SMA Actuators for Optical Image Stabilization

Abstract

Broadly speaking, embodiments of the present technology provide a shape memory alloy (SMA) actuation device for moving a movable component relative to a static component or support structure and along an imaginary primary axis. The SMA actuation device may include a biasing element for resisting movement of the movable component in a particular direction relative to the primary axis, or may include an arrangement of SMA actuator wires that provide a biasing function.

Description

[0001] The present application generally relates to a shape memory alloy (SMA) actuator for moving a movable component relative to a support structure, and more particularly to an SMA actuator including a biasing element for resisting movement of the movable component in a particular direction.

[0002] In a first solution of the present technology, a shape memory alloy (SMA) actuator device is provided, comprising: a support structure; a movable part, which is movable relative to the support structure; at least four SMA actuator wires, which are connected between the movable part and the support structure and are arranged to move the movable part relative to the support structure; and a biasing element, which is used to resist the translation of the movable part in a plane perpendicular to an imaginary primary axis.

[0003] In an embodiment, the two pairs of wires may provide a force on the movable member having force components in opposite directions along the primary axis.

[0004] In an embodiment, the biasing element may resist rotation of the movable component about the primary axis.

[0005] The term "biasing element" is used herein to refer to any element or component or mechanism used to allow or guide a movable part to move in a specific direction or degree of freedom relative to a main axis, while limiting / resisting / constraining the movement of the movable part in other directions or other degrees of freedom. The biasing element may also be referred to as a "bearing element" herein. The biasing element or bearing element may be a flexure, a rolling bearing, a ball bearing, a sliding bearing, etc. In an embodiment, the biasing element may include more than one biasing element, which may be of the same type or different types.

[0006] In a second solution of the present technology, a shape memory alloy (SMA) actuator device for moving a telephoto lens is provided, the device comprising: a support structure; a movable part, which is movable relative to the support structure; and eight SMA actuator wires, which are connected between the movable part and the support structure, so that when contracted, two groups of four SMA actuator wires provide forces on the movable part with components in opposite directions along an imaginary main axis, while resisting translation of the movable part in a plane perpendicular to the main axis, and resisting rotation of the movable part around the main axis.

[0007] In a third solution of the present technology, there is provided a device comprising an SMA actuation device of the type described herein.

[0008] The apparatus may be any of the following: a smartphone, a camera, a foldable smartphone, a foldable image capture device, a foldable smartphone camera, a foldable consumer electronic device, an image capture device, a 3D sensing device or system, a consumer electronic device, a mobile computing device, a mobile electronic device, a laptop, a tablet computing device, an e-reader (also known as an e-book reader or e-book device), a computing accessory or computing peripheral device (e.g., a mouse, a keyboard, a headset, earphones, earbuds, etc.), a security system, a medical device (e.g., an endoscope), a gaming system, a gaming accessory (e.g., a controller, a headset, a wearable controller, etc.), an augmented reality system, an augmented reality device, a virtual reality system, a virtual reality device, a wearable device, a drone (air, water, underwater, etc.), an autonomous vehicle, and a vehicle (e.g., an aircraft, a spacecraft, a submarine, a car, etc.). It should be understood that this is a non-exhaustive list of exemplary apparatuses.

[0009] The SMA actuators described herein may be used in devices / systems suitable for, for example, image capture, 3D sensing, depth mapping, aerial surveying, terrestrial surveying, surveying in or from space, hydrographic surveying, underwater surveying, scene detection, collision warning, security, medical imaging, facial recognition, augmented and / or virtual reality, advanced driver assistance systems in vehicles, autonomous vehicles, gaming, gesture control / recognition, and robotic devices.

[0010] Preferred features are set out in the attached dependent claims.

[0011] Embodiments of the present technology will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0012] Figures 1A to 1C shows perspective views of three SMA actuation devices having four SMA actuator wires in different arrangements;

[0013] Figure 2A and Figure 2B shows perspective views of two SMA actuation devices having four SMA actuator wires arranged differently;

[0014] Figure 3 is a perspective view of an SMA actuation device having eight SMA actuator wires;

[0015] FIG. 4A to FIG. 4C shows a schematic diagram of three SMA actuation devices having at least one biasing element;

[0016] Figure 5 shows a schematic diagram of an SMA actuation device for moving a telephoto lens; and

[0017] Figure 6 A schematic diagram showing another mechanism for moving the telephoto lens.

