Shape Memory Alloy Actuator

Abstract

A shape memory alloy actuator device is provided that is arranged to drive the operation of a diaphragm element. The actuator device includes: a diaphragm drive mechanism that is arranged to open and close the aperture of the diaphragm based on an input motion; and at least one shape memory alloy actuator wire that is arranged to provide the input motion when the actuator wire contracts. The actuator device can have a low form factor and can be applicable to, for example, folded camera assemblies and other devices where the available space for the control assembly is limited.

Description

[0001] The present technology generally relates to providing control of an aperture using a shape memory alloy (“SMA”) actuator wire.

[0002] There are various devices that are desired to provide control of a movable element. Multiple shape memory alloy wires can be advantageous as actuators in such devices, for example due to their high energy density, which means that the shape memory alloy actuators required to apply a given force to the movable element can be relatively small.

[0003] One type of known device using shape memory alloy wires as actuators is micro-cameras, such as those used in smartphones or other portable electronic devices. WO 2011 / 104518 discloses examples of shape memory alloy actuator devices suitable for use in micro-cameras.

[0004] Some micro-cameras have a folded optical arrangement in which the optical axes of one or more lens elements are arranged perpendicular to the axis along which light first passes into the camera. Mirrors or prisms can be used to “fold” the optical path. Figure 1 The general configuration of a possible folded optical arrangement contained within a housing or cover 1 is schematically shown. In Figure 1 this, the optical axis of the lens element 10 is along the z-axis between the prism / mirror 12 and the image sensor 20. Before being “folded” to pass along the z-axis, light enters the optical arrangement in the y-direction as shown. As Figure 1 shown, movement in the x and y directions can provide optical image stabilization (“OIS”), while movement in the z-direction can provide auto-focusing (“AF”). In some arrangements, the lens element 10 can include multiple lenses that are movable relative to each other, and these relative movements provide zoom.

[0005] The folded optical arrangement is particularly useful in devices where the device thickness in the initial light entry direction ( Figure 1 the y-direction in

[0006] this) is limited. For example, smartphones are becoming thinner, making it more difficult to mount all elements of a camera device along a single optical axis in the thickness direction of the phone. Figure 1As shown, the aperture can be placed between the prism / mirror 12 and the lens element 10 (it should be understood that the aperture can also be placed at various other positions along the optical path). The aperture controls the amount of light entering the lens element 10 (and thus reaching the image sensor 20). Many existing aperture configurations are known to be usable in such a device. However, a large range of mechanical movement is typically required to operate the aperture, which may be difficult to provide in the case of, for example, a micro camera, and especially for a folded optical arrangement where the available space around the optical elements of the actuator is limited. For example, in some arrangements, the available space for the elements of the actuator arrangement for operating the aperture can be limited to a height of a few millimeters and, in some cases, less than 1 millimeter.

[0007] An object of the present technology is to provide a component for controlling the operation of an aperture.

[0008] Another object of the present technology is to provide a component for controlling the operation of an aperture, which has a low form factor and is suitable, for example, for a folded camera assembly and other devices where the available space for the control component is limited.

[0009] The method of the present technology aims to provide an actuator assembly that meets one or more of the above objects.

[0010] Generally speaking, the method of the present technology provides a component that uses a shape memory alloy actuator wire to control an aperture.

[0011] A first method of the present technology provides a shape memory alloy actuating device arranged to drive the operation of an aperture element, the actuating device comprising: an aperture driving mechanism arranged to open and close the aperture of the aperture based on an input movement; and at least one shape memory alloy actuator wire arranged to provide the input movement when the actuator wire contracts.

[0012] In the case of limited available space, the shape memory alloy actuator wire may be particularly useful in providing drive to the aperture element.

[0013] Preferably, the device is arranged to magnify the movement range of the actuator wire to provide the input movement. This can allow an actuator wire with a relatively small movement range (or "stroke"), which is typically determined by the length of the wire and the strain it can produce when contracting, to drive an aperture driving mechanism that has a much larger movement range between its extreme positions.

