CN117561467A - Actuator assembly - Google Patents

Abstract

An actuator assembly, comprising: a static component; a moving member; an intermediate member; a first support means guiding the movement of the intermediate member relative to the stationary member; a second supporting means guiding the movement of the moving member with respect to the intermediate member; and an actuator device arranged to drive movement of the moving part relative to the stationary part; and at least one universal termination located between the static component and the moving component and arranged such that the moving component contacts the static component at a limit of movement of the moving component relative to the static component.

Description

Actuator assembly

FIELD

The present invention relates to actuator assemblies, and in particular to actuator assemblies comprising one or more sections of Shape Memory Alloy (SMA) wire.

Background

For example, in a camera, an actuator assembly may be used to move the lens assembly in a direction perpendicular to the optical axis to provide Optical Image Stabilization (OIS), and/or in a direction parallel to the optical axis to provide Autofocus (AF). In the case where such a camera is to be incorporated into a portable electronic device (such as a mobile phone), miniaturization may be important.

Such actuator assemblies typically include a moving part, an intermediate part, and a stationary part. When used in a camera, the moving part may comprise a lens element and the static part may comprise a camera housing surrounding the lens element. The moving member is movable relative to the intermediate member. The intermediate member is movable relative to the stationary member. Actuator means, such as a multi-segment SMA wire, is used to drive relative movement between the components.

The termination is used to limit the range of relative motion between the moving and intermediate members and between the intermediate and stationary members. The function of these terminations is twofold. First, the termination retains the moving and intermediate components within the housing of the actuator assembly. Second, the termination protects the components joining the different parts from damage. For example, these members may be electrical connectors, SMA actuator wires, ball bearings, or springs, such as flexures. Conventionally, all the terminating portions perform both functions, and therefore all the terminating portions need to be strong enough to withstand the inertia of the moving parts.

SUMMARY

According to a first aspect of the present invention there is provided an actuator assembly comprising: a static component; a moving member; an intermediate member; a first support means (bearing arrangement) guiding the movement of the intermediate part relative to the static part; a second supporting means guiding the movement of the moving member relative to the intermediate member; and actuator means arranged to drive movement of the moving part relative to the stationary part; and at least one universal termination (overlap) located between the static component and the moving component and arranged such that the moving component contacts the static component at a limit of movement of the moving component relative to the static component.

In conventional assemblies, different terminations are used between the moving part and the intermediate part and between the intermediate part and the static part. The termination between the moving part and the intermediate part and the termination between the intermediate part and the static part must be strong enough to transfer the inertia of the moving part to the static part. However, in the present invention, a universal stop is used to limit the movement of the moving part relative to the stationary part. This means that only the universal termination needs to be strong enough to absorb the inertia of the moving part. Other terminations, such as terminations between the moving part and the intermediate part and terminations between the intermediate part and the stationary part, can be designed smaller and more compact, as they do not need to absorb the inertia of the moving part.

The invention is particularly useful in cases where the mass of the moving part is greater or even significantly greater than the mass of the intermediate part. This is typical for actuator assemblies used in cameras, where the assembly is used to move moving parts including lens elements to provide Optical Image Stabilization (OIS) and/or auto-focusing (AF). In such an actuator assembly, any termination between the moving part and the intermediate part need only resist the inertia of the intermediate part. The inertia of the moving part can be absorbed by the larger general purpose termination between the moving part and the stationary part. The universal termination retains the moving part within the housing of the actuator assembly. The termination between the moving part and the intermediate part may be used to protect the means joining the moving part to the intermediate part, the dual function of a conventional termination being assigned to a plurality of different terminations.

The actuator assembly may further comprise at least one intermediate movement termination located between the intermediate member and the moving member and arranged such that the moving member contacts the intermediate member at a movement limit of the moving member relative to the intermediate member. The actuator assembly may further comprise at least one static intermediate termination located between the intermediate member and the static member and arranged such that the intermediate member contacts the static member at a limit of movement of the intermediate member relative to the static member. The moving intermediate termination and the static intermediate termination may define a moving housing of the moving part relative to the intermediate part, or a moving housing of the intermediate part relative to the static part, thereby protecting components (such as FPCs, SMA wires, supports, etc.) connected between these respective parts. As described above, the movement intermediate termination portion does not have to absorb the inertia of the movement portion, and thus can be smaller and weaker than the general-purpose termination portion.

The actuator means may comprise an actuator stage arranged to drive movement of the moving part relative to the intermediate part guided by the second support means. The actuator stage may be connected between the moving part and the intermediate part.

The actuator arrangement may further comprise a second actuator stage arranged to drive movement of the intermediate member relative to the stationary member guided by the first support arrangement. The second actuator stage may be connected between the intermediate member and the stationary member.

The actuator assembly may further comprise (e.g. as an alternative to the second actuator stage) biasing means arranged to bias the movement of the intermediate member guided by the first support member relative to the stationary member towards the central position. The biasing means may allow the intermediate member to move from its central position during an impact event, such as a fall. This provides some flexibility in protecting the components on or between the intermediate part and the moving part (e.g. the support means between the intermediate part and the moving part).

The movement of the moving part relative to the intermediate part guided by the second support means may comprise a translational movement along a predetermined axis or a translational movement along a predetermined axis. Thus, the movement of the moving member relative to the intermediate member may be a translational movement along a predetermined axis or a helical movement about a predetermined axis. The predetermined axis may be an optical axis of the lens fixed relative to the moving member. In the case where the assembly is used in a camera, this may provide autofocus capabilities.

The movement of the intermediate member relative to the stationary member, guided by the first support means, may be a translational movement orthogonal to the predetermined axis. This movement may provide OIS when the assembly is used with a camera.

The movement of the intermediate member relative to the stationary member, guided by the first support means, may be a rotational movement about two orthogonal axes perpendicular to the predetermined axis. This movement may provide OIS when the assembly is used with a camera.

The actuator arrangement may comprise a single actuator stage arranged to drive relative movement between any two of the moving, intermediate and stationary components. This may provide movement in multiple directions with fewer components. This is useful where miniaturization is important.

The single actuator stage may be configured to independently drive movement of the moving part relative to the intermediate part guided by the second support means and movement of the intermediate part relative to the stationary part guided by the first support means.

The actuator assembly may further comprise third support means guiding the movement of the moving part relative to the stationary part.

The movement of the moving part relative to the intermediate part guided by the second support means may be a helical movement about a predetermined axis, the movement of the intermediate part relative to the stationary part guided by the first support means may be a translational movement orthogonal to the predetermined axis and/or a rotational movement about a line parallel to the predetermined axis, and the movement of the moving part relative to the stationary part guided by the third support means may be a translational movement along the predetermined axis and/or a translational movement orthogonal to the predetermined axis.

