actuator assembly

Abstract

Actuator assembly (1) comprising: a support structure (2); a movable part (10) movable with respect to the support structure; a bearing mechanism (20) supporting the movable part on the support structure and arranged to guide a helical movement of the movable part with respect to the support structure about a helical axis (H), wherein the bearing mechanism comprises at least one flexure (22) arranged to flex to cause said guiding; and at least one actuator part connected between the support structure and the movable part and arranged to, upon contraction, drive a rotation of the movable part about the helical axis, said rotation being converted by the bearing mechanism into a helical movement about the helical axis, wherein the actuator assembly comprises a resilient portion (41a, 41b) configured not to deform during normal operation of the assembly and such that, when the assembly is subjected to an external load exceeding normal operation, the resilient portion is arranged to deform, thereby allowing the movable part to move with respect to the support structure in a plane normal to the helical axis.

Description

[0001] The present invention generally relates to an actuator assembly in which at least one actuator component drives movement of a movable component relative to a support structure to produce helical movement, and the actuator assembly is adapted to reduce or avoid damage to the assembly during drop testing, and particularly to shape memory alloy (SMA) actuator assemblies. The invention also relates to a method of manufacturing such an actuator assembly.

[0002] Actuator assemblies can be used to drive translational movement of a movable part relative to a support structure. For example, such actuator assemblies can be used in optical devices (such as cameras) to drive translational movement of a camera lens element along its optical axis, for example, to achieve focusing (autofocus, AF) or zooming. Some examples of this type of actuator assembly are disclosed in WO 2007 / 113478. Here, the movable part is a camera lens element supported on a support structure, and an SMA cable is connected at its end to the support structure and hooked onto a hook on the camera lens element to drive translational movement.

[0003] Miniaturization is an important design criterion for many types of actuator assemblies, including SMA actuator assemblies. In many applications, it is desirable to minimize the size of the actuator assembly in the direction of movement. For example, in cases where the actuator assembly includes a lens element that moves along an optical axis, it is desirable to minimize the size along the optical axis.

[0004] WO 2019 / 243849 A1 discloses an exemplary actuator assembly including a helical bearing arrangement that guides a movable part to helical movement relative to a support structure. This helical movement involves rotation about a helical axis and overall translation along the helical axis. An SMA line connects the support structure and the movable part to drive the movable part to rotate about the helical axis. The rotation driven by the contraction of the SMA line is converted into helical movement of the movable part by the helical bearing arrangement. Therefore, the translational movement of the movable part is realized along the helical axis as part of the helical movement.

[0005] The actuator assembly may include a support mechanism disposed between a support structure and a movable component, which guides the movement of the movable component within a desired range of motion. The support mechanism may include multiple flexural elements disposed between the support structure and the movable component, these flexural elements being arranged to flex to allow and guide the movement of the movable component.

[0006] However, even under moderate tensile or compressive loads, flexural elements are susceptible to damage. Excessive tensile or compressive loads can cause flexural elements to stretch or compress inelastically, resulting in permanent damage to the support mechanism. Significant tensile or compressive loads may occur when components (or the equipment to which they belong) undergo drop tests, or if equipment with actuator components is dropped for other reasons or subjected to sudden high lateral forces.

[0007] If the large inertial force generated by this motion is borne by the supporting mechanism, this may lead to damage, such as damage through indentation or irreversible bending or stretching.

[0008] One object of the present invention is to provide an actuator assembly adapted to reduce or avoid damage during drop tests or other impacts that impose loads on the actuator assembly exceeding those of normal operation.

[0009] A first aspect of the invention provides an actuator assembly comprising: a support structure; a movable member movable relative to the support structure; a support mechanism supporting the movable member on the support structure and arranged to guide helical movement of the movable member relative to the support structure about a helical axis, wherein the support mechanism includes at least one flexure arranged to flex to induce the guidance; and at least one actuator member connected between the support structure and the movable member and arranged to drive the movable member to rotate about the helical axis upon contraction, the rotation being converted into helical movement about the helical axis by the support mechanism, wherein the actuator assembly includes an elastic portion configured not to deform during normal operation of the assembly and such that when the assembly is subjected to an external load exceeding the external load of normal operation, the elastic portion is arranged to deform, thereby allowing movement of the movable member relative to the support structure.

[0010] The elastic portion can be configured to deform by compression, extension, flexion, or deformation in any other way.

[0011] Normal operation of the assembly refers to the movement of the movable part relative to the support structure due to the actuation of the actuator component and the deflection of the flexure of the support mechanism. The resilient portion is arranged not to deform due to the force exerted on the support mechanism by the actuation of the actuator component. When the assembly is subjected to an external load exceeding the external load exerted by the actuator component (or, more generally, a force other than the force exerted by the actuator component) – for example, a force exceeding a certain threshold (e.g., exceeding the maximum force exerted by the actuator component) – the resilient portion can deform to prevent or reduce any undesirable deformation and damage to the flexure. Such a force exceeding the threshold may be reached when the actuator assembly is dropped. The resilient portion may deform only during impact events on the actuator assembly, such as when subjected to a drop or other impact.

[0012] The elastic element allows the movable component to move relative to the support structure in ways that are not permitted under normal operation of the support mechanism. Normal operation of the support mechanism allows the movable component to move relative to the support structure along a helical path around the helical axis. When the actuator assembly is subjected to an external load exceeding normal operating limits (abnormal load), such as during drop tests or impacts, the movable component may move away from or deviate from the helical path.

[0013] Preferably, when the actuator assembly is no longer subjected to abnormal loads, the elastic properties of the elastic portion enable the movable part to return to its normal position and normal range of motion.

[0014] The deformation of the elastic portion can be arranged to take precedence over the deformation of the flexure, or over portions of the flexure that flex during normal operation of the actuator assembly. Therefore, when the assembly is subjected to abnormal loads, the elastic portion can protect the flexure or its operating portion from damage.

[0015] The support mechanism may include a movable plate mechanically connected to a movable component and a support plate mechanically connected to a support structure. At least one flexural element may be arranged between the movable plate and the support plate to guide the movable plate to move helically about a helical axis relative to the support plate.

