WO2024153933A1

WO2024153933A1 - Actuator assembly

Info

Publication number: WO2024153933A1
Application number: PCT/GB2024/050131
Authority: WO
Inventors: Nicholas HEIJNE; Alexander Johnson; James Howarth; Stephen Matthew BUNTING; Robert LANGHORNE; Robin Eddington; Andrew Benjamin Simpson Brown
Original assignee: Cambridge Mechatronics Limited
Priority date: 2023-01-17
Filing date: 2024-01-17
Publication date: 2024-07-25

Abstract

An actuator assembly 2 comprising: a first part 10, wherein a first primary axis P is defined with reference to the first part 10; a second part 100 that is movable relative to the first part 10, wherein a second primary axis P is defined with reference to the second part 100; a third part 200 that is movable relative to the second part 100 and the first part 10; a first group of actuating units 30 each configured to apply an actuating force to the second part 100 capable of tilting the second part 100 relative to the first part 10 about a first tilt axis x perpendicular to the first primary axis P; and a second group of actuating units 30 each configured to apply an actuating force to the third part 200 capable of tilting the third part 200 relative to the second part 100 about a second tilt axis y perpendicular to the second primary axis P; wherein the first and second tilt axes x, y are non-parallel axes.

Description

ACTUATOR ASSEMBLY

Field

The present application relates to an actuator assembly with one or more actuating units, at least one actuating unit including a shape memory alloy (SMA) element, e.g. an SMA wire.

Background

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

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.

Typically, the range of movement (also known as "stroke") of such SMA actuator assemblies is limited by the maximum contraction of the SMA wires, and the actuating force is limited by the maximum force that can be generated by the SMA wires. To increase the movement range or the actuating force, longer or thicker SMA wires can be used, but this may be at the expense of increased cost, size and/or power, which may not be practical in miniature applications.

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. The actuating unit may be configured to increase the stroke or the actuating force and/or to re-direct the force applied by the SMA wire.

Summary

According to an aspect of the present invention, there is provided an actuator assembly comprising: a first part, wherein a first primary axis is defined with reference to the first part; a second part that is movable relative to the first part, wherein a second primary axis is defined with reference to the second part; a third part that is movable relative to the second part and the first part; a first group of actuating units each configured to apply an actuating force to the second part capable of tilting the second part relative to the first part about a first tilt axis perpendicular to the first primary axis; and a second group of actuating units each configured to apply an actuating force to the third part capable of tilting the third part relative to the second part about a second tilt axis perpendicular to the second primary axis; wherein the first and second tilt axes are non-parallel axes. At least one actuating unit of the first group 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; and 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. Additionally or alternatively, at least one actuating unit of the second group of actuating units comprises: a body portion; a shape memory alloy (SMA) element connected between the body portion and one of the second and third parts, and configured, on actuation, to apply an input force to the body portion; and a forcemodifying element connected between the body portion and the one of the second and third parts, and configured to modify the input force so as to give rise to the actuating force.

The at least one actuating unit of the first group of actuating units may comprise at least two, three or four actuating units. The at least one actuating unit of the second group of actuating units may comprise at least two, three or four actuating units.

The first primary axis may be the longitudinal axis of the first part. The first primary axis may be the primary axis and/or longitudinal axis of the actuator assembly. The first primary axis may pass through the first, second and third parts.

The second primary axis may be the longitudinal axis of the second part. The second primary axis may pass through the first, second and third parts.

The actuator assembly may comprise a third primary axis defined with reference to the third part. The third primary axis may be the longitudinal axis of the third part. The third primary axis may pass through the first, second and third parts.

The first part may be a support structure. The second part may be an intermediate part. The third part may be a (e.g. final) movable part. The third part may be a camera module comprising an image sensor and a lens assembly including one or more lenses configured to focus an image on the image sensor. 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 one of the other components. Such an indirect connection may involve a connection via further component(s) which is/are movable relative to the other components. For example, an SMA element may be connected to the one of the first and second parts via a further flexure, e.g. as described in WO 2022/144541 (which is herein incorporated by reference).

Optionally, the at least one actuating unit of the first group of actuating units further comprises: a coupling link connected between the body portion and the other of the first and second parts (different from the 'one of the first and second parts' the SMA element and the force-modifying element are connected to), wherein the coupling link is configured to transmit the actuating force 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.

Optionally, the at least one actuating unit of the second group of actuating units further comprises: a coupling link connected between the body portion and the other of the second and third parts (different from the 'one of the second and third parts' the SMA element and the force-modifying element are connected to), wherein the coupling link is configured to transmit the actuating force from the body portion to the other of the second and third parts, and wherein the coupling link is compliant in a direction perpendicular to the actuating force.

The coupling link may be, or may comprise, a coupling flexure. The coupling link may be elongate and stiff along its length and compliant in a direction perpendicular to its length.

The coupling link may comprise an SMA wire. In such a case, the actuator assembly may be equivalent to that specified in clause 1, below.

The force-modifying element may be, or may comprise, a force-modifying flexure. The forcemodifying element may be elongate and may be stiff along its length and compliant in a direction perpendicular to its length. The body portion, the coupling link and/or the force-modifying element of the at least one actuating unit(s) may be integrally formed.

Optionally, the first group of actuating units are configured to rotate the second part relative to the first part about the first primary axis.

Optionally, the second group of actuating units are configured to rotate the third part relative to the second part about the second primary axis.

Optionally, the actuator assembly comprises a first bearing arrangement configured to allow tilting of the second part relative to the first part about the first tilt axis, and to constrain tilting of the second part relative to the first part about the second tilt axis or an axis parallel to the second tilt axis.

Optionally, the first bearing arrangement is configured to allow rotation of the second part relative to the first part about the first primary axis.

Optionally, the first bearing arrangement is configured to constrain translational movement of the second part relative to the first part. For example, translational movement along a plane parallel to the first and second axes, translational movement along a plane perpendicular to the first primary axis, and/or translational movement in a direction (e.g. upwards or downwards direction) along the first primary axis.

Optionally, the actuator assembly comprises a second bearing arrangement configured to allow tilting of the third part relative to the second part about the second tilt axis, and to constrain tilting of the third part relative to the second part about the first tilt axis or an axis parallel to the first tilt axis.

Optionally, the second bearing arrangement is configured to allow rotation of the third part relative to the second part about the second primary axis.

Optionally, the second bearing arrangement is configured to constrain translational movement of the third part relative to the second part. For example, translational movement along a plane parallel to the first and second axes, translational movement along a plane perpendicular to the first primary axis, and/or translational movement in a direction (e.g. upwards or downwards direction) along the first primary axis.

Optionally, each actuating unit of the first group of actuating units is configured to exert a force on the second part with a component in a first direction along the first primary axis; and/or wherein each actuating unit of the second group of actuating units is configured to exert a force on the third part with a component in a first direction along the second primary axis.

Optionally, the force component in the first direction along the first primary axis is configured to urge the first and second parts towards each other. Optionally, the force component in the first direction along the second primary axis is configured to urge the second and third parts towards each other.

The urging of the first and second parts towards each other may bring the first and second parts into engagement with the first bearing arrangement provided between the first and second parts. The urging of the second and third parts towards each other may bring the second and third parts into engagement with the second bearing arrangement provided between the second and third parts.

Optionally, the first directions (i.e. the first direction along the first primary axis and the first direction along the second primary axis) are generally opposite directions. For example, the first directions are parallel and opposite directions when the actuator assembly is in an untilted configuration - i.e. wherein the second part is untilted relative to the first part, and the third part is untilted relative to the second part, such that the first, second, and third primary axes are parallel.

Optionally, the first group of actuating units comprises a total of two or four actuating units. Optionally, the second group of actuating units comprises a total of two or four actuating units.

Where the first group of actuating units comprises a total of two actuating units, the bearing arrangement may be configured to constrain rotational movement of the second part relative to the first part about the first primary axis. Where the second group of actuating units comprises a total of two actuating units, the bearing arrangement may be configured to constrain rotational movement of the third part relative to the second part about the second primary axis. Optionally, the first group of actuating units comprises half (e.g. a first pair) of the actuating units on a first side of the actuator assembly and the other half (e.g. a second pair, not overlapping with the first pair) of the actuating units on a second side of the actuator assembly opposite the first side.

Optionally, the second group of actuating units comprises half (e.g. a first pair) of the actuating units on a third side of the actuator assembly and the other half (e.g. a second pair, not overlapping with the first pair) of the actuating units on a fourth side of the actuator assembly opposite the third side.