[0018] Broadly speaking, embodiments of the present technology provide a shape memory alloy (SMA) actuation device for moving a movable component relative to a static component or support structure and along an imaginary major axis. The SMA actuation device may include a biasing element for resisting movement of the movable component in a particular direction relative to the major axis, or may include an arrangement of SMA actuator wires that provide a biasing function.

[0019] The SMA actuators described herein can be used to provide position control of various types of movable components. One specific, non-limiting example is the use of an SMA actuator to provide optical image stabilization (OIS) for a camera. In this case, the principal axis is the optical axis of the lens or lens group of the camera. The SMA actuator can be used to drive the tilt of the lens (or lens group, or even the entire camera unit). The tilt can provide stability to overcome blur caused by tilt or translation orthogonal to the optical axis. The SMA actuator can be used to drive movement of the lens transverse to the optical axis, and such lateral movement can provide stability to overcome blur caused by tilt or translation orthogonal to the optical axis. The SMA actuator can be used to provide OIS for the camera and movement of the camera lens along the optical axis, for example, to focus.

[0020] International Patent Publication No. WO2011 / 104518 describes an SMA actuation device that uses eight SMA actuator wires to provide position control of a movable element with multiple degrees of freedom. However, the present applicant has determined that focusing and OIS can be achieved using only four wires in combination with a biasing element. This is advantageous because fewer wires means that the SMA actuation device can be cheaper and simpler to manufacture.

[0021] The present technology is now described in more detail with reference to the accompanying drawings. In each case, the movable component 102 is supported on or by a support structure 106 by four or more SMA actuator wires 104a-104h. The arrangement of the SMA actuator wires 104a-104h may be different, but common elements have common reference numerals.

[0022] Figures 1A to 1CPerspective views of three SMA actuation devices 100, 120, 140 having four SMA actuator wires in different arrangements are shown. The SMA actuation devices 100, 120, 140 include a movable component 102, which can generally be any type of component. In each device 100, 120, 140, the movable component 102 is shown as having a square or rectangular shape when viewed along a primary axis P, but it should be understood that the movable component 102 can have any shape. In each device, a support structure 106 supports the movable component 102 in a manner that allows the movable component 102 to move relative to the support structure. Figures 1A to 1C In the arrangement shown, the movable part 102 is supported on the support structure 106 solely by the SMA actuator wires 104a - 104d , but in principle the SMA actuation device 100 may include a suspension system that additionally supports the movable part 102 on the support structure 106 .

[0023] Each SMA actuator wire 104a-104d includes a piece of SMA wire connected to the movable member 102 at one end and to the support structure 106 at its other end, possibly via an intermediate member. The SMA actuator wires 104a-104d may be mechanically and electrically connected to the movable member 102 and the support structure 106 by any suitable means.

[0024] exist Figure 1A, the SMA actuator wires 104a-104d are tilted relative to the main axis P. In the case where the movable component is or includes a lens, the main axis P may be the optical axis of the lens. Specifically, the SMA actuator wires 104a-104d are tilted at a certain angle relative to a plane perpendicular to the main axis. When the SMA actuator wires 104b and 104d are energized and heated, they contract and cause the movable component 102 to move. Because the wires are tilted, when the SMA actuator wire 104b contracts, it applies a force to the movable component 102 that has force components in the +y direction and the +z direction, and when the SMA actuator wire 104d contracts, it applies a force to the movable component 102 that has force components in the -y direction and the +z direction. If the SMA actuator wires 104b and 104d contract by the same amount, it will cause the movable component to rotate about the z-axis (i.e., the main axis P). However, the SMA actuation device includes a biasing element (not shown here) to resist rotation of the movable part about the main axis P. Therefore, in the SMA actuation device 100, when the SMA actuator wires 104b and 104d are contracted by the same amount, the movable part 102 cannot rotate about the main axis / z-axis, but is instead forced by the biasing element to move along the main axis / z-axis. The biasing element can be shaped or configured so that any attempted rotation is converted into movement along the main axis instead. In embodiments where the movable part 102 is a camera lens or camera unit, this movement can be used to achieve autofocus / focus.