[0016] Preferably, the support mechanism includes multiple flexural elements, such as four or more. This allows for more precise and / or reliable guidance of the movable component relative to the support structure.

[0017] The elastic part can take various forms and can be located in various positions within the actuator assembly.

[0018] The elastic portion can be arranged in mechanical series with the support mechanism. Therefore, the elastic portion can be arranged, for example, between the support mechanism and the movable part (particularly between the movable plate and the movable part of the support mechanism). Alternatively or additionally, the elastic portion can be arranged between the support mechanism and the support structure (particularly between the support plate and the movable part of the support mechanism).

[0019] The elastic portion here can, for example, take the form of a compliant adhesive used to bond the support mechanism to the movable part and / or support structure. Alternatively, the elastic portion can take the form of a spring or other elastic element, disposed between the support mechanism and the movable part and / or support structure. For example, the elastic portion can be formed as an extension of the support mechanism and can be integrally formed with the support mechanism.

[0020] The elastic portion can be integrated into the support mechanism, i.e., incorporated within it. For example, the movable plate of the support mechanism can be formed as an annular member including the elastic portion. The annular member can be connected to a flexure at a first angular position and to a movable component at a second angular position offset from the first angular position. Preferably, the circular annular member is connected to the movable component between (e.g., in the middle) the connection points of the flexure. The portion of the circular annular member between the connection points with the flexure and the connection points with the movable component can be elastic to deform during a drop or other impact event.

[0021] The elastic portion can be arranged in mechanical series with the flexure of the support mechanism. Preferably, the assembly includes multiple elastic portions, each elastic portion being mechanically connected in series with a corresponding flexure among multiple flexures of the support mechanism. The elastic portions can be arranged between each flexure and the movable plate and / or between each flexure and the support plate. Thus, the elastic portions can be arranged between each flexure and the movable component and / or between each flexure and the support structure.

[0022] The elastic portion can be integrally formed with the support mechanism. For example, the support mechanism includes a movable plate, a support plate, and a flexural element, and the elastic portion can be integrally formed from a sheet material such as a metal plate.

[0023] Therefore, a single elastic portion or multiple elastic portions may exist. In the case of multiple elastic portions, these portions can be arranged to deform in different directions relative to each other, enabling the actuator assembly to respond to external loads in different directions. In the case of multiple elastic portions, some, all, or no elastic portions may be arranged to compress when subjected to external loads exceeding normal operating limits, while some, all, or no elastic portions may be arranged to extend under such loads, and some, all, or no elastic portions may be arranged to flex under such loads. The actuator assembly may include any combination of elastic portions arranged to extend, compress, or flex.

[0024] In some embodiments, the resilient portion may be arranged between the support mechanism and the movable component. Therefore, under abnormal loads, the resilient portion allows the movable component to move relative to both the support mechanism and the supporting structure.

[0025] In some embodiments, a resilient portion is arranged between the support mechanism and the supporting structure. Therefore, under abnormal loads, the resilient portion allows the support mechanism and movable components to move relative to the supporting structure.

[0026] In some embodiments, the resilient portion is part of the support mechanism. Therefore, the resilient portion can allow the movable component to move relative to the support structure under abnormal loads within a range different from that typically allowed by the support mechanism during normal operation.

[0027] The support mechanism includes at least one flexible element, and may include multiple flexible elements. Compared with support mechanisms that include, for example, plain bearings or roller bearings, the use of flexible elements in the support mechanism can reduce friction.

[0028] The actuator assembly may include multiple elastic portions, and each elastic portion may be coupled to only one of the flexures. The actuator assembly may also include multiple elastic portions, for example, two elastic portions corresponding to each flexure.

[0029] One or more elastic parts can be arranged to allow a range of motion. In some devices, motion in certain directions or in certain planes may be particularly desirable when the actuator assembly is subjected to abnormal loads. Multiple elastic parts can be set and arranged so that motion in a series of different directions (e.g., along the helical axis or in a plane orthogonal to the helical axis) is allowed by compression, extension or flexure of the multiple elastic parts in different combinations.

[0030] For example, the elastic portion can deform in a plane orthogonal to the helical axis. The elastic portion can be restricted to deforming in a direction along the helical axis. This can reduce the height of the actuator assembly along the helical axis, and is therefore particularly advantageous in compact actuator assemblies, such as those used in mobile devices.

[0031] Alternatively, the elastic portion may be allowed to deform in a direction parallel to the helical axis. The elastic portion may also be restricted to deforming in any direction orthogonal to the helical axis.

[0032] The elastic portions can be arranged to deform to allow the movable component to move in at least two opposite directions. For example, when the elastic portions are arranged at both ends of the flexural member, one of the elastic portions may allow the movable component to move in a first direction, while the other of the elastic portions may allow the movable component to move in a second direction opposite to the first direction.

[0033] Alternatively or additionally, the elastic portion may be arranged to deform to allow the movable component to move in at least two orthogonal directions.

[0034] The elastic portion is configured not to deform during normal operation of the component, but to deform when the component is subjected to an external load exceeding the normal operating load. This can be achieved in various different ways.

[0035] The stiffness of the elastic component can be higher than that of the flexural element of the support mechanism. This prevents or limits deformation of the elastic component during normal operation of the assembly. The stiffness of the elastic component can be selected such that it is allowed to deform under external loads exceeding those of normal operation. Therefore, the deformation of the elastic component during abnormal loading can at least reduce the deformation of the flexural element during abnormal loading, thereby reducing the risk of damage to the flexural element.

[0036] In a preferred embodiment, the elastic portion is preloaded so that it will not deform until it withstands a force exceeding a predetermined amount. In such an embodiment, the stiffness of the elastic portion (once it withstands a force exceeding the predetermined amount) can be less than the stiffness of the flexural member. This may mean that the elastic portion will not be "engaged" until the component withstands a force exceeding the predetermined amount. This ensures that the arrangement of the elastic portion does not affect the normal operation of the component, particularly the normal operation of the support mechanism when guiding the movement of movable parts.

[0037] Preloading can be accomplished in several ways.