[0014] In some arrangements, amplification is achieved by arranging the actuator wire at an angle to the direction of input movement. In particular, the angle between the length direction of the actuator wire and the direction of input movement can be greater than 45 degrees. In such an arrangement, contraction of the actuator wire can cause the aperture drive mechanism to move in an orientation where the actuator wire is moved closer to being perpendicular to the direction of input movement. For an angle close to (but less than) 90 degrees, particularly but not limited to between 60 - 80 degrees, preferably around 75 degrees, a relatively small change in the length of the actuator wire can cause a significant degree of movement of the aperture drive mechanism.

[0015] The device can include a plurality of shape memory alloy actuator wires arranged such that at least one of the actuator wires is arranged to provide the input movement in a first direction upon contraction, and at least another of the actuator wires is arranged to provide the input movement in a second direction opposite to the first direction upon contraction. In this way, the actuator wires can drive the aperture drive mechanism in two directions.

[0016] In some arrangements, the input movement can be a lateral movement. In other arrangements, the input movement can be a rotational movement. When the input movement is a rotational movement, the "direction" of the movement is the instantaneous direction of movement during operation (i.e., at any point within the range of movement), and particularly includes the direction of movement that occurs at the steady state or rest position of the aperture mechanism (e.g., which may be at the extremes of the movement range of the mechanism).

[0017] The device can also include at least one set of shape memory alloy actuator wires arranged to provide the input movement in one or two directions when all the wires in the set contract. By arranging multiple wires into a set, the wires can be arranged such that, although they do not individually act exactly in the direction of input movement, when co - activated, they apply a force only in the direction of input movement. The device can include two such sets, with one set acting in each direction.

[0018] In certain arrangements, the device further includes an intermediate movable element, where at least one shape memory alloy actuator wire is arranged between the aperture drive mechanism and the intermediate element, and another shape memory alloy actuator wire is arranged between the intermediate element and a fixed point. This arrangement can allow multiple shape memory alloy actuator wires to be connected "in series" to provide the input movement. Thus, even if it is not possible to arrange a single actuator wire to produce a sufficient stroke (even if the wire is angled), multiple wires can be combined to produce a sufficient stroke across the combination.

[0019] In some arrangements, the device further includes a rigid element that connects the actuator wire to the aperture drive mechanism. The rigid element can be used to change the direction of motion generated by the actuator wire into the input motion direction required by the aperture drive mechanism. This can allow the actuator wire to be positioned at a location removed from the aperture drive mechanism, which can allow the use of a longer actuator wire while maintaining the desired form factor and dimensions of the device in which the actuator device is incorporated.

[0020] The rigid element can alternatively or additionally provide its own amplification of the actuator wire stroke, for example by using the lever principle.

[0021] For example, in certain arrangements, the rigid element is arranged to pivot about a pivot point, the actuator wire is arranged to cause a rotational motion of the rigid element upon contraction, and the connection point of the aperture drive mechanism to the rigid element is further from the pivot point than the connection point of the actuator wire to the rigid element. By arranging the rigid element between the actuator wire and the aperture drive mechanism in this way, a lever with a displacement ratio greater than 1 can be created, such that the stroke of the actuator wire driving the rigid element is converted into a greater stroke at the aperture drive mechanism. The pivot in such a lever can be a fixed point (which can include a bearing), or there can be multiple actuator wires arranged to apply torque to the rigid element and cause the rigid element to pivot about a point in space where the rigid element is not attached to any other element (and, by controlling the relative activation of the actuator wires, this point can be in different positions).

[0022] In certain arrangements, the actuator wire is arranged to cause a translational motion of the rigid element upon contraction, and the connection between the rigid element and the aperture drive mechanism is configured to convert the translational motion into the input motion, where the directions of the translational motion and the input motion are different. This can allow the actuator wire to be arranged in a position that allows the use of a longer wire while still at least substantially conforming to the overall shape and dimensions of the device.

