Actuator assembly

Abstract

An actuator assembly includes: a first member; a second member movable with respect to the first member; and one or more actuation units each configured to apply an actuation force to the second component, the actuation force being capable of moving the second component relative to the first component, where each actuation unit includes: a body portion; an SMA element connected between the body portion and the first component and arranged to apply an input force to the body portion upon actuation; and a force adjustment element connected between the body portion and the first component and configured to adjust an input force so as to generate an actuation force, where the force adjustment element directs movement of the body portion along a path in an actuation plane upon actuation of the SMA element, and means configured to move the force adjustment element along the path in the actuation plane upon actuation of the SMA element. The force adjusting element is configured to increase the effective stiffness of the force adjusting element in a direction orthogonal to the actuation plane.

Description

field

[0001] The present application relates to an actuator assembly having one or more actuation units, each of which comprises a shape memory alloy (SMA) element. background

[0002] SMA actuator assemblies may be used in a variety of applications for moving a movable component relative to a support structure.

[0003] For example, WO 2013 / 175197 A1 describes a camera in which four SMA wires are arranged to move a lens element relative to an image sensor in a plane perpendicular to the optical axis of the lens element, thereby achieving optical image stabilization (OIS). WO 2010 / 029316 A1 describes SMA actuator wires for providing OIS in a camera by tilting the camera module. WO 2011 / 104518 A1 describes an actuator assembly with eight SMA wires that enables position control of a movable element in multiple degrees of freedom.

[0004] Typically, the range of motion (also called "stroke") of such an SMA actuator assembly is limited by the maximum contraction of the SMA wire, and the actuation force is limited by the maximum force that the SMA wire can generate. To increase the range of motion or actuation force, longer or thicker SMA actuator wires can be used, but this may come at the expense of increased cost, size, and / or power, which may not be practical in miniature applications.

[0005] WO 2022 / 084699 A1 discloses an actuator assembly comprising at least one actuation unit (comprising an SMA wire) which, when actuated, moves a movable part relative to a support structure. The actuation unit may be configured to amplify the range of motion of the movable part, thereby amplifying the actuation force acting on the movable part, or redirect the force applied by the SMA wire. Overview

[0006] According to aspects of the present invention, an actuator assembly is provided, which includes: a first component; a second component, the second component being movable relative to the first component; and one or more actuating units, each actuating unit being configured to apply an actuating force to the second component, the actuating force being capable of causing the second component to move relative to the first component, wherein each actuating unit includes: a main body portion; an SMA element, which is connected between the main body portion and the first component and is arranged to apply an input force to the main body portion during actuation; and a force adjustment element, which is connected between the main body portion and the first component and is configured to adjust the input force to generate the actuating force, wherein the force adjustment element guides the main body portion to move along a path in an actuation plane when the SMA element is actuated, and a device, which is configured to increase the effective stiffness of the force adjustment element in a direction orthogonal to the actuation plane.

[0007] In some embodiments, the force adjustment element includes a first portion and a second portion, wherein the second portion is offset and / or spaced apart from the first portion in a direction orthogonal to the actuation plane, thereby forming a device configured to increase the effective stiffness of the force adjustment element in a direction orthogonal to the actuation plane.

[0008] In some embodiments, when viewed in a direction along the actuation plane, a gap is formed between the first part and the second part, wherein, in a direction orthogonal to the actuation plane, the extension range of the gap can be at least half of the extension range of the thinner one of the first part and the second part, and preferably at least equal to or at least twice the extension range of the thinner one.

[0009] In some embodiments, the SMA element and each of the first and second portions extend parallel to the actuation plane, and a position of the SMA element along an axis normal to the actuation plane is located between, preferably substantially midway between, the positions of the first and second portions along the axis normal to the actuation plane.

[0010] In some embodiments, each actuation unit further comprises a foot portion, the force adjustment flexible member being connected to the first component via the foot portion, wherein each of the foot portion, the main body portion and the force adjustment flexible member comprises a first portion and a second portion spaced apart in a direction along the main axis.

[0011] In some embodiments, the first portions are integrally formed with each other, and the second portions are integrally formed with each other.

[0012] In some embodiments, each of the body portion and the foot portion further includes a third portion located between and attached to each of the corresponding first portion and the second portion.

[0013] In some embodiments, the SMA element is connected to the body portion via a connecting element, wherein the connecting element is integrally formed with the third portion of the body portion.

[0014] In some embodiments, the first portion and the second portion comprise sheets of material, optionally wherein the third portion comprises a sheet of material.

[0015] In some embodiments, the device comprises a compliant material arranged between a component of the actuation unit and at least one of the first component and the second component.

[0016] In some embodiments, the flexible material comprises gel.

[0017] In some embodiments, the flexible material is further configured to dampen oscillations of the actuation unit and / or oscillations of the second component relative to the first component.

[0018] In some embodiments, the device includes a first magnet on the actuation unit, wherein the first magnet repels a second magnet spaced apart from the first magnet in one direction orthogonal to the actuation plane, and the first magnet repels a third magnet spaced apart from the first magnet in another direction orthogonal to the actuation plane.

[0019] According to another aspect of the present invention, an actuator assembly is provided, which includes: a first component; a second component, the second component being movable relative to the first component; and one or more actuating units, each actuating unit being configured to apply an actuating force to the second component, the actuating force being capable of causing the second component to move relative to the first component, wherein each actuating unit includes: a main body portion; an SMA element, which is connected between the main body portion and the first component and is arranged to apply an input force to the main body portion during actuation; and a force adjustment element, which is connected between the main body portion and the first component and is arranged to adjust the input force to generate the actuating force, wherein the force adjustment element guides the main body portion to move along a path in an actuation plane when the SMA element is actuated, wherein at least one endstop is arranged between the actuating unit and the first component or the second component, the endstop being arranged to limit deformation of the actuating unit in a direction orthogonal to the actuation plane.

[0020] In some embodiments, at least one end stop is configured to engage a component of the actuation unit when the component of the actuation unit moves in a first direction orthogonal to the actuation plane, and at least one additional end stop is arranged between the actuation unit and the first component or the second component and is configured to engage a component of the actuation unit when the component of the actuation unit moves in the first direction orthogonal to the actuation plane, wherein the second direction is opposite to the first direction.

[0021] In some embodiments, each end stop comprises a first end stop surface on the actuation unit and a second end stop surface on the first component or the second component, wherein during normal operation of the actuation unit, the first end stop surface and the second end stop surface are spaced apart, in particular spaced apart by a constant distance.

[0022] In some embodiments, wherein the first end stop and the second end stop are parallel to the actuation plane.

[0023] In some embodiments, the first end stop surface is formed on a protrusion protruding from the actuation unit, and / or the second end stop surface is formed on a protrusion protruding from the first component or the second component.

[0024] In some embodiments, the end stop is formed on a body portion of the actuation unit.

[0025] In some embodiments, the end stop is formed on a coupling link of the actuation unit.

[0026] In some embodiments, during normal operation, the gap of the end stop is in the range of 0 to 25% of the length of the force adjustment element, preferably in the range of 5% to 15% of the length of the force adjustment element. Generally, alternatively, the gap can be greater than 1%, 2%, 3%, 7%, 12% or 15% of the length of the force adjustment element. The gap can be less than 20%, 12%, 10%, 8%, 6% or 4% of the length of the force adjustment element.

[0027] In some embodiments, during normal operation, the gap of the end stop is in the range of 0 to 500um, preferably in the range of 100um to 300um. Typically, alternatively, the gap may be greater than 10um, 20um, 40um, 60um, 80um, or 150um. The gap may be less than 1mm, 700um, 500um, 300um, 250um, 200um, or 150um.

[0028] In some embodiments, the force-modifying element includes a force-modifying flexure.

[0029] In some embodiments, the force adjustment element is arranged to be in tension when the SMA element is actuated.

[0030] In some embodiments, the force modulation element is arranged at an angle relative to the SMA wire, preferably at an angle in the range of 13 degrees to 77 degrees, optionally at an angle in the range of 13 degrees to 40 degrees or 77 degrees to 50 degrees.

[0031] In some embodiments, each actuation unit is configured to amplify an actuation of the SMA element to a relatively greater movement of the second component relative to the first component, optionally by a factor greater than 1.5, preferably greater than 2, and even more preferably greater than 3.

[0032] In some embodiments, each actuation unit is configured to amplify the input force such that the actuation force is greater than the input force, optionally by a factor greater than 1.5, preferably greater than 2, and even more preferably greater than 3.

[0033] In some embodiments, each actuation unit further comprises a coupling link connected between the main body portion and the second component, wherein the coupling link is configured to transmit the actuation force from the main body portion to the second component, and wherein the coupling link is flexible in a direction perpendicular to the direction of the actuation force.

[0034] In some embodiments, the coupling link includes a coupling flexure.

[0035] In some embodiments, the coupling link is arranged to be in tension when the SMA element is actuated.

[0036] In some embodiments, the angle between the coupling link and the SMA wire is in the range of 70 degrees to 110 degrees.

[0037] In some embodiments, each actuation unit extends substantially in an actuation plane.

[0038] In some embodiments, the body portion and the force modulating flexure are integrally formed from the same material, optionally wherein the coupling link is also formed from the same material.

[0039] Some embodiments include a total of four actuation units arranged to apply the actuation forces such that each of the actuation forces are collinear.

[0040] In some embodiments, the four actuation units are arranged such that a first pair of actuation units applies actuation forces in two opposite directions parallel to a first axis in a plane, and a second pair of actuation units applies actuation forces in two opposite directions parallel to a second axis in a plane, wherein the first axis and the second axis are not parallel.

[0041] In some embodiments, the first pair of actuation units are arranged to apply torque to the second component relative to the first component in a first orientation, and the second pair of actuation units are arranged to apply torque to the second component relative to the first component in a second orientation, wherein the second orientation is opposite to the first orientation.

[0042] Some embodiments include an image sensor and / or lens assembly wherein the image sensor or lens assembly is fixed relative to the second component and / or the lens assembly or image sensor is fixed relative to the first component.