[0038] For example, in some mechanisms, the resilient portion can be preloaded by biasing it in a direction opposite to its permissible direction of movement. The resilient portion can be preloaded against the surface of a movable part or against the surface of a supporting structure. Therefore, the resilient portion can engage (i.e., be adjacent to) the movable part or supporting structure during normal operation and can disengage from the movable part or supporting structure during a drop or other impact event.

[0039] In such a mechanism, at least one flexural member in the support mechanism may have a first end portion at one end of the flexural member and a second end portion at the other end of the flexural member relative to the first end portion, and the first end portion and the second end portion may include elastic portions. The first end portion may be configured such that it is biased in a first direction (e.g., toward a movable element), and the second end portion may be configured such that it is biased in a second direction opposite to the first direction (e.g., toward a support structure). The first end portion may be biased against the surface of the movable member, and the second end portion may be biased against the surface of the support structure.

[0040] The end portions may be biased due to fastening to the device, causing the end portions to bend away from their stress-free configuration.

[0041] The end portions can be arranged such that a force that causes tension in the flexure causes one deformation in the end portions, and a force that causes compression in the flexure causes another deformation in the end portions.

[0042] Preferably, the elastic portion can be preloaded in a plane orthogonal to the helical axis. The elastic portion can deform in the plane orthogonal to the helical axis. This can reduce the size of the actuator assembly in the direction along the helical axis, which may be desirable in actuator assemblies for mobile devices such as mobile phones.

[0043] Alternatively, the elastic portion can be preloaded in a direction parallel to the helical axis.

[0044] Alternatively or additionally, the resilient portion can be preloaded by a releasable attachment to the actuator assembly, such that the resilient portion is attached to the actuator assembly under normal operation and is released from the attachment when subjected to a force exceeding a predetermined amount. For example, a magnetic attachment can be provided such that the resilient portion is held by the magnetic force of the attachment, but when the actuator assembly is subjected to a force exceeding that magnetic force, the resilient portion is released and can deform.

[0045] The actuator assembly may also include a guide mechanism arranged to guide one or more of the following back to their normal position after the elastic portion has been compressed or extended: a movable part, a support mechanism, a flexure, or the elastic portion. This allows the actuator assembly to easily return to its normal position after being subjected to abnormal loads. Examples of guide mechanisms include self-centering components, such as holes located on conical protrusions.

[0046] The actuator assembly may further include an end stop arranged to prevent movement of the movable element in at least one direction. A support mechanism may be configured such that the movable element does not contact the end stop within its normal range of motion. A resilient portion may be configured to allow movement of the movable element to contact the end stop when the assembly is subjected to an external load exceeding the external load of normal operation.

[0047] In this mechanism, when a component is subjected to abnormal loads, the resilient portion allows the movable part to move in a controlled manner to contact one or more end stops. The end stops prevent the movable part from moving further in that direction, thus preventing damage to the movable part and / or the support mechanism.

[0048] The actuator assembly may also include a damping element arranged to increase the elasticity of the flexure when the assembly is subjected to an external load exceeding the external load of normal operation. The damping element may be arranged such that the elastic element deforms preferentially over the deformation of the flexure. For example, the damping element may be attached to or form part of the flexure and arranged such that when the flexure is subjected to a large force (causing rapid motion), the elasticity of the combination of the damping element and the flexure increases beyond the elasticity of the elastic element to forces acting in the same direction.

[0049] In any practical combination, the actuator component of this aspect may include some, all, or none of the optional and preferred features described above.

[0050] Another aspect of the present invention provides a camera device comprising: an actuator assembly as described above, including some and preferred features, all and preferred features, or excluding the optional and preferred features of the aspect; and an image sensor fixed relative to a support structure of the actuator assembly; wherein a movable part of the actuator assembly includes a lens assembly having one or more lenses configured to focus an image onto the image sensor.

[0051] The camera device may also include a controller arranged to control the position of the lens assembly relative to the image sensor by controlling the actuator assembly. Therefore, the controller can use the actuator assembly to achieve focusing (such as autofocus, AF) and / or zooming within the camera device.

[0052] Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of an actuator assembly according to an embodiment of the present invention; Figure 2 yes Figure 1 A plan view of the support mechanism for the actuator assembly shown; Figures 3A to 3C The permissible movement in an actuator assembly according to an embodiment of the present invention is schematically illustrated; Figures 4A to 4C A support mechanism used in an actuator assembly according to an embodiment of the present invention is shown; Figures 5A to 5E Several portions of an actuator assembly according to another embodiment of the present invention are shown; Figures 6A to 6C Multiple portions of an actuator assembly according to an embodiment of the present invention are shown; Figure 7 The use of damping in an embodiment of the present invention is illustrated schematically; Figure 8 A portion of a support mechanism forming part of an actuator assembly according to an embodiment of the present invention is shown; Figure 9A and Figure 9B The diagram illustrates a portion of an actuator assembly according to an embodiment of the present invention.

[0053] exist Figure 1 The diagram schematically illustrates an actuator assembly 1 incorporated in a camera device. The actuator assembly 1 includes a support structure 2 having an image sensor 3 mounted thereon. The support structure 2 can take any suitable form, typically including a base 4 to which the image sensor 3 is fixed. The support structure 2 may also support a controller 5. The controller 5 may be an integrated circuit (IC) chip 5.

[0054] The actuator assembly 1 also includes a movable part 10, which in this example includes a lens assembly. The lens assembly includes a lens 11, but alternatively, the lens assembly may include more than one lens. The lens assembly has an optical axis O aligned with the image sensor 3 and is arranged to focus an image onto the image sensor 3.

[0055] Actuator assembly 1 may be a microdevice. In some examples of microdevices, lens 11 (or more than one lens when provided) may have a diameter of up to 20 mm, preferably up to 15 mm, and even more preferably up to 10 mm. However, in alternative embodiments, a larger lens 11 may be used.

[0056] Although actuator component 1 is integrated into the camera device in this example, this is not necessary. In some examples, actuator component 1 may be integrated into an optical device, wherein the movable part 10 includes a lens assembly but no image sensor. In other examples, actuator component 1 may be integrated into a non-optical device type device, wherein the movable part 10 does not include a lens assembly and no image sensor. Examples include devices for depth mapping, facial recognition, game consoles, projectors, and security scanners or haptics.

