Actuator assembly

Abstract

An actuator assembly comprises: a first part, wherein a primary axis is defined with reference to the first part; a second part that is movable relative to the first part; and a plurality of actuating units each comprising a shape memory alloy, SMA, element and each configured to apply an actuating force to the second part, wherein the actuating units are capable of rotating the second part relative to the first part about a first axis and a second axis, wherein the first and second axes are perpendicular to the primary axis and to each other, and wherein there is at least one position of the second part relative to the first part at which each actuating force is in a direction perpendicular to the primary axis.

Description

[0001] ACTUATOR ASSEMBLY

[0002] Field

[0003] The present application relates to an actuator assembly with a plurality of actuating units, each comprising a shape memory alloy, SMA, element. Such an actuator assembly may be used, for example, in a camera to tilt a camera module, comprising a lens assembly and an image sensor, so as to provide optical image stabilization (OIS).

[0004] Background

[0005] SMA actuator assemblies may be used in a variety of applications for moving a movable part relative to a support structure.

[0006] For example, WO 2013 / 175197 Al describes a camera in which four SMA wires are arranged to move a lens element relative to an image sensor in a plane that is perpendicular to the optical axis of the lens element, thereby effecting optical image stabilization (OIS). WO 2010 / 029316 Al describes SMA wires used to provide OIS in a camera by tilting a camera module. WO 2011 / 104518 Al describes an actuator assembly having eight SMA wires capable of effecting positional control of a movable element with multiple degrees of freedom. WO 2022 / 084699 Al discloses an actuator assembly comprising at least one actuating unit incorporating an SMA wire that, on actuation, moves a movable part relative to the support structure, wherein the at least one actuating unit is configured to increase the range of movement (also known as "stroke") or the actuating force and / or to re-direct the force applied by the SMA wire.

[0007] The present application provides alternative SMA actuator assemblies that, for example, are suitable for providing OIS in a camera by tilting a camera module.

[0008] Summary

[0009] According to an aspect of the present invention, there is provided an actuator assembly comprising: a first part (e.g. a support structure), wherein a primary axis is defined with reference to the first part; a second part (e.g. a movable part) that is movable relative to the first part; and a plurality of actuating units (e.g. eight actuating units, or a total of eight actuating units) each comprising a shape memory alloy, SMA, element and each configured to (e.g. on contraction of its SMA element) apply an actuating force to the second part. The actuating units are capable of rotating (e.g. tilting) the second part relative to the first part about a first axis and a second axis, wherein the first and second axes are perpendicular to the primary axis and to each other. There is at least one position of the second part relative to the first part at which each actuating force is in a direction perpendicular to the primary axis. Such an actuator assembly may provide various advantages over the state of the art in terms of, for example, ease of manufacturing, compactness (e.g. minimising the height of the actuator assembly in the direction of the primary axis), robustness (e.g. reduction in risk of SMA elements being damaged from having SMA elements that cross and thus may rub against each other), performance (e.g. efficiency in providing tilt OIS), etc.

[0010] Each actuating unit may be configured to directly apply its actuating force to the second part.

[0011] The plurality of actuating units may be configured such that the rotational movement of the second part relative to the first part about each of the first and second axes are independently controllable. Thus, the actuating units are configured such that the second part is rotatable relative to the first part about any axis that is perpendicular to the primary axis and lies in a plane defined by the first and second axes.

[0012] It will be appreciated that the reference to each actuating force being in a direction 'perpendicular' to the primary axis, when the second part is in the at least one position relative to the first part, may mean that each actuating force may be inclined at an angle of less than e.g. 10 degrees relative to a plane perpendicular to the primary axis.

[0013] Optionally, the plurality of actuating units comprises eight actuating units.

[0014] The plurality of actuating units may consist of eight actuating units. In other words, the plurality of actuating units may comprise a total of eight actuating units.

[0015] Optionally, the actuator assembly comprises: a first set of actuating units together configured to apply a first total actuating force to the second part; and a second set of actuating units together configured to apply a second total actuating force to the second part; wherein the first and second total actuating forces are each in any direction in a plane perpendicular to the primary axis and are offset from each other along the primary axis.

[0016] The first set of actuating units may be together configured to apply the first total actuating force to the second part without applying any torque about the primary axis (or any axis parallel thereto). The second set of actuating units may be together configured to apply the second total actuating force to the second part without applying any torque about the primary axis (or any axis parallel thereto).

[0017] Optionally, the first and second sets of actuating units each comprise four actuating units. Optionally, the first set of actuating units apply actuating forces to the second part at points in a first plane, the second set of actuating units apply actuating forces to the second part at points in a second plane, wherein the first and second planes are parallel to each other and are offset from each other along the primary axis.

[0018] Optionally, the actuator assembly has four sides arranged in a loop around the primary axis, and two actuating units are arranged, at least in part, along each of the four sides.

[0019] The plurality of actuating units may be arranged with two-fold rotational symmetry about the primary axis. The first and second sets of actuating units may each be arranged with two-fold rotational symmetry about the primary axis.

[0020] Optionally, a first pair of the actuating units are configured to apply a torque to the second part to drive rotation of the second part relative to the first part in a first sense about the first axis; a second pair of the actuating units are configured to apply a torque to the second part to drive rotation of the second part relative to the first part in a second, opposite, sense about the first axis; a third pair of the actuating units are configured to apply a torque to the second part to drive rotation of the second part relative to the first part in a first sense about the second axis; and a fourth pair of the actuating units are configured to apply a torque to the second part to drive rotation of the second part relative to the first part in a second, opposite, sense about the second axis.

[0021] Optionally, the first, second, third, and fourth pair of actuating units are arranged, at least in part, along first, second, third and fourth sides of the actuator assembly respectively, wherein the first and second sides are opposite sides through which the first axis extends and the third and fourth sides are opposite sides through which the second axis extends. Alternatively, the first and second pair of actuating units are each arranged, at least in part, along first and second sides of the actuator assembly, wherein the first and second sides are opposite sides through which the first axis extends; and the third and fourth pair of actuating units are each arranged, at least in part, along third and fourth sides of the actuator assembly, wherein the third and fourth sides are opposite sides through which the second axis extends.

[0022] Optionally, the actuating units are arranged such that the second part is capable of being supported (e.g. suspended) on the first part exclusively by the actuating units. For example, the actuating units may be arranged such that the second part is capable of being positioned in the at least one position relative to the first part exclusively by the actuating units. Optionally, the second part is supported on the first part by a bearing arrangement.