[0023] For example, the rigid element can have an engagement portion that engages with the aperture drive mechanism, where the engagement portion includes an edge that engages with the aperture drive mechanism and is inclined relative to the direction of the input motion. This edge (or "ramp") can be used to convert the motion of the rigid element into motion in another plane, such as a plane perpendicular to the plane of motion of the rigid element. The configuration of the edge (or slot, which is actually an arrangement of two substantially parallel edges) can also provide a mechanical advantage and / or increase the displacement ratio between the motion of the rigid element and the input to the aperture drive mechanism.

[0024] The device may also include a bearing that is configured to restrict movement of the rigid element. The bearing may allow multiple actuator wires to be angled relative to a desired direction of movement of the rigid element without the need to apply a balanced set of forces to the rigid element to achieve the desired movement. In other arrangements, multiple actuator wires are provided such that activation of a set of wires produces a net force in the desired direction of movement of the rigid element. In such an arrangement, a bearing may not be necessary.

[0025] In some arrangements, there are multiple shape memory alloy actuator wires that are arranged such that at least one actuator wire is arranged to move the rigid element upon contraction to provide the input movement in a first direction, and at least one other actuator wire is arranged to move the rigid element upon contraction to provide the input movement in a second direction opposite to the first direction. In these arrangements, there are multiple actuator wires that are used to drive the aperture drive mechanism in opposite directions such that the aperture opening can be opened and closed by activating different sets of actuator wires.

[0026] In some arrangements, the device may additionally include a biasing element that biases the aperture drive mechanism towards one extreme of its range of motion. The biasing element can be, for example, a spring, which can mean that one or more actuator wires can be arranged to provide a force to the aperture drive mechanism in only one direction, while the biasing element is used to return the aperture drive mechanism when the actuator wire relaxes to its uncontracted state.

[0027] The device may additionally include a bearing that is arranged to restrict the movement of the aperture drive mechanism to the direction of the input movement. This can allow the device to include an arrangement of non - symmetric shape memory alloy actuator wires (or a single wire) because the asymmetry in the forces applied by the actuator wires can be compensated for and regulated by the bearing.

[0028] The device may also include a control circuit electrically connected to the shape memory alloy actuator wires for providing drive signals thereto.

[0029] The device may also include an aperture that is connected to the aperture drive mechanism and has an aperture that is opened and closed by the input movement.

[0030] In some arrangements, the device is an optical device and may further include an image sensor that is arranged to receive light passing through the aperture. Such an arrangement can be used, for example, in a micro - camera.

[0031] In some arrangements, the device may also include a deflector element that is fixed to a support structure and arranged to change the direction of light entering the device such that the light passes through the aperture to reach the image sensor. The deflector element can be, for example, a mirror or a prism. Such a device can form part of a folded camera, where the aperture and the image sensor are arranged along an axis different from the axis along which the light enters the device.

[0032] In some arrangements, the actuator wire and the rigid element (if present) are configured such that their profile in at least one direction is very thin (e.g., less than 5 mm, preferably less than 1 mm). In the case of a device including a deflector element, this direction can be the same as the direction in which the light enters the device.

[0033] In some arrangements including a deflector element, the non-optical elements of the device (e.g., the actuator wire, the aperture mechanism, and / or the rigid element, if present) are arranged such that they do not increase the size of the device in the direction in which the light enters the device by more than the size of the optical elements of the device (e.g., the image sensor, the aperture, the deflector element, and / or any lens).

[0034] The device may further include a sensor arranged to produce an output signal representing the amount or intensity of the light reaching the image sensor, and a control circuit arranged to produce a drive signal in response to the output signal to open or close the aperture and thereby regulate the amount of light reaching the image sensor. In this way, the aperture of the aperture can be adjusted to automatically calculate the intensity of the light reaching the image sensor.