[0057] Actuator assembly 1 includes support mechanism 20 (in Figure 1 (Schematably shown in the diagram), the support mechanism 20 supports the movable component 10 on the support structure 2. In this embodiment, the support mechanism 20 is arranged to guide the movable component 10 to move helically relative to the support structure 2 about a helical axis H. The movable component 10 can move relative to the support structure 2 along a helical path M. In this example, the helical axis H coincides with the optical axis O, and... Figure 1 The helical movement is indicated by arrow M. Preferably, the helical movement 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 can be constant or vary along the helical movement. Preferably, the helical movement is typically only a small fraction (less than a quarter) of a full turn of the helix.

[0058] The helical motion of the movable component 10, guided by the support mechanism 20, includes a translational component along the helical axis H and a rotational component about the helical axis H. The translational movement along the helical axis H is the desired movement of the movable component 10, for example, when integrated into a camera device, to change the focus of the image on the image sensor 3 and / or change the magnification (zoom) of the image on the image sensor 3. In this example, the rotational movement about the helical axis H is not required for optical purposes, but generally such helical movement is acceptable because rotation of the lens assembly included in the movable component 10 does not change the focus of the image on the image sensor 3.

[0059] Figure 2 A plan view of the support mechanism 20 according to an embodiment of the present invention is shown, that is, along... Figure 1 A plan view of the actuator assembly 1 along axes O and H.

[0060] The support mechanism 20 includes a movable plate 32. The movable plate 32 is mechanically connected to a movable component 10 in the actuator assembly 1. Therefore, the movable component 10 is mounted on the movable plate 32 and is fixed relative to the movable plate 32. The movable plate is connected to each of more than one flexure 22. The support mechanism 20 also includes a support plate 34, which in the described example is formed by five separate gaskets. In the actuator assembly 2, the support structure 2 is mounted to the support plate 34, and therefore the support structure 2 is fixed relative to the support plate 34. Although in Figure 2 The diagram shows a single common movable plate 32 and a separate support plate 34, but in some embodiments, multiple separate movable plates 32 may be present (e.g., one movable plate corresponding to each flexure 22). In some embodiments, a single common support plate 34 may be present. Using a single common movable plate or support plate can make the assembly of the support mechanism easier because the relative positions of the flexures 22 can be fixed.

[0061] The support mechanism 20 includes more than one flexure 22 (or flexure arm 22). The more than one flexure 22 may be arranged equidistantly around the circumference of the movable plate 32 or the movable component 10. In alternative embodiments, such as in an actuator assembly with a rectangular footprint, the flexures may not be arranged equidistantly around the circumference of the movable plate 32 or the movable component 10. In the described example, the support mechanism includes five flexures 22, such that the support mechanism exhibits fivefold rotational symmetry about the helical axis H. However, any number of flexures 22 can generally be provided. In some embodiments, the support mechanism may include four flexures 22. The flexures 22 are generally arcuate, such that they extend around a portion of a circle with a diameter slightly larger than the outer diameter of the movable component 10, and each flexure is attached to the movable plate 32 at a first end 24 and to the support plate 34 at a second end 26.

[0062] The flexure 22 converts the horizontal force applied to the movable part 10 by the actuator components (such as one or more SMA actuator lines (not shown)) into helical motion around the central axis O, H.

[0063] Embodiments of the present invention provide (and typically more) resilient portions within the actuator assembly 1, which are arranged to deform (e.g., compress, extend, and / or flex) when the actuator assembly is subjected to external loads exceeding normal operating conditions (abnormal loads). The resilient portions, or more than one resilient portion, can be arranged in a variety of different ways and can take many different forms. It should be understood that the embodiments described below are intended to illustrate (generally schematically) possible different configurations and mechanisms of the resilient elements, but do not cover every possible implementation.

[0064] In particular, for the purpose of improving efficiency, the elastic portion in many of the following embodiments is schematically depicted as a spring. However, the invention is not limited to the use of springs themselves, and covers any form of elastic element or component.

[0065] Furthermore, this "spring" can take many different forms and can be embodied, for example, in material properties or mechanical configurations.

[0066] Figures 3A to 3C The configuration of a portion of actuator assembly 1 is schematically shown, wherein two preloaded springs 41a, 41b are disposed at opposite ends of one of the flexures 22 of the support mechanism that connects the movable part 10 to the support structure 2. For ease of illustration, Figures 3A to 3C The flexural element 22 in the diagram is shown as a straight line, but it can also be shown as... Figure 2 The diagram shows an arc shape. Both springs 41a and 41b are preloaded so that they will not extend before being subjected to a force exceeding a predetermined threshold.

[0067] Figure 3A The actuator assembly during normal operation is shown, wherein the movable part 10 does not contact the support structure 2. Operation of the support mechanism 20 will guide the movable part 10 to move relative to the support structure 2.

[0068] Figure 3B This illustrates the effect of sudden abnormal forces on the actuator assembly (in Figure 3B The actuator assembly is observed when a force is applied horizontally from the right. The spring 41a, connecting one end of the flexure 22 and the support structure 2, extends preferentially to the stretching of the flexure 22 and has allowed the movable part 10 to move beyond the normal range of movement permitted by the support mechanism to contact the end stop 40b. The end stop 40b is... Figure 3B Part of the support structure 2 on the right side of component 1 as observed in the middle, and prevents the movable part 10 from moving further in this direction.

[0069] Figure 3C This illustrates the effect of sudden abnormal forces on the actuator assembly (in Figure 3C The actuator assembly is viewed from the left side as a horizontal force. In this case, the spring 41b connecting one end of the flexure 22 and the movable member 10 extends preferentially to the compression of the flexure 22, allowing the movable member 10 to move outside the normal range of movement allowed by the support mechanism to contact the end stop 40a. The end stop 40a is... Figure 3B Part of the support structure 2 on the left side of component 1 as observed in the middle, and prevents the movable part 10 from moving further in that direction.

