of the shape memory alloy wires are co-linear.

[0030] The first group of shape memory alloy wires may include four shape memory alloy wires arranged in a ring. The shape memory alloy wire in the first group may form different angles with each of a pair of adjacent (around the ring) shape memory alloy wires in the first group. The second group of shape memory alloy wires may include four shape memory alloy wires arranged in a ring. The shape memory alloy wire in the second group may form different angles with each of a pair of adjacent (around the ring) shape memory alloy wires in the second group. The angle between adjacent (around the ring) shape memory alloy wires may not be 90 degrees. The angle between adjacent (around the ring) shape memory alloy wires may be, for example, between 10 degrees and 80 degrees or between 100 degrees and 170 degrees. Optionally, the angle between adjacent (around the ring) shape memory alloy wires may be, for example, between 20 degrees and 70 degrees or between 110 degrees and 160 degrees.

[0031] The four shape memory alloy wires in the first group may be arranged to correspond to the edges of the rhombus shape. The four shape memory alloy wires in the second group may be arranged to correspond to the edges of the rhombus shape. The four shape memory alloy wires in the first group may correspond to the edges of the kite shape. The four shape memory alloy wires in the second group may correspond to the edges of the kite shape.

[0032] The first and second groups of shape memory alloy wires may consist of two pairs of shape memory alloy wires, wherein the shape memory alloy wires within each pair are arranged parallel to each other. However, this is not required, and the first group of shape memory alloy wires may include four shape memory alloy wires in an arrangement in which none of the shape memory alloy wires are parallel. The second group of shape memory alloy wires may include four shape memory alloy wires in an arrangement in which none of the shape memory alloy wires are parallel.

[0033] Each shape memory alloy wire in the first group may form an angle greater than 0° with each other shape memory alloy wire in the first group. Each shape memory alloy wire in the second group may form an angle greater than 0° with each other shape memory alloy wire in the second group.

[0034] The first group of shape memory alloy wires may include four shape memory alloy wires in an arrangement capable of applying torque around a vertical axis perpendicular to the first plane. The second group of shape memory alloy wires may include four shape memory alloy wires in an arrangement capable of applying torque around the vertical axis. This allows the rotation of the second portion and / or the third portion (relative to the first portion and / or the second portion) around the vertical axis to be controlled by the first and / or second group of shape memory alloy wires.

[0035] The first group of shape memory alloy wires may include shape memory alloy wires that cross when viewed along the vertical axis. The second group of shape memory alloy wires may include shape memory alloy wires that cross when viewed along the vertical axis. Compared to situations where such crossing is not allowed, this may allow the shape memory alloy wires to be made longer. Longer shape memory alloy wires achieve greater travel.

[0036] The first group of shape memory alloy wires may include a pair of shape memory alloy wires having mirror symmetry when viewed along a vertical axis. The second group of shape memory alloy wires may include a pair of shape memory alloy wires having mirror symmetry when viewed along a vertical axis.

[0037] The first group of shape memory alloy wires may include shape memory alloy wires arranged at an angle between 20° and 80° with the first axis. Each shape memory alloy wire in the first group may be arranged at an angle between 20° and 80° with the first axis. The second group of shape memory alloy wires may include shape memory alloy wires arranged at an angle between 45° and 77° with the second axis. Each shape memory alloy wire in the second group may be arranged at an angle between 45° and 77° with the second axis.

[0038] The edge of the first portion or the envelope surrounding the first portion may be substantially parallel to the first axis or the second axis. The edge of the second portion or the envelope surrounding the second portion may be substantially parallel to the first axis or the second axis. The edge of the third portion or the envelope surrounding the third portion may be substantially parallel to the first axis or the second axis.

[0039] The first group of shape memory alloy wires may include a first shape memory alloy wire, a second shape memory alloy wire, a third shape memory alloy wire, and a fourth shape memory alloy wire, and may be configured such that, relative to the first portion: actuation of the first shape memory alloy wire and the second shape memory alloy wire pushes the second portion in a negative direction along the first axis (e.g., x); Actuation of the third shape memory alloy wire and the fourth shape memory alloy wire pushes the second portion in a positive direction along the first axis (e.g., x); Actuation of the first shape memory alloy wire and the fourth shape memory alloy wire pushes the second portion in a negative direction along a second axis (e.g., y) perpendicular to the first axis (e.g., x); Actuation of the second shape memory alloy wire and the third shape memory alloy wire pushes the second portion in a positive direction along a second axis (e.g., y); Actuation of the first shape memory alloy wire and the third shape memory alloy wire urges the second portion to rotate counterclockwise; and Actuation of the second shape memory alloy wire and the fourth shape memory alloy wire forces the second portion to rotate clockwise.

[0040] The second group of shape memory alloy wires may include a first shape memory alloy wire, a second shape memory alloy wire, a third shape memory alloy wire, and a fourth shape memory alloy wire, and may be configured such that, relative to the second portion: actuation of the first shape memory alloy wire and the second shape memory alloy wire pushes the third portion in a negative direction along a second axis (e.g., y); Actuation of the third shape memory alloy wire and the fourth shape memory alloy wire pushes the third portion in a positive direction along the second axis (e.g., y); Actuation of the first shape memory alloy wire and the fourth shape memory alloy wire pushes the third portion in a positive direction along the first axis (e.g., x); Actuation of the second shape memory alloy wire and the third shape memory alloy wire pushes the third portion in a negative direction along the first axis (e.g., x); Actuation of the first shape memory alloy wire and the third shape memory alloy wire forces the third portion to rotate counterclockwise; and Actuation of the second shape memory alloy wire and the fourth shape memory alloy wire pushes the third portion to rotate clockwise.

[0041] The first plane and the second plane may be coplanar.The second portion may surround the third portion.

[0042] The first plane and the second plane may be parallel.The first portion, the second portion, and the third portion may be sequentially stacked along a vertical direction perpendicular to the first and second planes.

[0043] The third part may include a central hole. The central hole may be suitable for allowing an optical path to pass, for example, via one or more lenses that may be arranged in the central hole. No shape memory alloy wire may pass through the central hole. No shape memory alloy wire belonging to the first group may pass through the central hole. No shape memory alloy wire belonging to the second group may pass through the central hole. The shape memory alloy wires in the first group may be arranged to form a ring around the central hole. The shape memory alloy wires in the second group may be arranged to form a ring around the central hole.

[0044] The third portion may have a first surface and a second surface. The second surface may be opposite to the first portion across a gap. The shape memory alloy wire belonging to the first group may be routed through the gap. The shape memory alloy wire belonging to the second group may be routed through the gap. The separation of the second surface and the first portion across the gap may be parallel to the vertical axis.

[0045] The first group of shape memory alloy wires may include one or more actuation pairs. The second group of shape memory alloy wires may include one or more actuation pairs. Each actuation pair may include a long wire, which is arranged so that the movement of the corresponding part is amplified relative to the corresponding length change of the long wire. Each actuation pair may include a short wire, which has a length less than the long wire and is arranged to resist the contraction of the long wire.

[0046] The actuator assembly may include two or more actuation pairs. The short wire in one first actuation pair may be electrically connected in series or in parallel with a short wire in a different actuation pair.

[0047] The first set of shape memory alloy wires may also be configured to rotate the second portion relative to the first portion in the first plane. The second set of shape memory alloy wires may also be configured to rotate the third portion relative to the second portion in the second plane.

[0048] The controller may be configured to control the selective contraction of the first set of shape memory alloy wires to rotate the second portion relative to the first portion in a first plane around a vertical axis. The controller may be configured to control the selective contraction of the second set of shape memory alloy wires to rotate the third portion relative to the second portion in a second plane around a vertical axis.

[0049] The actuator assembly may also include a fourth portion movable relative to the third portion in a third plane. The third plane is parallel or coplanar with the second plane. The actuator assembly may also include a third group of one or more shape memory alloy wires, which are configured to move the fourth portion relative to the third portion in the third plane. The third group of shape memory alloy wires may be arranged so that the movement of the fourth portion is amplified relative to the corresponding length change of the third group of shape memory alloy wires.

[0050] Thus, movement of the fourth portion relative to the first portion is a combination of movement of the second portion relative to the first portion, movement of the third portion relative to the second portion, and movement of the fourth portion relative to the third portion.The fourth portion may be coupled to the third portion via a third set of shape memory alloy wires.

[0051] Alternatively, the fourth portion may be movable parallel to the third and fourth axes.

[0052] The fourth portion may include features corresponding to any features of the second portion and / or the third portion. The third group of shape memory alloy wires may include features corresponding to any features of the first group and / or the second group of shape memory alloy wires. The mechanical coupling between the fourth portion and the third portion may include features corresponding to any features of the mechanical coupling between the third portion and the second portion and / or between the second portion and the first portion.

[0053] If a fourth portion is included, the controller may be configured to control the selective contraction of the third group of shape memory alloy wires in any manner described above with respect to the first group of shape memory alloy wires and / or the second group of shape memory alloy wires.

[0054] When a fourth portion is included, the controller may be configured to extend the range of motion of the fourth portion (relative to the first portion) beyond the second motion envelope by combining movement of the second, third, and fourth portions along the same axis.

[0055] The camera may include an actuator assembly, an image sensor supported by one of the first portion, the second portion, and the third portion, and one or more lenses. At least one of the one or more lenses may be supported by one of the first portion, the second portion, and the third portion. The one or more lenses may be supported by one of the first portion, the second portion, and the third portion that is different from the image sensor.

[0056] Preferably, the image sensor may be supported by one of the first portion and the third portion, and at least one of the one or more lenses may be supported by the other of the first portion and the third portion.