[0035] The device of the method may include some, all, or none of the above preferred and optional features, and any combination thereof.

[0036] The present technology can generally be applied to any type of device that includes a stationary part and a movable part movable relative to the stationary part. By way of non-limiting example, the actuator assembly can be any one of or can be provided in any one of the following devices: a smart phone, a protective cover or case for a smart phone, a functional cover or case for a smart phone or an electronic device, a camera, a foldable smart phone, a foldable smart phone camera, a foldable consumer electronic device, a camera with a folding optics, an image capture device, an array camera, a three-dimensional sensing device or system, a servo motor, a consumer electronic device (including household appliances such as a vacuum cleaner, a washing machine, and a lawn mower), a mobile or portable computing device, a mobile or portable electronic device, a laptop computer, a tablet computing device, an e-reader (also referred to as an e-book reader or e-book device), a computing accessory or computing peripheral (e.g., a mouse, a keyboard, headphones, a receiver, earbuds, etc.), an audio device (e.g., headphones, a headset, a receiver, etc.), a security system, a gaming system, a gaming accessory (e.g., a controller, a headset, a wearable controller, a joystick, etc.), a robot or robotic device, a medical device (e.g., an endoscope), an augmented reality system, an augmented reality device, a virtual reality system, a virtual reality device, a wearable device (e.g., a watch, a smart watch, a fitness tracker, etc.), a drone (airborne, waterborne, underwater, etc.), an aircraft, a spacecraft, a submersible, a vehicle, an autonomous vehicle (e.g., a driverless car), a tool, a surgical tool, a remote control (e.g., for a drone or a consumer electronic device), clothing (e.g., apparel, shoes, etc.), a switch, a dial, or a button (e.g., a light switch, a thermostat dial, etc.), a display screen, a touch screen, a flexible surface, and a wireless communication device (e.g., a near field communication (NFC) device). It should be understood that this is a non-exhaustive list of exemplary devices.

[0037] The actuator assembly described herein can be used in devices / systems suitable for image capture, three-dimensional sensing, depth mapping, aerial surveying, land surveying, surveying in space or from space, hydrographic surveying, underwater surveying, scene detection, collision warning, security, face recognition, augmented and / or virtual reality, advanced driver assistance systems in vehicles, autonomous vehicles, gaming, gesture control / recognition, robotic devices, robotic device control, non-contact technologies, home automation, medical devices, and haptic devices / systems.

[0038] Embodiments of the technology will now be described by way of example with reference to the accompanying drawings, in which:

[0039] Figure 1 is a schematic diagram of a folding optical arrangement and has been described;

[0040] Figures 2A - 2CShows a shape memory alloy actuator assembly according to an embodiment of the present technology;

[0041] Figures 3A - 3D Shows a shape memory alloy actuator assembly according to an embodiment of the present technology;

[0042] Figure 4 Shows a shape memory alloy actuator assembly according to an embodiment of the present technology; and

[0043] Figure 5 Is a schematic diagram of a control circuit that can be used in an embodiment of the present technology.

[0044] Figures 2A - 4 Shows three embodiments of a shape memory alloy actuator assembly according to the present technology. In these embodiments, the same reference numerals are used to refer to the same / similar features, and the features described with respect to one embodiment apply equally to each other embodiment unless otherwise stated or impracticable.

[0045] Figures 2A - 2C Shows three variants of a first embodiment of a shape memory alloy actuator assembly according to the present technology. In Figures 2A - 2C The arrangement shown, the shape memory alloy actuator wires 51 are arranged at shallow angles with respect to the perpendicular to the desired direction of movement. This shallow angle arrangement magnifies the normal movement (stroke) when multiple shape memory alloy actuator wires contract.