The first and second sides may be different from the third and fourth sides. The first and second sides may be adjacent to the third and fourth sides. The first, second, third and fourth sides may be arranged in a loop around the first primary axis.

Optionally, each half comprises: a first actuating unit configured to exert a force on the second part with a component in a second direction in a plane perpendicular to the first and/or second primary axis, and a second actuating unit configured to exert a force with a component in a third direction in a plane perpendicular to the first and/or second primary axis; wherein the second and third directions are opposite directions.

In other words, each half may comprise: a first actuating unit configured to produce a first torque on the second part relative to the first part in a clockwise sense about the first and/or second primary axis, and a second actuating unit configured to produce a second torque on the second part relative to the first part in an anti-clockwise sense about the first and/or second primary axis.

Optionally, the third part comprises an electronic component. The electronic component may be an image sensor. The electronic component may be an emitter, a display, or a part thereof.

Optionally, the third part comprises one or more lenses and/or an image sensor. The first primary axis may be parallel to the optical axis of the one or more lenses and/or may be perpendicular to a light-sensitive region of the image sensor, for example, when the actuator assembly is in the untilted configuration.

The second group of actuating units may be connected between the first and third parts rather than between the second and third parts. In particular, at least one actuating unit of the second group of actuating units may comprise: a body portion; a shape memory alloy (SMA) element connected between the body portion and one of the first and third parts, and configured, on actuation, to apply an input force to the body portion; and a force-modifying element connected between the body portion and the one of the first and third parts, and configured to modify the input force so as to give rise to the actuating force. The at least one actuating unit of the second group of actuating units may further comprise: a coupling link connected between the body portion and the other of the first and third parts, wherein the coupling link is configured to transmit the actuating force from the body portion to the other of the first and third parts, and wherein the coupling link is compliant in a direction perpendicular to the actuating force.

According to another aspect of the present invention, there is provided an actuator assembly comprising: a first part, wherein a primary axis is defined with reference to the first part; a second part moveable relative to the first part; a plurality of actuating units each configured to apply an actuating force to the second part capable of tilting the second part relative to the first part about a first axis perpendicular to the primary axis; and a bearing arrangement configured to allow tilting of the second part relative to the first part about the first axis. At least one of the actuating units comprises: a body portion; a shape memory alloy (SMA) element connected between the body portion and the first part, and configured, on actuation, to apply an input force to the body portion; and a force-modifying element connected between the body portion and the first part, and configured to modify the input force so as to give rise to the actuating force.

The at least one actuating unit may comprise at least two, three or four actuating units.

The primary axis may be the longitudinal axis of the first part. The primary axis may be the primary axis and/or longitudinal axis of the actuator assembly. The primary axis may pass through the first and second parts.

The actuator assembly may comprise a second primary axis defined with reference to the second part. The second primary axis may be the longitudinal axis of the second part. The second primary axis may pass through the first and second parts.

Optionally, the at least one actuating unit further comprises: a coupling link connected between the body portion and the second part, wherein the coupling link is configured to transmit the actuating force from the body portion to the second part, and wherein the coupling link is compliant in a direction perpendicular to the actuating force. The coupling link may be, or may comprise, a coupling flexure. The coupling link may be elongate and stiff along its length and compliant in a direction perpendicular to its length.

The body portion, the coupling link and/or the force-modifying element of the at least one actuating unit(s) may be integrally formed.

Optionally, the bearing arrangement is configured to constrain tilting of the second part relative to the first part about a second axis which is perpendicular to the primary axis and the first axis.

Optionally, the bearing arrangement is configured to allow rotation of the second part relative to the first part about the primary axis.

Optionally, the bearing arrangement is configured to constrain translational movement of the second part relative to the first part. For example, translational movement along a plane parallel to the first axis (and the second axis), translational movement along a plane perpendicular to the primary axis, and/or translational movement in a direction (e.g. +z or -z direction) along the primary axis.

Optionally, the actuating units are configured to rotate the second part relative to the first part about the primary axis.

Optionally, each actuating unit is configured to exert a force on the second part with a component in a first direction along the primary axis.

Optionally, the plurality of actuating units comprises a total of two or four actuating units.

Where the plurality of actuating units comprises a total of two actuating units, the bearing arrangement may be configured to constrain rotational movement of the second part relative to the first part about the primary axis.

Optionally, the plurality of actuating units comprises half (e.g. a first pair) of the actuating units on a first side of the actuator assembly and the other half (e.g. a second pair, not overlapping with the first pair) of the actuating units on a second side of the actuator assembly opposite the first side. Optionally, each half comprises: a first actuating unit configured to exert a force on the second part with a component in a second direction in a plane perpendicular to the primary axis, and a second actuating unit configured to exert a force with a component in a third direction in a plane perpendicular to the primary axis; wherein the second and third directions are opposite directions.

In other words, each half may comprise: a first actuating unit configured to produce a first torque on the second part relative to the first part in a clockwise sense about the primary axis, and a second actuating unit configured to produce a second torque on the second part relative to the first part in an anti-clockwise sense about the primary axis.

Optionally, the second part comprises an electronic component. The electronic component may be an image sensor. The electronic component may be an emitter, a display, or a part thereof.

Optionally, the second part comprises one or more lenses and/or an image sensor. The primary axis may be parallel to the optical axis of the one or more lenses and/or may be perpendicular to a lightsensitive region of the image sensor, for example, when the actuator assembly is in the untilted configuration (i.e. wherein the second part is untilted relative to the first part).

The force-modifying element may be, or may comprise, a force-modifying flexure. The forcemodifying element may be elongate and may be stiff along its length and compliant in a direction perpendicular to its length.

Optionally, the force-modifying element and the body portion of the at least one actuating unit(s) are configured to amplify or de-amplify the magnitude of mechanical quantities provided by the SMA element(s) on actuation.

In other words, the force-modifying element and the body portion of the at least one actuating unit(s) are configured to act like a (e.g. class 1) lever mechanism capable of mechanically amplifying or de-amplifying the magnitude of mechanical quantities (e.g. force, displacement) provided by the SMA element(s) on actuation. For example, the at least one actuating unit of the first group of actuating units may be configured such that, on actuation (i.e. contraction) of the SMA element, the actuating unit is capable of moving the second part relative to the first part by an amount which is greater or smaller than a change in length of the SMA element (i.e. greater or smaller than an amount by which the SMA element contracts); and/or the at least one actuating unit of the second group of actuating units may be configured such that, on actuation (i.e. contraction) of the SMA element, the actuating unit is capable of moving the third part relative to the second part by an amount which is greater or smaller than a change in length of the SMA element (i.e. greater or smaller than an amount by which the SMA element contracts).

For example, the at least one actuating unit of the plurality of actuating units may be configured such that, on actuation (i.e. contraction) of the SMA element, the actuating unit is capable of moving the second part relative to the first part by an amount which is greater or smaller than a change in length of the SMA element (i.e. greater or smaller than an amount by which the SMA element contracts).

Optionally, the SMA elements are SMA wires.

The actuator assembly may be a micro-actuator for a camera assembly or a mobile phone. The above-described actuating units may provide optical image stabilisation (OIS) by providing tilting of a camera module comprising a lens assembly and an image sensor.

Brief Description of the Drawings

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

Figure 1 is a schematic cross-sectional view of a camera assembly incorporating a actuator assembly; Figure 2 is a schematic plan view of the actuator assembly;

Figure 3 is a schematic perspective view of part of the actuator assembly;

Figure 4 is a plan view of an actuating unit forming part of the actuator assembly;

Figures 5-8 are schematic cross-sectional views of different variations of the actuator assembly incorporating different variations of the actuating unit;

Figure 9 is a perspective view of a variation of the actuating unit;

Figure 10 is a schematic cross-sectional view of a variation of the actuator assembly incorporating the actuating unit of Figure 9;

Figures 11-14 are schematic cross-sectional views of different variations of the actuator assembly.

Detailed Description

Camera assembly

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

The actuator assembly 2 includes a support structure 10 (herein also referred to as the first part 10), an intermediate part 100 (herein also referred to as the second part 100), and a movable part 200 (herein also referred to as the third part 200). The intermediate part 100 is movable relative to the support structure 10. The movable part 200 is movable relative to the intermediate part 100 and 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 first group of actuating units 30 connected between (i.e. connected to) the support structure 10 and the intermediate part 100. The first group of actuating units 30 are arranged to apply actuating forces F between the intermediate part 100 and the support structure 10. Selectively varying these actuating forces F may cause the intermediate part 100 to move relative to the support structure 10. The first group of actuating units 30 are thus capable of driving movement of the intermediate part 100 relative to the support structure 10.