[0043] According to another aspect of the present invention, there is provided an actuator assembly, the actuator assembly comprising: a first component and a second component, the first component and the second component being movable relative to each other; and one or more actuating units, each actuating unit comprising: a main body portion; a force adjustment mechanism connected between the main body portion and the first component; a connecting link connected between the main body portion and the second component; and an SMA wire connected between the first component and the main body portion, for applying an input force on the main body portion, thereby causing the main body portion to apply an output force on the connecting link, and causing the connecting link to apply an actuating force on the second component; wherein the actuating force has at least a major component in a plane perpendicular to the main axis, and the connecting link is flexible in a direction perpendicular to the actuating force; and wherein the actuator assembly further comprises one or more limiting arrangements, each of the limiting arrangements being configured to limit movement of at least a portion of at least one of the actuating units along the main axis.

[0044] The one or more limiting means may be means for increasing stiffness in a direction orthogonal to the actuation plane, or may be end stops.

[0045] Thus, the limiting device may limit (eg, prevent or reduce) movement of the actuation unit along the primary axis, which movement may occur due to unstable / unbalanced forces in the actuation unit and may adversely affect performance or reliability of the actuator assembly.

[0046] An actuation force having at least a major component in a plane perpendicular to the main axis means, for example, that the actuation force is directed to the plane at an angle of less than 45°. The angle is typically substantially less than this 45° (e.g. less than 5°) and may be approximately zero, that is to say the actuation force is in the plane.

[0047] The coupling link may correspond to the coupling flexible member, and the force adjustment mechanism may correspond to the force adjustment flexible member.

[0048] Alternatively, the connecting link and / or force adjustment mechanism may correspond to any of the non-flexible examples provided in WO2022 / 084699, which is incorporated by reference.

[0049] At least one of the limiting means may comprise an end stop configured to engage a component of the actuation unit when the component is moved in one direction along the main axis.

[0050] At least one of the limiting means may comprise a further end stop configured to engage a component of the actuation unit when the component is moved in another direction along the main axis.

[0051] The end stop may be comprised in the first component or in the second component.The further end stop may be comprised in the first component or in the second component.

[0052] At least one of the limiting means may comprise a support, which is located between a component of the actuation unit and another component of the actuator assembly.

[0053] Another component may be included in the first component or the second component.

[0054] The actuator assembly may be configured to generate a biasing force to bias a component of the actuation unit against another component of the actuator assembly.

[0055] The biasing force may be generated by pre-stressing the force regulating flexure.

[0056] When the SMA wire is in tension, a biasing force may be generated by the SMA wire. To provide this, the SMA wire and / or the force adjustment flexure may extend at a non-zero angle relative to a plane perpendicular to the main axis.

[0057] The bearing may be a sliding bearing or a rolling (eg ball) bearing.

[0058] Another component of the actuator assembly may include a planar surface perpendicular to the main axis.

[0059] At least one of the limiting devices may include a first magnet on the actuation unit. The first magnet may repel a second magnet spaced apart from the first magnet in one direction along the main axis, and the first magnet may repel a third magnet spaced apart from the first magnet in another direction along the main axis.

[0060] At least one of the limiting means may comprise a flexible material, the flexible material being arranged between a component of the actuation unit and at least one of the first component and the second component.

[0061] During operation of the actuator assembly, the flexible material may remain in contact with components of the actuation unit.The flexible material may be a gel.

[0062] At least one of the limiting devices may be configured to limit movement of at least a portion of the body portion of the actuation unit.

[0063] When viewed along the major axis, the main body portion may be wider than the coupling flexure and / or the force adjustment flexure.

[0064] At least one of the limiting devices may be configured to limit movement of a plurality of components of the actuation unit, and the plurality of components are spaced apart from one another when viewed along the main axis.

[0065] In at least one of the actuation units, the force adjustment flexure may comprise a first portion and a second portion, the second portion being offset and / or spaced apart from the first portion in a direction along the main axis, thereby forming a restricting arrangement.

[0066] In at least one of the actuation units, the SMA wire and each of the first and second portions may extend perpendicular to the major axis, and a position of the wire along the major axis may be substantially midway between positions of the first and second portions along the major axis.

[0067] At least one of the actuation units may comprise a foot portion via which the force adjustment flexure is connected to the first component.

[0068] The body portion, the force modulation flexure, and the foot portion may be configured such that the force modulation flexure is in tension when the SMA wire is in tension.

[0069] In at least one of the actuation units, each of the foot portion, the body portion, and the force adjustment flexible member may include a first portion and a second portion, the second portion being spaced apart from the first portion in a direction along the main axis. The first portions may be formed integrally with each other, and the second portions may be formed integrally with each other. Each of the body portion and the foot portion may also include a third portion located between the first portion and the second portion and attached to each of the first portion and the second portion.

[0070] The first portion, the second portion and the third portion may be formed from sheet metal.

[0071] In at least one of the actuation units, the SMA wire may be connected to the body portion via a crimp.The crimp may be integrally formed with the third portion of the body portion.

[0072] The crimping piece may be formed integrally with the first portion or the second portion of the main body portion. The coupling flexible piece may be formed integrally with the first portion, the second portion or the third portion of the main body portion.

[0073] The actuator assembly may comprise at least two actuation units arranged to apply an actuation force to the second component in a perpendicular direction such that a coupling link of each of the two actuation units is flexible in the direction of the actuation force of the other of the two actuation units.

[0074] The first component and the second component may be movable relative to each other in any direction in a plane perpendicular to the main axis.

[0075] The actuator assembly may comprise four actuation units arranged to enable the second component to move relative to the first component in any direction in a plane perpendicular to the main axis without applying any net torque to the second component about the main axis.

[0076] The actuation unit may be arranged to be able to rotate the second component relative to the first component about any axis perpendicular to and intersecting the main axis.

[0077] The actuator assembly may include suitable support means to allow such movement.

[0078] A camera assembly may be provided comprising an actuator assembly, wherein the second component comprises an image sensor having an imaging axis parallel to the main axis, and wherein the actuator assembly is used to provide sensor-shift optical image stabilisation.

[0079] However, the actuator assembly may be used in any system or device, for example, in a head mounted display. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Certain embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 1A to 1E are schematic cross-sectional views of different variations of camera modules including actuator assemblies; Figure 2 is a schematic perspective view of an actuator assembly; 3A and 3B are perspective and plan views of an actuation unit forming part of an actuator assembly, and FIG. 3C is a plan view of another such actuation unit; Figure 4 is a schematic plan view of the arrangement of four actuation units; Figure 5 is a schematic perspective view of an arrangement of eight actuation units; Figure 6a and Figure 6b are examples of actuator assemblies with the actuation unit in a central position and with the actuation unit in two possible non-central positions; Figures 7a to 7e A two-layer actuation unit forming a means for increasing the stiffness of the force adjustment element in a direction orthogonal to the actuation plane is shown; Figure 8a and Figure 8b shows the way of forming a double-layer actuation unit; Figures 9a to 9c Further means for increasing the stiffness of the force adjustment element in a direction orthogonal to the actuation plane are shown; Fig.10 schematically illustrates an end stop for limiting deformation of the actuation unit in an out-of-plane direction; and Figure 11 to Fig.13 Shows Fig.10 A specific embodiment of an exemplary end stop is Fig.10 A perspective view of an example of an actuator assembly. Detailed Description

[0081] Camera Module 1A to 1E schematically show different variations of a device 1 comprising an actuator assembly 2. The device 1 is, for example, a camera module 1. Typically, the device 1 will be incorporated into a portable electronic device such as a smartphone. Therefore, miniaturization may be an important design criterion.

[0082] Figure 2 The actuator assembly 2 is schematically shown. The actuator assembly 2 comprises a support structure 10 and a movable part 20. The movable part 20 is movable relative to the support structure 10. When the actuator assembly 2 is included in, for example, an apparatus 1, the support structure 10 may be fixed relative to the body of the apparatus 1. However, in general, the support structure 10 need not be stationary and may be movable relative to the apparatus 1 or movable within the apparatus 1. The actuator assembly 2 comprises one or more actuation units 30. Each actuation unit 30 is configured to apply an actuation force to the movable part 20, which actuation force is capable of causing the movable part 20 to move relative to the support structure 10.

[0083] The movable part 20 may be supported on the support structure 10 (i.e. suspended on the support structure 10) only by the actuation unit 30. Alternatively, the actuator assembly 2 may include a support device 40 that supports the movable part 20 on the support structure 10. The actuation unit 30 and the support device 40 may together support the movable part 20 on the support structure 10. The support device 40 may have any suitable form that allows the movable part 20 to move with one or more degrees of freedom (DOF) relative to the support structure 10. The actuation unit 30 and / or the support device 40 may constrain (i.e. reduce or prevent) other degrees of freedom of movement of the movable part 20 relative to the support structure 10. To this end, the support device 40 may, for example, include one or more of the following bearings: a rolling bearing (such as a ball bearing), a flexible bearing (i.e. an arrangement of flexible members or other elastic elements that guide the movement) or a sliding (i.e. sliding contact) bearing.

[0084] The principal axis P may be defined with reference to the actuator assembly 2 and / or the support structure 10. The principal axis P may extend through the actuator assembly 2, for example through the center of the actuator assembly 2. In some examples, the actuator assembly 2, the support structure 10, and / or the movable component 20 extend primarily in a direction perpendicular to the principal axis P. In other words, the actuator assembly 2, the support structure 10, and / or the movable component 20 extend less along the principal axis P than in any direction perpendicular to the principal axis P. Alternatively or additionally, the support structure 10 and / or the movable component 20 may include a planar component extending perpendicular to the principal axis P. Alternatively or additionally, in examples where the device 1 includes an optical element having an optical axis (such as a lens assembly 3) or an imaging element having an imaging axis (such as an imager sensor 4), the principal axis P may be parallel to such an axis and / or may coincide with such an axis when the movable component 20 is in a central position or orientation (e.g., see FIG. 1A ).

