actuating device

Abstract

An actuation device comprising: a support structure; a movable element; a helical bearing mechanism supporting the movable element on the support structure and arranged to guide helical movement of the movable element relative to the support structure along a helical path about a helical axis; an actuation mechanism configured to drive rotation of the movable element about the helical axis, the helical bearing mechanism converting the rotation into the helical movement; and a loading mechanism configured to apply a biasing force to the movable element in a direction at least substantially normal to the helical path over an operating range of the helical movement.

Description

[0001] field

[0002] This disclosure relates to an actuation device in an actuation mechanism that drives a movable element to move relative to a support structure.

[0003] background

[0004] Actuators are known to be used to drive the translational movement of movable elements relative to a supporting structure, particularly voice coil motors (VCMs) or shape memory alloy (SMA) actuators. SMA actuator lines have particular advantages in microdevices and can be applied to a variety of devices, including handheld devices such as cameras and mobile phones. For example, such SMA actuator lines can be used in optical devices (such as cameras) to drive the translational movement of camera lens elements along their optical axis, for example, to achieve focusing (autofocus, AF) or zooming.

[0005] Examples of actuators for this type of camera are disclosed in WO-2007 / 113478. Here, the movable element is a camera lens element supported on a support structure by a helical bearing arrangement, which includes a flexure that guides translational movement along the optical axis. In one example described herein, the SMA actuator line is a piece of SMA wire connected at its end to the support structure and hooked onto a hook-shaped member on the camera lens element for driving translational movement. The straight SMA actuator line formed by the portion of this piece of SMA wire on either side of the hook-shaped member extends at an acute angle greater than 0 degrees relative to the direction of movement parallel to the optical axis. Inclined SMA actuator lines in this manner increase the amount of movement and also reduce the range of the actuator in the direction of movement compared to SMA actuator lines extending along the direction of movement.

[0006] Miniaturization is an important design criterion for many types of actuators. In many applications, it is desirable to minimize the size of the actuator in the direction of movement. For example, in cases where the actuator includes a lens element that moves along the optical axis, it is desirable to minimize the size along the optical axis.

[0007] In actuators where the SMA actuator line extends at an acute angle to the direction of movement, such as in the camera disclosed in WO 2007 / 113478, the SMA actuator line itself must have a range projected along the direction of movement. This sets a minimum dimension in the actuator along the direction of movement, even though other components can be made smaller in that direction. In particular, the range projected by the SMA actuator line along the direction of movement is determined by the required degree of translational movement, because the maximum variation in the length of the SMA actuator line is a given percentage of the total length of the SMA actuator line, which is caused by the electromechanical properties of the SMA material.

[0008] Overview

[0009] According to a first aspect of this disclosure, an actuation device is provided, comprising: a support structure; a movable element; a helical bearing mechanism supporting the movable element on the support structure and arranged to guide helical movement of the movable element relative to the support structure along a helical path about a helical axis; an actuation mechanism configured to drive the movable element to rotate about the helical axis, the helical bearing mechanism converting the rotation into the helical movement; and an elastic loading mechanism including an elastic element connected between the movable element and the support structure, the elastic element being configured to apply a biasing force to the movable element in a direction at least substantially orthogonal to the helical path within the operating range of the helical movement.

[0010] The actuation mechanism can include any suitable actuator, including, for example, a voice coil motor (VCM) or a piezoelectric element. Such an actuator may be able to drive a movable element to rotate about a helical axis, and the helical bearing mechanism converts this rotation into helical movement.

[0011] Alternatively or additionally, the actuation mechanism may include at least one shape memory alloy actuator wire connected between the support structure and the movable element, in a plane orthogonal to the helical axis or at an acute angle to the plane orthogonal to the helical axis, and arranged to drive the movable element to rotate about the helical axis during contraction, the helical bearing mechanism converting the rotation into said helical movement.

[0012] This type of actuator utilizes a helical bearing mechanism that guides the helical movement of a movable element relative to a supporting structure. This helical movement involves rotation about a helical axis and overall translation along that axis. Therefore, an SMA actuator line is connected between the supporting structure and the movable element to drive the movable element to rotate about the helical axis. The rotation driven by the contraction of the SMA actuator line is converted into helical movement of the movable element by the helical bearing mechanism. Thus, the translational movement of the movable element is achieved along the helical axis as part of the helical movement.

[0013] Since the SMA actuator line has the primary purpose of driving rotation, the range of the SMA actuator line projected along the helical axis can be minimized, allowing some other components of the actuator to determine the size of the actuator in the direction of the helical axis (to achieve translational movement along the helical axis).

[0014] The actuation mechanism (e.g., at least one shape memory alloy actuator wire) can be arranged to drive the movable element to rotate less than a quarter full revolution around the helical axis, or preferably less than 10°, or preferably less than 5°, or preferably less than 2.5°. This corresponds to the operating range described above. The actuation mechanism can also be arranged to drive the movable element to rotate more than 0.1° around the helical axis, preferably more than 0.5°, and more preferably more than 1°.

[0015] As described above, the elastic element connects the movable element and the support structure. The elastic element can be fixedly connected between the movable element and the support structure and extends between them. In particular, the elastic loading mechanism does not necessarily include any bearing element, such as rolling or sliding bearing elements.

[0016] This can help reduce the cost and complexity of manufacturing actuators and / or their components.

[0017] Advantageously, the resilient loading mechanism may not interfere with or require alteration of the bearing surface profile. Furthermore, the resilient loading mechanism can advantageously allow the biasing force to be uniformly distributed across the bearing surface, for example, on a sliding bearing or on more than one rolling bearing.

[0018] As described above, the elastic element applies a biasing force to the movable element in a direction at least substantially orthogonal to the helical path (along which the movable element moves). As will be understood, the direction of this helical path varies along its length and, in particular, as a function of the angle about the helical axis. The biasing force being orthogonal to the helical path can mean, for example, that the biasing force is perpendicular to the helical path at a point along the path, which is at the same angle about the helical axis as the (equivalent) point of application of the biasing force.

[0019] A helical bearing mechanism may include bearing surfaces on a support structure and / or on a movable element, which are aligned with a helical path to guide the helical movement of the movable element. Therefore, the aforementioned biasing force can generate positive and negative forces orthogonal to one or more of these bearing surfaces (or, in the case where the bearing surface consists of two faces, generate at least substantially equal reaction forces on each of the two faces).

[0020] When the biasing force is applied in a direction orthogonal to the bearing surface, it does not directly affect the helical movement of the movable element along the bearing surface, thus minimizing motion resistance and thereby improving efficiency.

[0021] However, the bias force can also be applied in a direction within the angular range of the normal described above. In particular, the bias force can form an angle of less than 20° with the normal, or preferably less than 10°, or preferably less than 5°.

[0022] Furthermore, the direction and / or magnitude of the bias force are preferably at least substantially constant (e.g., within 10%) within the operating range of the helical movement. Thus, within the operating range of the helical movement, the behavior of the helical bearing mechanism will be substantially constant, thereby contributing to the performance (e.g., controllability) of the actuator 1.

[0023] The resilient loading mechanism may be disposed near at least one of more than one bearing surfaces, which may or may not have bearing elements. For example, the resilient element may be disposed on or near only one of more than one bearing surfaces at each of the movable element and the support structure. For example, by applying a biasing force on a single bearing surface, the biasing force may be sufficient to be transmitted to all other bearing surfaces. In some embodiments, the resilient element may be disposed on or near some or all of more than one bearing surface at each of the movable element and the support structure. For example, by applying a biasing force on a single bearing surface, the biasing force may be sufficiently transmitted to all other bearing surfaces.

[0024] The gap can be a clearance that is substantially equal to the height of the bearing element, so that the bearing element is always in contact with the bearing surface. The gap can also be zero, where the bearing surfaces can be in contact with each other. For example, the bearing element can be a sliding bearing, or there may be no bearing element between the bearing surfaces.

[0025] Advantageously, embodiments of the invention can allow the application of a bias force throughout the entire range of rotational movement or when the actuator device (in particular, such as an SMA actuator line) is in an unpowered state.

[0026] Optionally, the helical bearing mechanism includes at least one or more of a rolling bearing, a sliding bearing, and a fluid bearing disposed between the bearing surfaces. Advantageously, such an arrangement reduces friction between the bearing surfaces. Preferably, a rolling bearing, such as a ball bearing, can be used. The bearings can be disposed on all or some of the bearing surfaces. In some embodiments, some of the more than one bearing surface may be provided with a resilient loading mechanism and ball bearings. In some embodiments, one of the more than one bearing surface may be provided with a resilient loading mechanism without ball bearings.

[0027] Optionally, the biasing force is applied throughout the entire range of helical movement. This allows for constant contact between the bearing surfaces or between the bearing elements and the bearing surfaces. Advantageously, by maintaining a constant interval between the movable element and the support structure throughout the entire range of movement, such an arrangement can reduce jitter and improve the accuracy of the movable element as it moves along the optical axis.

[0028] Optionally, the biasing force is applied when the actuation mechanism (e.g., an SMA line) is not energized. More specifically, the biasing force can allow maintaining the relative position (and / or spacing) of the movable element and the support structure. Advantageously, this can allow the movable element to remain in place, for example, to perform certain camera functions, including minimizing the risk of damage during transport when the device is off. Preferably, this applies to any orientation of the actuation mechanism.

[0029] Optionally, the elastic element is configured to apply a biasing force directly to the movable element and / or support structure, for example, by recovering from or resisting bending. Advantageously, such an arrangement allows for minimal biasing force to be applied at one end of the rotational movement, such as when the actuator is de-energized. At this location, the biasing force can only be generated by the reaction force on the movement of the movable part. Furthermore, using an elastic element such as a simple flexure not only reduces weight and extends reliability, but in some designs, it can also advantageously allow the flexure to be attached to the outer surface of the movable element and support structure. Thus, such an arrangement simplifies and streamlines the manufacturing process. Additionally, the use of a flexure allows for the application of bidirectional forces in opposite directions.

[0030] Optionally, the elastic element includes a flexure attached to one or both of the support structure and the movable element. For example, the flexure may bridge the two components. The elastic element may be attached to both the support structure and the movable element, wherein the elastic element can deform in the direction of rotation about the helical axis. The elastic element may be attached to one of the support structure and the movable element, such that, advantageously, the elastic element can move or rotate freely to the other of the support structure and the movable element.

[0031] Optionally, the flexural member includes a first portion and a second portion respectively connected to the support structure and the movable element. Optionally, the first and second portions are connected by an intermediate portion, wherein the biasing force is achieved by recovering from or resisting bending in the intermediate portion. More specifically, the intermediate portion may be an execution or jogged section for applying the biasing force. In this embodiment, the biasing force may arise from resistance to bending in the jogged section or from recovery from bending in the jogged section. Advantageously, such an arrangement prevents bending in the first and / or second portions, thereby allowing a larger contact area between the flexural member and the movable component and / or the support structure.