[0046] In Figure 2A The arrangement shown, a single shape memory alloy actuator wire 51a, 51b acts on the aperture mechanism 30 in each direction. Figure 2A The depicted top actuator wire 51a is used to push the mechanism 30 downward, while the lower actuator wire 51b is used to push the mechanism 30 upward. To open and close the aperture, the mechanism 30 typically needs to be able to move a distance of approximately 400 microns

[0047] To prevent rotational and / or translational movement of the aperture mechanism 30, the mechanism can be mounted on bearings that limit the movement of the mechanism to the desired linear movement (along Figure 2A the vertical axis).

[0048] Figure 2B The arrangement shown extends Figure 2A the arrangement of Figure 2Bin the left - right direction) and rotational forces, which can mean that it is not necessary to mount the mechanism 30 on bearings. However, such an arrangement may require more space to accommodate additional actuator lines.

[0049] Figure 2C An alternative arrangement is shown, in which a plurality of small - angle actuator lines 51c, 51d are connected in a "linked" configuration. In Figure 2C the arrangement shown, the aperture mechanism 30 is connected to two rigid movable plates 52 by a first set of actuator lines 51c. Each of these plates is in turn connected to two additional actuator lines 51d, which connect the plates to the structure of the device on which the arrangement is mounted. It should be understood that the "chain" of plates 52 and the plurality of actuator lines 51 can be further extended such that there are two (or more) plates and three (or more) sets of actuator lines on each side of the mechanism 30.

[0050] In an alternative arrangement, only one actuator line 51 can be used at each stage in the chain (between the mechanism 30 and the plate 52; and / or between subsequent plates; and / or between the final plate and the structure of the device), with a single plurality of actuator lines operating in a manner similar to Figure 2A that shown. Such an arrangement can use one or more bearings to restrict the movement of the mechanism 30 and / or the plate 52 to a desired direction.

[0051] The linking of the actuator lines 51 to the plate 52 allows the displacement achievable in each direction to be multiplied by the number of "links" in the chain. The plurality of actuator lines 51 used at each stage can be the same or different, thus providing a range of control options for actuating the mechanism.

[0052] It should be understood that although Figures 2A - 2C the arrangements shown in illustrate a plurality of actuator lines 51, a plurality of lines can be used in any or all positions, for example by positioning additional lines parallel to the plurality of lines shown in a direction perpendicular to the plane of the drawing. This can allow an increased force to be applied to the mechanism 30.

[0053] Furthermore, although Figures 2A - 2C each arrangement shown in illustrates (at least) a pair of actuator lines 51, which are arranged to act on the mechanism 30 in opposite directions, a plurality of lines that cause movement in one direction can be replaced by a biasing element, such as a return spring, which is capable of biasing the mechanism to one extreme position of its range of motion, and when the biasing element causes the mechanism 30 to move, the remaining plurality of lines act in opposition to the biasing element.

[0054] In testing, the applicant has determined that in a folding camera, using an arrangement such as Figure 2A and Figure 2BThe angled wire arrangement shown has the potential to achieve the desired stroke of the aperture mechanism. Specifically, using a shape memory alloy actuator wire capable of providing up to 2% strain, the applicant has determined that it is possible to achieve a 400-micron vertical stroke of the aperture mechanism (in the Figure 2A and Figure 2B shown directions), while ensuring that the actuator assembly does not exceed a height of 5.5 mm (as shown in Figure 2A and Figure 2B ; Figure 1 the y-direction in Figure 1 and a width of 12 mm (and potentially as low as 11 mm) (the x-direction in

[0055] Figures 3A - 3D Four variants of a second embodiment of a shape memory alloy actuator assembly according to the present technology are shown. In this embodiment, the shape memory alloy actuator wire 51 is connected to a mechanical arrangement that causes amplification of the movement range of the multiple actuator wires themselves. Figures 3A - 3D Each of

[0056] shows a possible positioning of the actuator assembly relative to the optical device 1 (such as a folding camera). The contour shape of the optical device 1 is shown in dashed lines. Figure 3A In the arrangement shown in