[0070] Generally, in various embodiments, the resilient portion can be configured such that it is mechanically located in one or more of the following locations within the actuator assembly: a) Between the support structure 2 and the support mechanism 20, such that when subjected to abnormal loads, the support mechanism 20 and the movable part 10 move together with respect to the support structure 2. b) Within the support mechanism 20, the support mechanism 20 allows the movable component 10 to move relative to the support structure 2 in a manner that exceeds the normal range of motion allowed by the support mechanism 20 when subjected to abnormal loads. c) Between the support mechanism 20 and the movable part 10, the movable part 10 is movable relative to the support element 20 (and thus relative to the support structure 2) when subjected to abnormal loads.

[0071] Embodiments of some of these mechanisms will now be described; however, it will be understood that many of the concepts presented are of general application and are not limited to a specific configuration or positioning of the resilient portion.

[0072] Figures 4A to 4C A perspective view of an embodiment of the invention is shown. In the described embodiment, the elastic portion 41 is arranged to deform in a plane perpendicular to the helical axis H. This reduces the height of the actuator assembly 1 along the helical axis compared to using an elastic portion 41 that allows deformation along the helical axis H. Figure 4A Only the main components of the support mechanism 20 are shown in the diagram, and many other elements of the actuator assembly (including the support structure 2 and the movable part 10) are omitted for clarity.

[0073] exist Figure 4A In this embodiment, the support mechanism includes more than one elastic portion 41a, 41b, which is disposed at the end of each flexure 22. Each elastic portion 41a is mechanically (rigidly) connected to the support structure 2 at one end via a support plate 32 and to the corresponding flexure 22 at the other end. Each elastic portion 41b is mechanically (rigidly) connected to the movable member 10 at one end via a movable plate 32 (in the illustrated embodiment, the movable plate 32 is formed as an annular member 32) and to the corresponding flexure 22 at the other end.

[0074] The elastic portion 41a is preloaded against the surface 2a of the support structure 2. During normal operation, the elastic portion 41a ensures that the static end of each flexure 22 remains stationary relative to the support structure 2. The elastic portion 41a is positioned and configured to allow movement of the flexure 22 (particularly the static end of the flexure) relative to the support structure under abnormal loads.

[0075] The elastic portion 41b is preloaded against the surface 10a of the movable member 10. During normal operation, the elastic portion 41b ensures that the movable end of each flexure 22 remains stationary relative to the movable member 10. The elastic portion 41b is positioned and configured to allow movement of the flexure 22 (particularly the movable end of the flexure) relative to the movable member 10. The elastic portions 41c and 41d are arranged to deform in a plane orthogonal to the helical axis H.

[0076] By providing elastic portions 41a, 41b on all flexures 22 and at each end of each flexure, the movable plate 32 can be permitted in all directions in the plane (“XY” plane) of the movable plate 32 when the assembly is subjected to abnormal loads. One or more elastic portions 41a, 41b may participate in such permitted movement depending on the exact direction of the applied force.

[0077] Figure 4B and Figure 4C Another embodiment of the elastic portions 41a, 41b is schematically depicted, which allows deformation in a plane perpendicular to the helical axis H. Figure 4B The entire support mechanism 20, connecting the movable part 10 and the support structure 2, is shown. Figure 4C Details of the connection point between the elastic portion 41 and the movable part 10 and the support mechanism 20 are shown.

[0078] like Figure 4C As shown, the elastic portion 41a is pre-biased against the surface 10a of the movable member 10. In the described embodiment, the surface 10a of the movable member 10 against which the elastic portion 41 is preloaded is disposed on a protrusion extending from the movable member 10. During normal operation, the surface 10a remains in direct contact with the support mechanism 20. During an impact event, the elastic portion 41 can deform in a manner that allows the surface 10a to disengage from the support mechanism 20. Therefore, the movable end of the flexure 22 can be allowed to move relative to the movable member 10. This can prevent or reduce deformation of the flexure 22, thereby preventing or reducing damage to the flexure 22 during an impact event.

[0079] Surface 10a can be tilted relative to the helical axis H and relative to a plane orthogonal to the helical axis H. This ensures that surface 10a can remain in contact with the support mechanism 20 when subjected to forces along or perpendicular to the helical axis H. The tilted surface 10a also allows the support mechanism 20 to return to its position after the elastic element 41a has deformed.

[0080] exist Figure 4B and Figure 4CIn this embodiment, the preload force can be achieved by rotating the movable plate 32 of the support mechanism 20 during assembly. This rotation can initially bring the support mechanism 20 into contact with the surface 10a of the movable part 10. Further rotation will cause deformation and preload of the elastic portion 41. The circular ring can then be secured to the movable part 10, for example, using an adhesive.

[0081] Although not shown in detail, the elastic portion 41b is pre-biased against the surface 2a of the support structure 2 in a manner similar to that described with respect to the elastic portion 41a.

[0082] Figures 5A to 5E Other embodiments of the invention are illustrated schematically. For ease of explanation, in Figures 5A to 5E Only a single flexure 22 is depicted in the figure; however, it should be understood that the support mechanism 20 may typically include more than one flexure 22. (See Figures 4A to 4B) Figure 4C Compared to the previous embodiment, the elastic portions 41c and 41d are arranged to deform in a direction parallel to the helical axis H.

[0083] Figure 5A A flexure 22 is schematically depicted between the support structure 2 and the movable part 10. An elastic portion 41 is arranged between the flexure 22 and the movable part 10, particularly between the flexure 22 and a movable plate of the support mechanism mechanically connected to the movable part 10. In the described embodiment, the elastic portion 41 has a higher spring constant than the flexure 22 due to its greater width (particularly the portion of the flexure 22 that flexes during normal operation). The elastic portion can have a sufficiently high spring constant to prevent any substantial deflection during normal operation, but it can also have a sufficiently low spring constant to deflect under impact events (abnormal loads), thereby preventing or reducing damage to the flexure 22. Therefore, a trade-off exists in the stiffness of the elastic portion 41 in this design.