[0032] Optionally, the elastic element is attached to a support structure or movable element at a first or second portion of the flexure or between a first and second position of the flexure via a clamp. Optionally, the flexure is a planar flexure extending substantially orthogonal to the helical axis. For example, the flexure may be planar, or at least conform to a portion of the surface profile of the movable element and / or support structure. Advantageously, such an arrangement allows the elastic element to be attached to the movable element and / or support structure after the two components are assembled. In some embodiments, the clamp may include an adjustable clamp, which advantageously allows for adjustable bias force. Optionally, the clamp may be a cantilever connecting the first and second portions. The connection between the flexure and the tip of the cantilever may be subject to interference fit or any other suitable mechanism. More specifically, the flexure may be suspended on the cantilever before loading. Advantageously, such an arrangement allows for efficient assembly or replacement of the flexure.

[0033] Optionally, the flexure is configured to extend about a helical axis. For example, the flexure can be a retaining ring, a circular spring, or a spiral spring wound around the helical axis. Optionally, the flexure includes an etched spring flexure. For example, an etched spring flexure can be provided as a compact arrangement compared to a retaining ring. Such an arrangement allows the movable element and the support structure to be offset toward each other in a direction orthogonal to at least one bearing surface. Generally, longer flexures are advantageous because longer flexures apply relatively low forces per unit length and are therefore less sensitive to, for example, positional tolerances during assembly, and can also apply forces in a manner less affected by the movement of the movable element.

[0034] Alternatively, the elastic element can be an elastic member (e.g., an elastic band) connected between the outer surface of the movable element and the support structure. Advantageously, such an arrangement (or an arrangement using etched springs, coiled springs, or other types of spring elements instead of the elastic member) allows the elastic member to be attached to the movable element and the support structure once they are assembled together.

[0035] Optionally, the elastic element comprises more than one opposing elastic element, and the biasing force comprises bidirectional biasing forces opposing each other. Optionally, the biasing forces applied by each of the opposing elastic elements can be substantially equal. Therefore, the biasing forces applied by each of the elastic elements can be balanced against each other. For example, the elastic elements can comprise opposing flexural elements positioned on the outer surfaces of the movable element and the support structure. Alternatively, a pair of opposing elastic bands can each have one end connected to the respective movable element and the support structure, while the other end is connected to the movable element. Advantageously, such an arrangement allows for the application of bidirectional biasing forces and thus can accurately maintain the spacing between the bearing surfaces.

[0036] According to a second aspect of this disclosure, an actuation device is provided, comprising: a support structure; a movable element; a helical bearing mechanism that supports the movable element on the support structure via respective bearing surfaces and is arranged to guide helical movement of the movable element relative to the support structure about a helical axis; and an elastic loading mechanism disposed between the support structure and the bearing surfaces of the movable element, the elastic loading mechanism being configured to apply a biasing force to the movable element and / or the support structure in a direction orthogonal to at least one of the bearing surfaces to maintain a gap between the bearing surfaces of the support structure and the movable element.

[0037] Advantageously, such an arrangement allows the biasing force to act directly and orthogonally on the bearing surface, and thus advantageously, the force can be applied more effectively at the bearing surface, and the possibility of separation and / or slippage at the bearing surface is minimized.

[0038] Optionally, the resilient loading mechanism is contained between the support structure and the bearing surface of the movable element. Advantageously, this allows the resilient loading mechanism to be concealed and shielded between the bearing surfaces, resulting in a more compact actuation device.

[0039] Optionally, the resilient loading mechanism includes a resilient element configured to apply a biasing force to a bearing element disposed between bearing surfaces, wherein the resilient loading mechanism is configured to apply a biasing force to one or both bearing surfaces through the bearing element. The resilient element may be configured to apply the biasing force in a direction substantially orthogonal to the bearing surfaces.

[0040] Optionally, the elastic element can be a flexure or a coiled spring for compressing the bearing element against the corresponding bearing surface. That is, an elastic loading mechanism can be used together or in place of a ball bearing. In some embodiments, a corresponding groove can be provided on the bearing surface to receive at least a portion of the bearing element in order to guide the movement of the bearing element.

[0041] According to a third aspect of the invention, an actuating device is provided, comprising: a support structure; a movable element; a helical bearing mechanism supporting the movable element on the support structure via respective bearing surfaces, the helical bearing mechanism being arranged to guide helical movement of the movable element relative to the support structure about a helical axis, wherein the bearing surfaces of the support structure and the movable element are angled relative to each other to form a narrowing gap therebetween; an actuation mechanism configured to drive the movable element to rotate about the helical axis, the helical bearing mechanism converting the rotation into the helical movement; and an elastic loading mechanism including an elastic element configured to apply a biasing force in a direction toward the narrow end of the gap and on the angled bearing surfaces to maintain the gap between the angled bearing surfaces. Optionally, the elastic loading mechanism includes a ball bearing biased toward the narrow end of the gap via the elastic element, wherein the ball bearing is configured to convert the biasing force into a direction substantially orthogonal to one or both bearing surfaces.

[0042] Advantageously, such an arrangement allows the bearing surfaces to slide relative to each other, which can provide a degree of play between the movable element and the support structure, and can be used in certain applications.

[0043] Optionally, the movable element is a lens element including at least one lens, wherein the helical axis is the optical axis of the lens element, and wherein the support structure has an image sensor mounted thereon, and the lens element is arranged to focus an image onto the image sensor. The lens element may have a diameter of up to 30 mm, up to 20 mm, or up to 10 mm.

[0044] Optionally, the movable element includes a tactile interface or a component connected to the tactile interface, and wherein the helical axis is the axis of tactile movement, so that the movable element can be actuated along the helical axis to achieve a tactile response at the tactile interface. Advantageously, such an arrangement allows for the application of longer segments of the SMA, and thus improves tactile performance.

[0045] Optionally, the actuation mechanism is configured to apply a driving force upon actuation to drive relative rotation between the movable element and the support structure, wherein such a driving force is sufficient to overcome the biasing force. Optionally, the biasing force applied by the elastic element is insufficient to cause relative rotation between the movable element and the support structure. For example, preferably, the biasing force should only be sufficient to maintain the gap between the movable element and the support structure, but it should not provide significant resistance to helical movement.

[0046] According to a fourth aspect of this disclosure, a method for assembling an actuating device according to any one of the first to third aspects is provided, the method comprising the steps of: attaching an elastic element to one of a movable element and a support structure; and assembling the movable element with the support structure before or after said attachment, wherein the elastic element is configured to apply a biasing force to the other of the movable element and the support structure in the assembled actuating device.

[0047] Optionally, the actuation device according to any one of the first to third aspects may include an SMA actuator line extending in a plane orthogonal to the helical axis. In this case, the SMA actuator line has a minimum range projected along the helical axis.

[0048] Alternatively, the SMA actuator line can extend at an acute angle to a plane orthogonal to the helical axis. In this case, the SMA actuator line has a range projected along the helical axis, but this can be controlled by adjusting the acute angle to suit the dimensional constraints of some other components of the actuator.

[0049] Various types of helical bearing mechanisms can be used to guide the helical movement of a movable element relative to a supporting structure. For example, a helical bearing mechanism may include at least one rolling or sliding bearing, or it may include at least one flexural element extending between the supporting structure and the movable element.

[0050] Similarly, various configurations of SMA actuator lines can be used to drive the rotation of a movable element about a helical axis. For example, there can be a single SMA actuator line or more than one SMA actuator line positioned at any location around the helical axis.

[0051] In a first-type embodiment, a resilient biasing element may be connected between the support structure and the movable element, and is arranged to resiliently bias at least one SMA actuator line. Generally, it is known to use resilient biasing elements with SMA actuator lines, whereby the resilient biasing element applies stress to the SMA actuator line and drives the SMA actuator line to move in the opposite direction to contraction. Such resilient biasing elements may be employed with a single SMA actuator line or more than one SMA actuator line.

[0052] In a second type of embodiment, a pair of SMA actuator lines can be arranged to drive the movable element to rotate about the helical axis in opposite directions during contraction. While the use of a pair of SMA actuator lines to apply opposing forces to the element during translation is known, here the SMA actuator lines apply opposing torques about the helical axis. However, in a manner similar to the known uses of opposing SMA actuator lines, the SMA actuator lines apply stress to each other and, during contraction, drive the lens element to rotate about the helical axis in opposite directions.

[0053] Specific advantages are achieved when applied to actuation devices (where the movable element is a lens element including at least one lens, for example, where the helical axis is the optical axis of the lens element). In many applications, it is desirable to minimize the size along the translational direction of such lens element. For example, the actuation device may be a camera, where a support structure has an image sensor mounted thereon, and the lens element is arranged to focus an image onto the image sensor. The size reduction advantage achieved by this technique is particularly valuable in space-constrained handheld devices and micro-devices (where, for example, at least one lens has a diameter of at most 30 mm, preferably at most 20 mm, preferably at most 15 mm, preferably at most 10 mm).

[0054] However, this technology can generally be applied to virtually any type of device, which includes a static part and a movable part that is movable relative to the static part. By way of non-limiting example, the actuator component can be, or can be disposed in, any of the following devices: smartphones, cameras, foldable smartphones, foldable smartphone cameras, foldable consumer electronics, image capture devices, foldable image capture devices, array cameras, 3D sensing devices or systems, servo motors, consumer electronics (including home appliances), mobile or portable computing devices, mobile or portable electronic devices, laptops, tablet computing devices, e-readers (also known as e-book readers or e-book devices), computing accessories or computing peripherals (e.g., mice, keyboards, headphones, earbuds, etc.), security systems, gaming systems, gaming accessories (e.g., controllers, headsets, wearable controllers, etc.), robots or robotic devices, medical devices (e.g., endoscopes), augmented reality systems, augmented reality devices, virtual reality systems, virtual reality devices, wearable devices (e.g., watches, smartwatches, fitness trackers, etc.), drones (airborne, waterborne, underwater, etc.), aircraft, spacecraft, submarines, vehicles, and automated vehicles. It should be understood that this is a non-exhaustive list of exemplary devices.

[0055] The actuator components described herein can be used in applications suitable for image capture, 3D sensing, depth mapping, aerial surveying, land surveying, surveying in or from space, hydrography, underwater surveying, scene detection, collision warning, security, facial recognition, augmented and / or virtual reality, advanced driver assistance systems in vehicles, automated vehicles, gaming, gesture control / recognition, robotic devices, robotic device control, contactless technology, home automation, medical devices, and tactile devices / systems.

[0056] According to a fifth aspect of this disclosure, an actuation device is provided, comprising: a support structure; a movable element; a helical bearing mechanism supporting the movable element on the support structure and arranged to guide helical movement of the movable element relative to the support structure along a helical path about a helical axis; an actuation mechanism configured to drive the movable element to rotate about the helical axis, the helical bearing mechanism converting the rotation into the helical movement; and an elastic loading mechanism configured to apply a biasing force to the movable element in a direction at least substantially orthogonal to the helical path within the operating range of the helical movement, wherein the elastic loading mechanism includes an elastic element having a first end and a second end, the first end being attached to one of the movable element and the support structure, and the bearing element being attached to the second end to apply a force to the other of the movable element and the support structure.