[0025] Similarly, in Figure 1A In the embodiment of the present invention, if the SMA actuator wires 104b and 104d contract by different amounts (for example, because they are provided with different amounts of electricity), the force applied by one wire will be greater than the force applied by the other wire. Therefore, the movable part can be caused to move along the y-axis again. However, the biasing element resists the movement of the movable part along the y-axis. Therefore, in the SMA actuator device 100, when the SMA actuator wires 104b and 104d contract by different amounts, the movable part 102 is forced to tilt about the x-axis. The direction of tilting about the x-axis can depend on which wire contracts more and / or the shape / structure of the biasing element. In an embodiment where the movable part 102 is a camera lens or camera unit, this movement can be used to achieve lens tilt OIS. For the sake of completeness, it should be noted that if the SMA actuator wires 104a and 104c contract by different amounts, the movable part 102 is forced to tilt about the y-axis for the same reason.

[0026] exist Figure 1B, the SMA actuator wires 104a-104d of the SMA actuator device 120 are parallel to a plane perpendicular to the main axis. That is, in this figure, the SMA actuator wires 104a-104d are parallel to the xy plane, which is perpendicular to the x-axis. Each SMA actuator wire 104a-104d is connected to the movable member 102 at one end (represented by a dot) and to a support structure (not shown for simplicity) at the other end. The SMA actuator device 120 includes a biasing element 108 to resist translation of the movable member 102 in a plane perpendicular to the main axis and to resist rotation of the movable member 102 about the main axis. The biasing element 108 is shown here as being disposed below or around the bottom of the movable member 102. However, it should be understood that the biasing element 108 can be disposed above or around the top of the movable member 102, or around the center / middle of the movable member 102.

[0027] In this embodiment, the movable component 102 cannot move along the principal axis P because the SMA actuator wires 104a-104d are not tilted relative to a plane perpendicular to the principal axis. That is, the SMA actuator wires 104a-104d only exert forces on the movable component 102 along the x-axis and the y-axis because the SMA actuator wires 104a-104d are not tilted and therefore there is no component of force along the z-axis. Therefore, in embodiments where the movable component 102 is or includes a lens, autofocus is not possible because the lens cannot move along the z-axis / principal axis P.

[0028] When the SMA actuator wires 104a and 104c coupled to opposite sides of the movable member 102 are caused to contract, the SMA actuator wires 104a and 104c attempt to move the movable member 102 along the x-axis. Specifically, the SMA actuator wire 104c exerts a force on the movable member 102 in the -x direction, while the SMA actuator wire 104a exerts a force on the movable member 102 in the +x direction. Because the biasing element 108 restricts the motion of the movable member 102 along the x-axis, the combination of the biasing element 108 and the forces exerted by the SMA actuator wires 104a, 104c cause the movable member to tilt about the y-axis. Similarly, when the SMA actuator wires 104b and 104d coupled to opposite sides of the movable member 102 are caused to contract, the SMA actuator wires 104b and 104d attempt to move the movable member 102 along the y-axis. Specifically, the SMA actuator wire 104d exerts a force on the movable component 102 in the -y direction, while the SMA actuator wire 104b exerts a force on the movable component 102 in the +y direction. Since the biasing element 108 restricts the motion of the movable component 102 along the y-axis, the combination of the biasing element 108 and the forces exerted by the SMA actuator wires 104d, 104b causes the movable component to tilt about the x-axis. Therefore, in embodiments where the movable component 102 is or includes a lens, OIS can be achieved by tilting the lens.

[0029] It should be understood that Figure 1B In an arrangement of , the biasing element 108 may not be necessary to prevent rotation about the primary axis (z-axis). This is because the SMA actuator wires 104a-104c are not angled / tilted relative to the z-axis, and therefore the movable component 102 does not move along the primary axis. In this arrangement, only movement along the x-axis and y-axis is desired or required to be constrained or limited, and therefore this can be achieved without the biasing element 108.