[0084] Figure 5B Another embodiment is schematically depicted. (Compared to...) Figure 5AUnlike the embodiments described, the elastic portion 41 here is preloaded. The support mechanism includes a first elastic portion 41a located at one end of each flexure 22 and a second elastic portion 41b located at the other end of each flexure 22. The first elastic portion 41a can be preloaded against the surface 2a of the support structure 2 (particularly in the direction parallel to the helical axis H). The second elastic portion 41b can be preloaded against the surface 10a of the movable member 10 (particularly in the direction parallel to the helical axis H). The first elastic portion 41a can be preloaded in the direction opposite to the direction in which the second elastic portion 41b is preloaded. In the described example, the first elastic portion 41a may deform due to an impact pushing the movable member 10 in an upward direction, while the second elastic portion 41b may deform due to an impact pushing the movable member 10 in a downward direction.

[0085] Figure 5C and Figure 5D The mechanism of the flexure 22 used in some embodiments of the invention is shown, and how the elastic portion is preloaded by bias is shown. Figure 5C The flexure 22b is shown in its natural, unloaded configuration. The flexure 22b has three zones, with a central zone 25b arranged between two outer zones 32 and 34. Fixing points 24b and 26b are located at the ends of the outer zones for attaching the flexure to the movable element 10 and the support structure 2, respectively.

[0086] Figure 5D The same flexure 22b is shown when the actuator assembly is assembled and the flexure 22b has been attached to the movable element 10 and the support structure 2 by means of fasteners 21 (such as heat stakes) passing through fixing points 24b, 26b.

[0087] As in Figure 5D As can be seen, in order to conform to their positioning relative to the movable element 10 and the support structure 2, the two outer parts 32, 34 are attached from their natural shapes (such as...) by means of fixing points 24b, 26b and attachment to protrusions 31, 33 on the movable element 10 and the support structure 2. Figure 5C (as shown in the diagram) Deformation. This deformation results in a preload on the outer regions 32, 34, causing them to be biased in the direction toward the movable element 10 or the support structure 2.

[0088] Therefore, during normal operation, where the movable element 10 and thus the flexure 22b are subjected to forces below a predetermined level (and below the force required to bias the outer regions 32, 34 into contact with the protrusions 31, 33), the movement of the movable element 10 is guided by the allowable range of movement of the central region 25b of the flexure 22b. Compared with other flexures ( Figure 5DTogether (not shown), this guides the movement of the movable element 10 in the aforementioned spiral manner.

[0089] However, when the actuator device 1 is subjected to lateral forces above a predetermined level, such as during a drop test, these forces are sufficient to cause further bending of one of the outer zones 32, 34, thereby providing different ranges of motion for the movable element 10.

[0090] For example, such as Figure 5E As shown, when the movable element is subjected to such... Figure 5E Under a large force acting horizontally to the right, the outer region 34, which is normally in contact with the support structure 2, is caused to bend further, causing it to detach from the protrusion 33. This bending occurs when the torque of the large force transmitted to the outer region 34 exceeds the biasing force generated by the bending of the outer region 34 in the preloading mechanism. The magnitude of the force required to cause this detachment can be selected by determining the degree of bending of the outer region 34 (and the corresponding outer region 32 at the movable element end of the flexure 22b) during assembly.

[0091] When the outer region 34 of the flexure 22b disengages from the protrusion 33, the movable element 10 can then move laterally in the direction of the applied force until it contacts a portion of the support structure 2, which is configured as an end stop 4. This allows the movable element 10 to contact the end stop 4 before the applied force damages the support mechanism (e.g., by irreversibly stretching the flexure 22b).

[0092] It should be understood that in the opposite direction (such as...) Figure 5E As shown, under a large force acting horizontally to the left, another outer region 32 will disengage from the protrusion 31 on the movable element 10, thereby allowing the movable element 10 to move laterally to the left until it encounters an end stop (not shown) on the support structure 2.

[0093] In alternative mechanisms, instead of preloading the outer regions 32, 34 of the flexure 22b against the movable element 10 and the support structure 2, the outer regions have higher stiffness than the central region 25b. This higher stiffness can be achieved, for example, by making these outer regions thicker than the central region, or by reinforcing them, or by changing or selecting the material. This higher stiffness means that when subjected to the forces required for the normal movement of the movable element 10, the outer regions will not bend or otherwise contribute to the operation of the flexure 22b, but when the movable element 10 and therefore the flexure 22b are subjected to large forces, they bend, thereby allowing additional range of motion, such as allowing the movable element to move laterally to contact the end stops, as... Figure 5E As shown.

[0094] Figures 6A to 6COther embodiments of the invention are shown, schematically depicting alternative ways of forming the elastic portion. Figure 6A In one embodiment, the elastic portion 41 takes the form of a compliant adhesive disposed between the movable part 10 and the support mechanism 20. The stiffness of the compliant adhesive can be selected to prevent deformation during normal operation of the actuator assembly and to allow deformation when the actuator assembly experiences abnormal loads. The compliant adhesive may be disposed in a cavity or gap between the support mechanism 20 and the movable part 10.

[0095] Figure 6B One embodiment is depicted in which the support mechanism 20 includes a spring element (in the form of a separate flexure) connected between the support mechanism 20 and the movable part 10. The spring element may be disposed between the support mechanism and the movable part 10. The stiffness of the spring element may be selected to prevent deformation during normal operation of the actuator assembly and to allow deformation when the actuator assembly is subjected to abnormal loads.

[0096] Figure 6C Another embodiment is depicted, wherein the support mechanism 20 includes a movable plate in the form of a circular annular member, the movable plate including a resilient portion. The circular annular member is connected to a flexure member at a first angular position (labeled "P1") and to a movable member at a second angular position (labeled "P2") offset from the first angular position. The portion of the circular annular member between the connection point with the flexure member and the connection point with the movable member may be resilient to deform during a drop or other impact event.

[0097] In another embodiment (not shown), by providing one or more splits in the flexure arm, the elastic portion is integrally formed within each flexure, such that the flexure is not a single solid portion, but rather has one or more openings when viewed from one side. By reducing the elasticity of the flexure, this one or more splits can effectively create a spring within the flexure to bend in a direction perpendicular to the longitudinal extent of the flexure. By combining with other flexures, this bending can allow one flexure to bend, thereby allowing movement of one or more other flexures that would otherwise compress or stretch the assembly.