The movement of the moving part relative to the intermediate part guided by the second support means may be a translational movement orthogonal to the predetermined axis, and the movement of the intermediate part relative to the stationary part guided by the first support means may be a helical movement about the predetermined axis.

The actuator means may comprise at least one shape memory alloy SMA wire. In particular, the or each actuator stage may comprise at least one shape memory alloy wire.

The universal termination is configured to limit translational movement (e.g., along one or more orthogonal axes, preferably three orthogonal axes) of the moving component relative to the stationary component and/or to limit rotational movement (e.g., about one or more orthogonal axes, preferably three orthogonal axes) of the moving component relative to the stationary component.

The universal termination may include at least one surface on the static component that is configured to engage (at a movement limit) a substantially conformal surface on the moving component so as to limit movement.

The moving part may comprise a lens element having an optical axis. The optical axis may be a predetermined axis.

The static component may comprise a shield extending around the lens element, the intermediate component and the actuator means, and the at least one universal termination may be provided at least in part by the shield.

The mass of the intermediate member may be less than the mass of the moving member.

According to a second aspect of the present invention there is provided an actuator assembly comprising: a static component; a moving member; an intermediate member; a first support device guiding movement of the intermediate member relative to the stationary member; a biasing means arranged to bias movement of the intermediate member relative to the stationary member, guided by the first support member, towards a central position; a second supporting means guiding the movement of the moving member relative to the intermediate member; and actuator means arranged to drive movement of the moving member relative to the intermediate member.

In some conventional actuator assemblies, such as cameras with Auto Focus (AF) but without Optical Image Stabilization (OIS), the intermediate component may be fixedly attached to the stationary component. Any impact that causes the moving part to move must be transmitted through the intermediate part. However, in a second aspect of the invention, the intermediate member is able to move on the first support means, allowing some of the impact energy to be dissipated. The biasing means provides a lightweight mechanism for restoring the intermediate member, and thus the moving member, to its central position. The device also allows the use of a universal termination between the moving part and the static part to further limit the impulse that must be transferred through the components of the intermediate part during impact.

The actuator means may comprise at least one shape memory alloy wire.

The moving part may comprise a lens element. The static component may comprise an image sensor.

The lens element has an optical axis and the second support means may guide movement of the moving part relative to the intermediate part along the optical axis and the first support means may guide movement of the intermediate part perpendicular to the optical axis.

The stationary part may comprise a shield extending around the lens element, the intermediate part and the actuator means, and at least one universal termination may be provided between the shield and the moving part, the at least one universal termination being arranged such that the moving part contacts the shield at a limit of movement of the moving part relative to the stationary part.

For a better understanding, embodiments of the invention will now be described by way of non-limiting example with reference to the accompanying drawings, in which:

FIG. 1 illustrates an actuator assembly employing a conventional stepped termination arrangement;

FIG. 2 illustrates an actuator assembly employing a universal termination in accordance with the present invention;

FIG. 3 illustrates an alternative embodiment of the actuator assembly of FIG. 2;

FIG. 4 illustrates another alternative embodiment of the actuator assembly of FIG. 2;

FIG. 5 illustrates another alternative embodiment of the actuator assembly of FIG. 2;

FIG. 6 illustrates an actuator assembly including a biasing mechanism in accordance with the present invention;

FIG. 7 illustrates an alternative embodiment of the actuator assembly of FIG. 6 including a universal termination;

FIG. 8 illustrates an actuator assembly employing a universal termination in accordance with the present invention;

FIG. 9 illustrates an alternative embodiment of the actuator assembly of FIG. 8;

FIG. 10 illustrates an example of the actuator assembly of FIG. 8 in an exploded view;

FIG. 11 illustrates an example of the actuator assembly of FIG. 9 in an exploded view;

FIGS. 12A and 12B illustrate an embodiment of the actuator assembly of FIG. 5 including a ball termination; and

fig. 13A and 13B show a concept of reducing the risk of rolling bearing dishing.

In order to enable a better understanding of the present invention, fig. 1 illustrates an actuator assembly 1 employing conventional, stepped-arrangement terminations 61 to 64. Fig. 2 illustrates an actuator assembly 2 according to the present invention, in which actuator assembly 2 universal terminations 71 to 73 are used.

The two actuator assemblies 1, 2 comprise a stationary part 10, a moving part 20 and an intermediate part 30. It should be understood that the use of the labels "static" and "moving" herein is merely for the purpose of illustrating that one component may move relative to another component. In practice, the stationary component 10 may move (e.g., within a device incorporating the actuator assembly) and the moving component may be stationary (e.g., stationary within a device incorporating the actuator assembly) so long as the moving component is movable relative to the stationary component. The stationary part may also be referred to as a support structure and the moving part may also be referred to as a movable part.

In the illustrated example, the actuator assembly 1, 2 is arranged for a camera. To this end, the actuator assembly 1, 2 comprises an image sensor 11 located on the stationary part 10 and a lens element 21 supported by the moving part 20. The lens element 21 focuses light on the image sensor 11 to form an image. The moving part 20 supporting the lens element 21 may be regarded as a lens carrier. The image sensor 11 may be a Charge Coupled Device (CCD) or a Complementary Metal Oxide Semiconductor (CMOS) device. In alternative embodiments, the image sensor 11 may be positioned on the intermediate member 30. In a further alternative embodiment, the image sensor 11 may be fixed relative to the moving part 20 and the lens element 21 may be fixed relative to the stationary part 10 or relative to the intermediate part 30. In general, the image sensor 11 and/or the lens element 21 need not be provided.

The moving part 20 is movable relative to the intermediate part 30 and the intermediate part 30 is movable relative to the stationary part 10 along the support means 41, 42. The first support means 41 guide the movement of the intermediate member 30 relative to the static member 10. In fig. 1 and 2, the movement is a translational movement orthogonal to the predetermined axis. The predetermined axis may be an axis of movement of the moving member 20 relative to the intermediate member 30. The predetermined axis may also be referred to as the main axis. In the case where the moving part 20 includes the lens element 21, as in the illustrated example, the predetermined axis may be an optical axis O defined by the lens element 21. Thus, in the actuator assembly 1, 2, if the optical axis O is considered as the z-axis in the xyz-coordinate system, the intermediate component 30 can be moved along the x-axis and/or the y-axis relative to the stationary component.

The second support means 42 guide the movement of the moving part relative to the intermediate part. In fig. 1 and 2, the movement includes a translational movement along a predetermined axis (e.g., optical axis O). The translational movement may be entirely linear or may be helical (i.e., the moving member 20 may rotate about a predetermined axis as it moves along the predetermined axis). An example of the helical motion is described in more detail below in connection with fig. 9.