[0057] According to a sixth aspect of this disclosure, an actuation device is provided, comprising: a support structure; a movable element; a helical bearing mechanism supporting the movable element on the support structure and arranged to guide helical movement of the movable element relative to the support structure along a helical path about a helical axis; an actuation mechanism configured to drive the movable element to rotate about the helical axis, the helical bearing mechanism converting the rotation into the helical movement; and an elastic loading mechanism configured to apply a biasing force to the movable element in a direction at least substantially orthogonal to the helical path within the operating range of the helical movement, wherein the elastic loading mechanism includes: a tapered gap between a surface of the movable element and a surface of the support structure; a bearing element in the tapered gap and in contact with the surface; and an elastic element connected to one of the movable element and the support structure and configured to push the bearing element into the tapered gap to cause the surfaces to separate and generate the biasing force.

[0058] According to a seventh aspect of this disclosure, an actuation device is provided, comprising: a support structure; a movable element; a helical bearing mechanism that supports the movable element on the support structure and is arranged to guide helical movement of the movable element relative to the support structure along a helical path about a helical axis; an actuation mechanism configured to drive the movable element to rotate about the helical axis, the helical bearing mechanism converting the rotation into the helical movement; and an elastic loading mechanism configured to apply a biasing force to the movable element in a direction at least substantially orthogonal to the helical path within the operating range of the helical movement, wherein the elastic loading mechanism includes: a gap between a surface of the movable element and a surface of the support structure, wherein one of these surfaces includes a region of elastic material; a bearing element located in the gap and in contact with the region of elastic material and another of these surfaces, wherein the elastic material deforms through the bearing element to generate the biasing force.

[0059] According to another aspect of this disclosure, an actuation device is provided, comprising: a support structure; a movable element; a helical bearing mechanism that supports the movable element on the support structure and is arranged to guide helical movement of the movable element relative to the support structure along a helical path about a helical axis; an actuation mechanism configured to drive the movable element to rotate about the helical axis, the helical bearing mechanism converting the rotation into the helical movement; and a magnetic loading mechanism configured to apply a biasing force to the movable element in a direction at least substantially orthogonal to the helical path within the operating range of the helical movement.

[0060] The magnetic loading mechanism may include a first magnetic element mounted to a movable element and a second magnetic element mounted to a support structure, wherein the first and second magnetic elements include surfaces facing each other. The facing surfaces of the first and second magnetic elements are arranged parallel to a helical movement path. The facing surfaces of the first and second magnetic elements are separated by a gap, wherein the range of the gap between the surfaces remains substantially constant within the operating range of the helical movement. One of the first and second magnetic elements includes a magnet, and the other of the first and second magnetic elements includes an ferrous material. The range of one of the facing surfaces of the first and second magnetic elements is greater than the range of the other facing surface.

[0061] Therefore, these aspects can provide alternative and / or advantageous ways to generate bias forces.

[0062] According to an eighth aspect of this disclosure, an actuation device is provided, comprising: a support structure; a movable element; a helical bearing mechanism that supports the movable element on the support structure and is arranged to guide helical movement of the movable element relative to the support structure along a helical path about a helical axis; an actuation mechanism configured to drive the movable element to rotate about the helical axis, the helical bearing mechanism converting the rotation into the helical movement; and an elastic loading mechanism configured to apply a biasing force to the movable element in a direction at least substantially orthogonal to the helical path within the operating range of the helical movement, wherein the helical bearing mechanism includes three sets of bearings, and the three sets of bearings and the elastic loading mechanism are spaced at least substantially equidistantly about the helical axis.

[0063] Therefore, these aspects can provide an advantageous way to arrange the components of the helical bearing mechanism and the elastic loading mechanism. As will be understood, such an actuation device can effectively utilize a square or rectangular footprint.

[0064] Additional (optional) features are specified in the dependent claims, and further advantages are described below.

[0065] To allow for a better understanding, embodiments of the technology will now be described by way of non-limiting examples with reference to the accompanying drawings, in which:

[0066] Figure 1 This is a schematic diagram of an actuator, which is a camera;

[0067] Figure 2 and Figure 3 This is a perspective view of two spiral bearings;

[0068] Figures 4 to 7 It is a schematic cross-sectional view of an actuation device with possible different helical bearing mechanisms;

[0069] Figure 8 It is a perspective view of an actuator with another possible helical bearing mechanism;

[0070] Figure 9A and Figure 9B These are perspective and cross-sectional views of a helical bearing mechanism according to an embodiment of the present invention;

[0071] Figures 10A to 10D This is a possible side view that can be loaded;

[0072] Figure 11A and Figure 11B It is a plan view of the possible loading arrangement;

[0073] Figures 12A to 12D This is a side view of a possible loading mechanism;

[0074] Figures 13A to 13C This is a side view of a possible loading mechanism;

[0075] Figure 14 This is a schematic cross-sectional view of an actuation device with yet another possible helical bearing mechanism;

[0076] Figure 15 This is a cross-sectional view of the first alternative bearing, taken perpendicular to the direction of bearing movement;

[0077] Figure 16 yes Figure 15 A side view of the first alternative bearing;

[0078] Figure 17 This is a cross-sectional view of the second alternative bearing, taken perpendicular to the direction of bearing movement;

[0079] Figure 18 yes Figure 17 Side view of alternative bearings;

[0080] Figure 19This is a side view of an actuation device with a helical bearing mechanism, which includes more than one flexure.

[0081] Figure 20 and Figure 21 yes Figure 19 A plan view of a spiral bearing mechanism, which has different forms of flexural elements;

[0082] Figure 22 It is a perspective view of an alternative helical bearing mechanism that includes more than one flexural element;

[0083] Figure 23 and Figure 24 This is a schematic side view of an SMA actuator device, which includes SMA actuator lines extending at two different angles; and

[0084] Figures 25 to 27 This is a schematic plan view of an SMA actuator device, which has different arrangements of SMA actuator lines and elastic biasing elements; and

[0085] Figures 28 to 30 This is a schematic plan view of an SMA actuator device, in which different arrangements of the SMA actuator lines are rotated in opposite directions.

[0086] Unless the context otherwise requires, the term "bearing" is used herein as follows. The term "bearing" as used herein includes the terms "sliding bearing," "plain bearing," "rolling bearing," "ball bearing," "roller bearing," "air bearing" (where compressed air causes the load to float), and "flexural element." The term "bearing" as used herein generally refers to any element or combination of elements used to restrict motion to only the desired motion and reduce friction between moving parts. The term "sliding bearing" is used to indicate a bearing in which the bearing element slides on a bearing surface, and includes "plain bearings." The term "rolling bearing" is used to indicate a bearing in which a rolling bearing element (e.g., a ball or roller) rolls on a bearing surface. Such a rolling bearing element can be a compliant element, such as a gas-filled bladder. In embodiments, the bearing may be disposed on a non-linear bearing surface or may include a non-linear bearing surface.

[0087] In some embodiments of this technology, more than one type of bearing element can be used in combination to provide bearing functionality. Therefore, the term "bearing" as used herein includes any combination of, for example, sliding bearings, ball bearings, roller bearings, and flexural elements.

[0088] Figure 1The image schematically shows an actuation device 1, which is a camera.

[0089] The actuation device 1 includes a support structure 2, on which an image sensor 3 is mounted. The support structure 2 can take any suitable form, but typically includes a base 4 to which the image sensor is fixed. The support structure 2 may also support an IC chip 5, which is further described below.

[0090] The actuation device 1 also includes a lens element 10, which in this example is a movable element. The lens element 10 includes a lens 11, although alternatively it may include more than one lens. The lens element 10 has an optical axis O aligned with the image sensor 3 and is arranged to focus an image onto the image sensor 3.

[0091] The actuation device 1 is a micro-device. In some examples of the micro-device, the lens 11 (or more than one lens, when provided) may have a diameter of up to 30 mm.

[0092] Although actuation device 1 is a camera in this example, this is generally not necessary. In some examples, actuation device 1 can be an optical device, where the movable element is a lens element, but there is no image sensor. In other examples, actuation device 1 can be a device that is not an optical device, and where the movable element is not a lens element and there is no image sensor. Examples include devices for depth mapping, facial recognition, game consoles, projectors, and security scanners.

[0093] Actuation device 1 also includes a helical bearing mechanism 20 (in Figure 1 (Schematally shown in the diagram) A helical bearing mechanism 20 supports the lens element 10 on the support structure 2. The helical bearing mechanism 20 is arranged to guide the helical movement of the lens element 10 relative to the support structure 2 about a helical axis H. In this example, the helical axis H coincides with the optical axis O, and the helical movement is indicated by arrow M. Figure 1 As shown in the diagram. Preferably, the helical motion is along a right-hand helix, i.e., a helix with a constant radius, but generally any helix is ​​possible. The pitch of the helix along the helical motion can be constant or variable. Preferably, the helical movement is typically only a small fraction (less than a quarter) of a full turn of the helix.

[0094] The helical motion of the lens element 10, guided by the helical bearing mechanism 20, includes translational movement along the helical axis H and rotational movement about the helical axis H. The translational movement along the helical axis H is the desired movement of the lens element 10, such as changing the focal length of the image on the image sensor 3 and / or changing the magnification (zoom) of the image on the image sensor 3. In this example, the rotational movement about the helical axis H is not desired for optical purposes, but is generally acceptable because the rotation of the lens element 10 does not change the focal length of the image on the image sensor 3.

[0095] The spiral bearing mechanism 20 can take many forms.

[0096] One possibility is that the helical bearing mechanism 20 comprises one or more helical bearings 30 that are rolling bearings, examples of which are shown in... Figure 2 and 3 As shown in [the image]. Figure 2 and Figure 3 In each of the components, the helical bearing 30 includes a pair of bearing surfaces 31 and 32, and more than one rolling bearing element 33, such as a ball, disposed between the bearing surfaces 31 and 32. One of the bearing surfaces 31 and 32 is disposed on the support structure 2, while the other of the bearing surfaces 31 and 32 is disposed on the lens element 10.

[0097] The helical bearing 30 guides the helical movement of the lens element 10 relative to the support structure 2, as indicated by arrow M. This is achieved by the bearing surfaces 31 and 32 extending helically around the helical axis H (i.e., along the line of the helix). That is, in practical embodiments, if one or more helical bearings of the helical bearing mechanism 20 guide the helical movement of the lens element 10 relative to the support structure 2, the lengths of the bearing surfaces 31 and 32 can be short compared to their distances from the helical axis H, making their shapes nearly straight or even each straight. Typically, there is more than one helical bearing 30 positioned at different angular locations around the helical axis H. In this case, the helical bearings 30 have different orientations, allowing them to cooperate and maintain sufficient constraint to guide the helical movement of the lens element 10 relative to the support structure 2, even if the bearing surfaces 31 and 32 of a single helical bearing 30 are straight.