[0085] Typically, the movable component 20 can be movable relative to the support structure 10 with up to six degrees of freedom (DOF). In the context of describing the degrees of freedom of movement, the main axis P can also be referred to as the z-axis, and the other two axes perpendicular to the main axis P and to each other can be referred to as the x-axis and the y-axis. The movable component 20 can be movable relative to the support structure 10 in all or any subset of the following degrees of freedom (including only one degree of freedom):

[0086] Tx and Ty: translational movement in the xy plane. In other words, the movable part 20 can be independently moved along the x-axis and the y-axis. The movable part 20 can be moved to any position in the xy plane within the range of movement. Instead of such a planar movement, the movable part 20 can be linearly movable, for example along the x-axis or the y-axis.

[0087] Rx and Ry: rotational movement (or simply rotation or tilt) about the x-axis and the y-axis. In other words, the movable part 20 can rotate about any line perpendicular to the main axis P. The movable part 20 can be rotated to any rotational position (i.e., to any orientation) within the range of movement. Instead of such a dual-axis rotation, the movable part 20 can rotate about a single axis (e.g., about the x-axis or the y-axis).

[0088] Tz: translational movement along the z axis. The movable component 20 can be moved to any translational position along the z axis within the movement range.

[0089] Rz: rotational movement about the z axis (or simply rotation). The movable part 20 can be rotated to any rotational position (ie, to any orientation) within the range of movement.

[0090] In some examples, the movable part 20 can be supported, for example, by a support device 40 so as to allow translational movement (Tx, Ty) in the xy plane and / or rotational movement (Rz) about the z axis. The translational movement (Tz) along the z axis and the rotational movement (Rx, Ry) about the x axis and the y axis can be constrained. For example, such support can be provided by a support device 40 having a suitable arrangement of ball bearings or sliding bearings that generate a support force in the +z direction and a biasing device that generates a biasing force in the -z direction. Examples of actuator assemblies having such support devices are disclosed in WO 2013 / 175197 A1 and WO 2017 / 072525 A1, each of which is incorporated herein by reference.

[0091] In some examples, the movable part 20 may be supported to allow tilting (Rx, Ry) about the x-axis and the y-axis and optionally rotation (Rz) about the z-axis. Other degrees of freedom of movement (i.e., Tx, Ty, Tz, Rz or Tx, Ty, Tz) may be constrained. Such support may be provided by a support device 40, for example in the form of a gimbal. An example of such a support device 40 is disclosed in WO 2021 / 209770 A1, which is incorporated herein by reference. Alternatively, such support may be provided only by the actuation unit 30, similar to WO 2011 / 104518 A1, which discloses an actuator assembly having 8 SMA wires connected between the support structure 10 and the movable part 20. WO 2011 / 104518 A1 is incorporated herein by reference.

[0092] In some examples, the movable part 20 may be supported to allow three-dimensional translational movement (Tx, Ty, Tz), while rotational movement (Rx, Ry, Rz) may be constrained. Such support may be provided by a support device 40 (e.g. in the form of nested linear supports). An example of such a support device 40 is disclosed in WO 2021 / 209769 A1, which is incorporated herein by reference. Alternatively, similar to WO 2011 / 104518 A1, such support may be provided only by the actuation unit 30.

[0093] Alternatively or additionally, the movable part 20 can move in other degrees of freedom. The movable part 20 can move in a degree of freedom that is a combination of any two or more of Tx, Ty, Tx, Rx, Ry and Rz. For example, the movable part 20 can move along a spiral path around the z axis (i.e., move spirally), and thus simultaneously move along the z axis and rotate around the z axis. In other words, Tz and Rz movements can be combined. An example of such a spiral actuator assembly is disclosed in WO2019 / 243849 A1, which is incorporated herein by reference.

[0094] The actuation unit 30 is connected between the support structure 10 and the movable part 20. The actuation unit 30 is arranged to apply an actuation force F between the movable part 20 and the support structure 10 (see, for example Figure 4 and Figure 5 ). Selectively varying the actuation force F can cause the movable part 20 to move relative to the support structure 10, for example within the degrees of freedom allowed by the bearing device 40. Thus, the actuation unit 30 is capable of driving the movement of the movable part 20 relative to the support structure 10.

[0095] The support means 40 can move the movable part 20 in a direction different from the direction of the actuation force F. In a simple example in this respect, one component of each actuation force F causes a movement of the movable part 20 and another component of each actuation force F opposes the support force generated by the support means 40 .

[0096] The camera module 1 also includes a lens assembly 3 and an image sensor 4. The lens assembly 3 includes one or more lenses configured to focus an image on the image sensor 4. The lens assembly 3 defines an optical axis O. The lens assembly 3 may include a lens holder, which supports the one or more lenses (e.g., in the form of a cylindrical body). The image sensor 4 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. The camera module 1 may be a compact camera module in which each lens has a diameter of 20 mm or less, such as a diameter of 12 mm or less.

[0097] In a ("sensor-shift") variation of the camera module 1 shown in Fig. 1A, the movable part 20 comprises an image sensor 4. The lens assembly 3 may be fixed relative to the support structure 10, or may be movable relative to the support structure 10 along an optical axis O (as described below).

[0098] In the ("lens-shift") variation shown in Fig. 1B, the image sensor 4 is fixed relative to the support structure 10, and the movable part 20 comprises a lens assembly 3. The lens assembly 3 may be movable relative to the movable part 20 along an optical axis O, as described below.

[0099] In both variants, the actuator assembly 2 is configured to move the lens assembly 3 relative to the image sensor 4 in any direction in a plane perpendicular to the main axis P and therefore perpendicular to the optical axis O. This movement has the effect of shifting the image on the image sensor 4 and enables optical image stabilization (OIS) to be implemented in the camera module 1. In the sensor-shift variant, the movable part 20 may also be rotatable about the main axis P so as to also be able to compensate for roll.

[0100] In the (“module-tilt”) variation shown in FIG. 1C , the movable part 20 includes both the lens assembly 3 and the image sensor 4. Again, as described below, the lens assembly 3 can be moved relative to the movable part 20 along the optical axis O. The actuator assembly 2 is configured to tilt the movable part 20 about two axes perpendicular to the main axis P and perpendicular to each other, and optionally to rotate the movable part 20 about the main axis P, so that OIS can be implemented in the camera module 1.

[0101] In the (“autofocus”) variant shown in FIG. 1D , the movable part 20 comprises a lens assembly 3 and the actuator assembly 2 moves the movable part 20 relative to the support structure 10 along the main axis P and hence along the optical axis O. Such movement has the effect of adjusting the focus of the image on the image sensor 4. Thus, an autofocus (AF) or zoom function can be implemented in the camera module 1.

[0102] In some examples (not shown), the camera module 1 may include a first actuator assembly for providing OIS as shown in FIGS. 1A to 1C , and a second actuator assembly for providing AF as shown in FIG. 1D . One or both of the first actuator assembly and the second actuator assembly may correspond to the actuator assembly 2 as described herein. One of the first actuator assembly and the second actuator assembly may be another type of SMA actuator assembly or may be a non-SMA actuator assembly, such as a voice-coil motor (VCM) actuator assembly. As will be appreciated, in the lens shift and module tilt variations, the support structure 10 of the second actuator assembly 2 is fixed to (or corresponds to) the movable component 20 of the first actuator assembly 2.

[0103] In the ("AF+OIS") variation shown in FIG. 1E , the movable part 20 comprises a lens assembly 3 , and the actuator assembly 2 produces a three-dimensional translational movement of the movable part 20 relative to the support structure 10 , enabling one actuator assembly 2 to be used to achieve both AF and OIS.

[0104] Other variations are possible. For example, in an autofocus variation or an AF+OIS variation, the movable part 20 may include an image sensor 4 instead of a lens assembly 3. The camera module 1 may include a combination of the above features, such as (a) lens shift and sensor shift, (b) module tilt and lens shift or sensor shift and autofocus, or (c) module tilt and AF+OIS.

[0105] The camera module 1 further comprises a controller 8. The controller 8 may be implemented in the form of an integrated circuit (IC) chip. The controller 8 generates a drive signal for the actuation unit 30, in particular for the SMA wire 34 forming part of the actuation unit 30. The SMA material has the property that when heated it undergoes a solid-state phase change causing the SMA material to contract. Therefore, applying a drive signal to the SMA wire 34, thereby heating the SMA wire 34 by causing an electric current to flow, will cause the SMA wire 34 to contract and thus actuate the actuation unit 30 so as to move the movable part 20. The drive signal is selected to drive the movement of the movable part 20 in a desired manner, for example, so as to achieve OIS by stabilizing the image sensed by the image sensor 4, or to achieve AF / zoom by adjusting the focus of the image sensed by the image sensor 4. The controller 8 provides the generated drive signal to the SMA wire 34.

[0106] Optionally, the camera module 1 also includes a motion sensor (not shown), which may include a 3-axis gyroscope and a 3-axis accelerometer. The motion sensor may generate a signal representing the motion (specifically vibration or "shake") of the camera module 1, which may be processed to generate a signal representing the desired movement of the movable component 20 to compensate for such shake. The controller 8 receives such a signal and may generate a drive signal for the SMA wire 34 to implement OIS.

[0107] Although the actuator assembly 2 is described in conjunction with the camera module 1, it will be understood that the actuator assembly 2 may be used in any device in which it is desired that the movable component 20 be moved relative to the support structure 10, for example, to provide tactile feedback in a tactile feedback device or to move a projector or display in an augmented reality (AR) or virtual reality (VR) device.

[0108] Actuating unit Fig. 3A shows a perspective view of an example of the actuation unit 30. Fig. 3B shows a part of the actuation unit 30 in a plan view.

[0109] A single actuation unit 30 is shown in FIGS. 3A and 3B , but it should be understood that the actuator assembly 2 typically has a plurality of actuation units 30 , each of which may include the same components described with reference to FIGS. 3A and 3B .