[0057] When the fourth portion is included, the image sensor may be supported by one of the first portion, the second portion, the third portion, and the fourth portion, and at least one of the one or more lenses may be supported by a different one of the first portion, the second portion, the third portion, and the fourth portion. When the fourth portion is included, the image sensor may preferably be supported by one of the first portion and the fourth portion, and at least one of the one or more lenses may be supported by another one of the first portion and the fourth portion.

[0058] In a camera, the first part may be fixed relative to the rest of the camera. In a camera, the second part may be fixed relative to the rest of the camera. Fixed relative to the camera may mean that the first part or the second part is mechanically fixed and has no degrees of freedom relative to the rest of the camera. For example, either the first part or the second part may be rigidly attached to (or integrally formed with) a screening can of the camera, a housing of the camera, a frame of the camera, a packaging of the camera, etc.

[0059] According to a second aspect of the present invention, a method for controlling an actuator assembly or a camera including the actuator assembly is provided. The method comprises controlling the contraction of the shape memory alloy wires in the first group and the second group so that the third part moves relative to the first part by a first component parallel to the first axis and a second component parallel to the second axis.

[0060] When a fourth portion is included, the method may further include controlling selective contraction of the third set of shape memory alloy wires to move the fourth portion relative to the third portion in a third plane.

[0061] The method according to the second aspect may comprise features corresponding to any features of the actuator assembly and / or a camera comprising the actuator assembly.Definitions applicable to the actuator assembly and / or a camera comprising the actuator assembly may equally apply to the method according to the second aspect.

[0062] In particular, the method according to the second aspect may comprise features corresponding to one or more of the first mode, the second mode and the third mode described in relation to the controller of the actuator of the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Certain embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 A camera is shown; Figure 2 is a plan view of a first actuator assembly; Figure 3A and Figure 3B A stroke amplification mechanism using a shape memory alloy wire is shown; Figure 4 shows a movement envelope of a control mode for an actuator assembly; Figure 5 is a plan view of a second actuator assembly; Fig. 6A is a projection diagram of a third actuator assembly; Figure 6B is a plan view of a third actuator assembly; Fig. 7A is a plan view of a fourth actuator assembly; Figure 7B is a side view along the minor axis of the fourth actuator assembly; Figure 7C is a side view along the long axis of the fourth actuator assembly; Figure 8 is a plan view of a fifth actuator assembly; Fig. 9 schematically illustrates a first example of a shape memory alloy wire electrical connection for a fifth actuator assembly; Fig.10 schematically illustrates a second example of a shape memory alloy wire electrical connection for a fifth actuator assembly; Fig.11A is a plan view of a third portion and a second set of shape memory alloy wires for a sixth actuator assembly; Fig. 11Bis a plan view of a second portion and a first set of shape memory alloy wires for a sixth actuator assembly; Fig. 11C is a side view of a sixth actuator assembly; Fig. 12A is a plan view of a second portion and a first set of shape memory alloy wires for a seventh actuator assembly; Fig. 12B is a plan view of a third portion and a second set of shape memory alloy wires for a seventh actuator assembly; and Fig. 12C is a side view of the seventh actuator assembly. Detailed Description

[0064] Reference Figure 1 , a camera 1 is shown including an SMA actuator assembly 2 (also referred to herein as an “SMA actuator” or an “actuator assembly”).

[0065] The camera 1 comprises a lens assembly 3 suspended from a first part (or "support structure" 4) by an actuator assembly 2 which supports the lens assembly 3 in a manner allowing movement of the lens assembly 3 relative to the first part 4 in a direction perpendicular to the optical axis O (in a first plane).

[0066] The first part 4 comprises a base 5. An image sensor 6 is mounted on the front side of the base 5. A controller 7 is mounted on the rear side of the base 5. For example, the controller 7 may take the form of an integrated circuit (IC) in which control circuitry is implemented. Optionally, for example when the camera 1 is configured with optical image stabilization (OIS), a gyroscopic sensor 8 may be mounted on the rear side of the base 5 and coupled to the controller 7. The precise location at which the controller 7 (and optionally the gyroscopic sensor 8, if present) is mounted relative to the actuator assembly 2 is not critical, although it is preferred that the arrangement is compact.

[0067] The first portion 4 further includes a shielding cover (or “cover”) 9 that protrudes forward from the base 5 to enclose and protect other components of the camera 1 .

[0068] The lens assembly 3 comprises a lens holder 10 in the form of a cylindrical body, which supports two lenses 11 arranged along an optical axis O (parallel to the z-axis shown). Generally, any number of one or more lenses 11 may be included. Preferably, each lens 11 has a diameter of at most about 20 mm. Therefore, the camera 1 may be referred to as a miniature camera.

[0069] The lens assembly 3 is arranged to focus the image onto an image sensor 6. The image sensor 6 captures the image and may be of any suitable type, such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) device.

[0070] The lens 11 is supported on the lens holder 10 so that the lens 11 can move relative to the lens holder 10 along the optical axis O, for example, to provide focusing or zooming. Specifically, the lens 11 is fixed to a lens holder 12 that is movable relative to the lens holder 10 along the optical axis O. In this example, although all of the lenses 11 are fixed to the lens holder 12, in general, one or more of the lenses 11 may be fixed to the lens holder 10 and therefore not movable relative to the lens holder 10 along the optical axis O, so that at least one of the lenses 11 is fixed to the lens holder 12.

[0071] An axial actuator assembly 13 disposed between the lens holder 10 and the lens support 12 is arranged to drive the movement of the lens support 10 and the lens 11 relative to the lens holder 10 along the optical axis O. The axial actuator device 13 may be of any suitable type, for example a voice coil motor (VCM) or an SMA wire device.

[0072] In operation, the lens assembly 3 is moved relative to the image sensor 6 orthogonal to the optical axis O by the actuator assembly 2, having the effect of moving the image on the image sensor 6. This serves to provide optical image stabilisation (OIS) which compensates for movement of the camera 1 which may be caused by hand shake or the like.

[0073] First actuator assembly Also refer to Figure 2 , a first exemplary actuator assembly 14 (hereinafter referred to as “first actuator assembly”) is shown.

[0074] The first actuator assembly 14 may provide the actuator assembly 2 of the camera 1, but is not limited to use in the camera 1. The first actuator assembly 14 includes a first portion 4 (also referred to as a "support structure"), a second portion 15 (also referred to as a "middle portion") movable relative to the first portion 4 in a first plane 16 (xy as shown), and a third portion 17 (also referred to as a "moving portion") movable relative to the second portion 15 in a second plane 18 (xy as shown). The second plane 18 is coplanar with the first plane 16 in the first actuator assembly 14. However, in variations of the first actuator assembly 14, the first plane 16 and the second plane 18 do not need to be coplanar and may be parallel to each other at different heights (z-axis as shown).

[0075] The first actuator assembly 14 includes a first set of shape memory alloy (SMA) wires 19 configured to move the second portion 15 relative to the first portion 4 in the first plane 16. In the first actuator assembly 14, the first set of shape memory alloy wires 19 includes a first SMA wire 191, a second SMA wire 192, a third SMA wire 193, and a fourth SMA wire 194 arranged in a ring around the center of the first actuator assembly 14. Generally, the first set may include more or fewer SMA wires 19, but the minimum number is one (whose contraction should be opposed by a spring as described below). Each SMA wire 19 in the first set is fixed to the first portion 4 at one end by a corresponding first crimp 20, and fixed to the second portion 15 at the other end by a corresponding second crimp 21.

[0076] The first actuator assembly 14 also includes a second set of shape memory alloy wires 22, which are configured to move the third portion 17 relative to the second portion 15 in the second plane 18. In the first actuator assembly 14, the second set of shape memory alloy wires 22 includes a first SMA wire 221, a second SMA wire 222, a third SMA wire 223, and a fourth SMA wire 224 arranged in a ring around the center of the first actuator assembly 14. Generally, the second set can include more or fewer SMA wires 22, but the minimum number is one (whose contraction should be opposed by a spring as described below). Each SMA wire 22 in the second set is fixed to the second portion 15 at one end by a corresponding third crimping piece 23, and is fixed to the third portion 17 at the other end by a corresponding fourth crimping piece 24.

[0077] In this way, the second portion 15 is coupled to the first portion 4 via the first set of shape memory alloy wires 19, and the third portion 17 is coupled to the second portion 15 via the second set of shape memory alloy wires 22. Therefore, the movement of the third portion 17 relative to the first portion 4 is a combination of the movement of the second portion 15 relative to the first portion 4 and the movement of the third portion 17 relative to the second portion 15.

[0078] The SMA wires 19 in the first group and the SMA wires 20 in the second group can be contracted by resistive heating provided by an electric current. The electrical connection between the first portion 4 and the second portion 15 is supported on (or provided by) a first flexure 25 connecting the first portion 4 and the second portion 15. Each first flexure 25 can support, for example, one, two or more separate electrical connections that are insulated from each other. Similarly, the electrical connection between the first portion 4 and the third portion 15 is supported on (or provided by) a second flexure 26 connecting the first portion 4 and the third portion 17. Each second flexure 26 can support, for example, one, two or more separate electrical connections that are insulated from each other. The first flexure 25 and the second flexure 26 are designed to be highly compliant so as not to interfere with the movement of the first actuator assembly 14. The first actuator assembly 14 includes a first pair of first flexures 25 and a pair of second flexures 26, although generally more or fewer first flexures 25 and / or second flexures 26 can be used to provide electrical connections to the SMA wires 19, 22. Alternative options for making the electrical connection may include sliding spring contacts, conductive ball bearings, etc.