The actuator assembly 2 also includes a second group of actuating units 30 connected between (i.e. connected to) the intermediate part 100 and the movable part 200. The second group of actuating units 30 are arranged to apply actuating forces F between the movable part 200 and the intermediate part 100. Selectively varying these actuating forces F may cause the movable part 200 to move relative to the intermediate part 100. The second group of actuating units 30 are thus capable of driving movement of the movable part 200 relative to the intermediate part 100.

The movable part 200 is supported on the support structure 10 via the intermediate part 100, and thus configured to move together with the intermediate part 100 when the intermediate part 100 is moved relative to the support structure 10. As such, the first group of actuating units 30 is also capable of moving the movable part 200 relative to the support structure 10 via the intermediate part 100.

A first primary axis P is defined with reference to the support structure 10. The first primary axis P extends through the support structure 10, e.g. through the centre of the support structure 10. In some examples, the support structure 10 extends predominantly in a direction perpendicular to the first primary axis P. In other words, the extent of the support structure 10 along the first primary axis P is less than the extent thereof along any direction perpendicular to the first primary axis P. The first primary axis P may be the longitudinal axis of the support structure 10. The first primary axis P may pass through the first, second and third parts 10, 100, 200.

A second primary axis S is defined with reference to the intermediate part 100 and thus moves (e.g. tilts) together with the intermediate part 100 when the intermediate part 100 is moved (e.g. tilted) relative to the support structure 10. The second primary axis S extends through the intermediate part 100, e.g. through the centre of the intermediate part 100. In some examples, the intermediate part 100 extends predominantly in a direction perpendicular to the second primary axis S. In other words, the extent of the intermediate part 100 along the second primary axis S is less than the extent thereof along any direction perpendicular to the second primary axis S. The second primary axis S may be the longitudinal axis of the intermediate part 100. The second primary axis S may pass through the first, second and third parts 10, 100, 200. A third primary axis T is defined with reference to the movable part 200. The third primary axis T thus moves (e.g. tilts) together with the movable part 200 when the movable part 200 is moved (e.g. tilted) relative to the intermediate part 100 (and, thus, also the support structure 10). The third primary axis T extends through the movable part 200, e.g. through the centre of the movable part 200. In some examples, the movable part 200 extends predominantly in a direction perpendicular to the third primary axis T. In other words, the extent of the movable part 200 along the third primary axis T is less than the extent thereof along any direction perpendicular to the third primary axis T. The third primary axis T may be the longitudinal axis of the movable part 200. The third primary axis T may pass through the first, second and third parts 10, 100, 200.

The movable part 200 (herein also referred to as a camera module 200) comprises an image sensor 220 and a lens assembly 210, including one or more lenses 211, configured to focus an image on the image sensor 220. The lens assembly 210 may include a lens carrier 210, for example in the form of a cylindrical body, supporting the one or more lenses 211. The image sensor 220 is configured to capture 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 1 in which each lens 211 has a diameter of 20mm or less, for example of 12mm or less.

The first group of actuating units 30 are configured to, upon selective actuation, tilt (i.e. rotate) the intermediate part 100 (and thus also the movable part 200) relative to the support structure 10 about a first tilt axis x which is perpendicular to the first primary axis P. The second group of actuating units 30 are configured to, upon selective actuation, tilt (i.e. rotate) the movable part 200 relative to the intermediate part 100 (and thus also the support structure 10) about a second tilt axis y which is perpendicular to the second primary axis S. The first and second tilt axes x, y are nonparallel axes. As shown in Figure 2, the first and second tilt axes x, y may be perpendicular to each other when viewed along the primary axis P. The first and second groups of actuating units 30 are capable of providing optical image stabilisation (OIS) by driving such tilting of the camera module 200 relative to the support structure 10. Such OIS functionality is herein also referred to as 'tilt-OIS'.

Figures 1 and 2 show the actuator assembly 2 in an untilted configuration wherein the intermediate part 100 is untilted relative to the support structure 10 and the movable part 200 is untilted relative to the intermediate part 100 (and the support structure 10) such that the first, second and third primary axes P, S, T are collinear (i.e. the first, second, and third primary axes P, S, T are parallel and coincide). In other embodiments, the first, second and third primary axes P, S, T may be parallel but may not necessarily coincide when the actuator assembly 2 is in the untilted configuration.

As shown in Figure 1, when the actuator assembly 2 is in the untilted configuration, the optical axis O of the lens assembly 210 and the imaging axis of the image sensor 220 may also be collinear with the first, second and third primary axis P, S, T (i.e. the first primary axis P, the second primary axis S, the third primary axis T, the optical axis O, and the imaging axis may be parallel and coincide). In other embodiments, or e.g. wherein the lens assembly 210 has been translated relative to the image sensor 220 in a direction perpendicular to the optical axis O, the first primary axis P, the second primary axis S, the third primary axis T, the optical axis O, and the imaging axis may be parallel to each other but may not necessarily coincide when the actuator assembly 2 is in the untilted configuration.

Each actuating unit 30 comprises a shape memory alloy (SMA) wire 34 configured to, upon actuation (i.e. on contraction), be capable of driving relative movement between the parts of the actuator assembly 2 to which the actuating unit 30 is connected to.

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 the SMA wires 34 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 wires 34, thereby heating the SMA wires 34 by causing an electric current to flow, will cause the SMA wires 34 to contract and thus actuate the actuating unit 30 so as to drive relative movement of the movable part 200. The drive signals are chosen to drive relative movement of the movable part 200 in a desired manner, for example, so as to achieve OIS by stabilizing the image sensed by the image sensor 220. The controller 8 supplies the generated drive signals to the SMA wires 34.

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 200 to compensate for such shake. The controller 8 receives such signals and can generate the drive signals for the SMA wires 34 to achieve OIS. The lens assembly 210 may be movable relative to the image sensor 220 along the optical axis O. Where this is the case, the actuator assembly 2 may comprise one or more further actuating units (not shown) configured to drive such relative movement. Such relative movement has the effect of adjusting the focus of the image on the image sensor 4, i.e. providing auto-focus (AF) functionality.

The lens assembly 210 and the image sensor 220 may be movable relative to each other in any direction perpendicular to the optical axis O. This relative movement may be translational and/or rotational (e.g. the image sensor 220 may be rotatable relative to the lens assembly 210 about the optical axis O). Where this is the case, the actuator assembly 2 may comprise one or more further actuating units (not shown) configured to drive such relative movement. Such relative movement has the effect of moving the image on the image sensor 4 and can provide OIS functionality. This variation of OIS is herein also referred to as 'shift-OIS'.

The controller 8 may also generate drive signals for these further actuating units. In other words, the controller 8 may also be configured to supply drive signals chosen to drive relative movement between the lens assembly 210 and the image sensor 220 in a desired manner, for example, so as to achieve AF and/or shift-OIS functionality. Alternatively, at least some of the drive signals for these further actuating units may be provided by one or more different controllers.

One or more of the further actuating units may be SM A actuating units - i.e. actuating units comprising SMA elements. One or more of the further actuating units may be non-SMA actuating units, e.g. voice coil motor (VCM) actuating units.

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 tilting of a movable part 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.

As shown in Figure 3, the actuator assembly 2 includes a first bearing arrangement 40i, 402 that supports the intermediate part 100 on the support structure 10. The first bearing arrangement 40i, 4O2 is provided between the intermediate part 100 and the support structure 10. The first bearing arrangement 40i, 4O2 is configured to allow the intermediate part 100 to tilt about the first tilt axis x relative to the support structure 10. The first bearing arrangement 40i, 4O2 is also configured to constrain, i.e. reduce or prevent, tilting of the intermediate part 100 relative to the support structure 10 about an axis perpendicular to the first tilt axis x and perpendicular to the first primary axis P. The first bearing arrangement 40i, 402 may also be configured to constrain translational movement of the intermediate part 100 relative to the support structure 10 in any direction (or at least one direction) perpendicular to the first primary axis P. The first bearing arrangement 40i, 4O2 may include one or more of the following bearings: a rolling bearing (such as a ball bearing as illustrated in Figure 3), a flexure bearing (i.e. an arrangement of flexures or other resilient elements that guide movement), or a plain (i.e. sliding contact) bearing.