[0110] The actuation unit 30 includes a body portion 31 to which several other components of the actuation unit 30 are connected, as described below. Typically, the body portion 31 is relatively rigid compared to the other components of the actuation unit and does not deform significantly when the actuation unit 30 is actuated. In some examples, the body portion 31 is not a separate component of the actuation unit 30. For example, the body portion 31 can be defined as part of one of the other components of the actuation unit 30, or simply as a connection point between the other components of the actuation unit 30.

[0111] The actuation unit 30 also includes a force adjustment flexible member 32. The force adjustment flexible member 32 is connected between the main body portion 31 and the support structure 10. One end of the force adjustment flexible member 32 is connected to the main body portion 31. The other end of the force adjustment flexible member 32 is connected to the support structure 10, for example, via a foot portion 36. The foot portion 36 is fixed relative to the support structure 10. In the depicted design, the force adjustment flexible member is integrally formed with the foot portion 36 and the main body portion 31, for example, formed by a single sheet of material (such as metal). The force adjustment flexible member 32 allows the main body portion 31 to pivot relative to the support structure 10 about an effective pivot point P. Although the effective pivot point P is shown in FIG. 3B as being positioned in the middle of the force adjustment flexible member 32, the effective pivot point P can have a different position and does not need to be located on the force adjustment flexible member 32. This pivotal movement of the main body portion 31 relative to the support structure 10 is initially performed in a direction substantially perpendicular to the force adjustment flexible member 32.

[0112] The actuation unit 30 further comprises an SMA element 34. In this example, the SMA element 34 is an SMA wire 34. The SMA wire 34 is connected between the body portion 31 and the support structure 10. One end of the SMA wire 34 is connected to the support structure 10, for example, by a crimp 15. The other end of the SMA wire 34 is connected to the body portion 31, for example, by a crimp 35.

[0113] The actuation unit 30 further includes a coupling link 33. In this example, the coupling link 33 is a coupling flexible member 33. The coupling flexible member 33 is connected between the main body portion 31 and the movable part 20. One end of the coupling flexible member 33 is connected to the main body portion 31. The other end of the coupling flexible member 33 is connected to the movable part 20. The coupling link 33 transfers or transmits the actuation force F from the main body portion 31 to the movable part 20. The coupling link 33 is flexible (i.e., deformable) in a direction (or multiple directions) perpendicular to the actuation force F. This allows the movable part 20 to move in a direction other than the direction of the coupling flexible member 33 and the actuation force F. For example, this may be required in a case where different actuation units 30 move the movable part 20 in different directions.

[0114] The SMA wire 34 is arranged to apply an input force Fi to the main body portion 31 when contracted. The input force Fi acts parallel to the length of the SMA wire 34. The force adjustment flexure 32 and the main body portion 31 are arranged to adjust the input force Fi so as to generate an actuation force F, which is transmitted from the main body portion 31 to the movable member 20 through the coupling flexure 33. In particular, the input force Fi deforms the force adjustment flexure 32, thereby causing the main body portion 31 to pivot about the effective pivot point P. In simple terms, the force adjustment flexure 32 and the main body portion 31 act like a lever. The force adjustment flexure 32 and the main body portion 31 can adjust the direction and / or magnitude of the input force Fi so as to generate the actuation force F.

[0115] In the example shown in FIGS. 3A and 3B , the coupling flexure 33 is at an angle of approximately 90° relative to the SMA wire 34. Furthermore, in this example, the force adjustment flexure 32 is arranged at an angle α of approximately 30° relative to the SMA wire 34, and when the SMA wire 34 contracts, the force adjustment flexure 32 is placed in tension. Therefore, upon contraction of the SMA wire 34 and the resulting deformation of the force adjustment flexure 32, the main body portion 31 initially moves at an angle of approximately 60° (90°-α) relative to the length of the SMA wire 34. Therefore, it should be understood that in this example, the force is de-amplified and the stroke is amplified, while the direction of the force / movement is changed by an angle of approximately 90°.

[0116] More generally, the change in direction of the force depends on the angle between the SMA wire 34 and the coupling flexure 33. Also more generally, the change in magnitude of the force depends on the ratio of i) the distance Ds from the effective pivot point P to the line where the SMA wire 34 is located and ii) the distance Dc from the effective pivot point P to the line where the coupling flexure 33 is located. In particular, F / Fi is proportional to Ds / Dc. If the line where the SMA wire 34 is located is closer to the effective pivot point P than the line where the coupling flexure 33 is located, the input force Fi is de-amplified. At the same time, the movement of the movable part 20 is amplified, that is, increased relative to the change in the length of the SMA wire 34. Alternatively, if the line where the SMA wire 34 is located is farther away from the effective pivot point P than the line where the coupling flexure 33 is located, the input force Fi is amplified. At the same time, the movement of the movable part 20 is de-amplified, that is, reduced relative to the change in the length of the SMA wire 34. Thus, the actuation unit 30 can be configured to amplify the movement caused by the contraction of the SMA wire 34 or to amplify the force caused by the contraction of the SMA wire 34. The actuation unit 30 can also be configured to change the direction of the input force Fi. In some examples, the actuation unit 30 is configured to change the direction of the input force Fi without changing the magnitude of the force or movement.

[0117] The ratio Ds / Dc depends on the position of the end of the SMA wire 34 connected to the main body portion 31 and the position of the end of the connecting flexure 33 connected to the main body portion 31. As an example, the distance Ds can be increased by connecting the connecting flexure to the left side of the main body portion 31 shown in Figure 3B, thereby reducing Ds / Dc and thus increasing the amount of stroke amplification. The ratio Ds / Dc also depends on the orientation of the SMA wire 34 and the orientation of the connecting flexure 33. Such an orientation can be defined with reference to the force adjustment flexure 32 (as above) or any suitable reference line. As an example, the distance Ds can be reduced by angling the SMA wire 34 shown in Figure 3B so that the SMA wire 34 shown in Figure 3B extends closer to the effective pivot point P, thereby reducing Ds / Dc and thus increasing the amount of stroke amplification. In summary, the amount by which the force adjustment flexure 32 amplifies or de-amplifies the force / stroke of the SMA wire 34 can be customized in the following ways:

[0118] adjusting the angle of the SMA wire 34 (and therefore the input force Fi); adjusting the location of the connection point between the SMA wire 34 and the body portion 31 (and therefore adjusting the location at which the input force Fi acts on the body portion 31); Adjusting the angle of the coupling flexure 33 (and therefore the actuation force F); and / or The position of the connection point between the coupling flexure 33 and the main body portion 31 is adjusted (and thus the position of the main body portion 31 at which the actuation force F is applied).

[0119] In some examples, at least one actuation unit 30 (preferably each actuation unit 30) is configured so that the force adjustment flexible member 32 and the main body portion 31 amplify the amount of contraction of the SMA wire 34. For example, the coefficient of such amplification can be greater than 1.5, preferably greater than 2, and further preferably greater than 3. To this end, in the examples shown in Figures 3A and 3B, the angle α between the SMA wire 34 and the force adjustment flexible member 32 can be in the range of 0 degrees to 45 degrees, preferably in the range of 13 degrees to 40 degrees. However, in general, the angle α can have other values, and the connection point of the SMA wire 34 and / or the connecting flexible member 33 to the main body portion 31 can be adjusted to achieve the desired amount of amplification.

[0120] As described above, in the example shown in FIGS. 3A and 3B , the coupling flexure 33 is at an angle of about 90 degrees relative to the SMA wire 34. This allows the actuation unit 30 to be folded around the corner of the movable part 20 in a compact manner. The angle between the coupling flexure 33 and the SMA wire 34 may be in the range of 70 to 110 degrees, preferably in the range of 80 to 100 degrees. However, in general, the angle between the coupling flexure 33 and the SMA wire 34 may be outside these ranges.

[0121] For example, in the actuation unit 30 shown in FIG. 3C , the coupling flexure 33 is substantially perpendicular to the SMA wire 34 .

[0122] In the above example, the actuation unit 30 is arranged in a plane. In particular, at least when the actuator assembly 2 is in an initial configuration, the SMA wire 34, the connecting flexure 33 and the force adjustment flexure 32 are arranged to extend substantially in a common plane. This allows a compact configuration of the actuation unit 30. When implemented as a plate, the main body portion 31 can also be arranged to extend in this plane. However, in general, the components of the actuation unit 30 do not have to be arranged in a common plane. For example, the SMA wire 34 and / or the connecting flexure 33 can be angled relative to the plane.

[0123] In the above example, the force adjustment flexible member 32 is placed in tension when the SMA wire 34 contracts. This reduces the risk of lateral bending deformation of the force adjustment flexible member 32, thereby reducing the risk of damage to the actuator assembly and making the actuator assembly 2 more reliable. However, the force adjustment flexible member 32 can alternatively be arranged to be placed in a compressed state when the SMA wire 34 contracts. Referring to Figure 3B, for example, the force adjustment flexible member 32 can extend from the connection point between the main body portion 31 and the force adjustment flexible member 32 to the lower right, and is therefore placed in a compressed state when the SMA wire 34 contracts. An arrangement for placing the force adjustment flexible member 32 in a compressed state is disclosed in WO 2022 / 084699 A1, which is incorporated herein by reference.

[0124] In the above example, the force adjustment flexure 32 and the SMA wire 34 are connected to the support structure 10 at one end, and the coupling flexure 33 is connected to the movable part 20 at one end. Generally, this arrangement can also be reversed, where the force adjustment flexure 32 and the SMA wire 34 are connected to the movable part 20 at one end, and the coupling flexure 33 is connected to the support structure 10 at one end.

[0125] In the above example, the actuation unit 30 includes a coupling link 33 in the form of a coupling flexible member 33. The purpose of the coupling link 33 is to allow the movable part 20 to move in a direction perpendicular to the actuation force F. However, in general, the actuation unit 30 does not need to include the coupling link 33 (for example, in an example in which the movable part 20 does not move in a direction perpendicular to the actuation force F). In addition, the coupling link 33 can be implemented as a component other than the coupling flexible member 33, for example, as a ball bearing or a sliding bearing, which is configured to transmit the actuation force F to the movable part 20 while allowing the movable part 20 to move in a direction perpendicular to the actuation force F. Such an alternative example of the coupling link 33 is disclosed in WO 2022 / 084699 A1.