[0098] exist Figure 2 In this example, bearing surfaces 31 and 32 each include corresponding grooves 34 and 35, in which rolling bearing element 33 is located. In this example, grooves 34 and 35 constrain the lateral translational movement of lens element 10 relative to support structure 2 (i.e., laterally to the direction of movement indicated by arrow M). Figure 2The grooves shown are V-shaped in cross-section, but other cross-sections are also possible, such as sections bent into a circle or ellipse. Typically, grooves 34 and 35 provide two contact points with the corresponding rolling bearing element 33. Grooves 34 and 35 can extend helically. Alternatively, in practical embodiments, if one or more helical bearings 30 of the helical bearing mechanism 20 guide the helical movement of the lens element 10 relative to the support structure 2, the lengths of bearing surfaces 31 and 32 can be short compared to the distances from the helical axis H to the bearing surfaces 31 and 32, in which case grooves 34 and 35 can be straight or nearly straight.

[0099] exist Figure 3 In the example, the first bearing surface 31 includes a groove 36 in which the rolling bearing element 33 is located, and the bearing surface in the second bearing surface 32 is "planar". The first bearing surface 31 including the groove 36 can be disposed on either the support structure 2 and the lens element 10, and the second bearing surface 32 can be disposed on the other of the support structure 2 and the lens element 10. Figure 3 In the example, the helical bearing 30 does not constrain the lateral translational movement of the lens element 10 relative to the support structure 2 (i.e., lateral to the direction of movement indicated by arrow M). The bearing surface 32 is "planar" in the sense that it is a non-grooved surface and provides only a single-point contact with the ball. In other words, the bearing surface 32 is practically planar over the entire width scale of the rolling bearing element 33, although it is helical on a larger scale. For example, as shown, this "planar" surface is helical, appearing as a line twisted helically in the direction of movement in cross-section, maintaining a single-point contact with the ball at all times. Alternatively, and as stated above, in practical embodiments, if one or more helical bearings 30 of the helical bearing mechanism 20 guide the helical movement of the lens element 10 relative to the support structure 2, the lengths of the bearing surfaces 31 and 32 may be short, in which case the bearing surface 32 may be planar or nearly planar.

[0100] Figure 2 and Figure 3 A single rolling bearing element 33 is shown as an example, but it can typically include any number of rolling bearing elements 33, more than one.

[0101] In some examples, the helical bearing 30 may comprise a single rolling bearing element 33. In that case, the helical bearing 30 itself does not constrain the rotational movement of the lens element 10 relative to the support structure 2 about the single rolling bearing element 33, i.e., rotational movement about an axis transverse to the direction of movement indicated by arrow M. However, this minimizes the overall size of the helical bearing 30, and in particular minimizes the height of the helical bearing 30 projected along the helical axis H, as it only needs to accommodate the size of the rolling bearing element 33 and the relative travel of the bearing surfaces 31 and 32.

[0102] In other examples, the helical bearing 30 may include more than one rolling bearing element 33. In this case, the helical bearing 30 constrains the rotational movement of the lens element 10 relative to the support structure 2 about any one of the rolling bearing elements 33, that is, rotational movement about an axis transverse to the direction of movement indicated by arrow M. However, this increases the overall size of the helical bearing 30 compared to using a single rolling bearing element 33, and in particular increases the height of the helical bearing 30 projected along the helical axis H.

[0103] A helical bearing mechanism may typically include any number of helical bearings 30, wherein the configuration of the helical bearings 30 is chosen to guide the helical movement of the lens element 10 relative to the support structure 2, while constraining the movement of the lens element 10 relative to the support structure 2 in other degrees of freedom. Many helical bearing mechanisms may include more than one helical bearing 30, and at least one helical bearing includes more than one rolling bearing element 30.

[0104] Some specific examples of actuator 1 with possible different helical bearing mechanisms are shown in Figures 4 to 6 The diagram in the middle shows, Figures 4 to 6 It is a schematic plan view orthogonal to the helical axis, showing the support structure 2, the lens element 10, and the helical bearing 30.

[0105] Figure 4 The illustration shows a possible helical bearing mechanism consisting of only two helical bearings 37 and 38. The helical bearings 37 and 38 are arranged on opposite sides of the lens element 10.

[0106] First spiral bearing 37 and Figure 2 The spiral bearings 30 shown belong to the same type, in Figure 2 The bearing surfaces 31 and 32 each include corresponding grooves 34 and 35. The first helical bearing 37 includes more than one rolling bearing element 33 to constrain the relative movement of the lens element 10 and the support structure 2.

[0107] Second spiral bearing 38 and Figure 3 The spiral bearings 30 shown belong to the same type, in Figure 3The first bearing surface 31 includes a groove 36, in which the rolling bearing element 33 is located, and the second bearing surface 32 is planar.

[0108] Figure 4 The illustration shows the first bearing surface 31 of the second helical bearing 38 on the support structure 2, but alternatively it can be on the lens element 10. The second helical bearing 38 may include a single rolling bearing element 33 or more rolling elements 33, and primarily increases the constraint on the relative rotation of the lens element 10 and the support structure 2 about the direction of movement (arrow M) of the first helical bearing 37.

[0109] Figure 4 The helical bearing mechanism includes fewer helical bearings (i.e., two) than in the other examples below, which simplifies the construction and reduces the footprint of the actuator 1.

[0110] Figure 5 The illustration shows a possible helical bearing mechanism comprising only three helical bearings 39, 40, and 41. The three helical bearings 39, 40, and 41 are spaced at equal angles around the helical axis H, but alternatively, they may be spaced unequally.

[0111] First spiral bearing 39 and second spiral bearing 40 and Figure 2 The spiral bearings 30 shown belong to the same type, in Figure 2 The bearing surfaces 31 and 32 each include corresponding grooves 34 and 35.

[0112] The third spiral bearing 41 and Figure 3 The spiral bearings 30 shown belong to the same type, in Figure 3 The first bearing surface 31 includes a groove 36, in which the rolling bearing element 33 is located, and the second bearing surface 32 is planar. Figure 5 The illustration shows the second bearing surface 32 of the third helical bearing 41 on the lens element 10, but alternatively, it can be on the support structure 2.

[0113] Each of the three helical bearings 39, 40, and 41 may comprise a single rolling bearing element or more than one bearing element 33. This is possible because the constraints imposed by the three helical bearings 39, 40, and 41, and particularly by the grooves of the first helical bearing 39 and the second helical bearing 40, are sufficient to constrain the movement of the lens element 10 relative to the support structure 2 in degrees of freedom other than helical movement. Since only a single rolling bearing element 33 is used in each of the three helical bearings 39, 40, and 41, therefore... Figure 4Compared to the helical bearing mechanism, the overall dimensions of the three helical bearings 39, 40 and 41, and especially the height of the projection of the three helical bearings 39, 40 and 41 along the helical axis H, are reduced.

[0114] Figure 6 The diagram illustrates a possible helical bearing mechanism comprising only four helical bearings 42 to 45. The four helical bearings 42 to 45 are spaced apart at equal angles around the helical axis H.

[0115] First spiral bearing 42 and Figure 2 The spiral bearings 30 shown belong to the same type, in Figure 2 The bearing surfaces 31 and 32 each include corresponding grooves 34 and 35.

[0116] The second spiral bearing 43, the third spiral bearing 44, and the fourth spiral bearing 45 each have their own... Figure 3 The spiral bearings 30 shown belong to the same type, in Figure 3 The first bearing surface 31 includes a groove 36, in which the rolling bearing element 33 is located, and the second bearing surface 32 is planar. Figure 6 The illustration shows the second bearing surfaces 32 of the second helical bearing 43, the third helical bearing 44, and the fourth helical bearing 45 on the lens element 10, but alternatively, they can be on the support structure 2.

[0117] Each of the second helical bearing 43, the third helical bearing 44, and the fourth helical bearing 45 may include a single rolling bearing element 33, while the first helical bearing 42 includes two rolling bearing elements. This is possible because the constraints imposed by the four helical bearings 42 to 45 are sufficient to constrain the movement of the lens element 10 relative to the support structure 2 in degrees of freedom other than helical movement.

[0118] Figure 7 Another possible helical bearing mechanism is illustrated, which consists of only four helical bearings 46 to 49. The four helical bearings 46 to 49 are spaced at equal angles around the helical axis H, but alternatively, they may be spaced unequally.

[0119] First spiral bearing 46 and second spiral bearing 47 and Figure 2 The spiral bearings 30 shown belong to the same type, in Figure 2 The bearing surfaces 31 and 32 each include corresponding grooves 34 and 35.

[0120] The third spiral bearing 48 and the fourth spiral bearing 49 and Figure 3 The spiral bearings 30 shown belong to the same type, in Figure 3 The first bearing surface 31 includes a groove 36, in which the rolling bearing element 33 is located, and the second bearing surface 32 is planar. Figure 7 The illustration shows the second bearing surface 32 of the third helical bearing 48 and the fourth helical bearing 49 on the lens element 10, but alternatively, it can be on the support structure 2.

[0121] Each of the four helical bearings 46 to 49 may include a single rolling bearing element 33. This is possible because the constraint imposed by the four helical bearings 46 to 49 is sufficient to constrain the movement of the lens element 10 relative to the support structure 2 in degrees of freedom other than helical movement. Since only a single rolling bearing element 33 is used in each of the four helical bearings 46 to 49, therefore... Figure 4 Compared to the spiral bearing mechanism, the overall size of the four spiral bearings 46 to 49, and in particular the height of the four spiral bearings 46 to 49 projected along the spiral axis H, is reduced.

[0122] exist Figures 4 to 5 In each helical bearing mechanism, the bearing surfaces 32 on the lens element 10 are each arranged on the same side (all above or all below) relative to the bearing surfaces 31 on the support structure 2. When the bearing surfaces 31 and 32 extend helically, this means that in Figure 5 In a cross-sectional view perpendicular to the helical axis H, viewed from the outside of the helical axis H, all bearing surfaces 32 on the lens element 10 are to the right of the bearing surface 31 on the support structure 2, and... Figure 6 and Figure 7 In the view, when viewed from outside the helical axis H, all bearing surfaces 32 on the lens element 10 are to the left of bearing surfaces 31 on the support structure 2. Due to this arrangement, all bearing surfaces 31 of the helical bearing on the support structure 2 face the same direction, which facilitates the manufacture of the bearing surfaces 31 using the same tools. Similarly, the manufacturing advantage applies to the bearing surfaces 32 on the lens element 10, which also face the same direction.

[0123] As a result of this arrangement, all the helical bearings 30 need to be loaded in the same helical direction. Therefore, loading of the helical bearings 30 can be provided by applying a loading force along the helical axis H, applying a loading force around the helical axis H, or a combination thereof. In some arrangements described below, this loading force is applied by an elastic biasing element 70 that elastically biases at least one SMA actuator line 60. In the embodiments described below, loading of the helical bearings 30 is provided by a loading mechanism 90 configured to apply a biasing force in a direction at least substantially orthogonal to the helical movement path within the operating range of helical movement.

[0124] Figure 8 Another possible helical bearing mechanism is shown, which is Figure 7The modification of the helical bearing mechanism. Therefore, the helical bearing mechanism consists of only four helical bearings 46 to 49, and the four helical bearings 46 to 49 are spaced apart at equal angles around the helical axis H, but alternatively, they may be spaced unequally.