[0079] When one of the SMA wires 19, 22 is heated, the stress in the SMA wire 19, 22 increases and it contracts, providing a force that forces the portions 4, 15, 17 connected by the SMA wires 19, 22 to pull toward each other (and move if there is a net force). A series of movements occur as the temperature of the SMA material increases within the temperature range where the SMA material transformation from the martensite phase to the austenite phase occurs. Conversely, when one of the SMA wires 19, 22 is cooled so that the stress in the SMA wire 19, 22 is reduced, it can extend under the force from the opposing SMA wire (or spring, flexure, etc.) of the SMA wires 19, 22. The SMA wires 19, 22 can be made of any suitable SMA material, such as Nitinol or another titanium alloy SMA material.

[0080] The drive signals for the SMA wires 19, 22 are generated and provided by the controller 7, such as a control circuit implemented in an IC as described above. For example, the drive signal can be generated by the controller 7 in response to the output signal of the gyro sensor 8 to drive the movement of the lens assembly 3 to stabilize the image focused on the image sensor 6 by the lens assembly 3, thereby providing OIS. The drive signal can be generated using a resistive feedback control technique, for example, as described in WO 2014 / 076463 A1, which disclosure is incorporated herein by this reference. The following describes examples of first, second and third control modes in which the controller 7 can operate to control the first actuator assembly 14.

[0081] In operation, the SMA wires 19, 22 are selectively driven to move the second portion 15 and / or the third portion 17 relative to the first portion in any lateral direction in the planes 16, 18 (i.e., a direction perpendicular to the optical axis O). Further details of methods of driving the SMA wires 19, 22 are also provided in WO 2013 / 175197 A1, which is incorporated herein by reference.

[0082] The first actuator 14 is a square having a first side 271, a second side 272, a third side 273, and a fourth side 274. The first side 271 and the third side 273 are parallel to each other and to a first axis (the x-axis as shown). The second side 272 and the fourth side 274 are parallel to each other and to a second axis (the y-axis as shown) perpendicular to the first axis x. In the first actuator 14, the side 27 of the actuator 14 coincides with the edge of the first part 4, which takes the form of a square plate. The first part 4 can provide a base 5 if used in the camera 1. Each of the second part 15 and the third part 17 takes the form of a flat thin ring having a square outer edge and an inner edge, defining a hole 28. When used in the camera 1, the hole 28 allows light focused by the lens 11 to pass through to the image sensor 6 (e.g., mounted on the first part 4). Therefore, neither of the SMA wires 19, 22 intersects the hole 28 of the third part 17. The third portion 17 is smaller than the second portion 15 and is received in the aperture 28 of the second portion 15 such that the second portion 15 and the third portion 17 are substantially coplanar and the first plane 16 and the second plane 18 coincide. The first portion 4, the second portion 15 and the third portion 17 are each substantially perpendicular to a vertical axis (the z-axis as shown). When used in a camera, the vertical axis z will be parallel to the optical axis O.

[0083] The first part 4, the second part 15 and the third part 17 may take the form of respective patterned metal sheets, such as etched or machined stainless steel, and may be coated with an electrically insulating dielectric material. The dielectric material layer may include one or more windows (not shown) to allow electrical connection.

[0084] Other example configurations may be used, and further details are provided in WO 2017 / 055788 A1 and WO 2019 / 086855 A1, which are incorporated herein by this reference.

[0085] The first part 15 is constrained to move in a first plane 16 at least in part using a first support device (not shown) coupling the first part 15 to the first part 4. The first part 15 may be held in contact with the first support device (not shown) by one or more flexures, springs or similar devices (not shown) that provide a force along the vertical axis z toward the first part 4. Similarly, the second part 17 is constrained to move in a second plane 18 (coinciding with the first plane 16 in this example) at least in part using a second support device (not shown) coupling the third part 17 to the first part 4. The first part 15 may be held in contact with the second support device (not shown) by one or more flexures, springs or similar devices (not shown) that provide a force along the vertical axis z toward the first part 4. The first support device and / or the second support device (not shown) may take the form of three or more sliding bearings, three or more roller bearings, corresponding sets of flexures, etc.

[0086] SMA wire layout of the first actuator assembly The first group of SMA wires 19 are arranged in a loop around the hole 28, with the first SMA wire 191 and the second SMA wire 192 in the first group opposing each other along the second edge 272 (in the case of contraction) and the third SMA wire 193 and the fourth SMA wire 194 in the first group opposing each other along the fourth edge 274. None of the SMA wires in the first group of SMA wires 19 are colinear, although they all form substantially the same angle with the first x-axis and the second y-axis. The first group of SMA wires 19 form a smaller angle with the second axis y than with the first axis x.

[0087] Actuating the first SMA wire 191 and the second SMA wire 192 in the first group to contract pushes the second portion 15 relative to the first portion 4 in a negative direction parallel to the first axis x. To push the second portion 15 in the opposite direction (positive direction parallel to the first axis x) relative to the first portion, the third SMA wire 193 and the fourth SMA wire 194 in the first group are actuated to contract.

[0088] In order to move the second part 15 relative to the first part 4 parallel to the second axis y, the second part 15 can be pushed in the negative y direction by actuating the first SMA wire 191 and the fourth SMA wire 194 in the first group to contract, and can be pushed in the positive y direction by actuating the second SMA wire 192 and the third SMA wire 193 in the first group.

[0089] The clockwise moment on the second portion 15 relative to the first portion 4 can be obtained by actuating the second SMA wire 192 and the fourth SMA wire 194 in the first group to contract together. Similarly, the counterclockwise moment on the second portion 15 relative to the first portion 4 can be obtained by actuating the first SMA wire 191 and the third SMA wire 193 of the first group to contract together.

[0090] If desired, one or more of the degrees of freedom of the second part 15 relative to the first part 4 may be constrained, for example using a first support arrangement (not shown). The second part 15 relative to the first part 4 should maintain at least one degree of freedom.

[0091] The second group of SMA wires 22 is also arranged in a loop around the hole 28, with the first SMA wire 221 and the second SMA wire 222 in the second group opposing each other along the first edge 271 (in the case of contraction), and the third SMA wire 223 and the fourth SMA wire 224 in the second group opposing each other along the third edge 273. None of the SMA wires in the second group of SMA wires 22 are colinear, although they all form substantially the same angle with the first x-axis and the second y-axis. The second group of SMA wires 22 forms a smaller angle with the first axis x than with the second axis y.

[0092] In order to move the third part 17 relative to the second part 15 parallel to the second axis y, the second part 15 can be pushed in the negative y direction by actuating the contraction of the first SMA wire 221 and the second SMA wire 222 in the second group, and can be pushed in the positive y direction by actuating the third SMA wire 223 and the fourth SMA wire 224 in the second group.

[0093] In order to move the third part 17 relative to the second part 15 parallel to the first axis x, the second part 15 can be pushed in the positive x direction by actuating the first SMA wire 221 and the fourth SMA wire 224 in the second group to contract, and can be pushed in the negative y direction by actuating the second SMA wire 222 and the third SMA wire 223 in the second group.

[0094] The clockwise moment on the third portion 17 relative to the second portion 15 can be obtained by actuating the second SMA wire 222 and the fourth SMA wire 224 in the second group to contract together. Similarly, the counterclockwise moment on the third portion 17 relative to the second portion 15 can be obtained by actuating the first SMA wire 221 and the third SMA wire 223 in the second group to contract together.

[0095] If desired, one or more of the degrees of freedom of the third portion 17 relative to the second portion 15 may be constrained, for example using a second support device (not shown). The third portion 17 should maintain at least one degree of freedom relative to the second portion 15, and the at least one degree of freedom should preferably be non-parallel to at least one degree of freedom of the second portion 15 relative to the first portion 4.

[0096] The total movement of the third portion 17 relative to the first portion 4 is the sum of the movement of the second portion 15 relative to the first portion 4 (from actuation of the first set of SMA wires 19) and the movement of the third portion 17 relative to the second portion 15 (from actuation of the second set of SMA wires 22). The total movement of the third portion 17 relative to the first portion 4 that can be obtained by combining the actuation of the first set of SMA wires 19 and the second set of SMA wires 22 is greater than the movement that can be obtained using a single set of SMA wires 19, 22.

[0097] The first set of shape memory alloy wires 19 are arranged such that the movement of the second portion 15 relative to the first portion 4 is amplified compared to the corresponding length change of the first set of shape memory alloy wires 19. Similarly, the second set of shape memory alloy wires 22 are arranged such that the movement of the third portion 17 relative to the second portion 15 is amplified compared to the corresponding length change of the second set of shape memory alloy wires 22.

[0098] SMA wire zoom Also refer to Figure 3A and Figure 3B , showing the SMA wire 19, 22 amplification mechanism.

[0099] Special reference Figure 3A , the angled SMA wire 29 forms an angle θ with the first axis x and an angle 90-θ with the second axis y. Figure 3A In the example shown, θ=45°.

[0100] The SMA wire 29 has an initial length L, a component x0 along the first axis x, and a component y0 along the second axis y. The first end 30 of the SMA wire 29 is fixed to Figure 3A The origin of the axis xy drawn in .

[0101] The SMA wire 29 is then actuated (by resistive heating using a drive current) and caused to contract by an amount δL to a new length L-δL. The locus of points that the second end 31 of the SMA wire 29 can reach is referenced Figure 3AA circle 32 of radius L-δL is drawn in FIG. 3. If the second end 31 of the SMA wire 29 is unconstrained, or is constrained to move in the direction in which the SMA wire 29 lies (θ=45°), then the total displacement of the second end 31 relative to the first end will simply be δL to the point marked P1. This represents an unamplified displacement, and many SMA actuators operate in this manner, pulling a portion of the actuator directly along the length of the SMA wire 29. However, this limits the travel of such an actuator to a maximum length change of δL.