[0023] The bearing arrangement may be configured to allow relative movement between the first and second parts. For example, the bearing arrangement may be configured to allow the rotation of the second part relative to the first part about the first and second axes. The bearing arrangement may also be configured to allow rotation of the second part about the primary axis relative to the first part. The bearing arrangement may also be configured to allow (translational) movement of the second part relative to the first part in any direction in a plane perpendicular to the primary axis.

[0024] The bearing arrangement may be configured to prevent the second part from translationally moving in a first direction along the primary axis relative to the first part when the second part is in the at least one position relative to the first part.

[0025] The actuator assembly may comprise a biasing arrangement configured to bias the first and second parts towards each other e.g. such that, when the actuating units are unpowered, the second part is biased into engagement with one or more end stops of the first part.

[0026] The actuator assembly may comprise a biasing arrangement configured, when the actuating units are unpowered, to bias the second part towards a pre-determined position and / or orientation relative to the first part.

[0027] Optionally, one or more of the actuating units (e.g. all of the plurality of actuating units) each consists of an SMA element with a first end connected to the first part and a second end connected to the second part.

[0028] It will be appreciated that a reference to a component being "connected to" another component may mean that the component is directly or indirectly connected to the other component. Similarly, it will be appreciated that a reference to a component being "connected between" two other components means, for example, that the component is directly or indirectly connected to each of the other components. Such an indirect connection may involve a connection via further component(s) (e.g. a connector) with fixed position(s) relative to the other component. For example, an SMA element may be connected to the movable part 20 and / or the support structure 10 via a further flexure, e.g. as described in WO 2022 / 144541 Al which is herein incorporated by reference to the maximum extent permissible by law. When the second part is in the at least one position relative to the first part, the SMA elements of the one or more actuating units may each extend from the first end to the second end in a direction perpendicular to primary axis.

[0029] Optionally, at least one of the actuating units (e.g. all of the plurality of actuating units) comprises: a body portion; a shape memory alloy, SMA, element connected between the body portion and one of the first and second parts, and configured, on actuation, to apply an input force to the body portion; a forcemodifying element connected between the body portion and the one of the first and second parts, and configured to modify the input force so as to give rise to the actuating force of the at least one actuating unit; and a coupling link connected between the body portion and the other of the first and second parts, wherein the coupling link is configured to transmit the actuating force of the at least one actuating unit from the body portion to the other of the first and second parts, and wherein the coupling link is compliant in a direction perpendicular to the actuating force of the at least one actuating unit.

[0030] When the second part is in the at least one position relative to the first part, the coupling links of the at least one actuating units may each extend in a direction perpendicular to the primary axis between the ends of the coupling link connected to the body portion and the other of the first and second parts.

[0031] The at least one actuating unit may be configured to increase the stroke or the actuating force and / or to re-direct the force applied by the SMA element.

[0032] Optionally, the force-modifying element comprises, or is, a force-modifying flexure. The forcemodifying element may be elongate and stiff along its length and compliant in a direction perpendicular to its length.

[0033] Optionally, the coupling link comprises, or is, a coupling flexure. The coupling link may be elongate and stiff along its length and compliant in a direction perpendicular to its length.

[0034] The body portion, the coupling link and / or the force-modifying element may be integrally formed.

[0035] The coupling link may comprise, or may be, an SMA element.

[0036] Optionally, the actuating units are capable of rotating the second part relative to the first part about the primary axis. Optionally, the actuating units are capable of (translationally) moving the second part relative to the first part in any direction in a plane perpendicular to the primary axis.

[0037] Optionally, the second part comprises an image sensor and one or more lenses configured to focus an image on the image sensor.

[0038] The actuator assembly may comprise a further ('AF' or 'auto-focus') actuator assembly configured to move the one or more lenses relative to the image sensor along an axis parallel to the optical axis (e.g. along the optical axis itself) of the one or more lenses.

[0039] Optionally, when the second part is in the at least one position relative to the first part, the primary axis is parallel to (e.g. is collinear with) the optical axis of the one or more lenses and / or is perpendicular to a light-sensitive region of the image sensor.

[0040] The second part may comprise an electronic component such as an emitter, a display, or a part thereof.

[0041] The primary axis may be perpendicular to a plane defined by the display and / or be parallel to the general direction in which radiation is emitted from the emitter.

[0042] Brief description of the drawings

[0043] Certain embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

[0044] Figure 1 is a schematic cross-sectional view of a camera assembly incorporating an actuator assembly;

[0045] Figure 2 is a schematic perspective view of the actuator assembly;

[0046] Figure 3 is a schematic perspective view of an arrangement of eight actuating units;

[0047] Figure 4 is a schematic perspective view of an arrangement of eight actuating units;

[0048] Figures 5A and 5B are perspective and plan views of an actuating unit; and

[0049] Figure 5C is a plan view of an actuating unit. Detailed description

[0050] Camera assembly

[0051] Figure 1 schematically shows an apparatus 1 incorporating an actuator assembly 2. The apparatus 1 is, for example, a camera assembly 1. Generally, the apparatus 1 is to be incorporated in a portable electronic device such as a smartphone. Thus, miniaturisation can be an important design criterion.

[0052] Figure 2 schematically shows the actuator assembly 2. The actuator assembly 2 includes a support structure 10 (herein also referred to as the first part 10) and a movable part 20 (herein also referred to as the second part 20). The movable part 20 is movable relative to the support structure 10. When the actuator assembly 2 is included e.g. in the apparatus 1, the support structure 10 may be fixed relative to the main body of the apparatus 1. However, in general, the support structure 10 need not be stationary and may be movable relative to or within the apparatus 1. The actuator assembly 2 includes a plurality of actuating units 30. Each actuating unit 30 is configured to apply an actuating force F capable of moving the movable part 20 relative to the support structure 10.

[0053] The actuating units 30 each comprise a shape memory alloy, SMA, element and are each configured to, on contraction of its SMA element, apply the actuating force F to the movable part 20.

[0054] The actuating units 30 may be arranged such that the movable part 20 may be supported (i.e. suspended) on the support structure 10 exclusively by the actuating units 30. In other words, the actuating units 30 may be arranged such that the movable part 20 is capable of being positioned in a suspended position relative to the support structure 10 (e.g. a position in which the movable part 20 is not in contact with the support structure 10) exclusively by the actuating units 30 as shown in Figure 1.