[0125] As in Figure 7 In the helical bearing mechanism, (a) the first helical bearing 46 and the second helical bearing 47 are connected to... Figure 2 The spiral bearings 30 shown belong to the same type, in Figure 2 The bearing surfaces 31 and 32 each include corresponding grooves 34 and 35, and (b) the third helical bearing 48 and the fourth helical bearing 49 with Figure 3 The spiral bearings 30 shown belong to the same type, in Figure 3 The first bearing surface 31 includes a groove 36, in which the rolling bearing element 33 is located, and the second bearing surface 32 is planar. Figure 8 The illustration shows the second bearing surface 32 of the third helical bearing 48 and the fourth helical bearing 49 on the lens element 10, but alternatively, it can be on the support structure 2.

[0126] like Figure 7 The helical bearing mechanism comprises four helical bearings 46 to 49, each of which may include a single rolling bearing element 33. This is possible because the constraints imposed by the four helical bearings 46 to 49 are sufficient to constrain the movement of the lens element 10 relative to the support structure 2 in degrees of freedom other than helical movement. Since only a single rolling bearing element 33 is used in each of the four helical bearings 46 to 49, the overall size of the four helical bearings 46 to 49, and in particular the height of the four helical bearings 46 to 49 projected along the optical axis, is reduced when each helical bearing has only a single rolling element.

[0127] However, with Figure 7 compared to, Figure 8 The helical bearing mechanism was modified to change the arrangement of bearing surfaces 31 and 32 in each of the bearings 46 to 49, as described below. In the first helical bearing 46, when viewed along the helical axis H, the bearing surface 32 on the lens element 10 is above the bearing surface 31 on the support structure 2; while in the second helical bearing 47, when viewed along the helical axis H, the bearing surface 32 on the lens element 10 is below the bearing surface 31 on the support structure 2. Similarly, in the third helical bearing 48, when viewed along the helical axis H, the bearing surface 32 on the lens element 10 is above the bearing surface 31 on the support structure 2; while in the fourth helical bearing 49, when viewed along the helical axis H, the bearing surface 31 on the lens element 10 is below the bearing surface 32 on the support structure 2.

[0128] This can be understood from the following basis by referring to the bearing constraints on a vertical plane (parallel to the helical axis). The first helical bearing 46 and the third helical bearing 48 prevent the lens element 10 from moving downward, and the second helical bearing 47 and the fourth helical bearing 49 prevent the lens element 10 from moving upward or rotating about the axis between the first helical bearing 46 and the third helical bearing 48.

[0129] As a result of this "over-constrained" arrangement, the helical bearings 46 to 49 do not need to be loaded entirely around the helical axis H in the same helical direction. This is advantageous for the loading of the helical bearings 46 to 49. For example, this arrangement allows loading via a coupling provided by the SMA actuator line 60.

[0130] Figure 9A and Figure 9B These are perspective and cross-sectional views of the actuation device 1 according to certain embodiments of the present invention. Each embodiment is generally similar except that an elastic loading mechanism 90 is provided to replace one of the four helical bearings (i.e., replacing the third helical bearing 48). Figure 8 Examples of implementations.

[0131] The remaining three bearings 46, 47, and 49 are sufficient to constrain the movement of the lens element 10 in five relevant degrees of freedom and guide the lens element 10 along a helical path (also referred to as the "helical movement path") around the helical axis H. This is because the bearings 46, 47, and 49 consist of two "pin" bearings 46 and 47 (where the rolling bearing element 33a is configured to move in grooves 34 and 35 provided in the respective bearing surfaces 31 and 32) and one "slider" bearing 49 (where the rolling bearing element 33b can slide on one of the two bearing surfaces 31 and 32).

[0132] As will be explained in more detail below, the loading mechanism 90 is configured to apply a bias force in a direction at least substantially orthogonal to the path of helical movement within the operating range of the helical movement.

[0133] In a broad sense, the loading mechanism 90 can function in compression, causing it to "push" the relevant portion of the lens element 10, or it can function in tension, causing it to "pull" the relevant portion of the lens element 10. Figure 9A and Figure 9B In this configuration, the loading mechanism 90 operates during compression. Therefore, for example, a biasing force is applied positively to the sliding bearing surface 32. As will be understood, an equivalent biasing force can be generated when the loading mechanism 90 operates during tension and the relative positions of the relevant parts of the support 2 and the lens element 10 are reversed.

[0134] As will become apparent, the loading mechanism 90 is configured to apply a bias force even when the SMA actuator line 60 is not energized (e.g., when the actuator is de-energized).

[0135] Various loading mechanisms 90 can be used to apply bias forces. In the first set of examples (illustrated in Figures 10 to 12), the loading mechanism 90 does not include any bearing elements, such as rolling bearing elements. In the second set of examples (illustrated in Figure 13), the loading device includes bearing elements.

[0136] The loading mechanism 90 can be used with any of the helical bearing mechanisms 20 described herein (see, for example, see...). Figure 3 ).

[0137] Figures 10A to 10D The loading mechanisms illustrated in the diagram each include a flexure 90, which connects between and is attached to each of the support structure 2 and the lens element 10. The flexure 90 is configured to apply a biasing force directly to the lens element and the support structure in a direction orthogonal to the helical movement path within the operating range of the helical movement. The flexure 90 has a planar (or substantially planar) profile and conforms to the profile of the corresponding surface to which it is attached. The flexure 90 can function in compression or tension; for example, the biasing force can be achieved through the flexure's recovery from bending or its resistance to bending.

[0138] exist Figure 10A In the embodiment illustrated in the figure, the flexure 90 includes a first portion 90a, a second portion 90b, and an intermediate portion 90c. In this case, the intermediate portion 90c is a pre-formed (or “assembled”) portion with a predetermined shape. More specifically, the intermediate portion 90c is at an angle to the first portion 90a and the second portion 90b. Therefore, the second portion 90b can be considered as a protrusion relative to the first portion 90a. As shown, the first portion 90a of the flexure can first be attached to the outer surface of the lens element 10. Then, attaching the second portion 90b to the support structure requires elastic deformation of the intermediate portion 90c (e.g., when the protruding second portion 90b is pressed vertically against the support structure 2). When the intermediate portion 90c recovers from this deformation, it pushes the lens element 10 and applies a biasing force in a direction orthogonal to the helical movement path, as indicated by the arrow. Furthermore, the flexure 90 is designed to provide a similar biasing force throughout the entire operating range of the helical movement. Since the biasing force acts in the direction orthogonal to the helical movement of the lens element, the resistance to this helical movement is significantly limited or reduced. Furthermore, since the force is similar throughout the entire operating range of the helical movement, the bearing behavior will be similar, thus contributing to the performance (e.g., controllability) of the actuator 1.

[0139] exist Figure 10B In another embodiment illustrated in the figure, the flexure 90 includes a first portion 90a, a second portion 90b, and an intermediate portion 90c. The first portion 90a and the second portion 90b of the flexure are aligned before assembly. In this embodiment, the intermediate portion 90c includes features that allow an interference fit with the tip of a cantilever 94, which is clamped to the support structure 2. The tip of the cantilever 94 pushes or compresses the first portion 90a and the second portion 90b onto the surfaces of each of the lens element 10 and the support structure 2. The flexure 90 then applies a biasing force directly to the surfaces of the lens element 10 and the support structure 2 in a direction orthogonal to the helical movement path.

[0140] In such Figure 10C In another embodiment illustrated in the figure, the flexure 90 initially comprises a planar profile. As shown, a first portion 90a of the flexure may first be attached to the surface of the lens element 10. Then, attaching a second portion 90b to the support structure requires elastic deformation of the flexure 90 (e.g., when the second portion 90b is pressed vertically against the support structure 2 to preload the flexure 90). As the flexure 90 recovers from this deformation, it applies a biasing force to the lens element 10 in a direction orthogonal to the helical movement path, as indicated by the arrow.

[0141] In such Figure 10D In another embodiment illustrated in the figure, the flexural member 90 is aligned with... Figure 10A The flexural element works in a similar manner. In this embodiment, the flexural element 90 includes a slightly curved profile (such as...) before attachment. Figure 10D (As shown by the dashed line in the diagram). Once the bent flexure 90 is attached to the lens element and the support structure, the bent flexure 90 is straightened. Preferably, a clamp 94 is used to properly deform (straighten) the flexure 90 for attachment. Thus, when the intermediate portion 90c recovers from deformation or straightening, it applies a biasing force to the lens element in a direction orthogonal to the bearing surface 102, as indicated by the arrow.

[0142] Figures 10A to 10D The embodiment illustrated in the figure uses a relatively short flexure. In other embodiments, other forms of flexure, including relatively long flexures, can be used to achieve similar effects.

[0143] For example, such as Figure 11A As illustrated in the plan view, the loading mechanism 90 may include a retaining spring 90 (or in other words, a circular flexure) extending around the helical axis of the helical bearing mechanism. The retaining spring 90 is connected at each end to the support structure 2 and the movable element 10. Once assembled, the retaining spring 90 is in a compressed or stretched state and applies a biasing force orthogonal to the helical movement path.

[0144] Alternatively, such as Figure 11B As illustrated in the plan view, the loading mechanism 90 may include an etched spring flexure 90, which is in a stretched or compressed state when attached to the movable element 10 and the support structure 2. The flexure 90 may have any suitable shape. The flexure 90 may be a coiled spring or a spring molded into the surface of the movable element 10 and / or the support structure 2, rather than being etched. The flexure 90 is connected to the support structure 2 and the movable element 10 at each of its ends. One or both ends of the flexure 90 may be secured or hooked to the corresponding support structure 2 or lens element 10. Once assembled, the flexure 90 is in a stretched or compressed state and applies a biasing force to the lens element 10, which remains similar throughout the helical movement range of the lens element 10, at least in part due to the relatively long length of the flexure 90.

[0145] Alternatively, such a flexure 90 can also be used to create a common electrical connection between the support structure 2 and the lens element 10. The crimped portion 61 for the SMA actuator line 60 (described below) can be mechanically and electrically connected to a common connector and insert or etched attachment on the support structure 2, for example, by laser welding.

[0146] Figures 12A to 12D Another example of loading mechanism 90 is illustrated.

[0147] Figure 12A and Figure 12B The examples illustrated each include an elongated elastic element 90 (e.g., an elastic band, a coiled spring, or a spring formed by molding or etching) attached between the lens element 10 and the support structure 2. The elastic element 90 extends in a direction orthogonal to the helical movement path. Thus, for example, when the elastic element 90 contracts, it applies a biasing force in a direction substantially orthogonal to that path.