[0102] However, if the second end 31 is constrained to move along a path that is not parallel to the initial orientation of the SMA wire 29, then amplification can be obtained. For example, if the second end 31 is constrained to move parallel to the second axis y, then the second end 31 is forced to reach a point P2 on the circle 32 that intersects the original component x0 along the first axis x. The total displacement is then Δy=y0-y1>δL. Alternatively, if the second end 31 is constrained to move parallel to the first axis x, then the second end 31 is forced to reach a point P3 on the circle 32 that intersects the sub-original component y0 along the second axis y. The total displacement is then Δx = x0-x1>δL.

[0103] for Figure 3A For the geometry shown, where θ=45°, the amplification is the same when constrained to the first or second axis, i.e., Δx=Δy, and the gain is Δx / δL≈1.5.

[0104] By changing the initial orientation angle θ, the gain for movement parallel to one axis x, y can be increased at the expense of reduced gain for movement parallel to the other axis y, x.

[0105] Also refer to Figure 3B , which shows that Figure 3A Same configuration, except the angle is θ=60° instead of θ=45°. Figure 3B In the configuration of θ=45°, when the second end 32 is constrained to move parallel to the first axis x to point P3, the gain increases to Δx / δL≈2.4. However, when the second end 32 is constrained to move parallel to the second axis y to point P2, the gain decreases (compared to θ=45°) to Δy / δL≈1.2.

[0106] It should be understood that constraining the second end 31 to any other path that is not parallel to θ will result in amplification since the shortest displacement corresponding to the length change δL (zero amplification) will always be directly along the initial orientation of the SMA wire 29. In other words, amplification does not require strict constraints to the first axis x or the second axis y.

[0107] Reference again Figure 2, the SMA wires 19 in the first group are tilted closer to the second axis y, so that relative to the first portion 4, the movement of the second portion 15 parallel to the first axis x is amplified by a greater multiple (gain) than the movement of the second portion 15 parallel to the second axis y. Conversely, the SMA wires 22 in the second group are tilted closer to the first axis x, so that relative to the second portion 15, the movement of the third portion 17 parallel to the second axis y is amplified by a greater multiple (gain) than the movement of the third portion 17 parallel to the first axis x.

[0108] In the first actuator assembly 14, the constraint that causes amplification of each SMA wire 19 in the first group is provided by the opposing SMA wire 19 in the first group. Similarly, the constraint that causes amplification of each SMA wire 22 in the second group is provided by the opposing SMA wire 22 in the second group. For example, to move the second portion 15 in a negative direction parallel to the first axis x, the first SMA wire 191 and the second SMA wire 192 in the first group are contracted by the same amount δL. The relative direction of the first SMA wire 191 and the second SMA wire 192 in the first group between the second portion 15 and the first portion 4 constrains the movement to be parallel to the first axis x, providing amplification of the movement of the second portion 15 relative to the first portion 4.

[0109] Typically, to optimize the amplification (gain) relative to the net component of the force in the desired direction, the SMA wires 19 in the first group are preferably arranged at an angle between 20° and 80° relative to the first axis x. Similarly, the SMA wires 22 in the second group are preferably arranged at an angle between 45° and 77° relative to the second axis y.

[0110] The controller 7 is configured to control the selective contraction of the shape memory alloy wires 19 in the first group and the shape memory alloy wires 22 in the second group so as to produce the desired total movement of the third part 17 relative to the first part 4 by a first component Δx parallel to the first axis x and a second component Δy parallel to the second axis y. The controller 7 can be configured to operate in one of the first, second or third control modes described below. Alternatively, the controller 7 can be configured to operate under a pair or all of the first, second or third control modes described below, and can switch between control modes according to the context. For example, when included in the camera 1, one control mode can be conducive to capturing still images, while another control mode can be conducive to capturing video. The first, second and third control modes described below are exemplary only, and many alternative control modes can be used with the first actuator assembly 14.

[0111] Regardless of which particular control mode is used, the controller 7 controls the contraction of the first group of SMA wires 19 and the second group of SMA wires 22 by controlling the drive signal supplied to the shape memory alloy wires 19, 22. The drive signal can be current controlled or voltage controlled. The drive signal can be generated using a resistive feedback control technique, such as described in WO 2014 / 076463A1.

[0112] First control mode In the first control mode, the controller 7 is configured to isolate movement parallel to the first x-axis and the second y-axis to be provided by the single set of SMA wires 19 .

[0113] Specifically, the controller 7 causes the first component Δx to correspond to controlling the selective contraction of the first group of shape memory alloy wires 19 so as to move the second portion 15 relative to the first portion 4 in the first plane 16 parallel to the first axis x. Specifically, the controller 7 causes the first SMA wire 191 and the second SMA wire 192 in the first group to contract as a pair to move in the negative x direction, or causes the third SMA wire 193 and the fourth SMA wire 194 in the first group to move as a pair in the positive x direction. This corresponds to the direction of maximum amplification (gain) of the first group of SMA wires 19.

[0114] At the same time, the controller 7 causes the second component Δy to correspond to controlling the selective contraction of the second group of shape memory alloy wires 22 so as to move the third portion 17 relative to the second portion 15 in the second plane 18 (coinciding with the first plane 16 in this example) parallel to the second axis y. Specifically, the controller 7 causes the first SMA wire 221 and the second SMA wire 222 in the first group to contract as a pair to move in the negative y direction, or causes the third SMA wire 223 and the fourth SMA wire 224 in the second group to move as a pair in the positive y direction. This corresponds to the direction of maximum amplification (gain) of the second group of SMA wires 22.

[0115] In the first control mode, the movement (Δx and Δy) of the third portion 17 relative to the first portion 4 is substantially isolated along the first axis x and the second axis y. This can simplify the drive signals required to control the first set of SMA wires 19 and the second set of SMA wires 22. First, the first mode helps reduce crosstalk between the intended movements parallel to the first x-axis and the second y-axis. In other words, the crosstalk between the two degrees of freedom of the third portion 17 relative to the first portion 4 is reduced.

[0116] Second control mode Although in the first control mode good isolation is obtained for the components Δx and Δy of the movement of the third part 17 relative to the first part 4, the overall movement range or movement envelope can be improved by additively combining the displacements of the second part 15 and the third part 17 along one or both axes x, y.

[0117] Also refer to Figure 4 , the second control mode will be described.

[0118] In the second control mode, the controller is configured such that within the first movement envelope 33 (of the third portion 17 relative to the first portion 4), the first component Δx corresponds to the movement of the second portion 15 relative to the first portion 4, and the second component Δy corresponds to the movement of the third portion 17 relative to the second portion 15. In other words, within the first movement envelope 33, the second control mode is identical to the first control mode.

[0119] like Figure 4 As shown, the first movement envelope 33 (or first trajectory) is generally square (assuming that the SMA wires 19 in the first group and the SMA wires 22 in the second group have equal travel lengths). The first movement envelope corresponds to a trajectory of all points to which the third portion 17 can move, centered about an origin corresponding to an equilibrium relative position with respect to the first portion 4. Thus, within the first movement envelope, the second control mode retains the advantages of the first control mode.

[0120] The second control mode differs from the first control mode in that the third portion 17 can be moved outside the first movement envelope 33 by additively combining the movements of the second portion 15 and the third portion 17 parallel to the same axis. The second movement envelope (or second trajectory) 34 corresponds to the maximum distance that the third portion 17 can move relative to the first portion 4 in any given direction. Figure 4 The second movement envelope 34 shown has the form of a regular octagon and completely surrounds the first movement envelope 33. The first region 351, the second region 352, the third region 353, the fourth region 354 correspond to points outside the first movement envelope 33 and within the second movement envelope 34.

[0121] In the first region 351, the second region 352, the third region 353, and the fourth region 354, the controller 7 selectively contracts the first group of SMA wires 19 and the second group of SMA wires 22 so that the first component Δx corresponds to the movement of the second portion 15 relative to the first portion 4 combined with the movement of the third portion 17 relative to the second portion 15, both of which are parallel to the first axis x. The same is true for the second component Δy.

[0122] For example, the third portion 17 can be moved from the origin to the edge of the first movement envelope 33 bordering the first region 351 by contracting the third SMA wire 193 and the fourth SMA wire 194 in the first group (corresponding to maximum amplification). However, in order for the third portion 17 to move further parallel to the first axis x and through the first region 351 to the edge of the second movement envelope 34, the first SMA wire 221 and the fourth SMA wire 224 in the second group are also contracted.

[0123] In this way, the controller 7 operating in the second mode can extend the range of movement of the third part 17 relative to the first part 15 beyond the first movement envelope 33 by combining movement of both the second part 15 and the third part 17 along the same axis.

[0124] The third control mode In the first and second control modes, the controller 7 is configured to isolate, as far as possible, the first component Δx and the second component Δy provided solely by the first set of SMA wires 19 and the second set of SMA wires 22. This reduces crosstalk between the two degrees of freedom of the third portion 17 relative to the first portion 4. However, in some applications / uses of the first actuator 14, it may be advantageous to blend the contributions of the first set of SMA wires 19 and the second set of SMA wires 22 to the first component Δx and the second component Δy of the movement of the third portion 17 relative to the first portion 4 over the entire second movement envelope 34.

[0125] In the third mode, the controller is configured such that the first component Δx comprises a first movement Δx1 and a second movement Δx2, Δx=Δx1+Δx2. Similarly, the second component Δy comprises a third movement δy1 and a fourth movement δy2, Δy=δy1+δy2.