[0030] exist Figure 1C 1, each of the SMA actuator wires 104a-104d of the SMA actuator device 140 is tangential to a side of the movable member 102. Each SMA actuator wire 104a-104d is connected to the movable member 102 at one end (represented by a dot) and to a support structure (not shown for simplicity) at the other end.

[0031] In this embodiment, the movable component 102 cannot move along the principal axis P because the SMA actuator wires 104a-104d are not tilted relative to a plane perpendicular to the principal axis. That is, the SMA actuator wires 104a-104d only exert forces on the movable component 102 along the x-axis and the y-axis, and because these SMA actuator wires 104a-104d are not tilted, there is no component of force along the z-axis. Therefore, in embodiments where the movable component 102 is or includes a lens, autofocus is not possible because the lens cannot move along the z-axis / principal axis P.

[0032] When the SMA actuator wires 104a and 104c coupled to opposite sides of the movable member 102 are caused to contract, they attempt to move the movable member 102 along the y-axis. Specifically, the SMA actuator wire 104c exerts a force on the movable member 102 in the -y direction, while the SMA actuator wire 104a exerts a force on the movable member 102 in the +y direction. The SMA actuator device 140 includes a biasing element (not shown) similar to that described above with respect to Figure 1B 104a, 104c causes the movable member 102 to tilt about the x-axis. Similarly, when the SMA actuator wires 104b and 104d coupled to opposite sides of the movable member 102 are caused to contract, the SMA actuator wires 104b and 104d attempt to move the movable member 102 along the x-axis. Specifically, the SMA actuator wire 104d exerts a force on the movable member 102 in the -x direction, while the SMA actuator wire 104b exerts a force on the movable member 102 in the +x direction. Since the biasing element 108 limits the movement of the movable member 102 along the x-axis, the biasing element 108 and the combination of the forces applied by the SMA actuator wires 104d, 104b cause the movable member 102 to tilt about the y-axis. Therefore, in embodiments where the movable component 102 is or includes a lens, OIS may be achieved by tilting the lens.

[0033] It should be understood that Figure 1C In an arrangement of , the biasing element may not be necessary to prevent rotation about the primary axis (z-axis). This is because the SMA actuator wires 104a-104c are not angled / tilted relative to the z-axis, and therefore the movable component 102 does not move along the primary axis. In this arrangement, only movement along the x-axis and y-axis is desired or required to be constrained or limited, and therefore this can be achieved without a biasing element.

[0034] Figures 1A-1COnly some non-limiting exemplary arrangements of SMA actuator wires are shown, and it should be understood that there may be other arrangements that can achieve the same effect. For example, another arrangement may include wires that are all inclined in the same direction. This can be achieved by using Figure 1B and angling / sloping all of the SMA actuator wires 104a-104d downward from their attachment points to the movable member 106. (For reference, in Figure 1A In one embodiment, two wires 104b, 104d are tilted upward, while two wires 104a, 104c are tilted downward from their attachment points to the movable member 106). In this arrangement, a biasing element 108 may be required to limit movement about the z-axis. In another example, Figure 1C The line can be inclined. For example, in Figure 1C In the embodiment, lines 104b, 104d may be inclined upward, while lines 104a, 104c may be inclined downward.

[0035] Figure 2A and Figure 2B 1 and 2. A perspective view of two SMA actuator devices 200, 220 having four SMA actuator wires arranged differently is shown. Here, the movable member 102 is Figure 1A The movable member shown is larger (e.g., longer or taller). In embodiments where the movable member 102 is a camera lens, Figure 1A The lens in can have a z-height of 4 mm, while Figure 2A and Figure 2B The lens in may be a telephoto lens with a z-height of 8 mm. It should be understood that these are merely exemplary dimensions for illustration purposes and are non-limiting. Figure 2A and Figure 2B The arrangement of SMA actuator wires shown can be used with any type or size of lens. However, Figure 2A The arrangement shown may not be suitable for miniature cameras where it is desired to have a low z-height camera and camera actuator.