The actuator assembly 1, 2 further comprises actuator means arranged to drive the movement of the moving part 20 relative to the stationary part 30. Thus, in the illustrated example, the actuator arrangement comprises a first actuator stage 51 and a second actuator stage 52. The first actuator stage 51 is arranged to drive the movement of the intermediate member 30 relative to the stationary member 10, guided by the first support means 41. Thus, the first actuator stage 51 in the illustrated example drives movement along the x-axis and/or the y-axis. This movement may be used to provide Optical Image Stabilization (OIS) in the camera. The second actuator stage 52 is arranged to drive the movement of the moving part 20 relative to the intermediate part 30 guided by the second support means 42. Thus, the second actuator stage in the illustrated example drives movement (e.g., translational or helical movement) along the z-axis parallel to the optical axis O. This movement may be used to provide Autofocus (AF) in the camera.

The first and second actuator stages 51, 52 may each include at least one Shape Memory Alloy (SMA) wire. Contraction of at least one SMA wire will exert a force between the respective components 10, 20, 30, thereby causing movement. Multiple segments of SMA wire may be used to provide translation and/or rotation in a desired direction. For example, the first actuator stage 51 may comprise four SMA wires arranged as described in WO2013175197, which WO2013175197 is incorporated herein by reference. The second actuator stage 52 may comprise one or more SMA wires arranged as described in WO2007113478, WO2017134456 or WO2019243849, each of which is incorporated herein by reference.

The stationary part 10 may include a protective housing to protect the moving part 20 and the intermediate part 30. In the illustrated actuator assembly 1, 2, arranged for use in a camera, the stationary part 10 comprises a shield 12 extending around the moving part 20 (and the lens element 21), the intermediate part 30 and the actuator means 51, 52. The shield may comprise holes to enable external light to be received by the lens element 21.

Referring to fig. 1, the comparative actuator assembly 1 includes a plurality of stepped stops 61 to 64, the stops 61 to 64 being arranged to limit the range of motion of the moving member 20 and the intermediate member 30. The stops 61 and 62, arranged in stages, limit the movement of the moving part 20 in the horizontal (x or y) and vertical (z) directions, respectively, with respect to the intermediate part 30. Although only illustrated as stopping movement towards the image sensor 11 or to the right of the figure (from the perspective of the viewer), it will be appreciated that there may be an additional termination limiting movement of the moving part 20 to the left of the figure; an additional termination remote from the image sensor 11; and/or additional terminations into or out of the plane of the figure. The hierarchically arranged stops 63 and 64 limit the movement of the intermediate part 30 relative to the static part 10 in the horizontal (x or y) and vertical direction (z), respectively. It should also be understood that only a limited set of terminations is illustrated and that other terminations may be used to limit movement in both directions along each axis.

Consider the case where an impact (e.g., an impact on the right side of the shield 12) moves the moving member 20 to the right in fig. 1, forcing the intermediate member 30 to contact the stationary portion 10 to the right as well. In this case, the impulse from the mass of the moving part 20 will pass through the termination 61 between the moving part 20 and the intermediate part 30, through the intermediate part 30 and then also through the termination 63 between the intermediate part 30 and the stationary part 10. This means that the two terminating portions 61, 63 need to be large enough to absorb the impulse of the mass of the moving part 20 without the minimum risk of damaging the terminating portions. This also means that the intermediate member needs to be made strong enough to withstand the stress of the impulse, so that the impulse is transferred between the terminating portions 61, 63. If the impact is to the left, the second support means 42 must also be strong enough to transfer the impulse from the mass of the moving part 20.

Thus, the termination serves to protect the component from damage during impact and to limit the range of motion of the component (such as moving part 20) within the housing of assembly 3. Conventional actuator assemblies use a stepped termination between the moving part 20 and the intermediate part 30 and between the intermediate part 30 and the static part 10. In this stepped arrangement, in the event of an impact forcing the moving part 20 to move, the impulse from the mass of the moving part 20 will pass the termination between the moving part 20 and the intermediate part 30. The impulse then passes through the intermediate member 30 and then also through the termination between the intermediate member 30 and the static portion 10. This means that all the hierarchically arranged terminations need to be large enough to withstand the impact of the mass of the moving part 20. This also means that the intermediate member 30 needs to be made strong enough to withstand the stress of the impulse, so that the impulse is transferred between the hierarchically arranged terminations. Similarly, components such as the second support 42 must also be able to withstand the impulse caused by the mass of the moving part 30.

In typical use, such as in the case of using the actuator assemblies 1, 2 in a camera, the mass of the moving part 20 is greater than the mass of the intermediate part 30. This means that in the conventional terminator arrangement of fig. 1, the components connecting the moving part 20 and the intermediate part 30 must be particularly strong to withstand the impact discussed above. Even in the case where the mass of the moving member 20 is smaller than or equivalent to the mass of the intermediate member 30, the ending parts 63, 64 between the intermediate member 30 and the static member 10 need to be strong enough to absorb the impact due to the combined mass of the moving member 20 and the intermediate member 30.

Unlike the stepped termination arrangement of fig. 1, in the present invention the actuator assembly 2 comprises at least one universal termination between the moving part 20 and the static part 10. The universal termination is arranged such that the moving part 20 contacts the static part 10 at the limit of movement of the moving part 20 relative to the static part 10. For the purposes of this application, the term termination is understood to refer to the combination of contact areas (or termination surfaces) on two components that contact each other at the limit of relative movement. The stop surface is the surface of the two parts that engage first when one part is moved towards the other. For example, the universal termination may include a termination surface on the moving part 20 and a termination surface on the static part 10. The two stop surfaces may engage to limit movement of the moving part 20 relative to the stationary part 10 at the limit of movement between the stationary part and the moving part. Thus, the universal termination receives an impulse from the mass of the moving part 20 (rather than the intermediate part 30 or the means connecting the intermediate part 30 to the moving part 20).

Arrangement of universal termination

Fig. 2 illustrates an embodiment of an actuator assembly 2 having universal terminations 71 to 73. In this example, the stationary part 10 is formed with protrusions 13 to 15 extending towards the moving part 20. The surfaces of the protrusions 13 to 15 facing the moving member 20 form part of the universal termination portions 71 to 73. For emphasis, the surfaces are shown with thicker lines in the figures, but it should be understood that the universal terminations 71 to 73 may simply be unaltered surfaces of the protrusions 13 to 15. These surfaces of each universal termination 71-73 may be configured to engage with a substantially conformal surface on the moving member 20 to limit movement of the moving member 20. In the illustrated embodiment, the substantially conformal surface (with which the illustrated surfaces of universal terminations 71-73 engage) is part of the outer surface of lens carrier/moving component 20.