[0057]

[0058] Figure 1 In the arrangement shown, two shape memory alloy actuator wires 51 are connected, their fixed ends 54 are attached to the optical device 1, and their movable ends 53 are connected to an arm 55 in a V-shape. The device is configured such that the actuator wires 51 face each other, and the actuator wires are arranged at a small angle relative to the arm 55. The arm 55 pivots about a pivot 56. The end of the arm 55 remote from the pivot drives the aperture mechanism 30, which controls the opening and closing of the aperture 14. In the arrangement shown, the distal end of the arm 55 is attached to a link 57, and the rotation of the link 57 about the center of the aperture 14 causes the aperture blades to decrease or increase the aperture at the center of the aperture. However, the distal end of the arm 55 can be connected to an alternative mechanism for controlling the aperture. Figure 1For an example of a folded camera oriented as shown, this uses the large area available on top of the camera, but will result in an overall increase in the height of the camera in the y direction, which may be undesirable. In this arrangement, the arm 55 and the actuator wire 51 can be mounted on the side of the optical device, similar to Figure 3B the arrangement shown.

[0059] In an alternative arrangement, the pivoting effect can be provided by a flexure that is arranged to guide the pivoting end of the arm 55 or another part of the arm 55 to allow it to rotate.

[0060] Figure 3B Another alternative arrangement of a shape memory alloy actuator assembly is shown. Again, two shape memory alloy actuator wires 51 are used in an opposing manner, and their fixed ends 54 are attached to the optical device 1, and their movable ends are attached to the arm 58. However, instead of causing a rotational movement of the arm 58, multiple actuator wires 51 are mounted to cause a lateral movement of the arm 58 (possibly together with a bearing (not shown)) in the direction indicated by the arrow.

[0061] The end of the arm 58 that engages with the link 57 of the aperture mechanism 30 is inclined to form an inclination or ramp 59. This ramp 59 engages with the link 57 to convert the lateral movement of the arm 58 in one plane into a movement of the link in a generally vertical direction, which is used to open or close the aperture 14. The angle of the ramp 59 and the length of the link 57 can be selected according to the force and stroke required to operate the aperture mechanism.

[0062] The link 57 can be urged in a direction that favors the positioning of the link at the "low" end of the ramp 59 by a biasing element (not shown) such as a spring. This means that there is no need to use the arm 58 to pull the link 57 back to the end position. Optionally, the arm 58 can be provided with a slot into which the end of the link 57 is inserted, thereby allowing translational movement of the arm 58 in two directions to cause vertical movement of the link 57. Optionally, another arm (not shown) can be provided with an opposing ramp to drive the link 57 in the opposite direction, or a second link that is part of the aperture mechanism 30 can be provided that provides drive in the opposite direction (e.g., mounted on the opposite side of the optical device 1).

[0063] In addition to the possibility of amplifying the stroke of the shape memory alloy actuator wire 51 by selecting the angle of the ramp 59, mounting the actuator assembly along the side of the optical device 1 allows the use of relatively long shape memory alloy actuator wires 51, which can provide the desired stroke to the link 57, although the dimensions of the available space next to the optical device 1 within the plane of the link 57 itself are more restricted.

[0064] By as Figure 3BAs shown, the actuator assembly is mounted on the "side" of the optical assembly 1, and the actuator assembly does not increase the height of the optical assembly ( Figure 1 The height is usually the most limiting dimension in, for example, a folded camera.

[0065] Figure 3C Another alternative arrangement is shown, which is Figure 3B The arrangement shown in FIG. operates in a similar manner. Figure 3C In the arrangement shown, the shape memory alloy actuator wire 51 drives another arm 60, which is connected to the drive arm 58. The drive arm 58 is bent so that the other arm 60 deviates from the ramp 59 in the plane of the assembly. For clarity, the aperture mechanism has been omitted from this figure, but can be seen from the Figure 3B The similarities to the arrangements shown are understood in their interaction with the actuator assembly.