[0036] exist Figure 2A and Figure 2B , four SMA actuator wires 104a-104d are arranged on two opposite sides of the movable member 102. In the SMA actuator device 200, the SMA actuator wires 104a-104d extend above and below the movable member 102, while the SMA actuator device 220 has a more compact arrangement of actuator wires. The operation of the SMA actuator devices 200, 220 is similar to Figures 1A-1C The operation of the device is shown.

[0037] exist Figure 2A, the SMA actuator wires 104a-104d are tilted relative to the main axis P. In the case where the movable component is a lens or includes a lens, the main axis P can be the optical axis of the lens. Specifically, the SMA actuator wires 104a-104d are tilted at a certain angle relative to a plane perpendicular to the main axis. When the SMA actuator wires 104a and 104d are energized and heated, they contract and apply a force to the movable component 102, which has components of force along the z-axis and the x-axis. If the SMA actuator wires 104a and 104d contract by the same amount, the movable component will be caused to rotate about the z-axis (i.e., the main axis P). However, the SMA actuator device includes a biasing element (not shown here) that resists the rotation of the movable component about the main axis P. Thus, in the SMA actuation device 200, when the SMA actuator wires 104a and 104d are contracted by the same amount, the movable component 102 cannot rotate about the main axis / z-axis, and is therefore instead forced by the biasing element to move along the main axis / z-axis. The biasing element may be shaped or configured such that any attempted rotation is converted into movement along the main axis instead. In embodiments where the movable component 102 is a camera lens or camera unit, this motion may be used to achieve autofocus / focusing.

[0038] exist Figure 2A , if SMA actuator wires 104d and 104b are energized, the movable member 102 may tilt in one direction about the y-axis due to the contraction of the SMA actuator wires and the presence of the biasing element (which resists translation along the y-axis). If SMA actuator wires 104a and 104c are energized, the movable member 102 may tilt in the opposite direction about the y-axis due to the contraction of the SMA actuator wires and the presence of the biasing element.

[0039] exist Figure 2A , if SMA actuator wires 104a and 104b are energized, the movable member 102 may tilt in one direction about the x-axis due to the contraction of the SMA actuator wires and the presence of the biasing element (which resists translation along the x-axis). If SMA actuator wires 104c and 104d are energized, the movable member 102 may tilt in the opposite direction about the x-axis due to the contraction of the SMA actuator wires and the presence of the biasing element.

[0040] Similarly, in Figure 2B, the combination of contraction of the SMA actuator wires 104b and 104c and the biasing element can cause the movable component to move along the primary axis P / z axis. If the SMA actuator wires 104d and 104b are energized, the movable component 102 can tilt in one direction about the y-axis due to contraction of the SMA actuator wires and the presence of the biasing element (which resists translation along the y-axis). If the SMA actuator wires 104a and 104c are energized, the movable component 102 can tilt in the opposite direction about the y-axis due to contraction of the SMA actuator wires and the presence of the biasing element. If the SMA actuator wires 104a and 104b are energized, the movable component 102 can tilt in one direction about the x-axis due to contraction of the SMA actuator wires and the presence of the biasing element (which resists translation along the x-axis). If the SMA actuator wires 104c and 104d are energized, the movable member 102 may tilt in opposite directions about the x-axis due to the contraction of the SMA actuator wires and the presence of the biasing elements.

[0041] Therefore, the present technology provides a shape memory alloy (SMA) actuator device, which includes: a support structure; a movable part that is movable relative to the support structure; at least four SMA actuator wires that are connected between the movable part and the support structure and are arranged to move the movable part relative to the support structure; and a biasing element that is used to resist translation of the movable part in a plane perpendicular to an imaginary main axis and resist rotation of the movable part around the main axis.

[0042] In an embodiment, the two pairs of wires may provide a force on the movable member having components of force in opposite directions along the primary axis.

[0043] In an embodiment, the biasing element may resist rotation of the movable component about the primary axis.

[0044] In an embodiment, each SMA actuator wire may be tilted relative to the main axis. Specifically, each SMA actuator wire may be tilted at a certain angle relative to a plane perpendicular to the main axis. Alternatively, each SMA actuator wire may be parallel to a plane perpendicular to the main axis. Further alternatively, each SMA actuator wire may be tangential to a side of the movable component.