[0148] exist Figure 12CIn the example illustrated, the loading mechanism 90 includes a quantity of elastic material 90, such as soft rubber, silicone, or other suitable material. The elastic material 90 is located between and adhered to the respective surfaces 101, 102 of the support structure 2 and the lens element 10. In this example, the elastic material 90 is compressed during operation and pushes against the lens element 10, wherein the direction of the biasing force is at least partially determined by the orientation of the surfaces 101, 102. This pre-compression can be achieved during assembly by introducing the elastic material 90 while the lens element 10 is held in place relative to the support structure 2, such that the surfaces 101, 102 are slightly further separated than during operation. Rolling bearing elements 33 can then be introduced into bearings 46, 47, 49 to move (rotate) the lens element 10 and compress the elastic material 90. The elastic material 90 can function in tension or shear, rather than in compression.

[0149] Figure 12D The loading mechanism 90 shown in the diagram is a magnetic loading mechanism 90. The magnetic loading mechanism 90 includes a first magnetic element 90a mounted to the lens element 10 and a second magnetic element 90b mounted to the support structure 2. The magnetic loading mechanism 90 is configured to apply a biasing force between the lens element 10 and the support structure 2 in a direction orthogonal to the helical movement path within the operating range of the helical movement.

[0150] At least one of the first magnetic element 90a and the second magnetic element 90b includes a magnet. The other of the first magnetic element 90a and the second magnetic element 90b includes a magnet or an iron-containing material, such as stainless steel. Alternatively, the other of the first magnetic element 90a and the second magnetic element 90b may include a magnetically permeable material, such as nickel and cobalt.

[0151] In the depicted embodiment, the first magnetic element 90a and the second magnetic element 90b are configured to attract each other. The portion of the support structure 2 where the second magnetic element 90b is mounted is pushed toward the portion of the lens element 10 where the first magnetic element 90a is mounted. However, in an alternative embodiment, the first magnetic element 90a and the second magnetic element 90b may be configured to repel each other. The portion of the support structure 2 where the second magnetic element 90b is mounted is pushed away from the portion of the lens element 10 where the first magnetic element 90a is mounted. In either case, the magnetic loading mechanism 90 may load a helical bearing.

[0152] The first magnetic element 90a and the second magnetic element 90b each include a surface facing the other of the first magnetic element 90a and the second magnetic element 90b. These two surfaces are opposite each other and separated by a certain gap. The range of the gap between the two surfaces can be kept substantially constant within the operating range of the helical movement. This helps to maintain a constant bias force between the lens element 10 and the support structure 2 within the operating range.

[0153] The two surfaces can be arranged parallel to the helical movement path. The magnetic field lines between the two surfaces can extend substantially orthogonally to the helical movement path, such that the biasing force on the lens element 10 and the support structure 2 is applied in a direction orthogonal to the helical movement path.

[0154] The extent of one of the first magnetic element 90a and the second magnetic element 90b in a direction parallel to the surfaces facing each other (e.g., parallel to the helical movement path) can be greater than the extent of the other of the first magnetic element 90a and the second magnetic element 90b in that direction. Therefore, in the direction along the helical movement path, the extent of one of these surfaces is greater than the extent of the other surface. For example, as... Figure 12D As shown, along the helical movement path, the first magnetic element 90a can be longer than the second magnetic element 90b. Therefore, as the lens element 10 moves along the helical movement path, the ratio of the surfaces of the first magnetic element 90a and the second magnetic element 90b facing each other remains constant. This helps to maintain a constant bias force between the lens element 10 and the support structure 2 within the operating range.

[0155] Figures 13A to 13C Another example of the loading mechanism 90 is illustrated. In each of these cases, the loading mechanism includes a bearing element 90b supported on surface 101 of the support structure 2 and / or surface 102 of the lens element 10. The loading mechanism 90 is preferably located between surfaces 101 and 102.

[0156] Figure 13A A loading mechanism 90 is illustrated. The loading mechanism 90 includes a coiled spring 90a, which is attached at one end to one of the surfaces 101 and applies a biasing force in a direction orthogonal to the other surface 102. A ball bearing 90b is disposed at the free end of the coiled spring 90a and contacts the surface 102, which may include grooves or other suitable features to guide movement of the ball bearing 90b. In other embodiments, another type of bearing element with a circular contact surface may be used instead of the ball bearing 90b. Another type of spring element may also be used instead of the coiled spring 90a.

[0157] Figure 13BAnother loading mechanism 90 is illustrated. In this example, surfaces 101 and 102 are angled relative to each other, thus forming a narrowing gap between them. A coiled spring 90a is configured to apply force to a rolling bearing element 90b (e.g., a ball or roller) in a direction toward the narrower end of the gap. The ball bearing 90b transmits the force to the angled bearing surfaces 101 and 102, which are configured such that the lens element 10 is biased in a direction orthogonal to the helical movement path.

[0158] Figure 13C Another loading mechanism 90 is illustrated. In this embodiment, a rolling bearing element 90b (e.g., a ball or roller) is disposed between two surfaces 101, 102. One (or possibly both) of surfaces 101, 102 comprises a quantity of elastic (e.g., elastomer) material 90a that contacts and is compressed against the rolling bearing element 90b during operation, thereby generating a force transmitted via the rolling bearing element 90b to the other of surfaces 101, 102. Similarly, surfaces 101, 102 are configured such that the lens element 10 is biased in a direction orthogonal to the helical movement path.

[0159] Figure 14 An example of an actuator 1 with a helical bearing mechanism is shown, which is similar to... Figure 6 The spiral bearing mechanism is modified as will now be described. This spiral bearing mechanism comprises four spiral bearings 42 to 45, which are coupled to the structure described above. Figure 6 They are arranged in the same manner. Each of the helical bearings 42 to 45 includes a single rolling bearing element 33, thus providing a total of five constraints. The first helical bearing 42 and... Figure 2 The spiral bearings 30 shown belong to the same type, in Figure 2 The surfaces 31 and 32 of the intermediate bearing each include corresponding grooves 34 and 35. The second spiral bearing 43, the third spiral bearing 44, and the fourth spiral bearing 45 each have... Figure 3 The spiral bearings 30 shown belong to the same type, in Figure 3 The first bearing surface 31 includes a groove 36, the rolling bearing element 33 is located in the groove 36, and the second bearing surface 32 is planar. For example... Figure 6 As shown, the first bearing surface 31 of the second spiral bearing 43, the third spiral bearing 44 and the fourth spiral bearing 45 is illustrated as being located on the lens element 10, but alternatively, it can be on the support structure 2.

[0160] The bearing surfaces 32 on the lens element 10 are each arranged on the same side of the bearing surfaces 31 on the support structure 2 (all above or all below). When the bearing surfaces 31 and 32 extend helically, this means that in the cross-section perpendicular to the helical axis H... Figure 14 In the view, when viewed from outside the helical axis H, all bearing surfaces 32 on the lens element 10 are to the left of the bearing surface 31 on the support structure 2. Due to this arrangement, all helical bearings 42 to 46 need to be in the same helical direction (corresponding to...). Figure 14 (Clockwise rotation of the middle lens element 10) loading.

[0161] To provide this loading, and Figure 6 In contrast, the helical bearing mechanism is modified to include two additional rolling bearings 110, which are helical bearings arranged as follows. Each rolling bearing 110 includes a first bearing surface 111, a second bearing surface 112, and a rolling bearing element 113 (e.g., a ball or roller) disposed between the first bearing surface 111 and the second bearing surface 112. The first bearing surface 111 is movable relative to the support structure 2, and an elastic element 114 is disposed between the first bearing surface 111 and the support structure 2. The elastic element 114 loads the first bearing surface 111 away from the support structure 2, thereby acting as an elastic loading mechanism that elastically loads the first bearing surface 111 against the rolling bearing element 113. Alternatively, the rolling bearing element 110 can be inverted such that the second bearing surface 112 is movable relative to the lens element 10, and the elastic element 114 loads the second bearing surface 112 against the rolling bearing element 113. The additional rolling bearings 110 can have any suitable configuration, including the configuration of the rolling bearing 110 in any of the examples of Figures 9 to 13.

[0162] The additional rolling bearings 110 are arranged in the opposite manner to the helical bearings 42 to 46, such that they are in the same helical direction (corresponding to...). Figure 14 (Clockwise rotation of the middle lens element 10) loads the spiral bearings 42 to 46. As a result, Figure 14 The illustrated helical bearing mechanism is highly balanced and has reduced tolerances, which facilitates manufacturing. Similar to... Figure 6 The spiral bearing mechanism, in which all bearing surfaces 31 on the support structure 2 face the same direction as each other and all bearing surfaces 32 on the lens element 10 face the same direction as each other, facilitates the manufacture of spiral bearings 42 to 46.

[0163] Two additional rolling bearings 110 are shown here, arranged on opposite sides of the lens element 10. More generally, any number of one or more additional rolling bearings 110 can be provided, but more than one additional rolling bearing 110 spaced apart around the lens element 10 is beneficial for balancing forces. Instead of two additional rolling bearings 110, any loading mechanism 90 described with respect to Figures 9 through 13 can be provided.

[0164] In the above example, the helical bearing 30 is a rolling bearing; however, in each case, the helical bearing 30 can be replaced by a sliding bearing. Figures 15 to 18 Two examples of sliding bearings are shown in the figure.

[0165] exist Figure 15 and Figure 16 In the first example shown, the sliding bearing 81 includes an elongated bearing surface 83 located on one of the support structure 2 and the lens element 10. The sliding bearing 81 also includes a protrusion 85 formed on the other of the support structure 2 and the lens element 10, the end of which forms a bearing surface 86 supported on the elongated bearing surface 83. Although two protrusions 85 are shown in this example, any number of one or more protrusions 85 can typically be provided. The elongated bearing surface 83 and the bearing surface 86 are conformal; in this example, both are planar, thereby allowing relative movement of the lens element 10 relative to the support structure 2. Ideally, the elongated bearing surface 83 and the bearing surface 86 have a coefficient of friction of 0.2 or less.

[0166] exist Figure 17 and Figure 18 In the second example shown, the sliding bearing 91 includes a channel 92 located on one of the support structure 2 and the lens element 10, the inner surface of which forms a bearing surface 93. The sliding bearing 91 includes a protrusion 95 formed on the other of the support structure 2 and the lens element 10, the end of which forms a bearing surface 96 supported on the bearing surface 93. Although two protrusions 95 are shown in this example, any number of one or more protrusions 95 can typically be provided. The elongated bearing surfaces 93 and 92, and bearing surface 96, are conformal; in this example, both are planar, thereby allowing relative movement of the lens element 10 relative to the support structure 2. Ideally, the elongated bearing surfaces 93 and 96 have a coefficient of friction of 0.2 or less.

[0167] In each of sliding bearings 81 and 91, the material of bearing surfaces 83, 86, 93, 96 is selected to provide smooth movement and long service life. Bearing surfaces 83, 86, 93, 96 may be integral with the underlying component or may be formed by a surface coating. Suitable materials include, for example, PTFE or other polymer bearing materials or metals.

[0168] In each of the sliding bearings 81 and 91, a lubricant may be provided on the bearing surfaces 83, 86, 93, 96. For example, this lubricant may be a powder or a fluid. Suitable lubricants include: graphite; silicon paste; or low-viscosity oil.