Similarly, the actuator assembly 2 also includes a second bearing arrangement 40a, 4O4 that supports the movable part 200 on the intermediate part 100. The second bearing arrangement 40a, 4O4 is provided between the movable part 200 and the intermediate part 100. The second bearing arrangement 40s, 404 is configured to allow the movable part 200 to tilt about the second tilt axis y relative to the intermediate part 100. The second bearing arrangement 40s, 404 is also configured to constrain, i.e. reduce or prevent, tilting of the movable part 200 relative to the intermediate part 100 about an axis perpendicular to the first tilt axis x and perpendicular to the second primary axis S. The second bearing arrangement 40s, 404 may also be configured to constrain translational movement of the movable part 200 relative to the intermediate part 100 in any direction (or at least one direction) perpendicular to the second primary axis S. The second bearing arrangement 40s, 404 may 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.

The first bearing arrangement 40i, 4O2 may be configured to allow rotation of the intermediate part 100 relative to the support structure 10 about the first primary axis P. Where this is the case, the first group of actuating units 30 may be configured to, upon selective actuation, rotate the intermediate part 100 (and thus also the movable part 200) relative to the support structure 10 about the first primary axis P.

The second bearing arrangement 40s, 404 may also be configured to allow rotation of the movable part 200 relative to the intermediate part 100 about the second primary axis S. Where this is the case, the second group of actuating units 30 may also be configured to, upon selective actuation, rotate the movable part 200 relative to the intermediate part 100 (and thus also the support structure 10) about the second primary axis S. The first and second groups of actuating units 30 can provide OIS (i.e. compensation for roll movements) by driving such rotations of the camera module 200 (in particular the image sensor 220) relative to the support structure 10 about the first and second primary axes P, S. Such OIS functionality is herein also referred to as 'roll-OIS'.

First stage of the actuator assembly

Figure 3 illustrates a 'first tilt stage' of the actuator assembly 2 including the support structure 10, the intermediate part 100, the first group of actuating units 30, and the first bearing arrangement 40i, 402. The term 'first tilt stage' is herein used to refer to the group of components of the actuator assembly 2 which are configured to enable the tilting of the intermediate part 100 relative to the support structure 10 about the first axis x.

As shown in Figure 3, the first bearing arrangement 40i, 4O2 includes a first bearing 40i and a second bearing 4O2. The first bearing 40i is located on a first side 2a of the actuator assembly 2 and the second bearing 4O2 is located on a second, opposite side 2b of the actuator assembly 2. The first bearing arrangement 40i, 4O2 (i.e. the first and second bearings 40i, 4O2 thereof) defines the first tilt axis x. The two bearings 40i, 4O2 allow the intermediate part 100 to rotate about the first tilt axis x relative to the support structure 10. Such a rotation is labelled Rx in Figure 3. The two bearings 40i, 4O2 may also allow the intermediate part 100 to rotate relative to the support structure 10 about the first primary axis P.

As shown in Figure 3, the first group of actuating units 30 includes four SMA actuating units 301-304 which are depicted in Figures 2 and 3 merely with crossed lines for simplicity. Each of these SMA actuating units 301-304 are connected between the intermediate part 100 and the support structure 10. In particular, one end of each of these SMA actuating units 301-304 is connected to the intermediate part 100, and the other end of each of these SMA actuating units 301-304 is connected to the support structure 10. Each SMA actuating unit 301-304 provides a downwards force on the intermediate part 100 (i.e. exerts a force on the intermediate part 100 with a component in a downwards direction along the first primary axis P) when the SMA actuating unit 301-304 is in tension. The downwards force component urges the intermediate part 100 and the support structure 10 towards each other. A first pair of SMA actuating units 30i, SCh are located on a third side 2c of the actuator assembly 2, and a second pair of SMA actuating units 30a, 3C are located on a fourth, opposite side 2d of the actuator assembly 10. The first and second sides 2a, 2b are different from the third and fourth sides 2c, 2d. The first and second sides 2a, 2b are adjacent to the third and fourth sides 2c, 2d. The first, second, third and fourth sides 2a-2d arranged in a loop around the first primary axis P. The first pair of SMA actuating units 30i, 302 generally lie in a first plane parallel to the first primary axis P, and the second pair of SMA actuating units 30a, 3O4 generally lie in a second plane parallel to the first primary axis P.

The first pair of SMA actuating units 30i, 302 may be actuated so as to produce a first, downwards force on a first side of intermediate part 100 (located on the third side 2c of the actuator assembly 2). The second pair of SMA actuating units 30s, 3O4 may be actuated so as to produce a second, downwards force on a second, opposite side of the intermediate part 100 (located on the fourth side 2d of the actuator assembly 2).

When these first and second forces are suitably balanced (e.g. equal), the intermediate part 100 may be held in its untilted position relative to the support structure 10 against the first bearing arrangement 40i, 4O2 (such that the first and second primary axes P, S are at least parallel to each other).

When these first and second forces are unbalanced (e.g. different), the intermediate part 100 tilts relative to the support structure 10 about the first tilt axis x in one sense or another depending on which of the first and second forces are greater. As mentioned above, such a rotation is labelled Rx in Figure 3.

The first and third SMA actuating units 30i, 30s may be actuated so as to produce (among other things) a first torque on the intermediate part 100 in a clockwise sense about the first primary axis P relative to the support structure 10. The second and fourth SMA actuating units 302, 304 may be actuated so as to produce (among other things) a second torque on the intermediate part 100 in an anticlockwise sense about the first primary axis P relative to the support structure 10. When the first and second torques are unbalanced (e.g. different), the intermediate part 100 may rotate relative to the support structure 10 about the first primary axis P in one sense or another depending on which of the first and second torques are greater. Relative rotation of the intermediate part 100 about the first primary axis P and (simultaneously) about the first tilt axis x can be produced by a combination of the above-described actuations.

Second stage of the actuator assembly

The term 'second tilt stage' is herein used to refer to the group of components of the actuator assembly 2 which are configured to enable the tilting of the movable part 200 relative to the intermediate part 100 about the second tilt axis y. The second tilt stage of the actuator assembly 2 includes the intermediate part 100, the movable part 200, the second group of actuating units 30, and the second bearing arrangement 40a, 404. The second tilt stage works in the same manner as the first tilt stage. The second tilt stage may be considered as an upside-down version of the first tilt stage which is arranged to tilt the movable part 200 relative to the intermediate part 100 about the second tilt axis y, rather than to tilt the intermediate part 100 relative to the support structure 10 about the first tilt axis x.

The second bearing arrangement 40a, 4O4 includes a third bearing 40a and a fourth bearing 4O4. The third bearing 40s is located on the third side 2c of the actuator assembly 2 and the fourth bearing 4O4 is located on the fourth, opposite side 2d of the actuator assembly 2. The second bearing arrangement 4O3, 404 (i.e. the first and second bearings 40i, 4O2 thereof) defines the second tilt axis y. The two bearings 40s, 404 allow the movable part 200 to rotate about the second tilt axis y relative to the intermediate part 100. Such a rotation may be referred to as rotation Ry. The two bearings 40s, 404 may also allow the movable part 200 to rotate relative to the intermediate part 100 about the second primary axis S.

The second group of actuating units 30 includes four SMA actuating units 30 which are depicted in Figure 2 merely with crossed lines for simplicity. Each of these SMA actuating units 30 are connected between the movable part 200 and the intermediate part 100. In particular, one end of each of these SMA actuating units 30 is connected to the movable part 200, and at the other end connected to the intermediate part 100. Each of these SMA actuating units 30 provides an upwards force on the movable part 200 (i.e. exerts a force on the movable part 200 with a component in an upwards direction along the second primary axis S) when they are in tension. The upwards force component urges the movable part 200 and the intermediate part 100 towards each other.

A first pair of these SMA actuating units 30 are located on the first side 2a of the actuator assembly 2, and a second pair of these SMA actuating units 30 are located on the second, opposite side 2b of the actuator assembly 10. The first pair of these SMA actuating units 30 generally lie in a first plane parallel to the second primary axis S, and the second pair of these SMA actuating units 30 generally lie in a second plane parallel to the second primary axis S.

The first pair of these SMA actuating units 30 may be actuated so as to produce a first, upwards force on a first side of movable part 200 (located on the first side 2a of the actuator assembly 2). The second pair of these SMA actuating units 30 may be actuated so as to produce a second, upwards force on a second, opposite side of the movable part 200 (located on the second side 2b of the actuator assembly 2).

When these first and second forces are suitably balanced (e.g. equal), the movable part 200 may be held in its untilted position relative to the intermediate part 100 against the second bearing arrangement 40a, 404 (such that the second and third primary axes S, T are at least parallel to each other).