[0055] The primary axis P can be defined with reference to the actuator assembly 2 and / or the support structure 10. The primary axis P may extend through the actuator assembly 2, e.g. through the centre of the actuator assembly 2. In some examples, the actuator assembly 2, the support structure 10 and / or the movable part 20 extends predominantly in a direction perpendicular to the primary axis P. In other words, the extent of the actuator assembly 2, the support structure 10 and / or the movable part 20 along the primary axis P is less than the extent thereof along any direction perpendicular to the primary axis P. The primary axis P may be the longitudinal axis of the actuator assembly 2 and / or the support structure 10. Alternatively or additionally, the support structure 10 and / or movable part 20 may include a planar component that extends perpendicularly to the primary axis P. Alternatively or additionally, in examples in which the apparatus 1 includes an optical element (such as a lens assembly 3) with an optical axis O, or an imaging element (such as an imager sensor 4) with an imaging axis I, the primary axis P may be parallel to such an axis and / or may coincide or be collinear with such an axis when the movable part 20 is in a central position or orientation (as shown in, for example, Figure 1).

[0056] The actuating units 30 are capable of rotating (e.g. tilting) the movable part 20 relative to the support structure 10 about a first and second axes x, y (herein also referred to as simply x and y axes), wherein the first and second axes x, y are perpendicular to the primary axis P and to each other. The plurality of actuating units 30 may be configured such that the rotational movement of the movable part 20 relative to the support structure 10 about each of the first and second axes x, y are independently controllable. In other words, the movable part 20 is movable, by the actuating units 30, relative to the support structure 10 in the following degrees of freedom (DOF):

[0057] Rx and Ry: Rotational movement (or simply rotation or tilting) about the x and y axes. In other words, the movable part 20 may be rotated about any line that is perpendicular to the primary axis P and e.g. that lies in the plane defined by x and y axes. The movable part 20 may be rotatable about the x and y axes to any rotational position (i.e. to any orientation) within a range of movement.

[0058] The actuating units 30 are also capable of rotating the movable part 20 relative to the support structure 10 about the primary axis P. In other words, the movable part 20 is movable, by the actuating units 30, relative to the support structure 10 in the following DOF:

[0059] Rz: Rotational movement (or simply rotation) about the z axis. The movable part 20 may be rotatable about the primary axis P to any rotational position (i.e. to any orientation) within a range of movement.

[0060] The actuating units 30 are also capable of moving the movable part 20 relative to the support structure 10 in any direction in a plane perpendicular to the primary axis P. In other words, the actuating units 30 are capable of moving the movable part 20 relative to the support structure 10 along the first and second axes x, y. In other words, the movable part 20 is movable, by the actuating units 30, relative to the support structure 10 in the following DOF:

[0061] Tx and Ty: Translational movement in the x-y plane (i.e. the plane defined by the first and second axes x, y). In other words, the movable part 20 may be independently movable along the x and y axes. The movable part 20 may be movable to any position in the x-y plane within a range of movement.

[0062] The actuating units 30 are connected between the support structure 10 and the movable part 20. The actuating units 30 are arranged to apply actuating forces F (see, for example, Figs. 3 and 4) between the movable part 20 and the support structure 10. Selectively varying the actuating forces F causes the movable part 20 to move relative to the support structure 10 in the DOF mentioned above.

[0063] The camera assembly 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 carrier, for example in the form of a cylindrical body, supporting the one or more lenses. The image sensor 4 captures an image and may be of any suitable type, for example a charge coupled device (CCD) or a complementary metal-oxide- semiconductor (CMOS) device. The camera assembly 1 may be a compact camera assembly in which each lens has a diameter of 20mm or less, for example of 12mm or less.

[0064] As shown in Figure 1, the movable part 20 includes both the lens assembly 3 and the image sensor 4. As discussed, the actuator assembly 2 is configured to tilt the movable part 20 about two axes x, y perpendicular to the primary axis P and to each other (i.e. provide Rx, Ry movement). This enables optical image stabilisation (OIS) to be implemented in the camera assembly 1. This type of OIS is herein also referred to as 'tilt OIS'. As discussed, the actuator assembly 2 is also configured to rotate the movable part 20 about the primary axis P. This also enables OIS - specifically "roll" compensation - to be implemented in the camera assembly 1. As discussed, the actuator assembly 2 is also configured to move the movable part 20 relative to the support structure 10 in any direction in a plane perpendicular to the primary axis P (i.e. provide Tx, Ty movement). Combining this Tx, Ty translational movement with the Rx, Ry tilt movement, enables tilting of the movable part 20 about axes perpendicular to the primary axis P that are spaced apart from the x-y plane. As discussed in WO 2023 / 007157 Al this can make it easier to control the movement of the movable part 20.

[0065] The camera assembly 1 also includes a controller 8. The controller 8 may be implemented in an integrated circuit (IC) chip. The controller 8 generates drive signals for the actuating units 30, in particular for SMA elements forming part of the actuating units 30. SMA material has the property that, on heating, it undergoes a solid-state phase change that causes the SMA material to contract. Thus, applying drive signals to the SMA elements, thereby heating the SMA elements by causing an electric current to flow, will cause the SMA elements to contract and thus actuate the actuating unit 30 so as to drive relative movement of the movable part 20. The drive signals are chosen to drive relative 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. The controller 8 supplies the generated drive signals to the SMA elements. Optionally, the camera assembly 1 also includes a motion sensor (not shown), which may include a 3- axis gyroscope and a 3-axis accelerometer. The motion sensor can generate signals representative of the motion (specifically vibrations or "shake") of the camera assembly 1, which can be processed so as to produce signals representative of the required movement of the movable part 20 to compensate for such shake. The controller 8 receives such signals and can generate the drive signals for the SMA elements to achieve OIS.

[0066] Although the actuator assembly 2 is described in connection with a camera assembly 1, it will be appreciated that the actuator assembly 2 may be used in any device in which movement of a movable part 20 relative to a support structure 10 is desired, e.g. to provide haptic feedback in a haptic feedback device or to move a projector or display in an augmented reality (AR) or virtual reality (VR) device.