[0126] The first movement δx1 is a movement of the second part 15 relative to the first part 4 parallel to the first axis x. The second movement δx2 corresponds to a movement of the third part 17 relative to the second part 15 parallel to the first axis x. The second movement δx2 is smaller than the first movement, δx2<δx1, which corresponds to a greater amplification of the movement of the second part 15 relative to the first part 4 parallel to the first axis x.

[0127] The third movement δy1 is a movement of the third part 17 relative to the second part 15 parallel to the second axis y. The fourth movement δy2 corresponds to a movement of the second part 15 relative to the first part 4 parallel to the second axis y. The fourth movement δy2 is smaller than the third movement, δy2<δy1, which corresponds to a greater amplification of the movement of the third part 17 relative to the second part 15 parallel to the second axis y.

[0128] In this way, the controller 7 can use the most amplified movement of the second and third portions 15, 17 to provide a relatively coarse movement, and use less amplified movement of the second and third portions 15, 17 to provide a relatively fine movement, thereby moving the third portion 17 to a position relative to the first portion 4 within the second movement envelope 34. This can achieve more accurate positioning because greater amplification of the intended movement also results in greater amplification of the error.

[0129] Any of the first, second and third control modes may optionally be combined with a rotation of the second part 15 and / or the third part 17 (about the vertical axis z).

[0130] For example, the controller 7 can be configured to control the selective contraction of the first group of shape memory alloy wires 19 so as to rotate the second portion 15 relative to the first portion 4 about a vertical axis z perpendicular to the first plane 16. Contraction of any single SMA wire 19 in the first group will generate a net moment about the vertical axis z, however, it is preferred to cause contraction of the second SMA wire 192 and the fourth SMA wire 194 in the first group to rotate the second portion 15 clockwise, and cause contraction of the first SMA wire 191 and the third SMA wire 193 in the first group to rotate the second portion 15 counterclockwise.

[0131] Similarly, the controller 7 can be configured to control the selective contraction of the second group of shape memory alloy wires 22 to rotate the third portion 17 relative to the second portion 15 about a vertical axis z that is perpendicular to the second plane 18 (coincident with the first plane 16 in the first actuator assembly 14). Contraction of any single SMA wire 22 in the second group will generate a net moment about the vertical axis z, however, it is preferred to cause contraction of the second SMA wire 222 and the fourth SMA wire 224 in the second group to rotate the third portion 17 clockwise, and cause contraction of the first SMA wire 221 and the third SMA wire 223 in the second group to rotate the third portion 17 counterclockwise.

[0132] In this way, the rotations generated by the first and second sets of SMA wires 19, 22 may also be additively combined, which allows for an increased maximum rotation of the third portion 17 relative to the first portion 4 compared to either set of SMA wires 19, 22 alone.

[0133] Included in camera The first actuator assembly 14 may be incorporated into the camera in a number of different ways.

[0134] For example, the first actuator assembly 14 may be coupled to Figure 1The camera 1 is shown in which the image sensor 6 is supported on the first part 4 and the lens holder 10 is supported on the third part 17. The first part 4 is connected to the cover 9 and serves as a fixed reference point with respect to the camera 1.

[0135] However, the first actuator 14 can be incorporated into the camera in other ways. For example, another camera (not shown) can be similar to the camera 1, except that the second part 15 is fixed relative to the camera (not shown) (for example, relative to the cover 9). In this way, the image sensor 6 supported on the first part 4 and the lens holder 10 supported on the third part 17 can be independently moved relative to the optical axis O.

[0136] Typically, for inclusion in a camera, any of the first part 4, the second part 15 or the third part 17 may support the image sensor 6, while one of the remaining pair of parts 4, 15, 17 supports at least one lens 11. Typically, any of the first part 4, the second part 15 or the third part 17 may be fixed relative to the camera. Fixed relative to the camera means that the part 4, 15, 17 in question is mechanically fixed and has no degrees of freedom relative to the rest of the camera. For example, any of the fixed parts 4, 15, 17 may be rigidly attached to (or integrally formed with) a hood 9, a housing (not shown), a frame (not shown) or an enclosure of the camera.

[0137] Although the first actuator assembly 14 has been described in which none of the shape memory alloy wires 19 in the first group are collinear, and none of the shape memory alloy wires 22 in the second group are collinear, this is not required. In other examples, one or more of the SMA wires 19 in the first group can be arranged to be collinear, and / or one or more of the SMA wires 22 in the second group can be arranged to be collinear.

[0138] A first actuator assembly 14 has been described in which the shape memory alloy wires 19 in the first group are arranged in a loop forming a bow tie shape such that each SMA wire 19 in the first group forms the same angle with a pair of adjacent (surrounding the loop) SMA wires 19 in the first group. For example, the first SMA wire 191 in the first group is oriented at the same angle relative to the second SMA wire 192 and the fourth SMA wire 194 in the first group. In addition, the first SMA wire 191 and the third SMA wire 193 in the first group are parallel, as are the second SMA wire 192 and the fourth SMA wire 194 in the first group. The SMA wires 22 in the second group are similarly configured, except rotated 90° and formed into a loop with slightly smaller dimensions.

[0139] However, the first group of SMA wires 19 and / or the second group of SMA wires 22 need not be so configured, and instead the first group of SMA wires 19 and / or the second group of SMA wires 22 may be arranged to form a loop corresponding to a quadrilateral shape, such as a square, rectangle, diamond, kite, etc. Alternatively, the first group of SMA wires 19 and / or the second group of SMA wires 22 may be arranged such that none of the SMA wires 19, 22 in a given group are parallel to each other.

[0140] The first actuator assembly 14 has been described in which the first set of SMA wires 19 is capable of applying a net moment (torque) about the vertical axis z and in which the second set of SMA wires 22 is capable of applying a net moment about the vertical axis z. However, in other examples, the first set of SMA wires 19 and / or the second set of SMA wires 22 may be arranged so that no net moment is provided and / or the net moment may be small.

[0141] The first actuator assembly 14 has been described wherein the first set of SMA wires 19 and the second set of SMA wires 22 each include multiple pairs of SMA wires that have mirror symmetry when viewed along the vertical axis z. However, this is not required, and in other examples, the first set of SMA wires 19 and / or the second set of SMA wires 22 may include fewer or even no pairs of SMA wires 19, 22 that have mirror symmetry when viewed along the vertical axis z.

[0142] The first actuator assembly 14 has been described relative to orthogonal first x-axis and second y-axis. However, this is not required, and in other examples, the first and second axes may be arranged at any non-parallel angle to each other, such as any angle between 10° and 80°.

[0143] Additionally, the first actuator assembly 14 has been described as having movement of the third portion 17 relative to the second portion 15 along the same axis as movement of the second portion 15 relative to the first portion 4. Alternatively, the third portion 17 may move relative to the second portion 15 in the second plane 18 along third and fourth non-parallel axes (not shown) that need not have any orientation relationship to the first or second axes. Movement of the third portion 17 parallel to the third axis is amplified by a greater factor than movement of the third portion 17 parallel to the fourth axis.

[0144] The first actuator assembly 14 has been described in which the constraint of the SMA wires 19, 22 results in amplification provided by the opposing SMA wires 19, 22 belonging to the same group. However, in other examples, the constraint of the SMA wires 19, 22 that results in amplification may be provided by one or more elastic elements (e.g., springs, flexures, etc.). Alternatively, the constraint of the SMA wires 19, 22 that results in amplification may be provided by one or more supports. In further examples, the constraint of the SMA wires 19, 22 that results in amplification may be provided by a combination of two or more of the opposing shape memory alloy wires in the respective first / second groups, one or more elastic elements, one or more springs, one or more flexures, and one or more supports.

[0145] The sides 27 of the first actuator assembly 14 form a square shape, however this is not required. In other examples, the sides of the actuator assembly can form other shapes, such as, for example, a rectangle, a diamond, a kite, or any other regular or irregular trapezoid. In still other examples, the actuator assembly can have more or less than four sides, such as three, five, six, or eight sides.

[0146] In the first actuator assembly 14, the third portion 17 is substantially coplanar with the second portion 15 and is received within the second portion 15. However, in other examples, the third portion 17 can be stacked above the second portion 15 (along the vertical axis z) and substantially coextensive with the second portion 15 (see, e.g., FIG. 6 , Fig. 9 and Figure 12).

[0147] Second Exemplary Actuator Assembly Also refer to Figure 5 , a second exemplary actuator assembly 36 (hereinafter referred to as “second actuator assembly”) is shown.

[0148] The second actuator assembly 36 is the same as the first actuator assembly 14, except that each of the first set of SMA wires 19 has an increased length, and each of the second set of SMA wires 22 has an increased length. Preferably, each SMA wire 19 of the first set has a length that extends as much as possible along the length of the side 27 of the second portion 15 while still connecting the first portion 4 and the second portion 15. For example, when projected onto the second axis y, the projected length of each SMA wire 19 of the first set may preferably be at least 80% of the length of the side 27 of the second portion 15 (also projected onto the second axis y).

[0149] Preferably, each SMA wire 22 of the second group has a length that extends as much as possible along the length of the side 27 of the third portion 15 while still connecting the second portion 15 and the third portion 17. For example, when projected onto the first axis x, the projected length of each SMA wire 22 of the second group may preferably be at least 80% of the length of the side 27 of the third portion 17 (also projected onto the first axis x).

[0150] like Figure 5 As shown, when viewed along the vertical axis y, the extended lengths of the SMA wires 19 in the first group cause the SMA wires 19 in the first group to cross each other. Similarly, when viewed along the vertical axis z, the SMA wires 22 in the second group cross each other. The SMA wires 19, 22 that cross each other when viewed along the vertical axis z will be slightly offset along the vertical axis z so that they do not contact each other and cause a short circuit.