When these first and second forces are unbalanced (e.g. different), the movable part 200 tilts relative to the intermediate part 100 about the second tilt axis y in one sense or another depending on which of these first and second forces are greater.

Like with the first tilt stage, one of each of these pairs of SMA actuating units 30 may be configured to produce (among other things) a first torque on the movable part 200 in a clockwise sense about the second primary axis S relative to the intermediate part 100; and another of each of these pairs of SMA actuating units 30 may be configured to produce (among other things) a second torque on the movable part 200 in an anticlockwise sense about the second primary axis S relative to the intermediate part 100. When these first and second torques are unbalanced (e.g. different), the movable part 200 may rotate relative to the intermediate part 100 about the second primary axis S in one sense or another depending on which of these first and second torques are greater.

Relative rotation of the movable part 200 about the second primary axis S and (simultaneously) about the second tilt axis y can be produced by a combination of the above-described actuations.

An important difference between the first and second tilt stages is that the SMA actuating units 30 of the second tilt stage are configured to provide an upwards force along the second primary axis S (which, as discussed above, corresponds to the first primary axis P when the actuator assembly 2 is in the untilted configuration), instead of a downwards force along the first primary axis P (which, as discussed above, corresponds to the second primary axis S when the actuator assembly 2 is in the untilted configuration). In other words, the first group of actuating units 30 is configured to drive the intermediate part 100 generally downwards against the support structure 10, and the second group of actuating units 30 is configured to pull the movable part 200 generally upwards against the intermediate part 100.

This arrangement can be beneficial as e.g. it may allow the movable part 200 to move towards endstops located above and below the movable part 200 during drop events (e.g. in the event that a smartphone comprising the camera assembly 1 is dropped). However, it will be appreciated that such an arrangement is optional. The first and second tilt stages may instead be configured to exert forces that are generally in the same direction (e.g. upwards or downwards) along the first and/or second primary axes P, S.

SMA actuating units with force-modifying elements

A single SMA actuating unit 30 is shown in Figure 4, but it will be appreciated that the actuator assembly 2 generally has multiple actuating units 30, each of which include the same components described with reference to Figure 4.

The 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, 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.

The actuating unit 30 also includes a force-modifying flexure 32. The force-modifying flexure 32 is connected between the body portion 31 and one of the first, second and third parts 10, 100, 200 of the actuator assembly 2 (e.g. 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 one of the first, second and third parts 10, 100, 200, e.g. via a foot portion 36. The foot portion 36 is fixed relative to the one of the first, second and third parts 10, 100, 200. The force-modifying flexure 32 allows the body portion 31 to pivot relative to the one of the first, second and third parts 10, 100, 200 about an effective pivot point V. Although the effective pivot point V is shown in Figure 4 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 one of the first, second and third parts 10, 100, 200 is initially in a direction that is substantially perpendicular to the (e.g. length of the) force-modifying flexure 32.

The 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 one of the first, second and third parts 10, 100, 200. One end of the SMA wire 34 is connected to the one of the first, second and third parts 10, 100, 200, e.g. by a crimp (not shown). The other end of the SMA wire 34 is connected to the body portion 31, e.g. by a crimp 35.

The actuating unit 30 also includes a coupling link 33. In the illustrated examples, the coupling link 33 is a coupling flexure 33. The coupling flexure 33 is connected between the body portion 31 and another of the first, second and third parts 10, 100, 200 (different from the one of the first, second and third parts 10, 100, 200 - e.g. the intermediate part 100). 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 other of the first, second and third parts 10, 100, 200. The coupling link 33 transfers or transmits an actuating force F from the body portion 31 to the other of the first, second and third parts 10, 100, 200. The actuating force F acts parallel to the length of the coupling link 33. The coupling link 33 is compliant (i.e. deformable) in a direction (or in multiple directions) perpendicular to the actuating force F and/or in a direction (or in multiple directions) perpendicular to its length. This allows the another of the first, second and third parts 10, 100, 200 to move in directions other than the direction of the coupling flexure 33 and actuating force F. This can be needed, for example, where different actuating units 30 cause the other of the first, second and third parts 10, 100, 200 to move in different directions.

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.

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 other of the first, second and third parts 10, 100, 200 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. In other words, the force-modifying flexure 32 and the body portion 31 are configured to amplify or de-amplify the magnitude of mechanical quantities provided by the SMA element 34 on actuation. In other words, the force-modifying flexure 32 and the body portion 31 are configured to act like a (e.g. class 1) lever mechanism capable of mechanically amplifying or de-amplifying the magnitude of mechanical quantities (e.g. force, displacement) provided by the SMA wire 34 on actuation.

As shown in Figure 4, the length of the SMA wire 34 and the length of the coupling link 33 may be, at least generally, parallel. Alternatively, as shown in Figures 5-10, the length of the SMA wire 34 and the length of the coupling link 33 may not be parallel to each other (i.e. may be angled relative to each other). As shown in Figures 9 and 10, the coupling flexure 33 may be at an angle of ~90° relative to the SMA wire 34.

As shown in Figures 5-8, the body portion 31 may be curved towards the flexure-modifying element 32. One or both ends of the body portion 31 - i.e. the section of the body portion 31 connected to the SMA element 34 and/or the section of the body portion 31 connected to the coupling link 33 - may be curved towards the flexure-modifying element 32. Having the section of the body portion 31 connected to the SMA element 34 curved towards the flexure-modifying element 32 can help ensure that a longer SMA element 34 is provided within the actuating unit 30, which e.g. could help increase stroke. Having the section of the body portion 31 connected to the coupling link 33 curved towards the flexure-modifying element 32 can help ensure that a longer coupling link 33 is provided within the actuating unit 30, which e.g. could help increase compliance of the coupling link 33.

In some examples, at least one SMA actuating unit 30 (preferably each SMA actuating unit 30) of the actuator assembly 2 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. In the provided examples, the actuating unit 30 is, at least substantially, arranged in a plane. In particular, the SMA wire 34, the coupling flexure 33 and the force-modifying flexure 32 are arranged so as to substantially extend in a common plane, at least when the actuator assembly 2 is in the untilted configuration. This allows for a compact configuration of the actuating unit 30. The body portion 31, when embodied by a plate, may further be arranged to extend in the plane. However, in general, the components of the actuating unit 30 need not be arranged in a common plane. The SMA wire 34 and/or the coupling flexure 33 may be angled relative to the plane, for example.

In the provided 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. 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.

In the provided 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 movement of the another of the first, second and third parts 10, 100, 200 in directions perpendicular to the actuating force F. In general, however, the actuating unit 30 need not include a coupling link 33, e.g. in examples in which there is no movement of the another of the first, second and third parts 10, 100, 200 in directions perpendicular to the actuating force F. Furthermore, 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 another of the first, second and third parts 10, 100, 200 while allowing movement of the another of the first, second and third parts 10, 100, 200 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 wire, 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.

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 one of the first, second and third parts 10, 100, 200. Such a force-modifying element may include, for instance, a rigid member with one end connected to the one of the first, second and third parts 10, 100, 200 via a suitable pivoting connection (e.g. a pin joint) and the other end connected to the body portion 31.

Specific examples of the first tilt stage

As shown in Figures 5, 6 and 10, each of the first group of SMA actuating units 30 (i.e. the SMA actuating units 30 of the first tilt stage) may have the force-modifying flexure 32 connected between the body portion 31 and the support structure 10. As discussed above, the force-modifying flexure 32 allows the body portion 31 to pivot relative to the support structure 10 about an effective pivot point.

Moreover, each of the first group of SMA actuating units 30 may have its SMA element 34 connected between the body portion 31 and the support structure 10. In other words, one end of the SMA wire 34 may be connected to the support structure 10 and the other end of the SMA wire 34 may be connected to the body portion 31.

Moreover, each of the first group of SMA actuating units 30 may have its coupling link 33 connected between the body portion 31 and the intermediate part 100. In other words, one end of the coupling link 33 may be connected to the body portion 31, and the other end of the coupling link 33 may be connected to the intermediate part 100. As discussed above, the coupling link 33 transfers or transmits an actuating force F from the body portion 31 to the intermediate part 100.

As shown in Figures 5 and 10, each of the first group of SMA actuating units 30 may have the body portion 31 located at a central region of the actuator assembly 2 when viewed along an axis perpendicular to the first tilt axis x and the first primary axis P. Also, each pair of adjacent SMA actuating units 30 may share a common foot portion 36 as shown in Figure 5.