[0067] Arrangement of eight actuating units

[0068] Figure 3 shows how the actuating units 30 may be arranged to provide the above-discussed relative movements of the movable part 20. Figure 4 shows an alternative way in which the actuating units 30 may be arranged to also provide the above-discussed relative movements of the movable part 20.

[0069] In both examples shown, eight actuating units 30 are provided. The actuator assembly 2 has four sides arranged in a loop around the primary axis P. Two actuating units 30 are arranged along each of the four sides.

[0070] Each actuating unit 30 comprises an SMA element (e.g. an SMA wire). Each actuating unit 30 is configured, on contraction of its SMA element, to apply an actuating force F to the movable part 20. Each actuating force F is in a direction perpendicular to the primary axis P when the movable part 20 is at a central (suspended) position and is untilted relative to the support structure 10, as shown in Figures 3 and 4.

[0071] In Figures 3 and 4, each actuating unit 30 consists of an SMA wire that is connected to the movable part 20 at one end (i.e. a first end) via a first connector 30M (e.g. a first crimp) and connected to the support structure 10 at the other (opposite) end (i.e. a second end) via a second connector 30S (e.g. a second crimp). Each SMA wire extends from the first end to the second end in a direction perpendicular to primary axis P when the movable part 20 is at the position and orientation shown in Figures 3 and 4 relative to the support structure 10. It will be appreciated, however, that one or more (e.g. all) of the actuating units 30 may be different in design. This is discussed in more detail below. A first set of actuating units 30, i.e. the upper set of four actuating units 30, are configured to together apply a first total actuating force to the movable part 20. A second set of actuating units 30, i.e. the lower set of four actuating units 30, are configured to together apply a second total actuating force to the movable part 20. The first set of actuating units 30 are each configured to apply actuating forces F to upper corners of the movable part 20. The second set of actuating units 30 are each configured to apply actuating forces F to lower corners of the movable part 20. The first and second total actuating forces are each in any direction in a plane perpendicular to the primary axis P and are offset from each other along the primary axis P. In other words, the first set of actuating units 30 apply actuating forces F to the movable part 20 at points in a first (upper) plane, the second set of actuating units 30 apply actuating forces F to the movable part 20 at points in a second (lower) plane, and the first and second planes are parallel to each other and are offset from each other along the primary axis P.

[0072] The first set of actuating units 30 are configured to be capable of together applying the first total actuating force to the movable part 20 without applying any torque about the primary axis Por any axis parallel thereto. Similarly, the second set of actuating units 30 are configured to be capable of together applying the second total actuating force to the movable part 20 without applying any torque about the primary axis P or any axis parallel thereto.

[0073] The plurality of actuating units 30 are arranged with two-fold rotational symmetry about the primary axis P. The first and second sets of actuating units 30 are each arranged with two-fold rotational symmetry about the primary axis P.

[0074] A first pair of the actuating units 30 are configured to apply a torque to the movable part 20 to drive rotation of the movable part 20 relative to the support structure 10 in a first sense about the first axis x. A second pair of the actuating units 30 are configured to apply a torque to the movable part 20 to drive rotation of the movable part 20 relative to the support structure 10 in a second, opposite, sense about the first axis x. A third pair of the actuating units 30 are configured to apply a torque to the movable part 20 to drive rotation of the movable part 20 relative to the support structure 10 in a first sense about the second axis y. A fourth pair of the actuating units 30 are configured to apply a torque to the movable part 20 to drive rotation of the movable part 20 relative to the support structure 10 in a second, opposite, sense about the second axis y. Each pair of actuating units 30 consists of an actuating unit 30 from the first set of actuating units 30, and an actuating unit 30 from the second set of actuating units 30.

[0075] In the example of Figure 3, the first, second, third, and fourth pair of actuating units 30 are arranged along first, second, third and fourth sides of the actuator assembly 2 (i.e. along each of the four sides of the actuating assembly 2 arranged in a loop around the primary axis P) respectively, wherein the first and second sides are opposite sides through which the first axis x extends and the third and fourth sides are opposite sides through which the second axis y extends.

[0076] In the example of Figure 4, unlike with the example of Figure 3, the first and second pair of actuating units 30 are each arranged along first and second sides of the actuator assembly 2, wherein the first and second sides are opposite sides through which the first axis x extends. Moreover, the third and fourth pair of actuating units 30 are each arranged along third and fourth sides of the actuator assembly 2, wherein the third and fourth sides are opposite sides through which the second axis y extends.

[0077] In both examples, the first and second pairs of actuating units 30 each comprise actuating units 30 configured to apply actuating forces F in opposite directions parallel to the second axis y, which are offset from each other along the primary axis P. Similarly, in both examples, the third and fourth pairs of actuating units 30 each comprise actuating units 30 configured to apply actuating forces F in opposite directions parallel to the first axis x, which are offset from each other along the primary axis P.

[0078] However, in the example of Figure 4, unlike with the example of Figure 3, the actuating units 30 of each of the first and second pairs are additionally offset from each other along the first axis x, and the actuating units 30 of each of the third and fourth pairs are offset from each other along the second axis y-

[0079] In both examples, the movable part 20 may be rotated in a first sense around the first axis x (e.g. driven in +Rx) by contracting the SMA elements of the first pair of actuating units 30 and may be rotated in a second opposite sense around the first axis x (e.g. driven in -Rx) by contracting the SMA elements of the second pair of actuating units 30. Moreover, the movable part 20 may be rotated in a first sense around the second axis y (e.g. driven in +Ry) by contracting the SMA elements of the third pair of actuating units 30 and may be rotated in a second opposite sense around the second axis y (e.g. driven in -Ry) by contracting the SMA elements of the fourth pair of actuating units 30.

[0080] In the example of Figure 3, the movable part 20 may be rotated in a first sense around the primary axis P (e.g. driven in +Rz) by: (i) contracting the two lower actuating units 30 (i.e. the actuating units 30 configured to apply actuating forces F to the second plane) of the first and second pairs of actuating units 30, and / or (ii) contracting the two upper actuating units 30 (i.e. the actuating units 30 configured to apply actuating forces F to the first plane) of the third and fourth pairs of actuating units 30. Moreover, the movable part 20 may be rotated in a second opposite sense around the primary axis P (e.g. driven in -Rz) by: (i) contracting the two upper actuating units 30 (i.e. the actuating units 30 configured to apply actuating forces F to the first plane) of the first and second pairs of actuating units 30, and / or (ii) contracting the two lower actuating units 30 (i.e. the actuating units 30 configured to apply actuating forces F to the second plane) of the third and fourth pairs of actuating units 30.