The common termination 72 restricts movement of the moving member 20 along the optical axis O in a direction away from the image sensor 11. The common termination 73 restricts movement of the moving member 20 along the optical axis in a direction toward the image sensor 11. Thus, the universal stops 72, 73 limit movement of the moving member 20 along the optical axis. The universal termination 71 limits movement of the moving member 20 perpendicular to the optical axis O, i.e. movement in the x or y direction. For clarity only one termination 71 is shown to limit movement perpendicular to the optical axis, in this case to the right of the figure. It will be appreciated that the actuator assembly 2 may include other general stops to limit movement to the left of the figure and into or out of the plane of the figure. In general, the actuator assembly 2 may include at least one universal termination configured to limit one-, two-, or three-dimensional translational movement of the moving component 20 relative to the static component 10 and/or to limit rotational movement of the static component 20 about a line parallel to a predetermined axis (which may be the optical axis O). One or more universal terminations may be provided at least in part by the shield 12, as in the illustrated embodiment, wherein universal terminations 71 and 72 are provided by the surface of the shield 12.

In the illustrated embodiment, the actuator assembly 2 further includes intermediate stops 61, 62, and 65, the intermediate stops 61, 62, and 65 limiting movement of the moving member 20 relative to the intermediate member. The intermediate termination is similar to the terminations 61, 62 of the actuator assembly 1 of fig. 1, but need not be designed to transfer impact from the moving part 20 to the static part 10. The intermediate stops 62 and 65 limit movement along the optical axis O. The intermediate termination 61 limits movement perpendicular to the optical axis O, in this case towards the right in the figure. Other intermediate stops may be used to limit movement to the left of the figure, or into or out of the plane of the figure, but are not shown for clarity. The intermediate stops 61, 62 may be specially configured to protect elements between the moving part 20 and the intermediate part 30, such as electrical connections or support means (including ball bearings or flexures).

Alternatively or additionally, the actuator assembly 2 may include one or more static intermediate stops that limit movement of the intermediate member 30 relative to the static member 10 in one or more dimensions. The static intermediate terminations may be similar to terminations 61, 63 shown in fig. 1, but need not be designed to resist impact from the moving part 20. Thus, the actuator assembly 2 may also include an intermediate termination between the intermediate member 30 and the static member 10. Such intermediate termination may be specially provided to protect elements between the static component 10 and the intermediate component 30, such as electrical connections or support means (including ball bearings or flexures). The universal termination between the static part 10 and the moving part 20 may be arranged such that the intermediate termination between the moving part 20 and the intermediate part 30 and the intermediate termination between the static part 10 and the intermediate part 30 may not be engaged at the same time.

In other embodiments, a dedicated intermediate termination (i.e., a surface specifically designed to contact first when the intermediate member moves relative to the stationary member or relative to the moving member) may be omitted.

Considering again the case of an impact moving the moving member 20 to the right in the figure, the actuator assembly 2 of fig. 2 is now being referred to. The universal termination 71 between the moving part 20 and the stationary part 10 (in a specific direction of movement) is such that the intermediate termination 61 between the moving part 20 and the intermediate part 30 (in a specific direction of movement) cannot be engaged simultaneously with the intermediate termination between the intermediate part 30 and the stationary part 10 (in a specific direction of movement). The universal termination 71 is designed such that the intermediate member 30 does not contact the stationary member 10 and the moving member 20 simultaneously in the direction of movement (in the x-direction in the depicted case) limited by the universal termination 71. Specifically, the distance between the termination surfaces of the universal termination 71 along the axis of movement is less than the sum of the distances between the moving member 20 and the intermediate member 10 and between the intermediate member 20 and the static member 10 along the axis of movement (as is the case with other universal terminations). This means that the impulse of the acceleration of the moving part 20 is not transmitted through the intermediate part 30. Instead, the impulse from the mass of the moving part 20 passes through the universal termination 71. This means that the impulse through the intermediate termination 61 is only as large as that required to accelerate the mass of the intermediate member 30, not as large as that required to accelerate the moving member 20.

Thus, the intermediate termination 61, and similarly any other components between the moving member 20 and the intermediate member 30 (e.g., the second support means 42), may be made smaller and lighter. The intermediate member 30 itself need not be as strong as conventionally, but can be made smaller and lighter. This is particularly beneficial when the actuator assembly is used in a portable device, such as a camera or smart phone, where reduced size and mass is desirable. The general termination 73 may also be beneficial to the design of the first support means 41. There may also be a benefit of reducing tolerances during AF and OIS integration if the lens holder/moving part 20 is available for aligning OIS.

Note that in fig. 2, the distance between the surfaces of the intermediate termination 61 is smaller than the distance between the termination surfaces of the universal termination 71. In general, any relative distance may be used as long as the universal termination 71 engages before the intermediate member 30 contacts the stationary and moving members. In other words, the distance between the end surfaces of the universal end 71 is smaller than the sum of the distances between the intermediate member 30 and the stationary member and between the intermediate member 30 and the surface of the intermediate end between the moving member 20.

In fig. 2, the universal termination 71 to 73 is formed in part by the surfaces of the protrusions 13 to 15 extending from the static component 10. However, in other embodiments, the moving member 20 may be formed with protrusions. Fig. 3 shows this alternative embodiment of the actuator assembly 2. In fig. 3, the protrusions 22, 23 extend from the moving part 20 to reduce the distance between the static part 10 and the moving part 20. The protrusion 22 reduces the distance parallel to the optical axis O. The protrusion 23 reduces the distance perpendicular to the optical axis O. In the embodiment of fig. 3, the protrusions 13, 14 on the static part 10 in fig. 2 are omitted. The universal terminations 71, 72 are still partly formed by the surfaces of the static part 10, but these surfaces are now substantially continuous with the adjacent surfaces of the static part 10. In this embodiment, the universal termination 71 limits movement perpendicular to the optical axis O when the moving member 20 is moved far enough to the right in the figure that the end surface of the projection 23 engages the universal termination 71. Similarly, the universal termination 72 limits movement parallel to the optical axis when the end surface of the projection 22 engages the universal termination 72.

In the illustrated embodiment, the universal termination 73 is still formed by the protrusion 15 of the static component 10. However, any of the universal stops 71-73 (including any additional universal stops to limit movement and/or rotational movement in both the x-axis and y-axis directions) may be formed by protrusions on the stationary component 10 or arranged to engage protrusions on the moving component 20. The remaining features of fig. 3 are substantially the same as those of fig. 2 discussed above. Similarly, protrusions may be provided on the moving part and the stationary part to form the termination. In general, there is no need to provide a distinct protrusion, but rather the termination surface may simply be formed by surfaces on the individual components that contact first when the components are moved toward each other in a particular direction.