[0169] Although the helical bearing mechanism 20 includes a helical bearing 30, which in the above example is a rolling bearing, another possibility is that the helical bearing mechanism 20 includes at least one flexure extending between the support structure 2 and the lens element 10, for example as... Figure 19 As shown, the helical bearing mechanism 20 includes two flexural elements 50, each flexural element including four flexural members 51, the flexural members 51 having the following characteristics: Figure 20 or Figure 21 The configuration shown. (As shown) Figure 19 As shown, each of the flexural elements 51 pre-deflects along the helical axis H, and as... Figure 20 and Figure 21 As shown, each flexure 51 extends in an arc around the helical axis H. Due to this configuration, the flexure 51 guides the lens element 10 to move helically relative to the support structure 2 around the helical axis H. Figures 19 to 21 The specific number and arrangement of the flexure 51 are not required, and the same function can be provided by other constructions of the flexure (other constructions of the flexure are pre-deflected along the helical axis H and extend in an arc around the helical axis H).

[0170] Figure 22 This is a perspective view of an alternative helical bearing mechanism 20 that includes more than one flexural member 120. Figure 22 Four flexures 120 are shown, although any number of flexures 120 can typically be provided. In this example, the helical bearing mechanism also includes a movable plate 121 mounted on the lens element 10 and a support plate 122 mounted on the support structure 2. The movable plate 121 and the support plate 122 are spaced apart along the helical axis H, and the flexures 120 extend along the helical axis H and are inclined relative to a plane orthogonal to the helical axis H, and are rotationally symmetrical about the helical axis H. With this arrangement, the flexures 120 guide the helical movement of the lens element 10 relative to the support structure 2 about the helical axis H.

[0171] The flexure 120 is integrally formed with the movable plate 120 and the support plate 122. This form of connection is advantageous because it allows the helical bearing mechanism to be manufactured as a single part, for example, in molding, thus providing precise constraints. Therefore, this solution combines precision with low manufacturing costs. That is, in principle, the flexure 120 can be a separate element connected to the lens element 10 and the support structure 2 in any suitable manner.

[0172] The use of SMA actuator lines to rotate lens element 10 will now be described.

[0173] Actuation device 1 includes at least one SMA actuator line 60 for rotating lens element 10. The SMA actuator line 60, or each SMA actuator line 60, is connected between support structure 2 and lens element 10, for example as... Figure 23 and Figure 24 As shown. The SMA actuator line 60 is connected to the support structure 2 and the lens element 10 via a crimp portion 61, which crimps the SMA actuator line 60 to provide mechanical and electrical connection. Figure 23 In this case, the SMA actuator line 60 extends in a plane orthogonal to the helical axis H. Figure 24 In this case, the SMA actuator line 60 extends at an acute angle θ to the plane orthogonal to the helical axis H. The SMA actuator line 60 deviates from the helical axis. Therefore, in Figure 23 and Figure 24 In both cases, the contraction of the SMA actuator line 60 drives the lens element 10 to rotate about the helical axis H. Therefore, Figure 23 or Figure 24 Any of the orientations of the SMA actuator line 60 can be used in any of the arrangements described below.

[0174] Because the helical bearing mechanism 20 guides the helical movement of the lens element 10 relative to the support structure 2 and constrains its movement in other degrees of freedom, the rotation driven by the contraction of the SMA actuator line 60 is converted by the helical bearing mechanism 20 into helical movement of the lens element 10 relative to the support structure 2. Therefore, in addition to the rotational component, the translational component of the lens element 10 relative to the support structure 2 is realized along the helical axis H. As described above, this changes the focal length of the image on the image sensor 3.

[0175] Since the SMA actuator line 60 has the primary purpose of driving the lens element 10 to rotate, the range of the SMA actuator line projected along the helical axis H can be minimized. Therefore, the dimensions of other components of the actuator 1 along the helical axis H are reduced. Typically, the height projected along the helical axis H becomes dependent on the helical bearing mechanism 20, for example, the helical bearing mechanism, which... Figure 23 and Figure 24 The diagram is shown schematically.

[0176] exist Figure 23In this case, when the SMA actuator line 60 extends in a plane orthogonal to the helical axis H, the SMA actuator line 60 has a minimum range projected along the helical axis H, which is essentially the thickness of the SMA actuator line 60. This minimum range is significantly smaller than the range E projected by the helical bearing mechanism 20 along the helical axis H. B However, the SMA actuator line 60 is angled relative to the flexure to allow the desired movement. Therefore, in Figure 23 In the process, the flexural element of the spiral bearing mechanism needs to be at a certain angle to the SMA actuator line 60.

[0177] exist Figure 24 In this case, since the SMA actuator line 60 extends at an acute angle relative to the plane orthogonal to the helical axis H, the SMA actuator line 60 has a greater... Figure 23 In the case of a larger range of projections along the helical axis H, E S However, the range E S This acute angle can be adjusted to fit any desired dimensional constraints, within the range E. S The range E, which is typically smaller than the projection of the helical bearing mechanism along the helical axis H, is usually chosen. B .

[0178] Various arrangements of the at least one SMA actuator line 60 can be used in the actuation device 1, as long as at least one SMA actuator line 60 drives the lens element 10 to rotate relative to the support structure 2. (Reference) Figures 25 to 30 Some examples of possible arrangements of at least one SMA actuator line 60 are as follows. Figures 25 to 30 These are various schematic diagrams of the actuation device 1, including a schematically illustrated connection portion 65, which is part of the lens element 10, and SMA actuator lines 60 connected to the connection portion 65. In each case, the SMA actuator line 60, or each SMA actuator line 60, is connected between the support structure 2 and the lens element 10 in the corresponding orientation shown.

[0179] In the first type of embodiment, the actuating device 1 further includes an elastic biasing element 70 connected between the support structure 2 and the lens element 10, such as Figure 25 As shown. The elastic bias element 70 is typically a spring, as in the example below, but in principle it can be formed from any other element, such as a flexure or a piece of elastic material.

[0180] This resilient biasing element 70 is arranged to resiliently bias at least one SMA actuator line 60. Generally, it is known to use the resilient biasing element 70 with an SMA actuator line, whereby the resilient biasing element 70 applies stress to the SMA actuator line 60 and drives the SMA actuator line 60 to move in the opposite direction to contraction. Therefore, this resilient biasing element 70 can be employed with a single SMA actuator line 60 or more. In the specific case of SMA actuation 1, the resilient biasing element 70 can be arranged in various ways, some of which are shown below.

[0181] Figure 25 An example is shown in which the actuator 1 includes only a single SMA actuator line 60, and an elastic biasing element 70 extends about the helical axis H, thereby providing a force about the helical axis H. Figure 25 In this configuration, the elastic biasing element operates under tension, but alternatively, it can operate under compression, for example, by being arranged side-by-side with the SMA actuator line 60. The use of extending the elastic biasing element 70 around the helical axis H minimizes the range of the elastic biasing element 70 projected along the helical axis H.

[0182] Figure 26 An example is shown in which the actuation device 1 includes only a single SMA actuator line 60, and a resilient biasing element 70 extends parallel to the helical axis H, thereby providing a force along the helical axis H. In this case, the force applied by the resilient biasing element 70 acts in a direction different from that of the SMA actuator line 60, but resilient bias is still provided due to the action of the helical bearing mechanism 20. Figure 26 In this diagram, the helical spring is an elastic biasing element 70, whose axis is shown as parallel to the optical axis. Alternatively, the spring axis may be at an angle to the optical axis.

[0183] Figure 25 and Figure 26 The example shown includes a single SMA actuator line 60, but it can be modified to include more than one SMA actuator line 60 that operates in parallel.

[0184] Figure 27 It shows the corresponding Figure 25This is an example of such a case, but in which the SMA actuator line 60 and the elastic biasing element 70 are replicated on opposite sides of the lens element 10. The SMA actuator line 60 and the elastic biasing element 70 have rotational symmetry about the helical axis, and therefore the SMA actuator line 60 is complementary and drives the lens element 10 to rotate relative to the support structure 2 about the helical axis H in parallel (that is, in the same direction and therefore together). However, since the SMA actuator line 60 is arranged on opposite sides of the helical axis H, the SMA actuator line 60 also provides a translational force on the lens element 10 in opposite directions in a plane orthogonal to the helical axis H. Figure 27 (Left and right in the middle). Therefore, the net translational force applied by the SMA actuator line 60 is minimized, thereby reducing the force applied to the helical bearing mechanism 20.

[0185] In the second type of embodiment, instead of providing an elastic biasing element, the actuation device 1 includes at least one pair of SMA actuator lines 60 arranged to drive the lens element 10 to rotate about the helical axis H in opposite directions. Similar to the known use of opposing SMA actuator lines to provide opposing forces in the translation of a linearly moving object, the pair of SMA actuator lines 60, or each pair of SMA actuator lines 60, applies opposing torques about the helical axis H. Therefore, the pair of SMA actuator lines 60 exerts stress on each other, which can be acted upon by the helical bearing mechanism 20 and drive the lens element 10 to rotate about the helical axis H in opposite directions.

[0186] In the case of SMA actuator 1, at least one pair of SMA actuator lines 60 can be arranged in various ways, some of which are shown below.

[0187] Figure 28 An example is shown in which the actuating device 1 includes a pair of SMA actuator lines 60 arranged on opposite sides of the helical axis H. Therefore, the pair of SMA actuator lines 60 are parallel in a plane orthogonal to the helical axis (i.e., in...). Figure 28 A lateral force is applied to the lens element 10 (from left to right). In this case, the helical bearing mechanism 20 resists the combined lateral force. This is advantageous for the type of helical bearing mechanism 20 that requires loading, when using a helical bearing 30 (such as...). Figure 4 This might be the case when (as in the example).

[0188] Figure 29 An example is shown in which the actuation device 1 includes a pair of SMA actuator lines 60 arranged on the same side of the helical axis H. Although Figure 29The SMA actuator lines 60 are shown side-by-side when viewed along the helical axis H; however, the SMA actuator lines 60 can alternatively overlap each other to reduce the footprint of the actuator 1. Therefore, the SMA actuator lines 60 exert lateral forces on the lens element 10 in opposite directions within a plane orthogonal to the helical axis H (i.e., in...). Figure 29 In this configuration, one SMA actuator line 60 applies force from left to right, while the other SMA actuator line 60 applies force from right to left. Therefore, the net translational force applied to the helical bearing mechanism 20 by the SMA actuator lines 60 is minimized, thereby reducing the force applied to the helical bearing mechanism 20. This may be advantageous for the type of helical bearing mechanism 20 under unfavorable loading conditions, when using the flexural element 51 (e.g., Figure 19 (The example in the text) might be in this situation.

[0189] Figure 30 An example is shown in which the actuation device 1 includes a pair of SMA actuator lines 60 on two adjacent sides of the lens element 10 and at an angle of 90 degrees between them. More generally, the orientation of the SMA actuator lines 60 can be varied such that the angle between them has any size less than 180 degrees, but preferably, when viewed along the helical axis H, this angle is in the range of 70 to 110 degrees. In this case, with Figure 28 Compared to the previous example, the net translational force applied to the helical bearing mechanism 20 by the SMA actuator line 60 is reduced. Figure 30 In the example, the reduction is a coefficient of √2, but this coefficient can be controlled by selecting the angle between the SMA actuator lines. This type of construction is useful for controlling the load applied to the helical bearing mechanism 20. This is advantageous for the type of helical bearing mechanism 20 that requires loading, which may be the case when using the helical bearing 30.