[0081] In the example of Figure 4, unlike with the example of Figure 3, the movable part 20 may be rotated in a first sense around the primary axis P (e.g. driven in +Rz) by, for example, contracting the third and fourth pairs of actuating units 30 and rotated in a second sense around the primary axis P (e.g. driven in -Rz) by, for example, contracting the first and second pairs of actuating units 30.

[0082] In the example of Figure 3, the movable part 20 may be translationally moved in a first direction along the first axis x (e.g. driven in +Tx) by contracting the lower actuating unit 30 of the third pair of actuating units 30 and the upper actuating unit 30 of the fourth pair of actuating units 30. The movable part 20 may be translationally moved in a second opposite direction along the first axis x (e.g. driven in -Tx) by contracting the upper actuating unit 30 of the third pair of actuating units 30 and the lower actuating unit 30 of the fourth pair of actuating units 30. Similarly, the movable part 20 may be translationally moved in a first direction along the second axis y (e.g. driven in +Ty) by contracting the lower actuating unit 30 of the first pair of actuating units 30 and the upper actuating unit 30 of the second pair of actuating units 30. The movable part 20 may be translationally moved in a second opposite direction along the second axis y (e.g. driven in -Ty) by contracting the upper actuating unit 30 of the first pair of actuating units 30 and the lower actuating unit 30 of the second pair of actuating units 30.

[0083] In the example of Figure 4, unlike with the example of Figure 3, the movable part 20 may be translationally moved in a first direction along the first axis x (e.g. driven in +Tx) by contracting the two actuating units 30 (forming part of the third and fourth pairs of actuating units 30) configured to apply actuating forces F to the third side of the actuator assembly 2, and may be translationally moved in a second opposite direction along the first axis x (e.g. driven in -Tx) by contracting the two actuating units 30 (forming part of the third and fourth pairs of actuating units 30) configured to apply actuating forces F to the fourth side of the actuator assembly 2. Similarly, the movable part 20 may be translationally moved in a first direction along the second axis y (e.g. driven in +Ty) by contracting the two actuating units 30 (forming part of the first and second pairs of actuating units 30) configured to apply actuating forces F to the second side of the actuator assembly 2, and may be translationally moved in a second opposite direction along the second axis y (e.g. driven in -Ty) by contracting the two actuating units 30 (forming part of the first and second pairs of actuating units 30) configured to apply actuating forces F to the first side of the actuator assembly 2.

[0084] In Figures 3 and 4, the movable part 20 is suspended on the support structure 10 exclusively by the actuating units 30 at a central position and in an untilted state. When the movable part 20 is in this central position and untilted orientation relative to the support structure 10, the primary axis P is parallel to (e.g. is collinear with) the optical axis O of the one or more lenses of the lens assembly 3 and / or is perpendicular to a light-sensitive region of the image sensor 4. Moreover, as mentioned above, at this position and orientation, each actuating force F of the actuating units 30 is in a direction perpendicular to the primary axis P. It will be appreciated that the actuating forces F will remain as being in directions perpendicular to the primary axis P as the movable part 20 is moved from this central position in Tx, Ty and / or Rz, as long as there is no tilting about the first and / or second axes x, y. Thus, it will be appreciated that there may be more than one position of the movable part 20 relative to the support structure 10 at which each actuating force F is in a direction perpendicular to the primary axis P.

[0085] As shown in Figures 3 and 4, each actuating unit 30 may be configured to directly apply its actuating force F to the movable part 20.

[0086] The actuator assemblies 2 described may provide various advantages over the state of the art in terms of, for example, ease of manufacturing, compactness (e.g. minimising the height of the actuator assembly in the direction of the primary axis), robustness (e.g. reduction in risk of SMA elements being damaged from having SMA elements that cross and thus may rub against each other), performance (e.g. efficiency in providing tilt OIS), etc.

[0087] Actuating units

[0088] In Figures 3 and 4, each actuating unit 30 consists of an SMA element (e.g. SMA wire) with a first end connected to the support structure 10 and a second end connected to the movable part 20. However, as mentioned above, it will be appreciated that one or more (e.g. all) of the actuating units 30 may have different designs.

[0089] Figure 5A shows a perspective view of an alternative actuating unit 30 design. Figure 5B shows part of this alternative actuating unit 30 in plan view.

[0090] This actuating unit 30 includes a body portion 31 to which several other components of the actuating unit 30 are connected as described below. Typically, the body portion 31 is relatively rigid compared to the other components of the actuating unit 30, and does not deform significantly on actuation of the actuating unit 30. In some examples, the body portion 31 is not a distinct part of the actuating unit 30. For example, the body portion 31 may be defined as part of one of the other components of the actuating unit 30 or simply as a connection point between other components of the actuating unit 30. This actuating unit 30 also includes a force-modifying flexure 32. The force-modifying flexure 32 is connected between the body portion 31 and the support structure 10. One end of the force-modifying flexure 32 is connected to the body portion 31. The other end of the force-modifying flexure 32 is connected to the support structure 10, e.g. via a foot portion 36. The foot portion 36 is fixed relative to the support structure 10. The force-modifying flexure 32 allows the body portion 31 to pivot relative to the support structure 10 about an effective pivot point V. Although the effective pivot point V is shown in Figure 5B as being positioned in the middle of force-modifying flexure 32, the effective pivot point V may have a different position and also need not lie on the force-modifying flexure 32. Such pivotal movement of the body portion 31 relative to the support structure 10 is initially in a direction that is substantially perpendicular to the force-modifying flexure 32.

[0091] This actuating unit 30 also includes 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, e.g. by a crimp 15. The other end of the SMA wire 34 is connected to the body portion 31, e.g. by a crimp 35.

[0092] This actuating unit 30 also includes a coupling link 33. In this example, the coupling link 33 is a coupling flexure 33. The coupling flexure 33 is connected between the body portion 31 and the movable part 20. One end of the coupling flexure 33 is connected to the body portion 31. The other end of the coupling flexure 33 is connected to the movable part 20. The coupling link 33 transfers or transmits an actuating force F from the body portion 31 to the movable part 20. The coupling link 33 is compliant (i.e. deformable) in a direction (or in multiple directions) perpendicular to the actuating force F. This allows the movable part 20 to move in directions other than the direction of the coupling flexure 33 and actuating force F.