Alternatively, as shown in Figure 6, each of the first group of SMA actuating units 30 may have the body portion 31 located at a non-central region of the actuator assembly 2 (e.g. at peripheries of the actuator assembly 2) when viewed along an axis perpendicular to the first tilt axis x and the first primary axis P. Also, the SMA wires 34 may cross when viewed along an axis perpendicular to the first tilt axis x and the first primary axis P.

In the examples shown in Figures 5, 6 and 10, each of the first group of SMA actuating units 30 have the force-modifying flexure 32 and the SMA wire 34 connected at one end to the support structure 10, and the coupling flexure 33 connected at one end to the intermediate part 100. However, this arrangement may be reversed, with the force-modifying flexure 32 and the SMA wire 34 connecting at one end to the intermediate part 100, and the coupling flexure 33 connecting at one end to the support structure 10.

Specific examples of the second tilt stage

As shown in Figures 7 and 8, each of the second group of SMA actuating units 30 (i.e. the SMA actuating units 30 of the second tilt stage) may have the force-modifying flexure 32 connected between the body portion 31 and the intermediate part 100. As discussed above, the force-modifying flexure 32 allows the body portion 31 to pivot relative to the intermediate part 100 about an effective pivot point.

Moreover, each of the second group of SMA actuating units 30 may have its SMA element 34 connected between the body portion 31 and the intermediate part 100. In other words, one end of the SMA wire 34 may be connected to the intermediate part 100 and the other end of the SMA wire 34 may be connected to the body portion 31.

Moreover, each of the second group of SMA actuating units 30 may have its coupling link 33 connected between the body portion 31 and the movable part 200. In other words, one end of the coupling link 33 may be connected to the body portion 31, and the other end of the coupling link 33 may be connected to the movable part 200. As discussed above, the coupling link 33 transfers or transmits an actuating force F from the body portion 31 to the movable part 200.

As shown in Figure 7, each of the second group of SMA actuating units 30 may have the body portion 31 located at a central region of the actuator assembly 2 when viewed along an axis perpendicular to the second tilt axis y and the second primary axis S. Also, each pair of adjacent SMA actuating units 30 may share a common foot portion 36.

Alternatively, as shown in Figure 8, each of the second group of SMA actuating units 30 may have the body portion 31 located at a non-central region of the actuator assembly 2 (e.g. at peripheries of the actuator assembly 2) when viewed along an axis perpendicular to the second tilt axis y and the second primary axis S. Also, the SMA wires 34 may cross when viewed along an axis perpendicular to the second tilt axis y and the second primary axis S. In the examples shown in Figures 7 and 8, each of the second group of SMA actuating units 30 have the force-modifying flexure 32 and the SMA wire 34 connected at one end to the intermediate part 100, and the coupling flexure 33 connected at one end to the movable part 200. However, this arrangement may be reversed, with the force-modifying flexure 32 and the SMA wire 34 connecting at one end to the movable part 200, and the coupling flexure 33 connecting at one end to the intermediate part 100.

Applications

As discussed 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 tilting of a movable part 200 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.

The actuator assembly may be used to move at least part of an illumination source in a 3D imaging system such as described in W02020/030916 (which is incorporated by reference to the maximum extent permissible by law).

The actuator assembly may be used to move at least part of a light source (e.g. a projector), a display or one or more other optical components of a display system for an augmented reality (AR) system or other electronic device.

Other variations

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

For example, the actuator assembly 2 may include different types of actuating units to those described above. Examples of such actuating units include a hooked SMA wire arrangement as shown in Figure 11, wherein an SMA element 340 is connected between the first part 10 and the second part 100 or between the second part 100 and the third part 200 via a hook 360 or a connector 360 configured to engage a mid-portion of the SMA element 340. Other examples of such actuating units include: a folded SMA wire arrangement as disclosed in Figures 12 to 14 (described in more detail below), 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, a two-stage arrangement as disclosed in WO 2021/111181 Al, or simply an SMA wire connected between the first part 10 and the second part 100 or connected between the second part 100 and the third part 200. 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.

Although the actuator assembly 2 is depicted in Figures 5-10 as only comprising actuating units 30 having SMA wires 34 and force-modifying elements 32, it will be appreciated that at least one of the actuating units 30 may be another type of SMA actuating unit or a non-SMA actuating unit, e.g. a voice coil motor (VCM) actuating unit.

In Figures 5-10 the actuator assembly 2 comprises four actuating units 30 in each tilt stage. However, the first tilt stage may instead comprise two opposing actuating units, for example, wherein these actuating units are configured to apply forces that are parallel to the primary axis P or wherein the first bearing arrangement is configured to constrain rotations around the primary axis P. Similarly, the second tilt stage may instead comprise two opposing actuating units, for example, wherein these actuating units are configured to apply forces that are parallel to the primary axis S or wherein the second bearing arrangement is configured to constrain rotations around the primary axis S.

Instead of the second group of actuating units 30 being connected between the intermediate part 100 and the movable part 200 (see e.g. Figure 2), the second group of actuating units 30 may be connected 'directly' between the support structure 10 and the movable part 200. For instance, each such actuating unit 30 may have a force-modifying flexure 32 and an SMA element 34 connected to the support structure and may have a coupling link 33 connected to the movable part 200. Such an arrangement may be simpler to manufacture but may perform less well due to interaction between the first and second groups of actuating units 30.

It will be appreciated that an actuator assembly comprising only a single tilt stage (e.g. only the first tilt stage) may be used in some cases. For example, a single tilt stage may be used for providing OIS in periscope cameras.

It will be appreciated that the first bearing arrangement may not need to be provided in the actuator assembly 2 e.g. wherein the first group of actuating units comprises one or more actuating units which do not require bearings for providing tilting about the first tilt axis x. Similarly, it will be appreciated that the second bearing arrangement may not need to be provided in the actuator assembly 2 e.g. wherein the second group of actuating units comprises one or more actuating units which does not require bearings for providing tilting about the second tilt axis y.

SMA

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

Folded wires variation One or more of the SMA actuating units 30 described above may be replaced with the SM A actuating units 30' depicted in Figures 12 to 14, each comprising an SMA element 34' (e.g. SMA wire 34') having a first portion and a second portion respectively coupled to the first part 10 and the second part 100 (i.e. when the actuating unit 30' forms part of the first group of actuating units) or respectively coupled to the second part 100 and the third part 200 (i.e. when the actuating unit 30' forms part of the second group of actuating units), and at least one intermediate component 110 configured to engage the SMA element 34' at a location between the first and second portions such that the second portion is held at an oblique angle relative to the first portion.

The second portion of the SMA element 34' may extend at a smaller angle than that of the first portion with respect to the first primary axis P.

The second portion of the SMA element 34' may extend by a greater amount than that of the first portion along the first primary axis P.

The first portion of the SMA element 34' may be longer in length than the second portion.

The first portion of the SMA element 34' may extend substantially perpendicular to, or at an acute angle relative to, the first primary axis P.

The intermediate component(s) 110 may extend from the first part 10.

As shown in Figure 12, each intermediate component 110 may comprise a roller configured to engage the SMA elements 34'.

As shown in Figure 12 and 13, each intermediate component 110 may comprise a flexure for engaging the SMA element(s) 34'. The flexures may be compliant in a plane in which the corresponding SMA element 34' extends.

The intermediate component(s) 110 may be configured to increase the stroke of the SMA element(s) 34'.

Clauses

Also disclosed herein is what is described in the following clauses: Clause 1. An actuator assembly comprising: a first part, wherein a first axis is defined with reference to the first part; a second part moveable relative to the first part; a drive arrangement comprising a total of four shape memory alloy (SMA) elements each having a first portion and a second portion respectively coupled to the first part and the second part, and wherein the four SMA elements of the drive arrangement are configured to rotate the second part about the first axis and to rotate the second part about a second axis perpendicular to the first axis; and at least one intermediate component configured to engage one of the four SMA elements of the drive arrangement at a location between the first and second portions such that the second portion is held at an oblique angle relative to the first portion.

Clause 2. An actuator assembly according to clause 1, comprising a bearing arrangement configured to allow rotation of the second part about the first and second axes, to constrain rotation of the second part about a third axis, and to constrain movement of the second part along the third axis, wherein the third axis is perpendicular to the first and second axes.

Clause s. An actuator assembly according to clause 1 or clause 2, wherein the four SMA elements of the drive arrangement comprise a first pair of SMA elements on a first side of the actuator assembly and a second pair of SMA elements on a second side of the actuator assembly opposite the first side.