[0066] By arranging the actuator wires 51 in an angled and crossed configuration within the available footprint of the side (in this example the top) of the optical device 1, Figure 3C The arrangement shown further amplifies the travel available from the multiple actuator wires 51. This allows the longest available actuator wire lengths to be used within the footprint.

[0067] Figure 3D Another alternative arrangement is shown in which an arm 55 is used to connect between a plurality of actuator wires 51 and a link 57 of the aperture mechanism 30. In this arrangement, four actuator wires 51 are arranged with a pair of crossing wires on each side of the arm 55, with fixed ends connected to the optical device (not shown in this figure for clarity) approximately at the corners of the top surface of the device.

[0068] By appropriately activating the pair of actuator wires 51, the arm 55 can be rotated about a virtual axis at the approximate center of the arm. In this regard, the movement and operation of the actuator assembly and the linkage 57 in the aperture mechanism are similar to those described above with respect to Figure 3A Alternatively, by different methods of activating the pair of actuator wires 51, the arm 55 can be moved in the plane of the actuator assembly, or perpendicular to the optical axis passing through the aperture 14 (in Figure 3D Oriented generally "up" and "down"), or parallel to the optical axis (in Figure 3D In the case of parallel motion, such as the above Figure 3B and 3C The ramps described in the arrangement may be used to convert the movement of the arm 55 into the desired movement of the link 57 .

[0069] Figure 4 A third embodiment of an actuator assembly according to the present technology is shown. Figure 4The actuator assembly shown is arranged similarly to Figures 2A - 2C that shown. However, in Figure 4 the arrangement shown, multiple actuator wires 51 are arranged on one side of the aperture mechanism 30. This means that the fixed ends 54 of two wires 51 are located in similar parts of the device, making it simpler to provide proper electrical connections.

[0070] Figure 4 The aperture mechanism 30 in the arrangement shown is arranged to rotate about an axis 61 such that the input force from the multiple actuator wires 51 is converted into a rotational movement of the mechanism, as represented by the double-headed arrow. Although Figure 4 the arrangement shown has two actuator wires 51 that are arranged to operate the mechanism 30 in opposite directions, the arrangement can also be set up to have a single actuator wire 51 that acts against a biasing element that pushes the mechanism 30 in the opposite direction.

[0071] Figure 5 A schematic arrangement of a control circuit 40 for controlling shape memory alloy actuator assemblies such as these, as Figures 2A - 4 shown, is illustrated. The control circuit 40 generates drive signals for each shape memory alloy actuator wire 51. The control circuit 40 obtains the drive signals from the desired movement represented by the movement signal 41.

[0072] The movement signal is supplied to a matrix controller 42, which can be implemented in a processor or hardware. The matrix controller 42 generates control signals for each shape memory alloy actuator wire 51 to achieve the desired movement in the movement signal 41 by correlating the necessary contractions of each actuator wire based on the movement signal 41. Further details of the operation of the controller and the driving of the shape memory alloy actuator wires are known to those skilled in the art, for example from WO 2011 / 104518, the relevant content of which is hereby incorporated by reference.

[0073] The movement signal 41 can be generated based on sensor input, for example based on the amount or intensity of light sensed on an image sensor 20.

[0074] Unless the context otherwise requires, the term "bearing" is used herein as follows. The term "bearing" as used herein includes the terms "plain bearing", "slider bearing", "rolling bearing", "ball bearing", "roller bearing", and "flexure". The term "bearing" as used herein generally refers to any element or combination of elements that serves to restrict motion to only the desired motion and reduce friction between moving parts. The term "plain bearing" is used to denote a bearing in which a bearing element slides on a bearing surface and includes "slider bearings". The term "rolling bearing" is used to denote a bearing in which rolling bearing elements (such as balls or rollers) roll on a bearing surface. In an embodiment, a bearing may be disposed on a non-linear bearing surface or may include a non-linear bearing surface.