[0126] Arrangement of four actuating units Figure 4 A plan view of an example of an actuator assembly 2 is schematically shown, showing the arrangement of the actuation units 30. In this example, the actuator assembly 2 comprises a total of four actuation units 30. The four actuation units 30 can apply an actuation force F between the movable part 20 and the support structure 10. The actuation force F is applied to the movable part 20 relative to the support structure 10.

[0127] Figure 4 The arrangement of the actuation unit 30 may for example be used in examples in which the movable part 20 is movable in a movement plane relative to the support structure 10. Thus, Tx, Ty and optionally Rz movements of the movable part 20 may be allowed.

[0128] Figure 4 The four actuation units 30 are in an arrangement capable of applying an actuation force F in order to move the movable part 20 relative to the support structure 10 to any position within a range of movement. The range of movement may be within a plane of movement perpendicular to the main axis P.

[0129] In particular, two actuation units 30 (eg, Figure 4 The top actuation unit and the bottom actuation unit in the actuation unit are arranged to apply an actuation force F in two opposite directions parallel to the first axis (e.g., the x-axis). The other two actuation units (e.g., Figure 4The left actuation unit and the right actuation unit in the embodiment of the present invention are arranged to apply an actuation force F in two opposite directions parallel to a second axis (e.g., the y-axis), which is perpendicular to the first axis. By appropriately changing the difference in the actuation amount between the opposing actuation units 30, the movable component 20 can therefore be independently moved along the first axis and the second axis. The opposite actuation forces F are not collinear, but are offset from each other in a direction perpendicular to the actuation forces. Providing opposing actuation units 30 allows control of the tension in the SMA wires 30 of the respective actuation units 30, which allows more accurate and reliable positioning of the movable component 20 compared to a case where the actuation units 30 are not opposed to each other.

[0130] In some examples, none of the actuation forces F are collinear. This allows the arrangement of the actuation unit 30 to translate the movable part 20 without applying any net torque to the movable part 20. Thus, the movable part 20 can be translated within the plane of movement without causing the movable part 20 to rotate within the plane of movement. In general, the arrangement of the actuation unit 30 is capable of precisely controlling the torque or moment of the movable part 20 about the main axis P. Thus, the actuation unit 30 is capable of causing the movable part 20 to rotate (or not rotate) relative to the support structure about the main axis P.

[0131] In particular, two actuation units 30 (eg, Figure 4 The top actuation unit and the bottom actuation unit in the embodiment of the present invention are arranged to apply an actuation force F so as to generate a torque or moment between the movable part 20 and the support structure 2 in a first direction (e.g., clockwise) about the main axis P. The other two actuation units 30 (e.g., Figure 4 The left actuation unit 30 and the right actuation unit 30 in the two actuation units 30 are arranged to apply an actuation force F so as to generate a torque or moment between the movable part 20 and the support structure 2 in a second opposite direction (e.g., counterclockwise) about the main axis P. This allows the movable part 20 to be rotated by increasing or decreasing the tension of the SMA wire in either of the two actuation units 30 at the same time.

[0132] As shown, two actuation units 30 can be arranged to apply an actuation force F in a corner portion of the actuator assembly 2. Another two actuation units 30 can be arranged to apply an actuation force F in another opposite corner portion of the actuator assembly 2. The actuator assembly 2, in particular the movable component 20 and / or the support structure 10, can have a square or rectangular footprint. Each actuation unit 30 can be disposed on one of the four sides of the actuator assembly 2. In particular, each actuation unit 30 can be bent around a corner portion of the movable component 20 so that the SMA wire 34 and the connecting flexible member 33 of each actuation unit 30 extend along the adjacent edge of the movable component 20. Therefore, the actuation unit 30 can be configured, for example, as shown in Figures 3A and 3B. The four SMA wires 32 of the four actuation units 32 can extend along four different edges of the movable component 20.

[0133] The arrangement of the actuation force F applied between the movable part 20 and the support structure 10 corresponds to the arrangement of the SMA wire 30 described in WO 2013 / 175197 A1, which is incorporated herein by reference.

[0134] In this example, the actuation force F is perpendicular to the main axis P and may be parallel to the plane of movement. However, in general, the actuation force F may be angled relative to the plane of movement. Thus, the actuation force F may have a component along the main axis P. This component along the main axis P may be resisted by the support device 40, for example, to provide for movement of the movable part 20 in the degrees of freedom allowed by the support device 40. In some examples, it may even be desirable that the actuation force F has a component parallel to the main axis P, for example in order to pressurize a sliding bearing or a rolling bearing arranged between the movable part 20 and the support structure 10.

[0135] Although for illustrative purposes, the arrangement of the actuation unit 30 is described as moving the movable part 20 in a movement plane (e.g., moving translationally along the x-axis and the y-axis, or moving rotationally around the main axis P), in other examples, the movable part 20 may be moved in different ways. For example, due to appropriate movement constraints provided by the support device 40, the same arrangement of the actuation force F can be used to tilt the movable part 20 relative to the support structure 10 around an axis perpendicular to the main axis P. For example, the support device 40 may include a plurality of flexures for guiding the movable part 20 to tilt around an axis perpendicular to the main axis P. An example of such a support device 40 is described in WO2022 / 029441 A1, which is incorporated herein by reference.

[0136] Although the actuator assembly 2 is described herein in the context of four actuation units 30, typically the actuator assembly 2 may include fewer actuation units 30. For example, the actuator assembly 2 may include two actuation units 30, such as Figure 4 The two actuation units 30 are depicted in the upper left corner of FIG. The force applied to the movable part 20 by the two actuation units 30 can be opposed by the biasing force of one or more elastic elements (such as springs). Figure 4 , the two actuation units 30 in the lower right corner may be replaced by springs applying a biasing force along the corresponding depicted arrows, for example.

[0137] Arrangement of eight actuator units Figure 5 Schematically shown is a perspective view of an actuator assembly 2 with a total of eight actuation units 30. The eight actuation units 30 can apply an actuation force F between the movable part 20 and the support structure 10. The actuation force F is applied to the movable part 20 relative to the support structure 10.

[0138] Figure 5 A and Figure 5 An arrangement of the actuation unit 30 of B can be used, for example, in which the movable part 20 is movable relative to the support structure 10 with three translational degrees of freedom (Tx, Ty, Tz) (see Figure 1E) or with two or three rotational degrees of freedom (Rx, Ry or Rx, Ry, Rz) (see Figure 1C).

[0139] The eight actuation units 30 may be arranged such that their actuation forces F are oriented or arranged in a manner equivalent to the orientation or arrangement of the forces applied by the eight SMA wires in the actuator assembly disclosed in WO 2011 / 104518 A1.

[0140] More specifically, the actuation force F (e.g., when visualized as a vector at a specific position in space) is arranged on each of the four sides (i.e., the first side, the second side, the third side, and then the fourth side) around the main axis P. When viewed perpendicularly to the main axis P, the two actuation forces F on each side are inclined in opposite directions relative to each other. The four sides on which the actuation forces F are arranged extend into a ring around the main axis P. In this example, the sides are vertical and therefore form a square (when viewed along the main axis P), but alternatively, the sides can take different shapes, such as a quadrilateral shape. In this example, the actuation forces F are parallel to the outer surface of the square envelope of the movable part 6, but this is not required.

[0141] The four actuation forces F, including one force on each side, form a "first" group having a component in one direction (the "upward" or +z direction), and the other four actuation forces F form a "second" group having a component in the opposite direction (the "downward" or -z direction). In this document, "up" and "down" refer to opposite directions along the main axis P.

[0142] These actuation forces F have a symmetrical arrangement, wherein their magnitudes and inclination angles are identical, so that the first set of actuation forces F and the second set of actuation forces F are each arranged with a two-fold rotational symmetry about the main axis P.

[0143] As a result of this symmetrical arrangement, different combinations of actuation forces F can drive movement of the movable member 20 in multiple degrees of freedom, as described below.

[0144] The first set of actuation forces F when generated together drives upward (+z) movement, and the second set of actuation forces F when generated equally drives downward (-z) movement.

[0145] Within each group, adjacent pairs of actuation forces F, when generated differently, drive a tilt (Rx or Ry) about a transverse axis perpendicular to the main axis P. Tilt in any direction can be achieved as a linear combination of tilts about two transverse axes.

[0146] A set of four actuation forces F, including two actuation forces F from each group, when generated together, drives movement (Tx or Ty) along a transverse axis perpendicular to the main axis P. Movement in any direction perpendicular to the main axis z can be achieved as a linear combination of movements along the two transverse axes.

[0147] The actuator assembly 2 may have other specific arrangements of the actuator unit 30, such as Figure 5 . For example, strict symmetry is not required. In addition, instead of having an up-pulling actuating unit 30 and a down-pulling actuating unit 30 on each side, there may be two up-pulling actuating units 30 on each of two opposite sides (e.g., the first side and the third side), and two down-pulling actuating units 30 on the other two sides (e.g., the second side and the fourth side).

[0148] Movement of the actuator along the main axis Special References Figure 6a and Figure 6b The problem of the movement of the actuating unit along the main axis will now be explained with reference to a comparative example of an actuator assembly without any support means 50 .

[0149] When the actuating unit 30 is subjected to relatively low forces, such as Figure 6a As shown, the actuation unit 30 (including the body portion 31, the force adjustment flexure 32 and the coupling link 33) extends parallel to the actuation plane. The size of the gap between the actuation unit 30 and the support structure 10 and / or the movable component 20 may be substantially constant.