[0093] In this example, the body portion 31, the force-modifying flexure 32, the coupling flexure 33 and the foot portion 36 are integrally formed, for example from a single sheet of material (such as metal). In other examples, one or more of these features, if present, may be formed from different parts or materials.

[0094] The SMA wire 34 is arranged, on contraction, to apply an input force Fi on the body portion 31. The input force Fi acts parallel to the length of the SMA wire 34. The force-modifying flexure 32 and the body portion 31 are arranged to modify the input force Fi so as to give rise to the actuating force F, which is transmitted from the body portion 31 to the movable part 20 by the coupling flexure 33. In particular, the input force Fi deforms the force-modifying flexure 32, thereby causing the body portion 31 to pivot about the effective pivot point V. In simple terms, the force-modifying flexure 32 and the body portion 31 act like a lever. The force-modifying flexure 32 and the body portion 31 may modify the direction and / or the magnitude of the input force Fi so as to give rise to the actuating force F.

[0095] In the example illustrated in Figures 5A and 5B, the coupling flexure 33 is at an angle of -90° relative to the SMA wire 34. Also, in this example, the force-modifying flexure 32 is arranged at an angle a of -30° relative to the SMA wire 34, and the force-modifying flexure 32 is placed in tension on contraction of the SMA wire 34. Hence, on contraction of the SMA wire 34 and on resulting deformation of the forcemodifying flexure 32, the body portion 31 initially moves at an angle of -60° (90°-a) relative to the length of the SMA wire 34. Thus, it will be appreciated that, in this example, the force is de-amplified and the stroke is amplified, while the direction of the forces / movements is changed by an angle of -90°.

[0096] 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 is dependent on the ratio of i) the distance Ds from the effective pivot point V to the line on which the SMA wire 34 lies and ii) the distance De from the effective pivot point V to the line on which the coupling flexure 33 lies. In particular, F / Fi is proportional to Ds / Dc. If the SMA wire 34 lies on a line that is closer to the effective pivot point V than the line on which the coupling flexure 33 lies, then the input force Fi is de-amplified. At the same time, the relative movement of the movable part 20 is amplified, i.e. increased relative to a change in length of the SMA wire 34. Alternatively, if the SMA wire 34 lies on a line that is further away from the effective pivot point V than the line on which the coupling flexure 33 lies, then the input force Fi is amplified. At the same time, the relative movement of the movable part 20 is de-amplified, i.e. decreased relative to a change in length of the SMA wire 34. This actuating unit 30 can thus be configured to amplify movement or to amplify force due to contraction of the SMA wire 34. This actuating unit 30 can also be configured to change the direction of the input force Fi. In some examples, this actuating unit 30 is configured to change the direction of the input force Fi without changing the magnitude of the force or movement.

[0097] The ratio Ds / Dc is dependent on the location of the end of the SMA wire 34 that is connected to the body portion 31, and on the location of the end of the coupling flexure 33 that is connected to the body portion 31. By way of example, the distance De could be increased by connecting the coupling flexure 33 further to the left of body portion 31 shown in Figure 5B, thereby decreasing Ds / Dc and so increasing the amount of stroke amplification. The ratio Ds / Dc is also dependent on the orientation of the SMA wire 34, and on the orientation of the coupling flexure 33. Such orientations can be defined with reference to the force-modifying flexure 32 (as above) or any suitable reference line. By way of example, the distance Ds could be decreased by angling the SMA wire 34 shown in Figure 5B so that it passes closer to the effective pivot point V, thereby decreasing Ds / Dc and so increasing the amount of stroke amplification. In summary, the amount by which the force-modifying flexure 32 amplifies or deamplifies the force / stroke of the SMA wire 34 may be tailored by: adjusting the orientation of the SMA wire 34 (and thus of the input force Fi); adjusting the location of the connection point between the SMA wire 34 and the body portion

[0098] 31 (and thus the location at which the input force Fi acts on the body portion 31); adjusting the orientation of the coupling flexure 33 (and thus of the actuating force F); and / or adjusting the location of the connection point between the coupling flexure 33 and the body portion 31 (and thus the location from which the body portion 31 applies the actuating force F).

[0099] In some examples, at least one actuating unit 30 (preferably each actuating unit 30) is configured such that the force-modifying flexure 32 and the body portion 31 amplifies an amount of contraction of the SMA wire 34. Such amplification, for example, may be by a factor greater than 1.5, preferably greater than 2, further preferably greater than 3. For this purpose, in the example illustrated in Figures 5A and 5B, the angle a between the SMA wire 34 and the force-modifying flexure 32 may be in the range from 0 to 45 degrees, preferably from 13 to 40 degrees. However, in general, the angle a may have other values and the connection points of the SMA wire 34 and / or coupling flexure 33 to the body portion 31 may be adjusted to achieve a desired amount of amplification.

[0100] As described above, in the example illustrated in Figures 5A and 5B, the coupling flexure 33 is at an angle of about 90 degrees relative to the SMA wire 34. This allows the actuating unit 30 to fold around a corner of the second part 20 in a compact manner. The angle between the coupling flexure 33 and the SMA wire 34 may be in the range from 70 to 110 degrees, or from 80 to 100 degrees. However, in general, the angle between coupling flexure 33 and SMA wire 34 may be outside these ranges.

[0101] For instance, in the actuating unit 30 illustrated in Figure 5C, the force-modifying flexure 32, the coupling flexure 33 and the SMA wire 34 are substantially parallel to one another.

[0102] In the above-described examples, the force-modifying flexure 32 is placed in tension on contraction of the SMA wire 34. This reduces the risk of buckling of the force-modifying flexure 32, reducing the risk of damage to the actuator assembly 2 and making the actuator assembly 2 more reliable. However, the force-modifying flexure 32 could instead be arranged so as to be placed under compression on contraction of the SMA wire 34. With reference to Figure 5B, for example, the force-modifying flexure

[0103] 32 could extend to the bottom-right from the connection point between the body portion 31 and the force-modifying flexure 32, and so be placed under compression on contraction of the SMA wire 34. An arrangement in which the force-modifying flexure 32 is placed under compression is disclosed in WO 2022 / 084699 Al, which is herein incorporated by reference to the maximum extent permissible by law. In the above-described examples, the actuating unit 30 includes a coupling link 33 in the form of a coupling flexure 33. The purpose of the coupling link 33 is to allow relative movement of the movable part 20 e.g. in directions perpendicular to the actuating force F. The coupling link 33 may be embodied by components other than the coupling flexure 33, for example by a ball bearing or plain bearing configured to transmit the actuating force F to the movable part 20 while allowing relative movement of the movable part 20 in directions perpendicular to the actuating force F. Such alternative examples of the coupling link 33 are disclosed in WO 2022 / 084699 Al. The coupling link 33 may (or may not) be formed by an SMA element, which may (or may not) be integral with the SMA wire 34 and may (or may not) be driven together with the SMA wire 34.