Fig. 4 shows a further alternative embodiment of the actuator assembly 2. In fig. 4, the universal terminations 71, 72 are combined into a combined universal termination 74. The combined universal termination 74 is arranged to limit movement of the moving part in both directions. In the illustrated embodiment, the combined universal termination 74 limits movement parallel to the optical axis O (away from the image sensor 11) and perpendicular to the optical axis O (on the right side of the figure). In other embodiments, the combined universal termination 74 may limit movement of the moving member 20 in more than two directions. For example, it may restrict movement out of the plane of the figure. In general, any number of the universal terminations discussed above with respect to fig. 2 or 3 may be combined into one or more combined universal terminations 74. The combined universal termination 74 may be formed by a protrusion on the static component 10 or may be arranged to engage with a protrusion on the moving component 20, as described above with respect to fig. 2 and 3. The remaining features of fig. 4 are substantially the same as those of fig. 2 discussed above.

Tilting of intermediate parts

Fig. 5 shows a further alternative embodiment of the actuator assembly 2. The embodiment of fig. 5 may generally correspond to the embodiment described with reference to fig. 2 to 4, except that the first support means 41 guide the rotational movement or tilting of the intermediate member 30 relative to the stationary member 10. The first actuator stage 51 may be adapted accordingly. The first support means 41 and the first actuator stage 51 may be as described in WO2010029316 or WO2011104518, each of WO2010029316 or WO2011104518 being incorporated herein by reference. The actuator assembly 2 may include a universal termination 71, the universal termination 71 limiting rotation of the moving member 20 relative to the stationary member 10 about one or more axes orthogonal to a predetermined axis (e.g., an optical axis).

Specifically, the intermediate member 30 (and the moving member 20) can be inclined with respect to a predetermined axis. The embodiment of fig. 5 is substantially similar to the embodiment of fig. 2, except that the movement of the intermediate member 30 relative to the stationary member 10, guided by the first support means 41, is a rotational movement about a point on a predetermined axis, rather than a translational movement along the predetermined axis. In particular, the rotational movement may be about one axis or two orthogonal axes perpendicular to the predetermined axis. In the illustrated embodiment, the predetermined axis is an optical axis O. This provides tilting of the intermediate member 30 relative to the optical axis O. Tilting may be limited to a single axis, such as the x-axis or the y-axis (where z is parallel to the optical axis O), or may be about multiple axes. In the illustrated embodiment, the image sensor 11 is supported on the intermediate member 30 such that the image sensor 11 is tilted together with the lens element 21. Tilting may be used to provide Optical Image Stabilization (OIS) in the camera. The second support means 42 guide the movement of the lens element 21 along the optical axis O to provide Autofocus (AF).

The universal termination 71 is modified with respect to fig. 2 to limit rotational movement of the moving member 20 about a point on a predetermined axis. In this case, the surface forming the universal termination 71 is angled relative to the optical axis such that the surface forming the universal termination 71 is substantially conformal to the surface of the moving component 20 at the expected limits of motion of the moving component 20. One or more other universal stops, including stops 72, 73 and stops not shown, limit movement to the left of the figure, or into or out of the plane of the figure, may also be adapted to limit rotational movement of the moving member 20. As will be appreciated, the number of universal terminations accommodated in this way will be related to the number of axes about which the first support means 41 is allowed to move. In general, a large universal termination may be provided that completely surrounds the moving part 20 (in a plane perpendicular to the optical axis). As with the embodiment of fig. 3, any protrusion may be provided on the moving part 20 instead of the stationary part 10 as shown. In general, it is not necessary to provide a distinct protrusion. For a universal termination that limits rotation of the moving member 20, the corresponding surfaces of the protrusions on the moving member 20 may be shaped such that these surfaces are parallel to a predetermined axis (e.g., optical axis O) at the intended rotational limit of the moving member 20. In this case, the corresponding universal termination may be substantially continuous with the surrounding surface of the static component 10. In other words, the surface of the protrusion on the moving member 20 may be angled such that the corresponding universal endpoint may be flat (like the termination 71 in fig. 3).

Offset device between intermediate part and static part in place of actuator stage

Fig. 6 illustrates an alternative embodiment of an actuator assembly 3 according to the invention. The actuator assembly 3 may generally correspond to the actuator assembly 1 described in relation to fig. 1, except that the biasing means 81 are provided instead of the actuator stage 51. The embodiment of fig. 6 does not include universal terminations 71 to 73. Fig. 7 depicts another embodiment combining the embodiment of fig. 6 with universal terminations 71 to 73.

The actuator assembly 3 comprises a stationary part 10, a moving part 20 and an intermediate part 30. The moving part 20 is movable relative to the intermediate part 30 and the intermediate part 30 is movable relative to the stationary part 10 along the support means 41, 42. A detailed description of these components of the actuator assembly 3 of fig. 1-5 is provided above, and for brevity, repetition will be avoided. It should be appreciated that although fig. 6 depicts the support device 41 guiding translational movement, the support device 41 may alternatively guide rotational movement or tilting, as described with respect to fig. 5.

The actuator assembly 3 further comprises an actuator device 52, the actuator device 52 being arranged to drive the movement of the moving part 20 relative to the stationary part 30. The actuator device 52 may correspond to the arrangement described in relation to fig. 1 and 2. The actuator device 52 may include one or more SMA wires. The actuator means 52 are arranged to drive the movement of the moving part 20 relative to the intermediate part 30 guided by the second support means 42. Thus, the second actuator stage in the illustrated example drives movement in the z-direction parallel to the optical axis O. This movement may be used to provide Autofocus (AF) in the camera. By moving the moving part 20 relative to the intermediate part 30 (the intermediate part 30 is attached to the stationary part via the first support 41), the actuator device 52 moves the moving part 30 relative to the stationary part 10.

In contrast to the actuator assembly 1, 2 of fig. 1-5, the actuator assembly 3 further comprises biasing means 81, the biasing means 81 being arranged to bias the movement of the intermediate member 30 relative to the static member 10, the static member 10 being guided towards the central position by the first support 41 member. The center position may be a center translational position or a center rotational position. In contrast to the actuator assembly 1 of fig. 1, there may be no actuator stage 51 between the intermediate part 30 and the static part 10 in the actuator assembly 3. Thus, if an impact causes the intermediate member 30 to move from its default central position, the biasing device 81 provides a force to automatically return the intermediate member 30 to its central position. This ensures that the horizontal (perpendicular to the optical axis O) position of the lens element 21 is quickly restored to its central position coincident with the image sensor 11. The biasing means 81 may be formed of any suitable biasing material, such as one or more springs. The biasing means 81 avoids any shock being absorbed only by the second support means 42 and/or the intermediate termination between the moving part 20 and the intermediate part 30, thereby reducing the risk of damaging these elements during a shock event such as a drop.