[0150] However, when the actuation unit 30 is subjected to relatively large forces, the actuation unit 30 may tend to bend out of the actuation plane, causing at least a portion of the actuation unit 30 to be displaced along the primary axis P. Such undesirable out-of-plane deformation may also occur when the SMA wire 34 and the coupling link 33 are not in the same plane as the force adjustment element 32 (e.g., due to assembly misalignment), and thus the forces on the body portion 31 may generate a moment that acts to rotate the body portion out of plane about the effective pivot of the force adjustment element 34. In extreme cases (high forces or large misalignments), the mobile crimp 35 may lift so far that the actuation unit 30 becomes unstable and collapses on itself.

[0151] This is Figure 6b Schematically shown in . Relatively large forces may be caused, for example, by tension in the SMA wire 34 of the actuating unit 30 and / or by other actuating units 30. As will be appreciated, this may be caused by unstable or unbalanced input and output forces on the main body portion 31. In addition, an impact acting on the actuator assembly 2, for example due to a fall or other impact, may cause the actuating unit 30 to deform out of the actuating plane. The deformation out of the actuating plane may be only a small amount, or may continue until a portion of the actuating unit 30 contacts the support structure 10 and / or the movable part 20. In any case, due to such undesirable deformation, the actuating accuracy of the actuating unit may be reduced and / or the actuating unit 30 may be at risk of damage. Therefore, the performance and / or reliability of the actuator assembly 2 may be adversely affected.

[0152] Managing out-of-plane deformations of the actuator The inventors have identified this problem of possible undesired out-of-plane deformations of the actuation unit 30. According to an aspect of the invention, a device is provided for increasing the effective stiffness of the actuation unit, in particular the force adjustment element 34, in a direction orthogonal to the actuation plane. This may reduce the extent and / or risk of undesired out-of-plane deformations. According to another aspect of the invention, an end stop device is provided that engages with the out-of-plane deformation of the actuation unit 30. This reduces the risk and / or extent of damage to the actuation unit 30 due to such out-of-plane deformations. Thus, the invention relates to improving the reliability and / or performance of the actuation unit 30.

[0153] Devices for increasing effective out-of-plane stiffness According to aspects of the invention, a device 50 is provided to increase the effective stiffness of the force adjustment element 34 in a direction orthogonal to the actuation plane. The effective stiffness of the force adjustment element 34 may be increased compared to a case where the device 50 is not provided. Thus, the device 50 may help resist out-of-plane deformations of the actuation unit 30, making the actuation unit 50 more reliable and reducing the risk of damage to the actuation unit 50.

[0154] Double-layer flexible device Figures 7a to 7d An embodiment of an actuator assembly 30 is schematically shown, wherein the device 50 forms part of the force adjustment element 32. In particular, the device 50 is embodied as the second part 32b of the force adjustment element 32.

[0155] Special References Figure 7a The force adjustment flexible member 32 includes a first portion 32a and a second portion 32b. The second portion 32b is offset and / or spaced apart from the first portion 32a in a direction orthogonal to the actuation plane.

[0156] This increases the effective stiffness of the force accommodation flexure 32 and reduces the likelihood of out-of-plane bending of the force accommodation flexure 32 .

[0157] exist Figure 7a and Figure 7b In the example of , the first part 32a and the second part 32b are spaced apart from each other. In particular, a gap is formed between the two parts 32a, 32b. The extension of the gap in a direction orthogonal to the actuation plane may be at least half of the extension of the thinner one of the first part 32a and the second part 32b, preferably at least equal to or at least twice the extension of the thinner one. This results in an increase in the relevant effective stiffness of the force adjustment flexure 32 without increasing the stiffness in the actuation plane of the force adjustment mechanism (beyond the initial increase associated with providing two parts 32a, 32b).

[0158] In addition, Figure 7a and Figure 7b In the example of FIG. 3 , the SMA wire 34 (particularly the portion of the SMA wire 34 connected to the main body portion 31 , i.e., the mobile crimping member 35 ) is positioned in the middle between the two portions 32 a, 32 b of the force adjustment flexure 32 . This is preferred because it can improve the stability of the system. Typically, the SMA wire 34 can be positioned between the two portions 32 a, 32 b.

[0159] In other embodiments, the two portions 32a, 32b of the force adjustment flexure 32 may contact each other but be offset in a direction orthogonal to the actuation plane. Figure 7c Shown in.

[0160] The two parts 32a, 32b may be sheets of different materials. For example, each part 32a, 32b may be formed from a metal sheet.

[0161] The two parts 32a, 32b can be connected to each other at least by a connection to the main body part 31 and by a connection to the support structure 10. Thus, each of the two parts 32a, 32b can be connected to the support structure 10 at one end and to the main body part 31 at the other end. When viewed along the actuation plane, the two parts 32a, 32b can extend substantially parallel to each other. When viewed orthogonally to the actuation plane, the two parts 32a, 32b can coincide between these connections, i.e., when viewed orthogonally to the actuation plane, the two parts 32a, 32b can have substantially the same shape, i.e., the same footprint or contour.

[0162] The two parts 32a, 32b are thus connected to each other at the body part 31 and at the foot part 36. This can be achieved in different ways.

[0163] In particular, if Figure 7b As depicted, each of the foot portion 36, the body portion 31, and the force adjustment flexure 32 may include a first portion (labeled a) and a second portion (labeled b), the second portion being spaced apart from the first portion in a direction orthogonal to the actuation plane. In the depicted embodiment, the first portions 36a, 32a, 31a are integrally formed with one another, and the second portions 36b, 32b, 31b are integrally formed with one another. However, in general, the first portion and the second portion may be separate components connected to one another.

[0164] Each of the main body portion 31 and the foot portion 36 may further include a third portion (labeled as c) located between the first portion and the second portion and attached to each of the first portion and the second portion. The third portion 36c of the foot portion 36 is disposed between the first portion 36a and the second portion 36b of the foot portion (particularly when viewed along the actuation plane). The third portion 36c of the foot portion 36 is disposed between the first portion 36a and the second portion 36b of the foot portion (particularly when viewed along the actuation plane). No third portion is provided for the force adjustment flexible member 32 because a gap is formed between the first portion 32a and the second portion 32b of the force adjustment flexible member 32 instead.

[0165] Figure 7dAn alternative embodiment is depicted in which the third portion 36c is provided as a plurality of smaller spacers between the first and second portions of the foot portion 36 and the body portion 31, rather than as a separate sheet or layer. In particular, the third portion is formed as a plurality of spacers 31c, 36c for spacing the first and second portions apart. The spacers 31c, 36c need not be disposed completely between the two portions, but may be disposed only in a relatively small proportion of the space between the two portions. Although not shown, such spacers may also be disposed between the two portions 32a, 32b of the force adjustment flexure 32.

[0166] In some embodiments, the gap between the portions 32a, 32b of the force adjustment flexure 32 may be filled with air or another atmosphere. Thus, the gap may be considered empty. Alternatively, a relatively low stiffness material (such as gel or foam) may be provided in the gap.

[0167] In the depicted embodiment, the first portion, the second portion and the third portion are formed from sheet material. These portions may be formed from a metal sheet, for example by etching.

[0168] The mobile crimping piece 35 (or other connecting element 35) may be integrally formed with the third portion 31c of the main body portion 31c. This allows the connecting element 35 to have an "intermediate" position as described above. Alternatively, (particularly when no third portion is provided) the mobile crimping piece 35 may be integrally formed with the first portion 31a or the second portion 32b of the main body portion, e.g. Figure 7c Similarly, the coupling flexible member 33 may be formed integrally with the first portion 31a, the second portion 31b or the third portion 31c of the main body portion.

[0169] Instead of using the third portion of the body portion 31 and / or the third portion of the foot portion 36 to connect to the two portions 32a, 32b of the force adjustment flexure 32 and act as a "spacer" as described above, the actuation unit 30 may include a "jog" 37. This is for example Figure 7e A step 37 may be provided on one side of the foot portion 36 and / or one side of the main body portion 31. The step 37 provides a space between the different portions 32a, 32b of the force adjustment flexible member 32.

[0170] Figure 8a and Figure 8bSchematically shows how the force adjustment flexure 32, the main body portion 31 and the first and second portions of the foot portion 36 can be formed from a single sheet of material. Thus, in some embodiments, the first and second portions are formed from a folded sheet of material, such as a metal sheet. The actuation unit 30 may include a fold between two portions of the main body portion 31 or between two portions of the foot portion 36.

[0171] Figure 8b Various ways of forming the first part and the second part are schematically depicted. The first part and the second part can be formed in the following ways:

[0172] A. Formed from a sheet material folded at one end with two parts in contact (ie, back to back). There may be no space between the two parts (note that it can be 2 separate parts, and can be more than 2 layers).

[0173] B. Formed from a sheet material that is folded at one end and has a step at the other end to form a gap / space.

[0174] C. Formed from a sheet material folded at one end and having a third portion or spacer at the other end to form a spacer.

[0175] D. Formed from separate sheets (ie, not connected by folding), one sheet having steps at both ends thereof to form a gap / space.

[0176] E. Formed from sheet material folded at one end into a wedge shape (no step required) and spaced apart.

[0177] F. Formed from a sheet material folded into a wedge shape which has been bent downwardly so that the nominal line of the SMA wire force acts along the middle of the wedge, thereby increasing stability.

[0178] Device and flexure separated Figures 9a to 9c Schematically illustrates an embodiment of the device 50 when the device 50 is not provided as part of the force adjustment flexure 32. In particular, the device 50 is formed separately from the force adjustment flexure 32 and is not used for force amplification or stroke amplification. It should be understood that in addition to the device 50 described with respect to FIGS. 7 and 8, other embodiments may be provided with respect to Figures 9a to 9c The described device 50 thereby further contributes to increasing the effective stiffness.

[0179] Special References Figure 9a , the device 50 is implemented as a flexible material 54 .

[0180] The flexible material 54 may be composed of a gel 54, such as a damping gel. Generally, the flexible material 54 may be any material having a relatively low shear modulus (thereby allowing flexibility in the direction along the actuation plane) and a relatively high elastic modulus in the direction orthogonal to the actuation plane. The flexible material 54 may be, for example, a liquid material and / or a viscous material.