[0075] In some embodiments of the present technology, more than one type of bearing element may be used in combination to provide a bearing function. Thus, the term "bearing" as used herein includes any combination of, for example, slider bearings, ball bearings, roller bearings, and flexures.

[0076] Although some of the methods have been specifically described with reference to cameras and camera assemblies, it should be understood that the configuration and / or control of the actuator assemblies involved may be applied to other fields that require aperture control.

[0077] Those skilled in the art should understand that although the foregoing has described what is considered to be the best mode of carrying out the present technology and other modes of carrying out the present technology where appropriate, the present technology should not be limited to the specific constructions and methods of the preferred embodiments disclosed in this specification. Those skilled in the art should recognize that the present technology has a wide range of applications and that embodiments may be modified extensively without departing from any inventive concept defined by the appended claims.

Claims

1. A shape memory alloy actuating device arranged to drive the operation of an aperture element, said actuating device comprises: an aperture driving mechanism arranged to open and close the aperture of said aperture based on an input motion; at least one shape memory alloy actuator wire arranged to provide said input motion when the actuator wire contracts; and a rigid element connecting said actuator wire to said aperture driving mechanism; wherein said at least one shape memory alloy actuator wire is arranged to cause a rotational or translational motion of said rigid element in a first plane when contracting, and the connection between said rigid element and said aperture driving mechanism is configured to convert said rotational or translational motion into said input motion in a second plane substantially perpendicular to said first plane.

2. The device according to claim 1, wherein, said device is arranged to amplify the motion range of the actuator wire to provide said input motion.

3. The device according to claim 1 or 2, wherein, said rigid element is arranged to pivot about a pivot point, and the connection point of said aperture driving mechanism and said rigid element is farther from said pivot point than the connection point of said actuator wire and said rigid element.

4. The device according to claim 1 or 2, wherein, said rigid element has an engaging portion engaging with said aperture driving mechanism, wherein said engaging portion includes an edge engaging with said aperture driving mechanism, and said edge is inclined with respect to the direction of said input motion.

5. The device according to claim 1 or 2, further comprising a bearing arranged to limit the motion of said rigid element.

6. The device according to claim 1 or 2, wherein, there are multiple shape memory alloy actuator wires arranged such that at least one of said actuator wires is arranged to move said rigid element when contracting to provide said input motion in a first direction, and at least another one of said actuator wires is arranged to move said rigid element when contracting to provide said input motion in a second direction opposite to said first direction.

7. The device according to claim 1 or 2, further comprising a biasing element pushing said aperture driving mechanism towards one extreme of its motion range.

8. The device according to claim 1 or 2, further comprising a bearing arranged to limit the motion of said aperture driving mechanism in the direction of said input motion.

9. The device according to claim 1 or 2, further comprising a control circuit electrically connected to said shape memory alloy actuator wire or multiple shape memory alloy actuator wires for providing a driving signal thereto.

10. The device according to claim 9, further comprising an aperture connected to said aperture driving mechanism and having an aperture opened and closed by said input motion.

11. The device according to claim 10, further comprising an image sensor arranged to receive light passing through said aperture.

12. The apparatus according to claim 11 further comprises a steering element arranged to change the direction of light entering the apparatus such that the light passes through the aperture to reach the image sensor.

13. The apparatus according to claim 11 or claim 12 further comprises a sensor arranged to generate an output signal representative of the amount or intensity of light reaching the image sensor, and the control circuit is arranged to generate a drive signal in response to the output signal to open or close the aperture so as to adjust the amount of light reaching the image sensor.

14. The apparatus according to any one of claims 1 - 2 and 10 - 12, wherein, the apparatus is any one of the following: a smart phone and a camera.

15. The apparatus according to any one of claims 1 - 2 and 10 - 12, wherein, the apparatus is a consumer electronic device.

Images