Clause 4. An actuator assembly according to clause 3, wherein each of the four SMA elements of the drive arrangement provide a force on the second part with a component in the same direction along the first axis.

Clause 5. An actuator assembly according to clause 3 or 4, wherein, within each pair of SMA elements of the drive arrangement, the SMA elements cross as viewed along a direction perpendicular to the first axis.

Clause 6. An actuator assembly according to clause 1 or clause 2, further comprising: a third part which is movable relative to the second part, wherein a fourth axis is defined with reference to the second part; a further drive arrangement configured to rotate the third part about the fourth axis and to rotate the second part about a fifth axis perpendicular to the fourth axis.

Clause 7. An actuator assembly according to clause 6, wherein the further drive arrangement comprises a total of four SMA elements each having a first portion and a second portion respectively coupled to the second part and the third part. Clause s. An actuator assembly according to clause 7, comprising at least one intermediate component configured to engage one of the four SMA elements of the further drive arrangement at a location between the first and second portions such that the second portion is held at an oblique angle relative to both the first axis and the first portion.

Clause 9. An actuator assembly according to any of clauses 6 to 8, comprising a further bearing arrangement configured to allow rotation of the third part about the fourth and fifth axes, to constrain rotation of the third part about a sixth axis, and to constrain movement of the second part along the sixth axis, wherein the sixth axis is perpendicular to the fourth and fifth axes.

Clause 10. An actuator assembly according to clause 7, clause 8 or clause 9 when dependent on clause 7, wherein each of the four SMA elements of the further drive arrangement provide a force on the third part with a component in the same direction along the first axis.

Clause 11. An actuator assembly according to clause 7 or any of clauses 8 to 10 when dependent on clause 7, wherein the four SMA elements of the further drive arrangement comprise a first pair of SMA elements on a third side of the actuator assembly and a second pair of SMA elements on a fourth side of the actuator assembly opposite the third side.

Clause 12. An actuator assembly according to clause 11 when dependent on clause 3, wherein the first and second sides of the actuator assembly are adjacent to the third and fourth sides of the actuator assembly.

Clause 13. An actuator assembly according to clause 11 or 12, wherein, within each pair of SMA elements of the further drive arrangement, the SMA elements cross as viewed along a direction perpendicular to the fourth axis.

Clause 14. An actuator assembly according to any of clauses 6 to 13, wherein, at least when the second part is in a particular position relative to the first part and the third part is in a particular position relative to the second part, the first and fourth axes are parallel or collinear and/or the fifth axis extends in a perpendicular direction to the second axis.

Clause 15. An actuator assembly according to any preceding clause, comprising a plurality of intermediate components each configured to engage different SMA elements at a location between the first and second portions such that the second portions are held at an oblique angle relative to both the first axis and the first portions.

Clause 16. An actuator assembly according to clause 15, wherein each SMA element engaged with one of the intermediate components has the second portion extend at a smaller angle than that of the first portion with respect to the first axis. Clause 17. An actuator assembly according to clause 15 or 16, wherein each SMA element engaged with one of the intermediate components has the second portion extend by a greater amount than that of the first portion along the first axis.

Clause 18. An actuator assembly according to any one of clauses 15 to 17, wherein for each SMA element engaged with one of the intermediate components, the first portion is longer in length than the second portion.

Clause 19. An actuator assembly according to any one of clauses 15 to 18, wherein for each SMA element engaged with one of the intermediate components, the first portion of the SMA element extends substantially perpendicular to, or at an acute angle relative to, the first axis.

Clause 20. An actuator assembly according to any one of the preceding clauses, wherein the intermediate component(s) extend from the first part.

Clause 21. An actuator assembly according to any one of the preceding clauses, wherein the intermediate component(s) comprise a roller configured to engage the SMA element(s).

Clause 22. An actuator assembly according to any preceding clause, wherein the intermediate component(s) comprise a flexure for engaging the SMA element(s), and, optionally, wherein the flexure is compliant in a plane in which the SMA element extends.

Clause 23. An actuator assembly according to any preceding clause, wherein the intermediate component(s) are configured to increase the stroke of the SMA element(s).

Clause 24. An actuator assembly comprising: a first part, wherein a first axis is defined with reference to the first part; a second part moveable relative to the first part; a drive arrangement comprising a total of four actuating units, each actuating unit comprising: a force-modifying mechanism connected to the first part; a coupling link connected between the force-modifying mechanism and the second part; and a shape memory allow (SMA) element coupled to the first part and the forcemodifying mechanism for applying an input force on the force-modifying mechanism thereby causing the force-modifying mechanism to apply an output force on the coupling link and causing the coupling link to apply an actuating force on the second part, wherein the coupling link is compliant in a direction perpendicular to the direction of the actuating force; and wherein the actuating units of the drive arrangement are configured to rotate the second part about the first axis and to rotate the second part about a second axis perpendicular to the first axis.

Clause 25. An actuator assembly according to clause 24, comprising a bearing arrangement configured to allow rotation of the second part about the first and second axes, to constrain rotation of the second part about a third axis, and to constrain movement of the second part along the third axis, wherein the third axis is perpendicular to the first and second axes.

Clause 26. An actuator assembly according to clause 24 or clause 25, wherein the four actuating units of the drive arrangement comprise a first pair of actuating units on a first side of the actuator assembly and a second pair of actuating units on a second side of the actuator assembly opposite the first side.

Clause 27. An actuator assembly according to clause 26, wherein each of the four actuating units of the drive arrangement provide a force on the second part with a component in the same direction along the first axis.

Clause 28. An actuator assembly according to clause 26 or 27, wherein, within each pair of actuating units of the drive arrangement, the SMA elements cross as viewed along a direction perpendicular to the first axis.

Clause 29. An actuator assembly according to any preceding clause, further comprising: a third part which is movable relative to the second part, wherein a fourth axis is defined with reference to the second part; a further drive arrangement configured to rotate the third part about the fourth axis and to rotate the second part about a fifth axis perpendicular to the fourth axis.

Clause 30. An actuator assembly according to clause 29, wherein the further drive arrangement comprises a total of four actuating units, each comprising: a force-modifying mechanism connected to the second part; a coupling link connected between the force-modifying mechanism and the third part; and an SMA element coupled to the second part and the force-modifying mechanism for applying an input force on the force-modifying mechanism thereby causing the force-modifying mechanism to apply an output force on the coupling link and causing the coupling link to apply an actuating force on the third part, wherein the coupling link is compliant in a direction perpendicular to the direction of the actuating force.

Clause 31. An actuator assembly according to clause 29 or 30, comprising a further bearing arrangement configured to allow rotation of the third part about the fourth and fifth axes, to constrain rotation of the third part about a sixth axis, and to constrain movement of the second part along the sixth axis, wherein the sixth axis is perpendicular to the fourth and fifth axes.

Clause 32. An actuator assembly according to any of clauses 29 to 31, wherein each of the four actuating units of the further drive arrangement provide a force on the third part with a component in the same direction along the first axis.

Clause 33. An actuator assembly according to any of clauses 29 to 32, wherein the four actuating units of the further drive arrangement comprise a first pair of actuating units on a third side of the actuator assembly and a second pair of actuating units on a fourth side of the actuator assembly opposite the third side.

Clause 34. An actuator assembly according to clause 33 when dependent on clause 26, wherein the first and second sides of the actuator assembly are adjacent to the third and fourth sides of the actuator assembly.

Clause 35. An actuator assembly according to clause 33 or 34, wherein, within each pair of actuating units of the further drive arrangement, the SMA elements cross as viewed along a direction perpendicular to the fourth axis.

Clause 36. An actuator assembly according to any of clauses 29 to 35, wherein, at least when the second part is in a particular position relative to the first part and the third part is in a particular position relative to the second part, the first and fourth axes are parallel or collinear and/or the fifth axis extends in a perpendicular direction to the second axis.

Clause 37. An actuator assembly according to any of clauses 29 to 36, wherein the forcemodifying mechanism is configured such that, in response to a change in length of the SMA element, the end of the SMA element that is connected to the force-modifying mechanism moves relative to the first part by a first distance, and the end of the coupling link that is connected to the forcemodifying mechanism moves relative to the first part by a second distance that is greater than the first distance.

Clause 38. An actuator assembly according to any one of clauses 29 to 37, wherein the forcemodifying mechanism is configured such that, in response to a change in length of the SMA element, the end of the coupling link that is connected to the force-modifying mechanism moves relative to the first part by a second distance that is greater than the change in length of the SMA element.