[0181] The flexible material 54 is disposed between a portion of the actuation unit 30 (e.g., a portion of the body portion 31) and the support structure 10. In this example, during operation of the actuator assembly 2, the flexible material 54 is attached to and / or remains in contact with both the actuation unit 30 (particularly the body portion 31) and the support structure 30. Although not shown, a pocket or depression (e.g., a partial etching in the body portion) may be formed in the support structure 10 and / or the body portion 31. The flexible material 54 may be disposed in the pocket or depression, thereby improving retention of the flexible material 54 in place.

[0182] Application of the flexible material 54 allows the body portion 31 to be suspended on or within the flexible material 54 and allows a full range of motion of the body portion 31 in the actuation plane while increasing stiffness in a direction orthogonal to the actuation plane.

[0183] The flexible material 54 may also have the added benefit of dampening the oscillatory and resonant behavior of the actuator assembly 2 .

[0184] Alternatively, the flexible material 54 may be attached to a component of the actuator assembly 2 other than the support structure 10 , for example to the movable component 20 or the body portion 31 of another actuation unit 30 .

[0185] Figure 9b A device 50 embodied as a magnetic arrangement 55 is schematically shown.

[0186] The magnetic device 55 includes a first magnet 55a located on the actuation unit 30 (e.g., on the main body portion 31). The first magnet 55a repels a second magnet 55b, which is spaced apart from the first magnet 55a in one direction (“downward”) along the main axis P. The first magnet 55a also repels a third magnet 55c, which is spaced apart from the first magnet 55a in another direction (“upward”) along the main axis P.

[0187] Such a magnetic device 55 has the advantage of not generating undesirable friction and providing a very low lateral biasing force acting in the actuation plane.

[0188] Instead of the flexible material 54 or the magnetic device 55, the device 50 may be implemented as other materials or elements that increase the stiffness of the force adjustment flexure 32 in a direction orthogonal to the actuation plane. For example, the device 50 may include an elastic element, such as a spring (e.g., a coil spring or other flexure separate from the force adjustment flexure).

[0189] References Fig.9c The position of the device 50 relative to the actuation unit 30 is described. Figure 9a and Figure 9b In the embodiment of the present invention, the device 50 is schematically shown as being located on or near the main body portion 31 of the actuation unit 30 (and directly restricting the movement of the main body portion 31). The device 50 can be located on an end of the main body portion 31 that is away from the connection between the main body portion 31 and the force adjustment flexible member 32. However, in general, the device can be located at any part of the main body portion 31, such as Fig.9c shown.

[0190] In other examples, the device 50 may be positioned differently. For example, the device 50 may be located on or near (and directly restrict the movement of) multiple components of the actuation unit 30 (when viewed orthogonally to the actuation plane, the multiple components of the actuation unit 30 are spaced apart from each other). This is because, in practice, the actuation unit 30 may be damaged due to excessive deflection at various points, and therefore multiple protection points may be required. Therefore, the device 50 does not have to be provided at one location on the actuation unit 30, but may be distributed at multiple separate locations.

[0191] Out-of-plane end stop Fig.10 Schematically, an embodiment of an actuator assembly 2 is shown, which has an end stop 51 for the actuation unit 30. The end stop 51 is arranged to limit the deformation of the actuation unit 30 (in particular the part of the actuation unit 30 provided with the end stop) in a direction orthogonal to the actuation plane. The end stop 51 can be combined with the above-mentioned device 50 or provided separately.

[0192] exist Fig.10 In the embodiment, the end stop 51 is arranged between the actuation unit 30 and the support structure 10. However, in general, the end stop may be provided between the actuation unit 30 and the movable part 20. In an embodiment in which a plurality of actuation units 30 are provided, the end stop may be provided between adjacent actuation units 30.

[0193] exist Fig.10In the embodiment of the present invention, two end stops 51a, 51b are provided, in particular a "lower" end stop 51a and an "upper" end stop 51b. The lower end stop 51a is configured so that when the actuating unit 30 moves along Fig.10 The upper end stop 51b is configured to engage with the actuation unit 30 when the actuation unit 30 moves in the "downward" direction (i.e., in the first direction orthogonal to the actuation plane). Fig.10 The second direction is opposite to the first direction.

[0194] In this way, only limited movement of the actuation unit 30 orthogonal to the actuation plane is allowed. During normal operation, the actuation unit 30 (particularly the main body 31 of the actuation unit 30) moves only within the actuation plane. Therefore, the end stop 51 is configured not to engage during normal operation of the actuation unit 30 or during normal operation of the actuator assembly 2 as a whole (e.g. due to actuation of other actuation units 30). However, when abnormal loads act on the actuation unit 30, for example due to an impact event such as a fall, the actuation unit 30 may move orthogonal to the actuation plane. The end stop 31 limits this movement in the out-of-plane direction, thereby reducing the risk of damage to the SMA element 34 and other components of the actuation unit 30.

[0195] Each end stop 51 includes a first end stop surface located on the actuation unit 30 and also includes a second end stop surface located on a different component. Preferably, the second end stop surface is provided on the support structure 10 or on the movable component 20. When the first end stop surface and the second end stop surface are engaged (i.e. in contact with each other), the end stops 51 are engaged. During normal operation (i.e., due to actuation of one or more actuation units 30 of the actuator assembly 2), the first end stop surface and the second end stop surface remain spaced apart.

[0196] During normal operation, the distance between the first end stop surface and the second end stop surface may remain substantially constant, thereby ensuring more reliable and predictable engagement of the end stop.The first end stop surface and the second end stop surface may be substantially parallel to each other and to the actuation plane.

[0197] The end stop may be formed on the body portion 31 of the actuation unit 30. Thus, the first end stop surface may be provided on the body portion 31. The second end stop surface is preferably provided on a component connected to the force adjustment flexure, such as the support structure 10. This is particularly desirable because the body portion 31 may be the heaviest component of the actuation unit 30 and therefore undesired movement of the body portion 31 is to be avoided.

[0198] Alternatively or additionally, the end stop may be formed on the coupling flexure 33 or other coupling link 33 of the actuation unit 30. Thus, the first end stop surface may be provided on the coupling flexure 33. The second end stop surface is preferably provided on a component connected to the coupling flexure 33, such as the movable component 20. An end stop for the coupling flexure 33 is desirable because the coupling flexure 33 may be relatively long and therefore presents a risk of damage due to excessive lateral bending deformation. An end stop for the coupling flexure 33 is preferably provided at a middle portion of the coupling flexure, such as between the body portion 31 and the movable component 20 within the middle 50% of the length of the coupling flexure 33.

[0199] Generally, the end stops may be formed on any one or more components of the actuation unit 30. For example, two end stops may be provided on the main body portion 31 (to limit the movement of the main body portion 31 in two opposite directions), and two end stops may be provided on the coupling flexible member 33 (to limit the movement of the coupling flexible member 33 in two opposite directions).

[0200] exist Fig.10 In the schematic diagram of , the lower end stop 51a comprises a separate piece attached to the base of the support structure 10, and the upper end stop 51b comprises a separate piece attached to the cover 11 of the support structure 10. However, in general, the end stops 51a, 51b can be formed on any other device of the actuator assembly 2. The end stops 51a, 51b can be integrally formed with the support structure 10, the cover 11, or other devices of the actuator assembly 2.

[0201] Fig.11a and Fig.11b Shows Fig.10 A specific example of an upper end stop 51a and a lower end stop 51b is schematically depicted in FIG.

[0202] Fig.11a An example of an upper end stop 51a is shown. The upper end stop 51a is formed between the support structure 10 (particularly the cover of the support structure 10) and the main body 31 of the actuation unit 30. In particular, the height of the support structure 10 above the actuation unit 30 is locally reduced to provide the end stop 51a. Therefore, the second end stop surface can be considered to be formed on a protrusion of the support structure 10.

[0203] Fig.11b An example of a lower end stop 51a is shown. The lower end stop 51a is formed between the support structure 10 (particularly the base of the support structure 10) and the main body 31 of the actuation unit 30. In particular, the space below the actuation unit 30 is locally reduced to provide the end stop 51b, in particular by providing Fig.11bThus, the second end stop surface can be considered to be formed on a protrusion of the support structure 10 .

[0204] exist Fig.11a and Fig.11b In the embodiment of the present invention, the first end stop surface (i.e., the end stop surface on the main body portion 31 of the actuation unit) is formed on the flat surface of the main body portion 31. In some embodiments, a protrusion may be provided on the actuation unit 30, for example, on the main body portion 31, to provide the first end stop surface. Fig.12 An example is shown in which depressions are formed in the sheet material of the body portion 31. In particular, one depression (pointing toward the upward end stop 51a) is formed in the uppermost portion (e.g., the first portion 31a) of the body portion 31. Another depression (pointing toward the downward end stop 51b) is formed in the uppermost portion (e.g., the first portion 31a) of the body portion 31. Thus, a protrusion is effectively provided on the body portion 31 to form a first end stop surface.

[0205] Fig.13 Another embodiment of an upper end stop 51a between the coupling flexure 33 and the movable part 20 and a lower end stop 51b between the coupling flexure 33 and the support structure 10 is shown. As shown, the distance between the movable part 20 and the coupling flexure 33 is locally reduced (due to the protrusion on the movable part 20), thereby providing the upper end stop 51a. The coupling flexure 33 is arranged close to the support structure 10, thereby providing the lower end stop 51b.