The actuator assembly 3 may be particularly useful in cameras with Autofocus (AF) but without active Optical Image Stabilization (OIS). The biasing means 81 may provide a small, low weight mechanism for maintaining the horizontal positioning of the lens element 21 without restricting control of the movement of the lens element 21 along the optical axis. Reducing the size and weight of components is particularly important for use in portable devices. In some embodiments, the biasing device 81 may also be used to connect the terminals of the SMA wires of the actuator device 52 to the static component 10 to enable the transmission of control signals to actuate the SMA wires. In some embodiments, an FPC may be used to connect the terminals of the SMA wires to the static component 10.

In some conventional autofocus actuator assemblies, the intermediate member 30 remains fixed relative to the stationary member 10 (i.e., without the first support device 41). The ball bearing race is used to allow the moving member 20 to move relative to the intermediate member 30 to provide autofocus. During the impact, the rigidity of the connection between the intermediate part 30 and the static part 10 means that the entire impulse of the mass of the moving part 20 has to be transferred to the components of the intermediate part 30. The intermediate member 30 and the components connecting the intermediate member 30 and the moving member 20 must be designed to withstand such an impulse. In contrast, the first support means 41 and the biasing means 81 of the actuator assembly 3 allow the intermediate member 30 to move in the impact, dissipating some of the impulse of the moving member 20. This arrangement also enables the use of a universal termination between the moving part 20 and the static part 10 to limit the movement of the moving part 20.

As previously mentioned, the universal termination serves to protect the component from damage during an impact and to limit the range of motion of the component (such as moving part 20) within the housing of assembly 3. Conventional actuator assemblies use a stepped termination between the moving part 20 and the intermediate part 30 and between the intermediate part 30 and the static part 10. In this stepped arrangement, in the event of an impact forcing the moving part 20 to move, the impulse from the mass of the moving part 20 will pass the termination between the moving part 20 and the intermediate part 30. The impulse then passes through the intermediate member 30 and then also through the termination between the intermediate member 30 and the static portion 10. This means that all the hierarchically arranged terminations need to be large enough to withstand the mass impulses of the moving part 20. This also means that the intermediate member 30 needs to be made strong enough to withstand the stress of the impulse, so that the impulse is transferred between the hierarchically arranged terminations. Similarly, components such as the second support 42 must also be able to withstand the impulse caused by the mass of the moving part 30.

The embodiment of the actuator assembly 3 shown in fig. 6 may comprise a conventional stepped termination arrangement as described in relation to fig. 1. Alternatively, the actuator assembly 3 may comprise at least one universal termination arranged to contact the moving part 20 at the limit of movement of the moving part 20 relative to the stationary part 10. The universal termination may correspond to the universal termination described with reference to the embodiment of any one of figures 2 to 5. The universal termination receives impulses from the mass of the moving part 20, not from the intermediate part 30 or the means connecting the intermediate part 30 to the moving part 20.

Fig. 7 illustrates an embodiment of the actuator assembly 3 of fig. 6, additionally having universal terminations 71 to 73. In the described embodiment, the universal terminations 71 to 73 correspond to those described in relation to fig. 2. Thus, the actuator assembly 3 of fig. 7 may generally correspond to the actuator assembly 2 of fig. 2, except that the actuator stage 51 is replaced by a biasing means 81. In the actuator assembly 3, there may be no actuator stage 51 between the intermediate member 30 and the static member 10. In general, the universal termination 71 to 73 of the embodiment of fig. 7 may take the form described with respect to any of fig. 2 to 5. Thus, the at least one universal termination may be configured to limit one-, two-or three-dimensional translational movement of the moving part 20 relative to the static part 10 and/or to limit rotational movement (tilting) of the moving part 20 about an axis parallel or orthogonal to the predetermined axis (which may be the optical axis O). One or more universal terminations may be provided at least in part by the shield 12, as in the illustrated embodiment, wherein universal terminations 71 and 72 are provided by the shield 12.

As shown, the actuator assembly 2 may optionally include intermediate stops 61, 62, and 65 that limit movement of the moving member 20 relative to the intermediate member 30 and/or intermediate stops (not shown) that limit movement of the intermediate member 30 relative to the stationary member 10. The intermediate termination may be similar to the stepped termination described with respect to fig. 1, but need not be designed to transfer impact from the moving part 20 to the static part 10. The intermediate termination may be as described with respect to fig. 2-5.

Single stage actuator with multiple degrees of freedom

Fig. 8 shows an alternative actuator assembly 4. The actuator assembly 4 uses a single stage actuator to (independently) produce movement of the moving member 20 parallel and perpendicular to a predetermined axis. The actuator assembly 4 may be considered as an embodiment of the actuator assembly 2 described above. The single stage actuator may be arranged to apply a force between the moving part 20 and the stationary part 10. In contrast to the embodiments of fig. 2 to 5, no actuator stage may be provided between the intermediate member 30 and the static member 10. In contrast to the embodiment of fig. 7, a single stage actuator may be arranged to move the moving member 20 in multiple degrees of freedom, e.g. along a predetermined axis and transverse to the predetermined axis.

The actuator assembly 4 comprises a stationary part 10, a moving part 20 and an intermediate part 30. A detailed description of these components is provided above with respect to fig. 1 and 2, which will be omitted here for brevity.

The moving part 20 is movable relative to the intermediate part 30 and the intermediate part 30 is movable relative to the stationary part 10 along the support means 41, 42. The first support means 41 guide the movement of the intermediate member 30 relative to the static member 10. In fig. 8, this movement is a helical movement about a predetermined axis. In the case where the moving part 20 includes the lens element 21, as in the illustrated example, the predetermined axis may be an optical axis O defined by the lens element 21. The first support means 41 is configured such that rotation of the intermediate member 30 about the predetermined axis causes translation of the intermediate member 30 along the predetermined axis. Such coupled rotation and translation produces a helical motion. In some embodiments, the first support means is a flexible support means comprising one or more flexible arms arranged to convert rotational movement into translational movement along a predetermined axis.

The second support means 42 guide the movement of the moving part 20 relative to the intermediate part 30. In fig. 8, the movement includes a translational movement perpendicular to a predetermined axis (e.g., optical axis O). The second support means 42 may guide movement along the x-axis and/or the y-axis taking into account an xyz coordinate system with the z-axis parallel to the optical axis O. The second support means 42 are configured such that rotation of the moving part 20 about a predetermined axis results in rotation of the intermediate part 30. Thus, any rotation of the moving member 20 also causes rotation of the intermediate member 30 as the moving member 20 is free to translate relative to the intermediate member 30.