[0045] In some embodiments, one SMA actuator wire of the at least four SMA actuator wires may be disposed on each side of the movable member. Alternatively, two SMA actuator wires may be disposed on two opposite sides of the movable member. In this case, on each side, the two SMA actuator wires may be parallel to each other, or may be tilted in opposite sense relative to each other and cross.

[0046] Figure 3 3 is a perspective view of an SMA actuated device 300 having eight SMA actuator wires 104a-104h. In this embodiment, the eight SMA actuator wires 104a-104h can be used to move the movable component 102 in a specific desired direction while preventing movement in other directions. In this manner, no separate biasing element may be required. The movable component 102 may be any object. In a specific embodiment, the movable component 102 in the device 300 may be a telephoto lens.

[0047] Therefore, the present technology provides a shape memory alloy (SMA) actuation device, which includes: a support structure 106; a movable part 102, which is movable relative to the support structure 106; and eight SMA actuator wires 104a-104h, which are connected between the movable part and the support structure, so that when contracted, two groups of four SMA actuator wires provide forces on the movable part (the forces have components in opposite directions along an imaginary main axis) while resisting translation of the movable part in a plane perpendicular to the main axis and resisting rotation of the movable part about the main axis.

[0048] In an embodiment, each SMA actuator wire 104a - 104h may be tilted at an angle relative to a plane perpendicular to the primary axis P.

[0049] In an embodiment, two of the eight SMA actuator wires 104a-104h may be disposed on each side of the movable member. That is, two SMA actuator wires may be coupled to each of the four sides of the movable member 102. Alternatively, two pairs of crossed wires may be disposed on opposite sides of the movable member 102, such as Figure 3 The wires may extend above and below the movable member 102 (as compared to Figure 2A ) or can be arranged in a more compact arrangement (compared to Figure 2B ).

[0050] It should be understood that Figure 3 One non-limiting exemplary arrangement of eight SMA actuator wires is shown, and other arrangements are possible that achieve the same effect. For example, instead of having two pairs of crossed wires on two opposing sides of the movable member 102 (e.g., Figure 3 As shown in FIG. 1 , two pairs of crossed wires may be provided on each side of the movable member 102. For example, the SMA actuator wires 104e and 104d may be moved to the sides of the movable member. Figure 3 The movable member may have one side without any wires, and the wires 104a and 104h may be moved to another such side of the movable member.

[0051] Figures 4A to 4CSchematic diagrams of three SMA actuation devices 400, 420, 440 having at least one biasing element are shown. For simplicity, the SMA actuator wires and support structures are not shown here. Figure 4A In FIG. 1 , the biasing element 108 is disposed around the center or middle of the movable member 102. Figure 4B In the embodiment of the present invention, the biasing element 108 is disposed below or around the base / bottom of the movable member 102. It should be understood that the biasing element 108 may alternatively be disposed above or around the top of the movable member 102. Figure 4C In the embodiment of the present invention, at least one biasing element 108 includes a first biasing element 108a disposed above or around the top of the movable member 102 and a second biasing element 108b disposed below or around the base of the movable member 102. It should be understood that the arrangement of the biasing element(s) shown here may be different from that shown in the embodiment of the present invention. Figures 1A to 2B In combination with any of the SMA actuation devices shown.

[0052] Figure 5 A schematic diagram of an SMA actuator for moving a telephoto lens 502 in a camera module 500 is shown. The camera module includes a telephoto lens 502, an SMA actuator 504, and an image sensor 510. The camera module 500 may include a mirror 514, a sensor bracket 512, and a rotation point 508, the sensor bracket 512 including an autofocus support element 506. Autofocus (AF) and optical image stabilization (OIS) may be achieved using an 8-wire SMA actuator (e.g., the device described in International Patent Publication No. WO2011 / 104518) with 4 wires removed. In this case, autofocus (i.e., movement of the telephoto lens 502 in the direction indicated by arrow 518) may be achieved by energizing the four wires of the SMA actuator 504 to act together against a spring or other resilient element (not shown). Alternatively, AF may be achieved by all 8 wires of the 8-wire actuator. The OIS function (ie, sideways motion as indicated by arrow 516) can be achieved by pivoting or tilting the telephoto lens 502 about the rotation point 508. This can be accomplished by referring to the above Figures 1A to 3 The described manner is achieved by energizing the wires of a four-wire actuator or an eight-wire actuator. The tilt amplitude can be increased by moving the actuator 504 closer to the pivot point 508.