[0098] Therefore, in this embodiment, instead of combining elastic portions that effectively protect individual flexural elements from compression or tension, the flexural elements work together to protect other flexural elements from compression or tension.

[0099] In some embodiments, in addition to the elastic portion 41, a damping element 70 may be provided to prevent or reduce undesirable deformation of the flexure 22 during an impact event. This is in Figure 7 There is an illustrative description. Specifically, Figure 7The use of damping gel 70 disposed between the flexure 22 and the support structure 2 is schematically illustrated. When subjected to a sudden large external force, the rapid movement of the flexure 22 / movable element 10 assembly causes the damping gel 70 to exhibit high resistance to the movement. This causes the elastic portion 41 to stretch (or compress), rather than the flexure 22 bearing the load.

[0100] The above embodiments describe certain mechanisms and configurations in which the elastic portion can be preloaded so that it is only allowed to move when the actuator assembly is subjected to a force exceeding a predetermined amount. Figure 8 A mechanism according to another embodiment of the invention is schematically shown, through which such preloading can be provided. Figure 8 In this structure, the flexure 22 (or at least one end of the flexure) is formed of a magnetic material. This end of the flexure 22 is attached to the support structure 2 via a magnet 50 (although the end in question could also be the end attached to the movable part 10). The magnetic force between the magnet 50 and the flexure 22 provides a preload force.

[0101] During normal operation, magnet 50 keeps the flexure firmly attached to support structure 2. Only when the actuator assembly is subjected to a force exceeding the magnetic force will the flexure 22 detach from support structure 2, and then the elastic portion allows the movable element to move beyond its normal range of motion.

[0102] It is also useful if the movable part can return to its normal position, or a position within its normal range of motion, such as the position it was in before experiencing the abnormal load, after the actuator assembly is no longer subjected to the abnormal load. In many cases, the elastic properties of the resilient part are sufficient to return the movable part to such a position. However, in some embodiments, an additional part may be provided, configured to guide the movable part back to such a position.

[0103] Figures 9A to 9B This mechanism, according to another embodiment of the invention, is shown, wherein the flexure 22 has a hole 60 arranged to mate with a conical (or truncated conical) protrusion 61 extending from the surface of the support structure 2. The hole 60 is sized such that it is larger than the narrowest cross-section of the protrusion 61 but smaller than the widest cross-section of the protrusion 61 (which is the point where the protrusion contacts the main part of the support structure 2). When subjected to abnormal loads, the flexure can move upward (e.g., when subjected to abnormal loads). Figure 8 As shown, this allows the hole 60 to have greater freedom of movement around the protrusion 61. When no longer subjected to abnormal loads, the hole 60 can sink back onto the protrusion 61 and be guided back to its original position by the conical shape of the protrusion 61.

[0104] A "hot nail" cap 62 larger than the hole 60 can be provided on top of the protrusion 61 to prevent the flexure 22 from sliding completely off the protrusion 61.

[0105] Embodiments of the present invention generally utilize an actuator component that causes a movable component to move relative to a support structure. The actuator component can be any component capable of generating actuating force, such as a voice coil motor (VCM), a piezoelectric element, or any other motor or actuator. In a preferred embodiment, the actuator component includes at least one SMA wire connected between the support structure and the movable component, and arranged to drive the movable component to rotate about a helical axis during retraction.

[0106] The term "shape memory alloy (SMA) wire" can refer to any element containing an SMA. An SMA wire can have any shape suitable for the purposes described herein. An SMA wire can be elongated and can have a circular or any other shaped cross-section. The cross-section can vary along the length of the SMA wire. It is also possible that the length of the SMA wire (however defined) can be similar to one or more of its other dimensions. An SMA wire can be bendable, or in other words, flexible. In some examples, when connected in a straight line between two elements, the SMA wire can only exert tension to force the two elements together. In other examples, the SMA wire can bend around the element, and the SMA wire can apply force to the element as it tends to straighten under tension. An SMA wire can be beam-like or rigid and capable of applying different forces (e.g., non-tension) to the element. An SMA wire may or may not include one or more materials and / or one or more components that are not SMA. For example, an SMA wire may include a core of SMA and a coating of non-SMA materials. Unless the context otherwise requires, the term "SMA line" can refer to any configuration of an SMA line that functions as a single actuating element, such that the single actuating element can be individually controlled to generate a force acting on the element. For example, an SMA line can comprise two or more sections of an SMA line arranged mechanically in parallel and / or in series. In some mechanisms, an SMA line can be part of a larger segment of SMA line. This larger segment of SMA line can comprise two or more sections that can be individually controlled, thus forming two or more SMA lines.

[0107] Although the above embodiments have described actuator assemblies using SMA wires, those skilled in the art will understand that the features of the described support mechanism and flexure can be readily used with other types of actuator components. For example, each actuator component may be a voice coil motor (VCM) actuator, but may also be other types of actuators, such as piezoelectric actuators, radial motors, or other actuators.

[0108] Those skilled in the art will understand that, although the foregoing has described what is considered the best mode for carrying out this disclosure and other modes for carrying out this disclosure where appropriate, this disclosure should not be limited to the specific configurations and methods of the preferred embodiments disclosed in this specification. Those skilled in the art will recognize that the invention has a wide range of applications and that embodiments can be modified extensively without departing from any inventive concept defined by the appended claims.

Claims

1. An actuator assembly, comprising: Support structure; A movable component, which is movable relative to the support structure; A support mechanism that supports the movable component on the support structure and is arranged to guide the movable component to move helically about a helical axis relative to the support structure, wherein the support mechanism includes at least one flexure member arranged to flex to induce the guidance; and At least one actuator component is connected between the support structure and the movable member, and is arranged to drive the movable member to rotate about the helical axis upon actuation, the rotation being converted into helical movement about the helical axis by the support mechanism during normal operation of the actuator assembly. The actuator assembly includes an elastic portion configured to remain undeformed during normal operation of the actuator assembly, and such that when the actuator assembly is subjected to an external load exceeding the external load of normal operation, the elastic portion is arranged to deform, thereby allowing the movable component to move relative to the support structure.