Clause 39. An assembly according to any one of the clauses 29 to 38, wherein the coupling link is a flexure, and, optionally, wherein the flexure is elongate and is stiff along its length and compliant in a direction perpendicular to its length.

Clause 40. An assembly according to any one of the clauses 29 to 38, wherein the coupling link comprises a ball bearing or a plain bearing. Clause 41. An actuator assembly according to any one of clauses 29 to 38, wherein the forcemodifying mechanism comprises: a moveable portion to which the SMA element and the coupling link are connected; and a force-modifying flexure connected between the moveable portion and the first part and configured to bend in response to the input force.

Clause 42. An actuator assembly according to clause 41, wherein the moveable portion is integrally formed with the force-modifying flexure and/or the coupling link.

Clause 43. An actuator assembly according to any one of clauses 41 to 42, wherein the forcemodifying flexure is elongate and is stiff along its length and compliant in a direction perpendicular to its length.

Clause 44. An actuator assembly according to any one of the preceding clauses, wherein the second part comprises one or more lenses and/or an image sensor, and wherein the first axis is the optical axis of the one or more lenses and/or is perpendicular to a light-sensitive region of the image sensor.

Clause 45. An actuator assembly according to any one of clauses 1 to 43, wherein the third part comprises one or more lenses and/or an image sensor, and wherein the fourth axis is the optical axis of the one or more lenses and/or is perpendicular to a light-sensitive region of the image sensor.

Clause 46. An actuator assembly according to any preceding clause, wherein the SMA elements are SMA wires.

Claims

1. An actuator assembly comprising: a first part, wherein a first primary axis is defined with reference to the first part; a second part that is movable relative to the first part, wherein a second primary axis is defined with reference to the second part; a third part that is movable relative to the second part and the first part; a first group of actuating units each configured to apply an actuating force to the second part capable of tilting the second part relative to the first part about a first tilt axis perpendicular to the first primary axis; and a second group of actuating units each configured to apply an actuating force to the third part capable of tilting the third part relative to the second part about a second tilt axis perpendicular to the second primary axis; wherein the first and second tilt axes are non-parallel axes; and wherein:

(i) at least one actuating unit of the first group 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; and 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; and/or

(ii) at least one actuating unit of the second group of actuating units comprises: a body portion; a shape memory alloy (SMA) element connected between the body portion and one of the second and third parts, and configured, on actuation, to apply an input force to the body portion; and a force-modifying element connected between the body portion and the one of the second and third parts, and configured to modify the input force so as to give rise to the actuating force.

2. An actuator assembly according to claim 1, wherein the at least one actuating unit of the first group of actuating units further comprises: 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 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; and/or wherein the at least one actuating unit of the second group of actuating units further comprises: a coupling link connected between the body portion and the other of the second and third parts, wherein the coupling link is configured to transmit the actuating force from the body portion to the other of the second and third parts, and wherein the coupling link is compliant in a direction perpendicular to the actuating force.

3. An actuator assembly according to claim 1 or 2, wherein the first group of actuating units are configured to rotate the second part relative to the first part about the first primary axis.

4. An actuator assembly according to any preceding claim, wherein the second group of actuating units are configured to rotate the third part relative to the second part about the second primary axis.

5. An actuator assembly according to any preceding claim, comprising a first bearing arrangement configured to allow tilting of the second part relative to the first part about the first tilt axis, and to constrain tilting of the second part relative to the first part about the second tilt axis or an axis parallel to the second tilt axis.

6. An actuator assembly according to claim 5, wherein the first bearing arrangement is configured to allow rotation of the second part relative to the first part about the first primary axis.

7. An actuator assembly according to claim 5 or 6, wherein the first bearing arrangement is configured to constrain translational movement of the second part relative to the first part.

8. An actuator assembly according to any preceding claim, comprising a second bearing arrangement configured to allow tilting of the third part relative to the second part about the second tilt axis, and to constrain tilting of the third part relative to the second part about the first tilt axis or an axis parallel to the first tilt axis.

9. An actuator assembly according to claim 8, wherein the second bearing arrangement is configured to allow rotation of the third part relative to the second part about the second primary axis.

10. An actuator assembly according to claim 8 or 9, wherein the second bearing arrangement is configured to constrain translational movement of the third part relative to the second part.

11. An actuator assembly according to any preceding claim, wherein each actuating unit of the first group of actuating units is configured to exert a force on the second part with a component in a first direction along the first primary axis; and/or wherein each actuating unit of the second group of actuating units is configured to exert a force on the third part with a component in a first direction along the second primary axis.

12. An actuator assembly according to claim 11, wherein the force component in the first direction along the first primary axis is configured to urge the first and second parts towards each other; and the force component in the first direction along the second primary axis is configured to urge the second and third parts towards each other.

13. An actuator assembly according to claim 11 or 12, wherein the first directions are generally opposite directions.

14. An actuator assembly according to any preceding claim, wherein: (i) the first group of actuating units comprises a total of four actuating units; and/or (ii) the second group of actuating units comprises a total of four actuating units.

15. An actuator assembly according to any preceding claim, wherein the first group of actuating units comprises half of the actuating units on a first side of the actuator assembly and the other half of the actuating units on a second side of the actuator assembly opposite the first side; and/or the second group of actuating units comprises half of the actuating units on a third side of the actuator assembly and the other half of the actuating units on a fourth side of the actuator assembly opposite the third side.

16. An actuator assembly according to claim 14, wherein each half comprises: a first actuating unit configured to exert a force on the second part with a component in a second direction in a plane perpendicular to the first and/or second primary axis, and a second actuating unit configured to exert a force with a component in a third direction in a plane perpendicular to the first and/or second primary axis; wherein the second and third directions are opposite directions.

17. An actuator assembly according to any preceding claim, wherein the third part comprises an electronic component.

18. An actuator assembly according to any preceding claim, wherein the third part comprises one or more lenses and/or an image sensor.

19. An actuator assembly comprising: a first part, wherein a primary axis is defined with reference to the first part; a second part moveable relative to the first part; a plurality of actuating units each configured to apply an actuating force to the second part capable of tilting the second part relative to the first part about a first axis perpendicular to the primary axis; and a bearing arrangement configured to allow tilting of the second part relative to the first part about the first axis; and wherein at least one of the actuating units comprises: a body portion; a shape memory alloy (SMA) element connected between the body portion and the first part, and configured, on actuation, to apply an input force to the body portion; and a force-modifying element connected between the body portion and the first part, and configured to modify the input force so as to give rise to the actuating force.

20. An actuator assembly according to claim 19, wherein the at least one actuating unit further comprises: a coupling link connected between the body portion and the second part, wherein the coupling link is configured to transmit the actuating force from the body portion to the second part, and wherein the coupling link is compliant in a direction perpendicular to the actuating force.

21. An actuator assembly according to claim 19 or 20, wherein the bearing arrangement is configured to constrain tilting of the second part relative to the first part about a second axis which is perpendicular to the primary axis and the first axis.

22. An actuator assembly according to any of claims 19 to 21, wherein the bearing arrangement is configured to allow rotation of the second part relative to the first part about the primary axis.

23. An actuator assembly according to any of claims 19 to 22, wherein the bearing arrangement is configured to constrain translational movement of the second part relative to the first part.

24. An actuator assembly according to any of claims 19 to 23, wherein the actuating units are configured to rotate the second part relative to the first part about the primary axis.

25. An actuator assembly according to any of claims 19 to 24, wherein each actuating unit is configured to exert a force on the second part with a component in a first direction along the primary axis.

26. An actuator assembly according to any of claims 19 to 25, wherein the plurality of actuating units comprises a total of four actuating units.

27. An actuator assembly according to any of claims 19 to 26, wherein the plurality of actuating units comprises half of the actuating units on a first side of the actuator assembly and the other half of the actuating units on a second side of the actuator assembly opposite the first side.

28. An actuator assembly according to claim 27, wherein, each half comprises: a first actuating unit configured to exert a force on the second part with a component in a second direction in a plane perpendicular to the primary axis, and a second actuating unit configured to exert a force with a component in a third direction in a plane perpendicular to the primary axis; wherein the second and third directions are opposite directions.

29. An actuator assembly according to any of claims 19 to 28, wherein the second part comprises an electronic component.

30. An actuator assembly according to any of claims 19 to 29, wherein the second part comprises one or more lenses and/or an image sensor.

31. An actuator assembly according to any preceding claim, wherein the force-modifying element and the body portion of the at least one actuating unit(s) are configured to amplify or de-amplify the magnitude of mechanical quantities provided by the SMA element(s) on actuation.