[0053] The moving ends of the four SMA actuator wires (not shown) can be attached to the lens bracket (not shown). The lens bracket can include bearings connected to the chassis / sensor bracket 512, and these bearings enable the telephoto lens 502 to move in a direction substantially perpendicular to the plane of the image sensor 510. The chassis / sensor bracket 512 can be quite tall (~7mm), so that good tilt performance can be achieved relatively easily. The image sensor pivot 508 resists AF movement and is connected to the camera body 520. The fixed ends of the 4 SMA wires are also connected to the camera body 520.

[0054] In an embodiment, image sensor 510 may be connected to a flexible printed circuit board (FPC). The FPC may need to be bent 90° within camera body 520, which may allow bending and twisting of telephoto lens 502 to be accommodated.

[0055] Figure 6 A schematic diagram of another mechanism for moving the telephoto lens 602 is shown. By moving an additional lens or lens array in the space between the telephoto lens and the image sensor, AF and OIS of the telephoto lens can be achieved. This mechanism uses the additional vacant space between the telephoto lens 602 and the image sensor 606 to achieve AF and OIS, which can provide a more compact telephoto camera module 600. The camera module 600 includes a telephoto lens 602, an actuator 604, an image sensor 606, a reflector 608, and three lenses: a collector 610, a focus group 612 (for achieving AF and OIS), and a projector 614. The actuator 604 can be used to move the focus group lens 612 to achieve AF and OIS. The telephoto lens 602 can remain stationary relative to the image sensor 606 and the reflector 608. The collector lens 610 and the projection lens 614 can also be fixed / stationary.

[0056] In any of the SMA actuation arrangements described herein, the biasing element may have a stiffness that biases the movable member against rotation about the primary axis while allowing the movable member to move along the primary axis.

[0057] The biasing element may include at least one flexure.

[0058] The flexure may be arranged around the center of the movable component and parallel to a plane perpendicular to the main axis. Additionally or alternatively, the flexure may be arranged above or below the movable component parallel to a plane perpendicular to the main axis.

[0059] The at least one flexure may include a first flexure above the movable component and a second flexure below the movable component, wherein both the first flexure and the second flexure are parallel to a plane perpendicular to the main axis. One of the first flexure and the second flexure may be more rigid than the other of the first flexure and the second flexure. In the case where only one flexure is used, the flexure needs to be rigid. In general, the stiffness of the (multiple) flexures may need to be larger relative to the weight of the movable component 102. In the case where more than one flexure is used, one flexure may need to be flexible to allow the movable component 102 to tilt.

[0060] The flexure(s) may include one or more flexure arms.

[0061] The SMA actuator wires may have electrical connections allowing each of the SMA actuator wires to receive a drive signal. The SMA actuation device may further include a control circuit for providing a drive signal to the SMA actuator wires, the control circuit being electrically connected to the SMA actuator wires via at least one flexure. The control circuit may be arranged to provide an independent drive signal to each SMA actuator wire.

[0062] Flexures may be imperfect and therefore, although they are designed to resist a particular movement, they may allow a small degree of undesired movement. Therefore, in an embodiment, the control circuit may be arranged to provide a signal to at least one SMA actuator wire to compensate for any undesired movement of the movable component, for example any movement in a plane perpendicular to the main axis and / or any rotation of the movable component about the main axis.

[0063] In any of the above embodiments, the movable component may be a camera lens such that the principal axis is an optical axis of the camera lens. In some cases, the movable component may be a camera unit comprising an image sensor and a camera lens arranged to focus light on the image sensor. The camera lens may have a diameter of up to 20 mm. The camera lens may be a compound lens or a telephoto lens.

[0064] Those skilled in the art will appreciate that, although the foregoing has described what are considered to be the best mode and other appropriate modes for carrying out the present technology, the present technology should not be limited to the specific configurations and methods disclosed in the description of the preferred embodiment. Those skilled in the art will recognize that the present technology has a wide range of applications, and that the embodiments can be extensively modified without departing from any inventive concept defined in the appended claims.