[0104] Furthermore, instead of the force-modifying flexure 32, the actuator assembly may include a different type of force-modifying element configured to enable the above-described movement of the body portion 31 relative to the support structure 10. Such a force-modifying element may include, for instance, a rigid member with one end connected to the support structure 10 via a suitable pivoting connection (e.g. a pin joint) and the other end connected to the body portion 31.

[0105] As described above, the SMA element of this actuating unit 30 may be connected between the body portion 31 and the support structure 10, the force-modifying element 32 may be connected between the body portion 31 and the support structure 10, and the coupling link 33 may be connected between the body portion 31 and the movable part 20. However, it will be appreciated that, instead, the SMA element may be connected between the body portion 31 and the movable part 20, the force-modifying element 32 may be connected between the body portion 31 and the movable part 20, and the coupling link 33 may be connected between the body portion 31 and the support structure 10.

[0106] Other variations

[0107] It will be appreciated that there may be many other variations of the above-described examples.

[0108] For example, the actuator assembly 2 may include different types of actuating units 30 to those described above. Examples of such actuating units include a folded SMA wire arrangement as disclosed in WO 2021 / 111131 Al, a V-shaped SMA wire with a compliant connector as disclosed in WO 2013 / 121225 Al, a scissor jack arrangement as disclosed in WO 2021 / 156458 Al, or a two-stage arrangement as disclosed in WO 2021 / 111181 Al. The documents referred to in the preceding sentence are each herein incorporated by reference to the maximum extent permissible by law. The actuator assembly 2 may have any number of different types of actuating units, and may have any suitable number of actuating units of each type. As mentioned above, the movable part 20 may be supported (i.e. suspended) on the support structure 10 exclusively by the actuating units 30. However, alternatively, the actuator assembly 2 may include a bearing arrangement that supports the movable part 20 on the support structure 10. The actuating units 30 and the bearing arrangement may together support the movable part 20 on the support structure 10. The bearing arrangement may have any suitable form for allowing relative movement between the movable part 20 and the support structure 10. For example, the bearing arrangement may be configured to allow the rotation of the movable part 20 relative to the support structure 10 about the first and second axes X, Y. The bearing arrangement may also be configured to allow rotation of the movable part 20 about the primary axis P relative to the support structure 10. The bearing arrangement may also be configured to allow (translational) movement of the movable part 20 relative to the support structure 10 in any direction in a plane perpendicular to the primary axis P. The actuating units 30 and / or the bearing arrangement may constrain, i.e. reduce or prevent, other DOFs of movement of the movable part 20 relative to the support structure 10. For example, the bearing arrangement may be configured to prevent the movable part 20 from translationally moving in a first direction (e.g. +Z or -Z direction) along the primary axis P relative to the support structure 10 when the movable part 20 is in the at least one position relative to the support structure 10. For this purpose, the bearing arrangement may, for example, include one or more of the following bearings: a rolling bearing (such as a ball bearing), a flexure bearing (i.e. an arrangement of flexures or other resilient elements that guide movement), or a plain (i.e. sliding contact) bearing.

[0109] The actuator assembly 2 may comprise a biasing arrangement configured to bias the moveable part 20 and the support structure 10 towards each other e.g. such that, when the actuating units 30 are unpowered, the moveable part 20 is biased into engagement with one or more end stops of the support structure 10. The actuator assembly 2 may comprise a biasing arrangement configured, when the actuating units 30 are unpowered, to bias the moveable part 20 towards a pre-determined ('parking') position and / or orientation relative to the support structure 10. Examples of biasing arrangements that may be used with the actuator assembly 2 are described in WO 2021 / 005351 Al which is herein incorporated by reference to the maximum extent permissible by law.

[0110] The actuator assembly 2 may comprise a further ('AF' or 'auto-focus') actuator assembly configured to move the one or more lenses of the lens assembly 3 relative to the image sensor 4 along an axis parallel to the optical axis (e.g. along the optical axis itself) of the one or more lenses. The 'AF' actuator assembly may be another type of SMA actuator assembly or may be a non-SMA actuator assembly, e.g. a voice-coil motor (VCM) actuator assembly. Although eight actuating units 30 are provided in the examples shown, it will be appreciated that a different number of actuating units may instead be provided.

[0111] As mentioned above, although the actuator assembly 2 is described in connection with a camera assembly 1, it will be appreciated that the actuator assembly 2 may be used in any device in which movement of a movable part 20 relative to a support structure 10 is desired, e.g. to provide haptic feedback in a haptic feedback device or to move an emitter or a display in an augmented reality (AR) or virtual reality (VR) device.

[0112] It will be appreciated that the reference to each actuating force F being in a direction 'perpendicular' to the primary axis P, when the movable part 20 is in the at least one position relative to the support structure 10, may mean that each actuating force F may be inclined at an angle of less than e.g. 10 degrees relative to a plane perpendicular to the primary axis P.

[0113] It will be appreciated that a reference to a component being "connected to" another component may mean that the component is directly or indirectly connected to the other component. Similarly, it will be appreciated that a reference to a component being "connected between" two other components means, for example, that the component is directly or indirectly connected to each of the other components. Such an indirect connection may involve a connection via further component(s) (e.g. a connector) with fixed position(s) relative to the other component. For example, an SMA element may be connected to the movable part 20 and / or the support structure 10 via a further flexure, e.g. as described in WO 2022 / 144541 Al which is herein incorporated by reference to the maximum extent permissible by law.

[0114] SMA

[0115] The above-described SMA actuator assemblies comprise SMA elements. The term 'shape memory alloy (SMA) element' may refer to any element comprising SMA. The SMA element may be described as an SMA wire. The SMA element may have any shape that is suitable for the purposes described herein.