The actuator assembly 4 further comprises actuator means 53, the actuator means 53 being arranged to drive relative movement between two of the moving part 20, the intermediate part 30 and the stationary part 10. The actuator device 53 comprises a single actuator stage configured to drive movement perpendicular to the predetermined axis and parallel to the predetermined axis. In the illustrated embodiment, the actuator device 53 is connected between the stationary part 10 and the moving part 20. The actuator means 53 are operable to drive a translation of the moving part 20 relative to the intermediate part 20 and the static part 10 in a direction perpendicular to the predetermined axis, which translation is guided by the second support means 42. The translation may be used to provide Optical Image Stabilization (OIS) in the camera.

The actuator device 53 is further operable to drive the moving member 20 in rotation about a predetermined axis (e.g., optical axis O). When the actuator means 53 drive the mobile part 20 in rotation, the second support means 42 rotate the intermediate part 30 about the predetermined axis as well. The first support means 41 configured to guide the helical movement convert the rotation of the intermediate member 30 into a translation of the intermediate member 30 along a predetermined axis. The second support means 42 allow the mobile part 20 to translate along a predetermined axis also together with the intermediate part 30. Thus, only a single stage actuator device 53 connected between the stationary part 10 and the moving part 20 is able to drive movements parallel and perpendicular to the predetermined axis. Translation of the moving part 20 along the optical axis may be used for auto-focusing in a camera.

The actuator means 53 comprises at least one Shape Memory Alloy (SMA) wire. In particular, a 4 wire SMA device may be used, as discussed in more detail in WO2013175197, WO2013175197 is incorporated herein by reference. Contraction of at least one SMA wire will exert a force between the respective parts 10 and 20, causing the moving part 20 to translate or rotate relative to the static part 10.

The stationary part 10 may include a protective housing to protect the moving part 20 and the intermediate part 30. In the illustrated actuator assembly 4 arranged for use in a camera, the stationary part 10 comprises a shield 12 extending around the moving part 20 (and the lens element 21), the intermediate part 30 and the actuator means 51, 52. The shield may comprise holes to enable external light to be received by the lens element 21.

Unlike conventional stepped termination arrangements, in the actuator assembly 4, the static part 10 comprises at least one universal termination arranged to contact the moving part 20 at the limit of movement of the moving part 20 relative to the static part 10. The universal termination receives an impulse from the mass of the moving part 20 (rather than from the intermediate part 30 or the means connecting the intermediate part 30 to the moving part 20).

Fig. 8 illustrates an actuator assembly 4 comprising universal terminations 71 to 73. The universal termination may be configured and arranged as discussed with respect to the embodiments of any of fig. 2-7. In the example described, the universal termination corresponds substantially to the termination in fig. 2, in that the static part 10 is formed with protrusions 13 to 15 extending towards the moving part 20. The surfaces of the protrusions 13 to 15 facing the moving member 20 form common terminating portions 71 to 73. In general, the actuator assembly 4 may include at least one universal termination configured to limit one-, two-, or three-dimensional translational movement of the moving member 20 relative to the stationary member 10 and/or to limit rotation of the moving member 20 relative to the stationary member 20 about any one of three perpendicular axes. One or more universal terminations may be provided at least in part by the shield 12, as in the illustrated embodiment, wherein universal terminations 71 and 72 are provided by the shield 12.

As discussed with respect to the previous embodiments, the actuator assembly 4 may also include intermediate stops 61, 62 that limit movement of the moving member 20 relative to the intermediate member 30, or intermediate stops (not shown) that limit movement of the intermediate member 30 relative to the support structure 10. These intermediate terminations may be similar to the stepped terminations between the moving component 20 and the intermediate component 30 used in conventional actuator assembly arrangements (such as in fig. 1), but need not be designed to transfer impacts from the moving component 20 to the static component 10.

Although the embodiment of fig. 8 uses a helical motion between the intermediate member 30 and the static member 10, the movement of the moving member 20 relative to the intermediate member 30, generally guided by the second support means 42, or the movement of the intermediate member 30 relative to the static member 10, guided by the first support means 41, may be a helical movement about a predetermined axis. For example, in the embodiment of fig. 8, the functions of the first support means 41 and the second support means 42 may be interchanged.

Fig. 10 illustrates a specific embodiment of the actuator assembly 4 of fig. 8. Fig. 10 illustrates an exploded perspective view of the actuator assembly 4. For clarity, the universal termination portions 71 to 73 are not illustrated in fig. 10. The embodiment of fig. 10 is a version of the embodiment discussed in relation to fig. 26 to 28 of GB2005573.6, which is incorporated herein by reference, modified to incorporate the general purpose termination 71 to 73 discussed above.

The actuator assembly 4 takes the form of a single stage, four SMA wire actuator assembly. The actuator assembly 4 may be used to effect three-dimensional translational movements Tx, ty and/or Tz of the moving part 20 without attempting to constrain the rotation Rz of the moving part 20 about the optical axis O (parallel to the main axis z).

The actuator assembly 4 includes a moving part 20, a static part 10, and an intermediate part 30, the intermediate part 30 mechanically coupling the moving part 20 to the static part 10. The actuator assembly 4 also includes an implementation of a 4-wire SMA actuator arrangement. The 4-wire actuator device includes four segments of SMA wires 53-1, 53-2, 53-3, 53-4. Each segment of SMA wire 53-1, 53-2, 53-3, 53-4 is attached to a respective point on the moving and static parts 20, 10. Contraction of one or more of the SMA wires 53-1, 53-2, 53-3, 53-4 drives translational or rotational movement of the moving part 20 relative to the static part 10. The actuator arrangement is discussed in more detail in GB2005573.6, GB2005573.6 being incorporated herein above. In particular, the actuator assembly is discussed with respect to fig. 3 of that document.

The static component 10 comprises a base plate 101 in the form of a ring having a rectangular outer periphery and a circular inner periphery. The main axis z extends perpendicular to the base plate 101. The first axis x and the second axis y are perpendicular to the predetermined axis z, and the second axis y is different from the first axis x. In fig. 10, the first axis x and the second axis y are perpendicular to each other.

A drive device (not shown) is attached between the moving part 20 and the static part 10 to drive translational movement of the static part 20 along the x-axis or the y-axis. The drive means further drive the rotation about a predetermined axis z.

The actuator assembly 4 comprises a first support configured to generate a movement of the moving part 20 along the main axis z towards or away from the static part 10 in response to a torque applied by the driving means around the main axis z. The first support provides this function by guiding a helical movement [ Tz, rz ] around and along the main axis z, by coupling a rotation Rz around a predetermined axis z with a translation Tz along the main axis z. The rotation Rz of the first support about the predetermined axis z will correspond to the rotation Rz of the first part 24 about the predetermined axis z relative to the second part 25.