2. The actuator assembly according to claim 1, wherein, The support mechanism includes a plurality of flexural elements arranged between the movable component and the support structure to guide the movable component to move helically about the helical axis relative to the support structure.

3. The actuator assembly of claim 2, comprising a plurality of elastic portions, each elastic portion being arranged in mechanical series with a corresponding flexure of the support mechanism, each elastic portion being configured to remain undeformed during normal operation of the actuator assembly, and such that when the actuator assembly is subjected to an external load exceeding the external load of normal operation, the elastic portion is arranged to deform, thereby allowing the movable component to move relative to the support structure.

4. The actuator assembly according to claim 3, wherein, The plurality of elastic portions include an elastic portion between each flexure and the support structure and an elastic portion between each flexure and the movable component.

5. The actuator assembly according to any one of claims 1-4, wherein, The elastic portion is part of the support mechanism.

6. The actuator assembly according to any one of claims 1-4, wherein, The elastic portion is integrally formed with the support mechanism.

7. The actuator assembly according to any one of claims 1-4 and 6, wherein, The support mechanism is integrally formed from a sheet metal.

8. The actuator assembly of claim 7, wherein, The support mechanism is integrally formed from a metal plate.

9. The actuator assembly according to any one of claims 1-4, 6 and 8, wherein, The support mechanism includes a movable plate formed as an annular member connected to one end of the flexure, wherein the annular member includes the elastic portion and is attached to the movable member at an angular position offset from the connection with the flexure.

10. The actuator assembly according to any one of claims 1-4, 6 and 8, wherein, The elastic portion is arranged in mechanical series with the flexural element.

11. The actuator assembly according to any one of claims 1-4, 6 and 8, wherein, The elastic portion is arranged in mechanical series with the support mechanism.

12. The actuator assembly according to any one of claims 1-4, 6 and 8, wherein, The elastic portion is arranged between the support mechanism and the movable component and / or between the support mechanism and the support structure.

13. The actuator assembly according to any one of claims 1-4, 6 and 8, wherein, The elastic portion is arranged to deform so as to allow the movable component to move relative to the support structure in a manner not permitted by the normal operation of the support mechanism.

14. The actuator assembly according to any one of claims 1-4, 6 and 8, wherein, The elastic portion is configured to deform in a plane orthogonal to the helical axis.

15. The actuator assembly according to any one of claims 1-4, 6 and 8, wherein, The elastic portion is configured to deform in a direction parallel to the helical axis.

16. The actuator assembly according to any one of claims 1-4, 6 and 8, wherein, The elastic portion is arranged to deform to allow the movable component to move in at least two opposite directions.

17. The actuator assembly according to any one of claims 1-4, 6 and 8, wherein, The elastic portion is arranged to deform to allow the movable component to move in at least two orthogonal directions.

18. The actuator assembly according to any one of claims 1-4, 6 and 8, wherein, The elastic portion is preloaded so that it will not deform until it withstands a force exceeding a predetermined amount.

19. The actuator assembly of claim 18, wherein, The elastic portion is preloaded in a plane orthogonal to the helical axis.

20. The actuator assembly of claim 18, wherein, The elastic portion is preloaded by biasing it in a direction opposite to the direction of movement it is allowed to move.

21. The actuator assembly of claim 18, wherein, The elastic portion is preloaded by the surface of the movable component or by the surface of the supporting structure.

22. The actuator assembly according to any one of claims 1-4, 6, 8 and 19-21, wherein, At least one flexural member in the support mechanism has a first end portion at one end of the flexural member and a second end portion at the other end of the flexural member relative to the first end portion, and the first end portion and the second end portion include the elastic portion.

23. The actuator assembly of claim 22, wherein, The first end portion is formed such that the first end portion is biased toward the movable member, and the second end portion is formed such that the second end portion is biased toward the support structure.

24. The actuator assembly of claim 22, wherein, The first end portion and the second end portion are biased due to being fastened to the actuator assembly, such that the first end portion and the second end portion are bent away from the stress-free configuration of the first end portion and the second end portion.

25. The actuator assembly of claim 24, wherein, The first end portion and the second end portion are arranged such that a force that causes tension in the flexure causes one of the first end portion and the second end portion to deform, and a force that causes compression in the flexure causes the other of the first end portion and the second end portion to deform.

26. The actuator assembly according to any one of claims 18, wherein, The resilient portion is preloaded by being releasably attached to the actuator assembly, the releasable attachment such that the resilient portion is attached to the actuator assembly under normal operation, and the resilient portion is released from the attachment when subjected to a force higher than a predetermined amount.

27. The actuator assembly according to any one of claims 1-4, 6, 8, 19-21 and 23-26, further comprising a guiding mechanism arranged to guide one or more of the following back to a normal position after the elastic portion has deformed: the movable member, the support mechanism, the flexure, or the elastic portion.

28. The actuator assembly according to any one of claims 1-4, 6, 8, 19-21, and 23-26, further comprising an end stop arranged to prevent movement of the movable member in at least one direction, wherein, The support mechanism is arranged such that the movable member does not contact the end stop within its normal range of motion, further wherein the resilient portion is arranged to allow the movable member to move in order to contact the end stop when the actuator assembly is subjected to an external load exceeding the external load of normal operation.

29. The actuator assembly according to any one of claims 1-4, 6, 8, 19-21 and 23-26, further comprising a damping element arranged to increase the elasticity of the flexure when the actuator assembly is subjected to an external load exceeding the external load of normal operation, such that the elastic portion deforms preferentially over the deformation of the flexure.

30. The actuator assembly according to any one of claims 1-4, 6, 8, 19-21, and 23-26, wherein, The actuator component includes at least one SMA line connected between the support structure and the movable component, and is arranged to drive the movable component to rotate about the helical axis during retraction.

31. A camera device, comprising: The actuator assembly according to any one of claims 1-30; and An image sensor, which is fixed relative to the support structure of the actuator assembly; The movable component of the actuator assembly includes a lens assembly having one or more lenses configured to focus an image onto the image sensor.

32. The camera device of claim 31, further comprising a controller arranged to control the position of the lens assembly relative to the image sensor by controlling the actuator components.

Images