[0151] In this way, the total length L of the SMA wires 19, 22 is increased. Since the maximum change in length δL obtainable from the phase change is proportional to the length L, the size of the movement envelope(s) 33, 34 of the second actuator assembly 36 is increased compared to the first actuator assembly 14. When rotational movement is optionally supported, the rotational travel will also be increased.

[0152] The variations and / or modifications described with respect to the first actuator assembly 14 are equally applicable to the second actuator assembly 36 .

[0153] Third Exemplary Actuator Assembly Also refer to Fig. 6A and Figure 6B , a third exemplary actuator assembly 37 (hereinafter referred to as “third actuator assembly”) is shown. The first flexure 25 and the second flexure 26 are omitted for visual clarity.

[0154] Fig. 6A is a projection view, in which the third portion 17 is offset along the vertical axis z for visual clarity. Figure 6B is the rear view along the positive z direction.

[0155] The third actuator assembly 37 is identical to the second actuator assembly 36, except that the first portion 4, the second portion 15, and the third portion 17 are stacked in sequence along the vertical direction z, and the first portion 4, the second portion 15, and the third portion 17 have different shapes from the second actuator assembly 36. The function of the third actuator assembly 37 is identical to that of the second actuator assembly 36 in terms of the relative movement of the SMA wires 19, 22 and the associated contraction.

[0156] The first part 4 and the second part 15 are each in the form of a flat thin ring having a rectangular outer edge and an inner edge defining a hole 28. The third part 17 is in the form of a flat thin square plate. The first part 4, the second part 15 and the third part 17 are stacked in sequence along the negative direction of the vertical axis z. When used in the camera 2, the hole 28 allows the light focused by the lens 11 to pass through to the image sensor 6 mounted on the third part 4. For this reason, none of the SMA wires 19 in the first group intersects the portion of the hole 28 corresponding to the area of ​​the third part 17, while the SMA wires 22 in the second group are routed below the third part 17 (relative to the vertical axis z).

[0157] The first plane 16 and the second plane 18 remain parallel, but in the third actuator assembly 37 , the first plane 16 and the second plane 18 are offset from each other along the vertical axis z.

[0158] The third actuator 37 may be particularly suitable for use with cameras that utilize a periscope lens configuration.

[0159] Although rectangular first and second portions 4, 15 and a square third portion 17 are shown, these shapes are not required for the third actuator 37. In other examples, the first portion 4, the second portion 15 and / or the third portion 17 (one or all of which may provide the sides 27 of the actuator assembly) may have other shapes, such as a rectangle, a diamond, a kite, or any other regular or irregular trapezoid, or may have more or less than four sides.

[0160] The variations and / or modifications described with respect to the first actuator assembly 14 and / or the second actuator assembly 36 are equally applicable to the third actuator assembly 37 .

[0161] Fourth exemplary actuator assembly Also refer to FIG. 7A to FIG. 7C , a fourth exemplary actuator assembly 38 (hereinafter referred to as “fourth actuator assembly”) is shown. The first flexure 25 and the second flexure 26 are omitted for visual clarity.

[0162] Fig. 7A is the rear view along the vertical axis z, Figure 7B is a side view along the second axis y, and Figure 7C is a side view along the first axis x.

[0163] The fourth actuator assembly 38 operates according to the same principle as the first actuator assembly 14, the second actuator assembly 36 and / or the third actuator assembly 37, with the main differences being that the fourth actuator assembly 38 also includes a fourth part 39 and a third set of SMA wires 40, and the shapes and stacking order of the first part 4, the second part 15 and the third part 17 are different.

[0164] The first part 4, the second part 15, the third part 17 and the fourth part 39 are stacked in sequence along the vertical direction z. The first part 4, the second part 15 and the third part 17 are each in the form of a flat thin ring having a rectangular outer edge and an inner edge defining a hole. The holes of the first part 4 and the third part 17 are empty, while the hole of the second part 15 is divided into two by a crossbar 41 aligned parallel to the first axis x. The crossbar 41 serves as an attachment point for the first group of SMA wires 19 and the second group of SMA wires 22. For the first actuator assembly 14, the second actuator assembly 36 and / or the third actuator assembly 37, the first group of SMA wires 19 connects the first part 4 to the second part 15, and the second group of SMA wires 22 connects the second part 15 to the third part 17. However, unlike the first actuator assembly 14 , the second actuator assembly 36 , and / or the third actuator assembly 37 , both the first set of SMA wires 19 and the second set of SMA wires 22 are arranged to provide maximum amplification for movement parallel to the first axis x.

[0165] The fourth portion 39 takes the form of a thin square plate and may be formed in any manner and / or using any of the materials described above with respect to the first portion 4, the second portion 15, and / or the third portion 17. The fourth portion 39 is movable relative to the third portion 17 in a third plane 41. The third plane 41 is parallel to the first plane 16 and the second plane 18, but offset from the first plane 16 and the second plane 18 along the vertical axis z. The third set of SMA wires 40 is configured to move the fourth portion 39 relative to the third portion 17 in the third plane 41. The SMA wires 40 in the third set are arranged so that the movement of the fourth portion 39 is amplified relative to the corresponding length change of the third set of SMA wires 40. The third set of SMA wires 40 is arranged to provide maximum amplification for movement parallel to the second axis y.

[0166] In this way, movement of the fourth portion 39 relative to the first portion 4 is a combination of movement of the second portion 15 relative to the first portion 4 , movement of the third portion 17 relative to the second portion 15 , and movement of the fourth portion 39 relative to the third portion 17 .

[0167] The fourth portion 39 may include features corresponding to any of the features described herein in conjunction with the second portion 15 and / or the third portion 17. Similarly, the third set of SMA wires 40 may include features corresponding to any of the features described herein in conjunction with the first set of SMA wires 19 and / or the second set of SMA wires 22. Similarly, the mechanical coupling between the fourth portion 39 and the third portion 17 may include features corresponding to any of the features described herein in conjunction with the mechanical coupling between any pair of the first portion 4, the second portion 15, and the third portion 17, such as a support member.

[0168] The controller may be configured to control the selective retraction of the third set of SMA wires 40 within the framework of any of the control modes described herein with respect to the first set of SMA wires 19 and / or the second set of SMA wires 22. For example, the controller may be configured to extend the range of motion of the fourth portion 39 relative to the first portion 4 beyond the second movement envelope 34 by combining the movement of the second portion 15, the third portion 17, and the fourth portion 39 along the same axis x, y. When rotational movement is optionally supported, the rotational travel will also be increased.

[0169] When the fourth actuator assembly 38 is incorporated into the camera 1 , the image sensor 6 is supported on the fourth part 39 , while the lens 11 remains fixed relative to the first part 4 .

[0170] Although in the fourth actuator assembly 38, the first part 4, the second part 15, the third part 17 and the fourth part 39 are stacked along the vertical direction z, in other examples, two, three or all of the first part 4, the second part 15, the third part 17 and the fourth part 39 can be configured to be substantially coplanar, for example by inserting the fourth part 39 into the hole 28 of the third part 17 in the first actuator assembly 14 and / or the second actuator assembly 36.

[0171] In the fourth actuator assembly 38 as shown, the image sensor 6 will be supported on the fourth portion 39 for inclusion into the camera. However, in other examples where one or more of the first portion 4, the second portion 15, the third portion 17, and the fourth portion 39 are shaped differently, the image sensor 6 can be coupled to any one of the first portion 4, the second portion 15, the third portion 17, and the fourth portion 39. Then, at least one lens 11 of the lens assembly 3 will be supported by a different one of the first portion 4, the second portion 15, the third portion 17, and the fourth portion 39.

[0172] The variations and / or modifications described with respect to the first actuator assembly 14 , the second actuator assembly 36 , and / or the third actuator assembly 37 are equally applicable to the fourth actuator assembly 38 .

[0173] Fifth actuator assembly Also refer to Figure 8 , a fifth exemplary actuator assembly 42 (hereinafter referred to as “fifth actuator assembly”) is shown. The first flexure 25 and the second flexure 26 are omitted for visual clarity.

[0174] The fifth actuator assembly 36 is similar to the first actuator assembly 14 and / or the second actuator assembly 36, except that each of the first group of SMA wires 19 and the second group of SMA wires 22 includes two actuation pairs. Each actuation pair includes a long wire and a short wire, the long wire being arranged so that the movement of the corresponding part 15, 17 is amplified relative to the corresponding length change of the long wire, the short wire having a length less than the long wire and being arranged to oppose the contraction of the long wire. In the first group of SMA wires 19, the first actuation pair includes the first SMA wire 191 as the short wire and the second SMA wire 192 as the long wire, and the second actuation pair includes the third SMA wire 193 as the short wire and the fourth SMA wire 194 as the long wire. Similarly, in the second group of SMA wires 22, the first actuation pair includes the first SMA wire 221 as the short wire and the second SMA wire 222 as the long wire, and the second actuation pair includes the third SMA wire 223 as the short wire and the fourth SMA wire 224 as the long wire.

[0175] The second portion 15 includes a pair of protrusions 431, 432 corresponding to the second side 272 and the fourth side 274, which allows the short SMA wires 191, 193 in the first group to be located substantially parallel to the second axis y in a neutral (or center) position of the second portion 15 relative to the first portion 4. Similarly, the third portion 17 includes a pair of protrusions 441, 442 corresponding to the first side 271 and the third side 273, which allows the short SMA wires 221, 223 in the second group to be located substantially parallel to the first axis x in a neutral (or center) position of the third portion 17 relative to the second portion 15. The second portion 15 includes a pair of cutouts 451, 452 that receive the protrusions to avoid unnecessary interference in the relative movement of the second portion 15 and the third portion 17.