[0116] The SMA element may be elongate and may have a round cross section or any other shape cross section. The cross section may vary along the length of the SMA element. The SMA element might have a relatively complex shape such as a helical spring. It is also possible that the length of the SMA element (however defined) may be similar to one or more of its other dimensions. The SMA element may be sheet-like, and such a sheet may be planar or non-planar. The SMA element may be pliant or, in other words, flexible. In some examples, when connected in a straight line between two components, the SMA element can apply only a tensile force which urges the two components together. In other examples, the SMA element may be bent around a component and can apply a force to the component as the SMA element tends to straighten under tension. The SMA element may be beam-like or rigid and may be able to apply different (e.g. non-tensile) forces to elements. The SMA element may or may not include material(s) and / or component(s) that are not SMA. For example, the SMA element may comprise a core of SMA and a coating of non-SMA material. Unless the context requires otherwise, the term 'SMA element' may refer to any configuration of SMA material acting as a single actuating element which, for example, can be individually controlled to produce a force on an element. For example, the SMA element may comprise two or more portions of SMA material that are arranged mechanically in parallel and / or in series. In some arrangements, the SMA element may be part of a larger SMA element. Such a larger SMA element might comprise two or more parts that are individually controllable, thereby forming two or more SMA elements. The SMA element may comprise an SMA wire, SMA foil, SMA film or any other configuration of SMA material. The SMA element may be manufactured using any suitable method, for example by a method involving drawing, rolling, deposition, sintering or powder fusion. The SMA element may exhibit any shape memory effect, e.g. a thermal shape memory effect or a magnetic shape memory effect, and may be controlled in any suitable way, e.g. by Joule heating, another heating technique or by applying a magnetic field.

Claims

Claims1. An actuator assembly comprising: a first part, wherein a primary axis is defined with reference to the first part; a second part that is movable relative to the first part; a plurality of actuating units each comprising a shape memory alloy, SMA, element and each configured to apply an actuating force to the second part, wherein the actuating units are capable of rotating the second part relative to the first part about a first axis and a second axis, wherein the first and second axes are perpendicular to the primary axis and to each other, and wherein there is at least one position of the second part relative to the first part at which each actuating force is in a direction perpendicular to the primary axis.

2. An actuator assembly according to claim 1, wherein the plurality of actuating units comprises eight actuating units.

3. An actuator assembly according to claim 1 or 2, comprising: a first set of actuating units together configured to apply a first total actuating force to the second part; and a second set of actuating units together configured to apply a second total actuating force to the second part; wherein the first and second total actuating forces are each in any direction in a plane perpendicular to the primary axis and are offset from each other along the primary axis.

4. An actuator assembly according to claim 3, wherein the first and second sets of actuating units each comprise four actuating units.

5. An actuator assembly according to claim 3 or 4, wherein the first set of actuating units apply actuating forces to the second part at points in a first plane, the second set of actuating units apply actuating forces to the second part at points in a second plane, and wherein the first and second planes are parallel to each other and are offset from each other along the primary axis.

6. An actuator assembly according to claim 2 or any preceding claim dependent thereon, wherein the actuator assembly has four sides arranged in a loop around the primary axis, and two actuating units are arranged, at least in part, along each of the four sides.

7. An actuator assembly according to claim 2 or any preceding claim dependent thereon, wherein:a first pair of the actuating units are configured to apply a torque to the second part to drive rotation of the second part relative to the first part in a first sense about the first axis; a second pair of the actuating units are configured to apply a torque to the second part to drive rotation of the second part relative to the first part in a second, opposite, sense about the first axis; a third pair of the actuating units are configured to apply a torque to the second part to drive rotation of the second part relative to the first part in a first sense about the second axis; and a fourth pair of the actuating units are configured to apply a torque to the second part to drive rotation of the second part relative to the first part in a second, opposite, sense about the second axis.

8. An actuator assembly according to claim 7, wherein the first, second, third, and fourth pair of actuating units are arranged, at least in part, along first, second, third and fourth sides of the actuator assembly respectively, wherein the first and second sides are opposite sides through which the first axis extends and the third and fourth sides are opposite sides through which the second axis extends.

9. An actuator assembly according to claim 7, wherein: the first and second pair of actuating units are each arranged, at least in part, along first and second sides of the actuator assembly, wherein the first and second sides are opposite sides through which the first axis extends; and the third and fourth pair of actuating units are each arranged, at least in part, along third and fourth sides of the actuator assembly, wherein the third and fourth sides are opposite sides through which the second axis extends.

10. An actuator assembly according to any preceding claim, wherein the actuating units are arranged such that the second part is capable of being supported on the first part exclusively by the actuating units.

11. An actuator assembly according to any of claims 1 to 9, wherein the second part is supported on the first part by a bearing arrangement.

12. An actuator assembly according to any preceding claim, wherein one or more of the actuating units each consists of an SMA element with a first end connected to the first part and a second end connected to the second part.

13. An actuator assembly according to any preceding claim, wherein at least one of the actuating units comprises: a body portion;a shape memory alloy, SM A, element connected between the body portion and one of the first and second parts, and configured, on actuation, to apply an input force to the body portion; a force-modifying element connected between the body portion and the one of the first and second parts, and configured to modify the input force so as to give rise to the actuating force of the at least one actuating unit; and a coupling link connected between the body portion and the other of the first and second parts, wherein the coupling link is configured to transmit the actuating force of the at least one actuating unit from the body portion to the other of the first and second parts, and wherein the coupling link is compliant in a direction perpendicular to the actuating force of the at least one actuating unit.

14. An actuator assembly according to claim 13, wherein the force-modifying element is, or comprises, a force-modifying flexure.

15. An actuator assembly according to claim 13 or 14, wherein the coupling link is, or comprises, a coupling flexure.

16. An actuator assembly according to any preceding claim, wherein the actuating units are capable of rotating the second part relative to the first part about the primary axis.

17. An actuator assembly according to any preceding claim, wherein the actuating units are capable of moving the second part relative to the first part in any direction in a plane perpendicular to the primary axis.

18. An actuator assembly according to any preceding claim, wherein the second part comprises an image sensor and one or more lenses configured to focus an image on the image sensor.

19. An actuator assembly according to claim 18, wherein, when the second part is in the at least one position relative to the first part, the primary axis is parallel to the optical axis of the one or more lenses and / or is perpendicular to a light-sensitive region of the image sensor.

Images