[0190] In general, any form of the helical bearing mechanism 20 described herein, including any helical bearing mechanism or flexural device, can be used with any arrangement of at least one SMA actuator line 60 described herein.

[0191] In all the examples above, the SMA actuator line 60 is driven by the control circuitry implemented in the IC chip 5. Specifically, the control circuitry generates a drive signal for each SMA actuator line 60 and provides the drive signal to the SMA actuator line 60. The control circuitry receives an input signal representing the desired position of the lens element 10 along the optical axis O and generates a drive signal selected to drive the lens element 10 to the desired position. The drive signal can be generated using a resistive feedback control technique, in which the control circuitry 20 measures the resistance of the length of the SMA actuator line 20 and uses the measured resistance as a feedback signal to control the power of the drive signal. This resistive feedback control technique can be implemented as disclosed in any of WO-2013 / 175197, WO-2014 / 076463, WO-2012 / 066285, WO-2012 / 020212, WO-2011 / 104518, WO-2012 / 038703, WO-2010 / 089529, or WO-2010029316, each of which is incorporated herein by reference. Alternatively, the control circuit may include a sensor that senses the position of the lens element 10, such as a Hall sensor that senses the position of the magnet fixed to the lens element 10. In this case, the drive signal uses the sensed position as a feedback signal to control the power of the drive signal.

[0192] Those skilled in the art will understand that, although the foregoing has described what is considered the best mode for carrying out this technology and other modes for carrying out this technology where appropriate, this technology should not be limited to the specific constructions and methods of the preferred embodiments disclosed in this specification. Those skilled in the art will recognize that this technology has a wide range of applications and that embodiments can be modified extensively without departing from any inventive concept defined by the appended claims.

[0193] For example, actuation device 1 may include a non-SMA actuator, such as a voice coil motor (VCM). This may be arranged in any suitable manner, for example, as described in PCT / GB2019 / 053260, which is incorporated herein by reference.

Claims

1. An actuating device, comprising: Support structure; Movable components; A helical bearing mechanism that supports the movable element on the support structure and is arranged to guide the movable element to move helically relative to the support structure along a helical path about a helical axis. An actuation mechanism configured to drive the movable element to rotate about the helical axis, wherein the helical bearing mechanism converts the rotation into the helical movement; as well as An elastic loading mechanism includes an elastic element connected between the movable element and the support structure, the elastic element being configured to apply a biasing force to the movable element only in a direction orthogonal to the helical path within the operating range of the helical movement.

2. The actuation device of claim 1, wherein the elastic element comprises a flexure preloaded to provide the bias force.

3. The actuation device according to claim 2, wherein the flexure is formed of sheet material.

4. The actuation device according to claim 2 or 3, wherein the preloading is achieved by deforming the flexure during assembly of the actuation device.

5. The actuation device according to claim 4, wherein the flexure is pre-formed prior to the assembly.

6. The actuation device of claim 4, wherein the flexure is deformed by being attached to the movable element and / or the support structure or by contacting a clamp attached to the movable element and / or the support structure.

7. The actuation device according to any one of claims 2-3 and 5-6, wherein the flexure is elongated and extends along a tortuous path orthogonal to the helical axis.

8. The actuation device according to any one of claims 2-3 and 5-6, wherein the flexure is elongated and extends along a path orthogonal to the helical axis, and passes through at least a portion of the helical axis.

9. The actuation device according to any one of claims 2-3 and 5-6, wherein the flexure is elongated and extends along a path orthogonal to the helical axis, and passes through at least half of the helical axis.

10. The actuation device according to claim 1, wherein the elastic element comprises an elastic material.

11. The actuation device of claim 10, wherein the elastic element comprises an elastic member fixed to the movable element at one end of the elastic member and fixed to the support structure at the other end of the elastic member.

12. The actuation device of claim 10, wherein the elastic material is located between the surface of the movable element and the surface of the support structure.

13. An actuating device, comprising: Support structure; Movable components; A helical bearing mechanism that supports the movable element on the support structure and is arranged to guide the movable element to move helically relative to the support structure along a helical path about a helical axis. An actuating mechanism configured to drive the movable element to rotate about the helical axis, wherein the helical bearing mechanism converts the rotation into the helical movement; as well as An elastic loading mechanism is configured to apply a biasing force to the movable element only in a direction orthogonal to the helical path within the operating range of the helical movement. The elastic loading mechanism includes an elastic element having a first end and a second end, the first end being attached to one of the movable element and the support structure, and a bearing element being attached to the second end to apply a force to the other of the movable element and the support structure.

14. An actuating device, comprising: Support structure; Movable components; A helical bearing mechanism that supports the movable element on the support structure and is arranged to guide the movable element to move helically relative to the support structure along a helical path about a helical axis. An actuating mechanism configured to drive the movable element to rotate about the helical axis, wherein the helical bearing mechanism converts the rotation into the helical movement; as well as An elastic loading mechanism is configured to apply a biasing force to the movable element only in a direction orthogonal to the helical path within the operating range of the helical movement. The elastic loading mechanism includes: A tapered gap, the tapered gap being located between the surface of the movable element and the surface of the support structure; A bearing element, the bearing element being located within the tapered gap and in contact with the surface of the movable element and the surface of the support structure; and An elastic element, connected to one of the movable element and the support structure, is configured to push the bearing element into the tapered gap to cause the surface of the movable element and the surface of the support structure to separate and generate the biasing force.

15. An actuating device, comprising: Support structure; Movable components; A helical bearing mechanism that supports the movable element on the support structure and is arranged to guide the movable element to move helically relative to the support structure along a helical path about a helical axis. An actuating mechanism configured to drive the movable element to rotate about the helical axis, wherein the helical bearing mechanism converts the rotation into the helical movement; as well as An elastic loading mechanism is configured to apply a biasing force to the movable element only in a direction orthogonal to the helical path within the operating range of the helical movement. The elastic loading mechanism includes: A gap, the gap being located between the surface of the movable element and the surface of the support structure, wherein one of the surfaces of the movable element and the support structure includes a region of elastic material; A bearing element located in the gap and in contact with a region of the elastic material and another surface of the movable element and the support structure, wherein the elastic material is deformed by the bearing element to generate the biasing force.

16. An actuating device, comprising: Support structure; Movable components; A helical bearing mechanism that supports the movable element on the support structure and is arranged to guide the movable element to move helically relative to the support structure along a helical path about a helical axis. An actuating mechanism configured to drive the movable element to rotate about the helical axis, wherein the helical bearing mechanism converts the rotation into the helical movement; as well as An elastic loading mechanism is configured to apply a biasing force to the movable element only in a direction orthogonal to the helical path within the operating range of the helical movement. The spiral bearing mechanism comprises three sets of bearings, and the three sets of bearings and the elastic loading mechanism are spaced at least substantially equidistant from each other around the spiral axis.

17. The actuation device according to any one of claims 2-3, 5-6, and 10-16, wherein the actuation mechanism comprises at least one shape memory alloy actuator wire connected between the support structure and the movable element, in a plane orthogonal to the helical axis or at an acute angle to the plane orthogonal to the helical axis, and arranged to drive the movable element to rotate about the helical axis during contraction, the helical bearing mechanism converting the rotation into the helical movement.

18. The actuation device of claim 17, wherein the at least one shape memory alloy actuator wire is arranged to drive the movable element to rotate less than a quarter full revolution around the helical axis during contraction.

19. An actuating device, comprising: Support structure; Movable components; A helical bearing mechanism that supports the movable element on the support structure and is arranged to guide the movable element to move helically relative to the support structure along a helical path about a helical axis. An actuating mechanism configured to drive the movable element to rotate about the helical axis, wherein the helical bearing mechanism converts the rotation into the helical movement; as well as A magnetic loading mechanism is configured to apply a biasing force to the movable element only in a direction orthogonal to the helical path within the operating range of the helical movement.

20. The actuation device of claim 19, wherein the magnetic loading mechanism comprises a first magnetic element mounted to the movable element and a second magnetic element mounted to the support structure, wherein the first magnetic element and the second magnetic element comprise surfaces facing each other.

21. The actuation device of claim 20, wherein the surfaces of the first magnetic element and the second magnetic element facing each other are arranged parallel to the helical path.

22. The actuation device according to claim 20 or 21, wherein the surfaces of the first magnetic element and the second magnetic element facing each other are separated by a gap, wherein the range of the gap between the surfaces remains substantially constant within the operating range of the helical movement.

23. The actuation device according to claim 20 or 21, wherein one of the first magnetic element and the second magnetic element comprises a magnet, and the other of the first magnetic element and the second magnetic element comprises an iron-containing material.

24. The actuation device according to claim 20 or 21, wherein the extent of one of the surfaces facing each other of the first magnetic element and the second magnetic element is greater than the extent of the other of the surfaces facing each other of the first magnetic element and the second magnetic element.

25. The actuation device according to any one of claims 2-3, 5-6, 10-16 and 18-21, wherein the biasing force is applied when the actuation mechanism is not energized.

26. The actuating device according to any one of claims 2-3, 5-6, 10-16 and 18-21, wherein the helical bearing mechanism comprises one or more of a rolling bearing, a sliding bearing and a liquid bearing.

27. The actuation device according to any one of claims 2-3, 5-6, 10-16 and 18-21, wherein the actuation mechanism comprises a voice coil motor and / or a piezoelectric element, the voice coil motor and / or piezoelectric element being arranged to drive the movable element to rotate about the helical axis upon actuation, the helical bearing mechanism converting the rotation into the helical movement.

28. The actuation device according to any one of claims 2-3, 5-6, 10-16 and 18-21, wherein the movable element is a lens element including at least one lens, and wherein the helical axis is the optical axis of the lens element, and wherein the support structure has an image sensor mounted thereon, the lens element being arranged to focus an image onto the image sensor.

29. The actuation device according to any one of claims 2-3, 5-6, 10-16 and 18-21, wherein the actuation mechanism is configured to apply a driving force upon actuation for driving relative rotation between the movable element and the support structure, wherein the driving force is sufficient to overcome the biasing force.

30. The actuation device according to any one of claims 2-3, 5-6 and 10-14, wherein the biasing force applied by the elastic element is insufficient to cause relative rotation between the movable element and the support structure.

31. The actuation device according to any one of claims 2-3, 5-6 and 10-14, wherein the support structure includes a housing for the actuation device, and the resilient element is attached to the housing.

32. A method of assembling an actuating device according to any one of claims 1-14, the method comprising: The elastic element is attached to one of the movable element and the support structure; as well as The movable element is assembled with the support structure before or after the attachment, wherein the elastic element is configured to apply a biasing force to another of the movable element and the support structure in the assembled actuation device.

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