[0176] The SMA wire 19, 22 configuration of the fifth actuator assembly 42 allows the natural length of the long wires 192, 194, 222, 224 to extend to increase the maximum obtainable amplified stroke (displacement) while avoiding the need for the SMA wires 19, 22 to cross each other. This can have beneficial effects, including simplified design and manufacturing, reduced overall height along the vertical axis z, and / or reduced risk of SMA wires 19, 22 entanglement.

[0177] In addition, because the short wires 191, 193, 221, 223 (through appropriate modifications to any of the control modes described herein) can be used primarily to oppose and constrain the contraction of the paired long wires 192, 194, 222, 224, the electrical connection of the SMA wires 19, 22 of the fifth actuator assembly 42 can also be simplified. In general, the short wires of one actuation pair can be electrically connected in series or in parallel with the short wires of different actuation pairs belonging to the same group or different groups.

[0178] For example, also refer to Fig. 9, the short lines in the same group can be connected in series. For example, the short lines 191 and 193 in the first group are connected in series, while the short lines 221 and 223 in the second group are connected in series.

[0179] Alternatively, also refer to Fig.10 , the short wires can be connected in series across the first group and the second group. For example, the short wire 191 in the first group is connected in series with the short wire 221 in the second group, while the short wire 193 in the first group is connected in series with the short wire 223 in the second group.

[0180] Although in the fifth actuator assembly 42, the first group of SMA wires 19 includes two actuation pairs, and the second group of SMA wires 22 also includes two actuation pairs, the configuration is not limited thereto. In other examples, any one of the first actuator assembly 14, the second actuator assembly 36, the third actuator assembly 37, and the fourth actuator assembly 38 can be modified so that the first group of SMA wires 19 includes one or more actuation pairs and / or the second group of SMA wires 22 includes one or more actuation pairs.

[0181] The fifth actuator assembly 42 may be modified to include the fourth portion 29 in the same manner as the fourth actuator assembly 38 .

[0182] The variations and / or modifications described with respect to the first actuator assembly 14 , the second actuator assembly 36 , the third actuator assembly 37 , and / or the fourth actuator assembly 38 are equally applicable to the fifth actuator assembly 42 .

[0183] Sixth actuator assembly While the actuator pair as configured in the fifth actuator assembly 42 avoids the need for the SMA wires 19 , 22 to cross over one another, in other examples, the actuator pair of SMA wires 19 , 22 may be arranged to cross over.

[0184] Also refer to FIG. 11A to FIG. 11C , a sixth exemplary actuator assembly 46 (hereinafter referred to as “sixth actuator assembly”) is shown.

[0185] Fig.11A The third portion 17 and the second set of SMA wires 22 are shown viewed from below along the vertical axis z. Fig. 11B The second portion 15 and the first set of SMA wires 19 are shown viewed from below along the vertical axis z. Fig. 11C The sixth actuator assembly 46 is shown viewed from the side along the second axis y. The first flexure 25 and the second flexure 26 are omitted for visual clarity.

[0186] The sixth actuator assembly 46 is similar to the fifth actuator assembly 42, except that the first portion 4, the second portion 15, and the third portion 17 are stacked along the vertical axis z and have different shapes, and the long and short lines of each actuation pair cross each other (but do not actually touch) when viewed along the vertical axis z. The first plane 16 and the second plane 18 remain parallel but are offset from each other along the vertical axis z.

[0187] The first part 4 is in the form of a flat thin plate. Each of the second part 15 and the third part 17 is in the form of a flat thin ring having a rectangular outer edge and a circular inner edge, defining a hole 28. The second part 15 slides relative to the first part 4 on a first plain bearing 47. Similarly, the third part 17 slides relative to the second part 15 on a second plain bearing 48. The first crimping member 20 is supported on the upper surface of the first part 4. The second part 15 supports the second crimping member 21 on the lower surface and supports the third crimping member 23 on the upper surface. The third part 17 supports the fourth crimping member 24 on the lower surface.

[0188] When used in the camera 2, the image sensor 6 is supported on the first portion 4, and at least one lens 11 of the lens assembly 3 is coupled to the third portion 17. The aperture 28 allows light to pass through and be focused onto the image sensor 6. Therefore, neither of the SMA wires 19, 22 intersects the aperture 28. Any of the first portion 4, the second portion 15, and the third portion 17 may be fixed relative to the rest of the camera 1 structure (e.g., the hood 9).

[0189] Although specific shapes of the first portion 4, the second portion 15, and the third portion 17 are shown, these shapes are not required for the sixth actuator assembly 46. In other examples, the first portion 4, the second portion 15, and / or the third portion 17 (one or all of which may provide the edge 27 of the actuator assembly) may have its inner and / or outer edges shaped, for example, as a rectangle, a diamond, a kite, or any other regular or irregular trapezoid, or may have more or less than four sides.

[0190] Although the sixth actuator assembly 46 includes sliding bearings 47 , 48 , any or all of these bearings may be replaced by other suitable bearings (eg, roller bearings, flexures, etc.).

[0191] The variations and / or modifications described with respect to any of the first to fifth actuator assemblies 14 , 42 are equally applicable to the sixth actuator assembly 46 .

[0192] Seventh actuator assembly In the first actuator assembly 14, the second actuator assembly 36, the third actuator assembly 37, the fourth actuator assembly 38, the fifth actuator assembly 42 to the sixth actuator assembly 46, the side 27 is substantially parallel to the first axis x and the second axis y, and the first group of SMA wires 19 and the second group of SMA wires 22 are configured to be constrained to provide maximum amplification for movement parallel to the first x-axis and / or the second y-axis. However, this is not required, and in other examples, the first group of SMA wires 19 and the second group of SMA wires 22 can be configured to provide maximum amplification for movement parallel to an axis that is oriented to be tilted rather than parallel / perpendicular to the side 27 of the actuator assembly.

[0193] Also refer to FIG. 12A to FIG. 12C , a seventh exemplary actuator assembly 49 (hereinafter referred to as “seventh actuator assembly”) is shown.

[0194] Fig. 12A The second portion 15 and the first set of SMA wires 19 are shown viewed from below along the vertical axis z. Fig. 12B The third portion 17 and the second set of SMA wires 22 are shown viewed from below along the vertical axis z. Fig. 12C The seventh actuator assembly 49 is shown viewed from the side along the second axis y. Fig. 12C The SMA wires 19 and 22 are omitted for visual clarity.

[0195] The seventh actuator assembly 49 has a stacked structure similar to the sixth actuator assembly 46, except that the second portion 15 and the third portion 17 are both in the form of thin flat square plates without holes 28. In the seventh actuator assembly 49, the second flexure 26 connects the third portion 17 to the second portion 15, and the electrical connection is then routed forward to the first portion 4 via one or more first flexures 25.

[0196] The seventh actuator assembly 49 has a similar SMA wire cross configuration to the second actuator assembly 36, except that the rotation causes the first set of SMA wires 19 to provide maximum amplification parallel to the line y=x along a rotated first axis 50. The second set of SMA wires 22 to provide maximum amplification parallel to the line y=-x along a rotated second axis 51.

[0197] In this way, the SMA wires 19, 22 can be oriented more diagonally relative to the edge 27, thereby allowing a further increase in the overall length and therefore increasing the maximum stroke (displacement). When rotational movement is optionally supported, the rotational stroke will also be increased.

[0198] The third portion 17 has an upper (first) surface 52 and a lower (second) surface 53. The second surface 52 is opposite the first portion 4 across the gap / space (which in this example includes the second portion 15). The SMA wires 19, 22 belonging to the first and second groups are routed through the gap separating the first portion 4 from the lower surface 53 of the third portion 17 and pass near the center of the seventh actuator assembly 49 (when viewed along the vertical axis z line). Thus, when included in the camera 1, the image sensor 6 is mounted on the upper surface 52 of the third portion 17, and the lens assembly 3 is connected to the camera 1 via, for example, the cover 9 (see Figure 1 ) is fixed relative to the first part 4.

[0199] The variations and / or modifications described with respect to any of the first to sixth actuator assemblies 14 , 46 are equally applicable to the seventh actuator assembly 49 .

[0200] Other variants It will be appreciated that many other variations of the embodiments described above are possible.

[0201] The first to seventh actuator assemblies 14 to 49 include four SMA wires 19, 22 in each of the first and second groups. However, more or fewer SMA wires 19, 22 may be used for one, some or all of the first, second and optional third groups.

[0202] Instead of opposing pairs of SMA wires, the contraction of each SMA wire 19 in the first group can be opposed by one or more springs (not shown) coupling the first portion 4 to the second portion 15. For example, the second SMA wire 192 and the third SMA wire 193 in the first group can be replaced by springs, so that the first group includes two SMA wires 19. Additionally or alternatively, the contraction of each SMA wire 22 in the second group can be opposed by one or more springs (not shown) coupling the third portion 17 to the second portion 15. For example, the second SMA wire 222 and the third SMA wire 223 in the second group can be replaced by springs, so that the second group includes two SMA wires 22.

[0203] At a minimum, the first set of SMA wires 19 may include a single SMA wire 19, and the second set of SMA wires 22 may include a single SMA wire 22, each opposed by one or more corresponding springs (not shown). This configuration is best suited for operation in the first control mode, where movement parallel to the first and second directions is isolated from the first and second SMA wires 19, 22. When used, the springs (opposing any SMA wires) may take the form of coil springs, flat springs, leaf springs, flexures, elements formed from elastomeric materials, and the like.

[0204] One or more of the first plane 16, the second plane 18, and if included, the third plane 41 need not be parallel to one or both of the other planes. One or more of the first plane 16, the second plane 18, and if included, the third plane 41 need not be perpendicular to the vertical axis z.