Claims

1. An SMA actuation device, comprising: Support structure; a movable member capable of moving relative to the support structure; at least four SMA actuator wires connected between the movable member and the support structure and arranged to move the movable member relative to the support structure; and a biasing element for resisting translation of the movable part in a plane perpendicular to the imaginary principal axis, wherein the at least four SMA actuator wires are configured in pairs, each pair of the SMA actuator wires being configured to apply forces on the movable member only along an x-axis in opposite directions or only along a y-axis in opposite directions, and at least two pairs of the SMA actuator wires are configured to apply forces along different ones of the x-axis and the y-axis, wherein the x-axis and the y-axis are perpendicular to the main axis; and in: When the SMA actuator wire selectively applies a force on the movable member only along the x-axis, the biasing element restricts movement of the movable member along the x-axis, and the combination of the biasing element and the force applied by the SMA actuator wire causes the movable member to tilt about the y-axis; or When the SMA actuator wire selectively applies a force on the movable member only along the y-axis, the biasing element restricts movement of the movable member along the y-axis, and the combination of the biasing element and the force applied by the SMA actuator wire causes the movable member to tilt about the x-axis.

2. An SMA actuation device according to claim 1, wherein the biasing element further resists rotation of the movable component about the primary axis.

3. An SMA actuation arrangement according to claim 1 or 2, wherein the movable component is a camera lens, and wherein the principal axis is the optical axis of the camera lens.

4. An SMA actuation device according to claim 1 or 2, wherein the movable component is a camera unit comprising an image sensor and a camera lens arranged to focus light on the image sensor, and wherein the principal axis is an optical axis of the camera lens.

5. An SMA actuation device according to claim 3 or 4, wherein the camera lens has a diameter of at most 20mm.

6. An SMA actuation device according to claim 3, 4 or 5, wherein the camera lens is a composite lens.

7. An SMA actuation device according to claim 3, 4 or 5, wherein the camera lens is a telephoto lens.

8. An SMA actuation apparatus according to any one of claims 1 to 7, wherein each SMA actuator wire is parallel to a plane perpendicular to the major axis.

9. An SMA actuation apparatus according to any one of claims 1 to 7, wherein each SMA actuator wire is tangential to a side surface of the movable member.

10. An SMA actuated apparatus according to any one of claims 1 to 7, wherein one SMA actuator wire of the at least four SMA actuator wires is provided on each side of the movable member.

11. An SMA actuation apparatus according to any preceding claim, wherein the biasing element has a stiffness to bias the movable member against rotation about the primary axis whilst allowing movement of the movable member along the primary axis.

12. An SMA actuation device according to any preceding claim, wherein the biasing element comprises at least one flexure.

13. The SMA actuation device of claim 12, wherein: The flexure is arranged around the center of the movable member and parallel to a plane perpendicular to the main axis; or The flexure is arranged above or below the movable component parallel to a plane perpendicular to the main axis; or The at least one flexure comprises a first flexure above the movable component and a second flexure below the movable component, wherein the first flexure and the second flexure are both parallel to a plane perpendicular to the main axis, wherein one of the first flexure and the second flexure is more rigid than the other of the first flexure and the second flexure.

14. An SMA actuation apparatus according to claim 12 or 13, wherein the flexure comprises one or more flexure arms.

15. An SMA actuation device according to any one of claims 12 to 14, wherein the SMA actuator wires have electrical connections allowing each of the SMA actuator wires to receive a drive signal, and the device further comprises a control circuit for providing a drive signal to the SMA actuator wires, the control circuit being electrically connected to the SMA actuator wires via the at least one flexure.

16. An SMA actuation apparatus according to claim 15, wherein the control circuit is arranged to provide an independent drive signal to each SMA actuator wire.

17. An SMA actuation device according to claim 15 or 16, wherein the control circuit is arranged to provide a signal to at least one SMA actuator wire to compensate for any movement of the movable part in a plane perpendicular to the main axis and / or any rotation of the movable part about the main axis.

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