[0206] SMA Components The above-mentioned SMA actuator assembly includes at least one SMA element. The term "shape memory alloy (SMA) element" may refer to any element including SMA. The SMA element may be described as an SMA wire. The SMA element may have any shape suitable for the purposes described herein. The SMA element may be elongated and may have a circular cross section or a cross section of any other shape. The cross section may vary along the length of the SMA element. The SMA element may have a relatively complex shape, such as a spiral spring shape. It is also possible that the length of the SMA element (however defined) may be similar to one or more of the other dimensions of the SMA element. The SMA element may be sheet-like, and such a sheet may be planar or non-planar. The SMA element may be flexible, or in other words, the SMA element may be flexible. In some examples, when connected in a straight line between two components, the SMA element can only apply tension that forces the two components together. In other examples, the SMA element may be bent around the component, and when the SMA element tends to straighten under tension, the SMA element may apply force to the component. SMA elements can be beam-shaped or rigid and can apply different forces (e.g., non-tension) to the elements. SMA elements may or may not include non-SMA materials and / or components. For example, an SMA element may include a core of SMA and a coating of non-SMA material. Unless the context requires otherwise, the term "SMA element" may refer to any configuration of SMA material that acts as a single actuating element, for example, the single actuating element can be individually controlled to generate a force acting on the element. For example, an SMA element may include two or more parts of SMA material that are mechanically arranged in parallel and / or in series. In some arrangements, an SMA element may be part of a larger SMA element. Such a larger SMA element may include two or more parts that can be individually controlled, thereby forming two or more SMA elements. SMA elements may include SMA wires, SMA foils, SMA films, or any other configuration of SMA materials. SMA elements may be manufactured using any suitable method (e.g., by methods involving drawing, rolling, deposition, and / or other molding processes). The SMA element may exhibit any shape memory effect, such as a thermal shape memory effect or a magnetic shape memory effect, and may be controlled in any suitable manner (eg, by Joule heating, another heating technique, or by applying a magnetic field).

Claims

1. An actuator assembly, comprising: first component; a second component, the second component being movable relative to the first component; and one or more actuation units, each actuation unit being configured to apply an actuation force to the second component, the actuation force being capable of moving the second component relative to the first component, Wherein, each actuation unit comprises: - the main part; - an SMA element connected between the body portion and the first component and arranged to apply an input force to the body portion upon actuation; and a force adjustment element connected between the main body portion and the first component and configured to adjust the input force to generate the actuation force, wherein the force adjustment element guides the main body portion to move along a path in an actuation plane when the SMA element is actuated, and - Means configured to increase the effective stiffness of the force adjustment element in a direction orthogonal to the actuation plane.

2. The actuator assembly according to claim 1, wherein: The force adjustment element comprises a first portion and a second portion, wherein the second portion is offset and / or spaced apart from the first portion in a direction orthogonal to the actuation plane, thereby forming the device configured to increase the effective stiffness of the force adjustment element in a direction orthogonal to the actuation plane.

3. An actuator assembly according to claim 1 or claim 2, wherein: When viewed in a direction along the actuation plane, a gap is formed between the first part and the second part, wherein, in a direction orthogonal to the actuation plane, the extension range of the gap can be at least half of the extension range of the thinner one of the first part and the second part, preferably at least equal to or at least twice the extension range of the thinner one.

4. An actuator assembly according to any one of the preceding claims, wherein: Each of the SMA element, the first portion and the second portion extends parallel to the actuation plane, and a position of the SMA element along an axis normal to the actuation plane is located between positions of the first portion and the second portion along the axis normal to the actuation plane, preferably substantially midway between positions of the first portion and the second portion along the axis normal to the actuation plane.

5. An actuator assembly according to any one of the preceding claims, wherein: Each actuation unit further comprises a foot portion, the force adjustment flexure being connected to the first component via the foot portion, wherein each of the foot portion, the main body portion and the force adjustment flexure comprises a first portion and a second portion spaced apart in a direction along the main axis.

6. The actuator assembly according to claim 5, wherein: The first portions are integrally formed with each other, and the second portions are integrally formed with each other.

7. An actuator assembly according to claim 5 or 6, wherein: Each of the body portion and the foot portion further includes a third portion located between and attached to each of the corresponding first portion and the second portion.

8. The actuator assembly according to claim 7, wherein: The SMA element is connected to the body portion via a connecting element, wherein the connecting element is integrally formed with the third portion of the body portion.

9. An actuator assembly according to any one of the preceding claims, wherein: The first portion and the second portion comprise sheets of material, optionally wherein the third portion comprises a sheet of material.

10. An actuator assembly according to any one of the preceding claims, wherein: The device comprises a flexible material arranged between a component of the actuation unit and at least one of the first component and the second component.

11. The actuator assembly of claim 10, wherein: The flexible material comprises gel.

12. An actuator assembly according to claim 10 or claim 11, wherein: The flexible material is further configured to dampen oscillations of the actuation unit and / or oscillations of the second component relative to the first component.

13. An actuator assembly according to any one of the preceding claims, wherein: The device includes a first magnet located on the actuation unit, wherein the first magnet repels a second magnet, the second magnet is spaced apart from the first magnet in one direction orthogonal to the actuation plane, and the first magnet repels a third magnet, the third magnet is spaced apart from the first magnet in another direction orthogonal to the actuation plane.

14. An actuator assembly comprising: first component; a second component, the second component being movable relative to the first component; and one or more actuation units, each actuation unit being configured to apply an actuation force to the second component, the actuation force being capable of moving the second component relative to the first component, Wherein, each actuation unit comprises: - the main part; - an SMA element connected between the body portion and the first component and arranged to apply an input force to the body portion upon actuation; and - a force adjustment element connected between the main body portion and the first component and configured to adjust the input force to generate the actuation force, wherein the force adjustment element guides the main body portion to move along a path in an actuation plane when the SMA element is actuated, Therein, at least one end stop is arranged between the actuation unit and the first component or the second component, and the end stop is arranged to limit the deformation of the actuation unit in a direction orthogonal to the actuation plane.

15. The actuator assembly of claim 14, wherein: At least one end stop is configured to engage the component of the actuation unit when the component of the actuation unit moves in a first direction orthogonal to the actuation plane, and at least one other end stop is arranged between the actuation unit and the first component or the second component and is configured to engage the component of the actuation unit when the component of the actuation unit moves in the first direction orthogonal to the actuation plane, wherein the second direction is opposite to the first direction.

16. An actuator assembly according to claim 14 or 15, wherein: Each end stop comprises a first end stop surface on the actuation unit and a second end stop surface on the first component or the second component, wherein during normal operation of the actuation unit the first end stop surface and the second end stop surface are spaced apart, in particular by a constant distance.

17. The actuator assembly of claim 16, wherein: The first end stop and the second end stop are parallel to the actuation plane.

18. An actuator assembly according to claim 16 or 17, wherein: The first end stop surface is formed on a protrusion protruding from the actuation unit, and / or the second end stop surface is formed on a protrusion protruding from the first component or the second component.

19. An actuator assembly according to any one of claims 14 to 18, wherein: The end stop is formed on the main body portion of the actuating unit.

20. An actuator assembly according to any one of claims 14 to 19, wherein: The end stop is formed on the coupling link of the actuating unit.

21. An actuator assembly according to any one of claims 14 to 20, wherein: During normal operation, the clearance of the end stop is in the range of 0 to 25% of the length of the force adjustment element, preferably in the range of 5 to 15% of the length of the force adjustment element.

22. An actuator assembly according to any one of claims 14 to 21, wherein: During normal operation, the gap of the end stop is in the range of 0 to 500 um, preferably in the range of 100 um to 300 um.

23. An actuator assembly according to any one of the preceding claims, wherein: The force adjustment element includes a force adjustment flexure.

24. An actuator assembly according to any one of the preceding claims, wherein: The force adjustment element is arranged to be in tension when the SMA element is actuated.

25. An actuator assembly according to any one of the preceding claims, wherein: The force adjustment element is arranged at an angle relative to the SMA wire, preferably at an angle in the range of 13 to 77 degrees, optionally at an angle in the range of 13 to 40 degrees or 77 to 50 degrees.

26. An actuator assembly according to any one of the preceding claims, wherein: Each actuation unit is configured to amplify an actuation amount of the SMA element to a relatively larger movement amount of the second component relative to the first component, optionally with a factor greater than 1.5, preferably greater than 2, and further preferably greater than 3.

27. An actuator assembly according to any one of the preceding claims, wherein: Each actuation unit is configured to amplify the input force so that the actuation force is greater than the input force. Optionally, the amplification factor is greater than 1.5, preferably greater than 2, and further preferably greater than 3.

28. An actuator assembly according to any one of the preceding claims, wherein: Each actuation unit further comprises a coupling link connected between the main body portion and the second component, wherein the coupling link is configured to transmit the actuation force from the main body portion to the second component, and wherein the coupling link is flexible in a direction perpendicular to the direction of the actuation force.

29. The actuator assembly of claim 28, wherein: The connecting link includes a connecting flexible member.

30. An actuator assembly according to any one of claims 28 and 29, wherein: The coupling link is arranged to be in tension when the SMA element is actuated.

31. An actuator assembly according to any one of claims 28 to 30, wherein: The angle between the coupling link and the SMA wire is in the range of 70 degrees to 110 degrees.

32. An actuator assembly according to any one of the preceding claims, wherein: Each actuation unit extends substantially in the actuation plane.

33. An actuator assembly according to any one of the preceding claims, wherein: The main body portion and the force adjustment flexure are integrally formed from the same material, and optionally, wherein the coupling link is also formed from the same material.

34. An actuator assembly according to any one of the preceding claims, comprising a total of four actuation units arranged to apply actuation forces such that each of the actuation forces are collinear.

35. The actuator assembly of claim 34, wherein: The four actuation units are arranged so that a first pair of actuation units applies actuation forces in two opposite directions parallel to a first axis in a plane, and a second pair of actuation units applies actuation forces in two opposite directions parallel to a second axis in the plane, wherein the first axis and the second axis are not parallel.

36. An actuator assembly according to claim 35, wherein: The first pair of actuation units is arranged to apply a torque to the second component relative to the first component in a first orientation, and the second pair of actuation units is arranged to apply a torque to the second component relative to the first component in a second orientation, wherein the second orientation is opposite to the first orientation.

37. An actuator assembly according to any preceding claim, comprising an image sensor and / or a lens assembly, wherein: The image sensor or the lens assembly is fixed relative to the second component and / or the lens assembly or the image sensor is fixed relative to the first component.

Images