[0205] The actuator assembly 2 , 14 , 36 , 37 , 38 , 42 , 46 , 49 or a portion 4 , 15 , 17 , 39 thereof need not be configured to support a lens assembly and may, for example, be configured to support another type of optical element, an image sensor, etc. The portion 4 , 15 , 17 , 39 may or may not include the aperture 28 .

[0206] The actuator assemblies 2, 14, 36, 37, 38, 42, 46, 49 do not necessarily have to be used in a camera.

[0207] The vertical axis z does not necessarily correspond to the optical axis O. The vertical axis z may correspond to a line perpendicular to a plane defined by the flat surfaces of the first portion 4, the second portion 15, the third portion 17 and / or the fourth portion 39. The vertical axis z may correspond to a line perpendicular to a plane defined by the moving direction of the second portion 15, the third portion 17 and / or the fourth portion 39.

[0208] The actuator assembly 2, 14, 36, 37, 38, 42, 46, 49 may be or may be arranged in any of the following devices: a smartphone, a protective cover or case for a smartphone, a functional cover or case for a smartphone or electronic device, a camera, a foldable smartphone, a camera of a foldable smartphone, a foldable consumer electronic device, a camera with folded optics, an image capture device, an array camera, a three-dimensional sensing device or system, a servo motor, a consumer electronic device, a mobile or portable computing device, a mobile or portable electronic device, a laptop, a tablet computing device, an e-reader, a computing accessory or computing peripheral device, an audio device, a security system, a gaming system, a gaming accessory, a robot or robotic device, a medical device, an augmented reality system, an augmented reality device, a virtual reality system, a virtual reality device, a wearable device, a drone, an aircraft, a spacecraft, a submersible, a vehicle, an autonomous vehicle, a tool, a surgical tool, a remote control, a garment, a switch, a dial or button, a display screen, a touch screen, a flexible surface, and a wireless communication device. It will be understood that this is a non-exhaustive list of example devices.

Claims

1. An actuator assembly, comprising: Part I; a second portion movable in a first plane relative to the first portion; a first set of one or more shape memory alloy wires configured to move the second portion relative to the first portion in the first plane, the first set of shape memory alloy wires being arranged such that movement of the second portion is amplified relative to a corresponding change in length of the first set of shape memory alloy wires; a third portion movable relative to the second portion in a second plane, the second plane being parallel or coplanar with the first plane; and A second set of one or more shape memory alloy wires are configured to move the third portion relative to the second portion in the second plane, the second set of shape memory alloy wires being arranged such that movement of the third portion is amplified relative to a corresponding change in length of the second set of shape memory alloy wires.

2. The actuator assembly according to claim 1, wherein: the second portion being movable relative to the first portion in the first plane parallel to the first axis and to a second, different axis; Wherein, the movement of the second part parallel to the first axis is amplified by a greater factor than the movement of the second part parallel to the second axis.

3. The actuator assembly according to claim 1 or 2, wherein: the third portion being movable relative to the second portion in the second plane parallel to the first axis and the second axis; Wherein, the movement of the third part parallel to the second axis is amplified by a greater multiple than the movement of the third part parallel to the first axis.

4. The actuator assembly according to any one of claims 1 to 3, further comprising a controller configured to control the selective contraction of the shape memory alloy wires in the first group of shape memory alloy wires and the second group of shape memory alloy wires so that the third portion moves a first component parallel to the first axis and a second component parallel to the second axis relative to the first portion.

5. The actuator assembly according to claim 4, wherein: The controller is configured such that in a first mode the first component corresponds to movement of the second part relative to the first part and the second component corresponds to movement of the third part relative to the second part.

6. An actuator assembly according to claim 4 or 5, wherein: The controller is configured such that in the second mode: within a first movement envelope, the first component corresponds to movement of the second portion relative to the first portion, and the second component corresponds to movement of the third portion relative to the second portion; Therein, outside the first movement envelope and within the second movement envelope, the first component and / or the second component corresponds to a combination of a movement of the second part relative to the first part and a movement of the third part relative to the second part.

7. An actuator assembly according to any one of claims 4 to 6, wherein: The controller is configured such that in a third mode: The first component includes a first movement of the second portion relative to the first portion parallel to the first axis and a second movement of the third portion relative to the second portion parallel to the first axis, the second movement being smaller than the first movement; The second component includes a third movement of the third portion relative to the second portion parallel to the second axis and a fourth movement of the second portion relative to the first portion parallel to the second axis, the fourth movement being smaller than the third movement.

8. An actuator assembly according to any two of claims 5 to 7, wherein: The controller is configured to be switchable between at least two of the first mode, the second mode, and the third mode.

9. An actuator assembly according to any one of claims 1 to 8, wherein: contraction of each shape memory alloy wire in the first set of shape memory alloy wires is opposed by one or more other shape memory alloy wires in the first set of shape memory alloy wires; and / or Contraction of each shape memory alloy wire in the second set of shape memory alloy wires is opposed by one or more other shape memory alloy wires in the second set of shape memory alloy wires.

10. An actuator assembly according to any one of claims 1 to 9, wherein: the first set of shape memory alloy wires comprises four shape memory alloy wires in an arrangement in which none of the shape memory alloy wires are co-linear; and / or Wherein, the second set of shape memory alloy wires includes four shape memory alloy wires in an arrangement in which none of the shape memory alloy wires are co-linear.

11. An actuator assembly according to any one of claims 1 to 10, wherein: The first group of shape memory alloy wires includes four shape memory alloy wires arranged in a loop, wherein a shape memory alloy wire in the first group of shape memory alloy wires forms a different angle with each of a pair of adjacent shape memory alloy wires in the first group of shape memory alloy wires; and / or The second group of shape memory alloy wires includes four shape memory alloy wires arranged in a loop, wherein a shape memory alloy wire in the second group of shape memory alloy wires forms a different angle with each of a pair of adjacent shape memory alloy wires in the second group of shape memory alloy wires.

12. An actuator assembly according to any one of claims 1 to 11, wherein: the first set of shape memory alloy wires comprising four shape memory alloy wires in an arrangement capable of applying torque about a vertical axis perpendicular to the first plane; and / or Wherein, the second set of shape memory alloy wires includes four shape memory alloy wires in an arrangement capable of applying torque about the vertical axis.

13. An actuator assembly according to any one of claims 1 to 12, wherein: The first set of shape memory alloy wires comprises shape memory alloy wires that cross when viewed along the vertical axis; and / or Wherein, the second group of shape memory alloy wires includes shape memory alloy wires that cross when viewed along the vertical axis.

14. An actuator assembly according to any one of claims 1 to 13, wherein: The first set of shape memory alloy wires comprises a pair of shape memory alloy wires having mirror symmetry when viewed along the vertical axis; and / or Wherein, the second group of shape memory alloy wires includes a pair of shape memory alloy wires having mirror symmetry when viewed along the vertical axis.

15. An actuator assembly according to any one of claims 1 to 14, wherein: The first set of shape memory alloy wires comprises shape memory alloy wires arranged at an angle between 20° and 80° to the first axis; and / or The second group of shape memory alloy wires includes shape memory alloy wires arranged at an angle between 45° and 77° to the second axis.

16. An actuator assembly according to any one of claims 1 to 15, wherein: The third portion includes a central hole, wherein no shape memory alloy wire passes through the central hole.

17. An actuator assembly according to any one of claims 1 to 15, wherein: The third portion has a first surface and a second surface, the second surface being opposite to the first portion across the gap; wherein a shape memory alloy wire belonging to the first group of shape memory alloy wires is routed through the gap; and / or Wherein, the shape memory alloy wire belonging to the second group of shape memory alloy wires is routed through the gap.

18. An actuator assembly according to any one of claims 1 to 17, wherein: The first set of shape memory alloy wires comprises one or more actuation pairs and / or the second set of shape memory alloy wires comprises one or more actuation pairs, wherein each actuation pair comprises: an elongate line arranged so that movement of the respective portion is amplified relative to a corresponding change in length of the elongate line; and A short line having a length shorter than that of the long line and arranged to oppose contraction of the long line.

19. The actuator assembly of claim 18, comprising two or more actuation pairs; in, The stub in one first actuation pair is electrically connected in series or in parallel with the stub in a different actuation pair.

20. An actuator assembly according to any one of claims 1 to 19, wherein: The first set of shape memory alloy wires is further configured to rotate the second portion relative to the first portion in the first plane; and / or Wherein, the second group of shape memory alloy wires is further configured to rotate the third portion relative to the second portion in the second plane.

21. The actuator assembly according to any one of claims 1 to 20, further comprising: a fourth portion, the fourth portion being movable relative to the third portion in a third plane, the third plane being parallel or coplanar with the second plane; A third set of one or more shape memory alloy wires is configured to move the fourth portion relative to the third portion in the third plane, the third set of shape memory alloy wires being arranged so that movement of the fourth portion is amplified relative to a corresponding length change of the third set of shape memory alloy wires.

22. A camera comprising: An actuator assembly according to any one of claims 1 to 21; an image sensor supported by one of the first portion, the second portion, and the third portion; One or more lenses, at least one of the one or more lenses is supported by one of the first portion, the second portion, and the third portion, wherein the one or more lenses are supported by a portion different from the image sensor.

23. The camera of claim 22, wherein: The first portion is fixed relative to the remainder of the camera.

24. The camera of claim 22, wherein: The second portion is fixed relative to the remainder of the camera.

25. A method of controlling an actuator assembly according to any one of claims 1 to 21 or a camera according to any one of claims 21 to 23, comprising controlling the contraction of the shape memory alloy wires in the first group of shape memory alloy wires and the second group of shape memory alloy wires to move the third part relative to the first part by a first component parallel to the first axis and a second component parallel to the second axis.

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