In the example shown in fig. 10, the first support takes the form of a spiral flexible member formed by four straight spiral beam portions 41-1, 41-2, 41-3, 41-4 extending from the intermediate member 30 to respective pads 102-1, 102-2, 102-3, 102-4 at the free ends. The pads 102-1, 102-2, 102-3, 102-4 are secured to the base plate 101 of the static component 10 at respective attachment locations 103-1, 103-2, 103-3, 103-4. In this way, the first support mechanically couples the static component 10 to the intermediate component 30.

The actuator assembly 4 further includes a second support assembly 42, the second support assembly 42 mechanically coupling the moving member 20 to the intermediate member 30 and configured to guide the movement Tx and/or Ty of the first member 24 relative to the third member 34 along the first axis x and/or the second axis y. The second support assembly 42 should also constrain the rotation Rz of the moving member 20 relative to the intermediate member 30 about the primary axis z.

In the example shown in fig. 10, the second support assembly 42 takes the form of the non-rotating universal support discussed in relation to fig. 12 of GB2005573.6, GB2005573.6 being incorporated herein by reference.

When the actuator means apply a force corresponding to a lateral movement (force perpendicular to the predetermined axis z) to the moving part 20, i.e. a movement having components Tx and/or Ty along the respective first and second axes x, y, the movement is constrained by first support means in the form of helically flexible arms 41-1, 41-2, 41-3, 41-4, but guided by second support means 42. Thus, the response to the application of a force corresponding to the lateral movement of the actuator device will be mainly the lateral movement of the moving part 20 relative to the stationary part 10 accommodated and guided by the second support 42. However, if the actuator device additionally or alternatively applies a torque about the predetermined axis z, the second support 42 is substantially restricted from rotating about the main axis z. Thus, the second support 42 will transmit substantially all of the applied torque to the first support in the form of flexible arms 41-1, 41-2, 41-3, 41-4. In response to the applied torque, the first support will perform a helical movement [ Tz, rz ] along and about a predetermined axis z. In this manner, the actuator assembly 4 may provide OIS functionality based on lateral movement Tx and/or Ty, and Autofocus (AF) functionality based on helical movement [ Tz, rz ] using a single stage actuator comprising four segments of SMA wire 53-1, 53-2, 53-3, 53-4. The two functions may be substantially independent in that the actuator means is capable of applying torque and lateral force substantially independently over at least a portion of the range of motion.

The first actuator assembly 4 of fig. 10 may further comprise third support means in the form of planar support means formed by the sliding of the moving part 20 with respect to the parts of the second support means 42 not fixed to the moving part 20.

Fig. 9 illustrates an alternative embodiment of the actuator assembly 4. In the present embodiment, the arrangement of the one or more common terminating portions 71 to 73 is similar to that of fig. 8. However, in fig. 9, the functions of the first support means 41 and the second support means 42 are interchanged with respect to fig. 8. In fig. 9, the first support means 41 guide the movement of the intermediate member 30 with respect to the stationary member 10. The movement guided by the first support means 41 is a translational movement orthogonal to the predetermined axis and/or a rotational movement about a line parallel to the predetermined axis (which may be the optical axis O). The second support means 42 guide the movement of the moving part 20 relative to the intermediate part 30. The movement of the second support means 42 is a helical movement about a predetermined axis. The support means 42 transform a rotation of the intermediate member 30 relative to the mobile member 20 about a predetermined axis (and vice versa) into a translational movement along the predetermined axis, similar to the operation of the first support 41 of fig. 8.

The actuator assembly 4 of fig. 9 further comprises third support means 43, the third support means 43 guiding the movement of the moving part 20 with respect to the stationary part 10. In the illustrated embodiment, the movement of the moving part 20 relative to the static part 10, guided by the third support means 43, is a translational movement along a predetermined axis and/or a translational movement perpendicular to the predetermined axis. The third support means 43 substantially prevent the mobile part 20 from rotating about a predetermined axis with respect to the static part 10. This arrangement is particularly useful when the moving part 20 comprises a lens element 21. In fact, any lens element 21 will have non-uniformities on its surface. Therefore, it is desirable to maintain the rotational position of the lens element 21 with respect to the image sensor 11. The third support means 43 maintains this rotational position even when the intermediate member 30 rotates.

In fig. 9, the actuator device 53 is connected between the intermediate member 30 and the stationary member 10, instead of between the moving member 20 and the stationary member 10 as in fig. 8. The actuator means are configured to drive a translational movement of the intermediate member 30 perpendicular to the predetermined axis with respect to the static member 10, which translational movement is guided by the first support means 41. Translation of the intermediate member 30 perpendicular to the predetermined axis also translates the moving member 20. Thus, translation of the intermediate member 30 may be used to provide Optical Image Stabilization (OIS) in the camera.

The actuator device 53 is further configured to drive the intermediate member 30 in rotation about a predetermined axis. Since the rotational position of the moving part 20 relative to the stationary part 10 is kept fixed by the third bearing means 43, the rotation of the intermediate part 30 engages with the second bearing means 42. Due to the helical nature of the second support means, this rotation is converted into a translation along a predetermined axis. Since the position of the intermediate member 30 relative to the stationary member 10 is kept fixed by the first support means 41, it is the moving member 20 that translates along a predetermined axis in response to rotation of the intermediate member 30. Thus, rotation of the intermediate member 30 can be used to provide autofocus in a camera.

The design and arrangement of the actuator device 53 itself may be substantially similar to that described with respect to fig. 8, although connected to the intermediate member 30 rather than the moving member 20. Specifically, the actuator device 53 comprises a single actuator stage and may comprise at least one SMA wire.

Fig. 11 illustrates a specific embodiment of the actuator assembly 4 of fig. 9. Fig. 11 illustrates an exploded perspective view of the actuator assembly 4. For clarity, the universal termination portions 71 to 73 are not illustrated in fig. 11. The embodiment of fig. 11 is a version of the embodiment discussed in relation to fig. 33 to 35 of GB2005573.6, GB2005573.6 being incorporated herein by reference, modified to incorporate the universal terminations 71 to 73 discussed above.

The actuator assembly 4 of fig. 11 takes the form of an actuator assembly of four SMA wires. The actuator assembly 4 comprises a moving part 20, a stationary part 10 and an intermediate part 30, the intermediate part 30 being mechanically coupled to the moving part 20 by a second (e.g. screw-type) support means 42, the second (e.g. screw-type) support means 42 being similar to the first support means 41 of fig. 10. However, unlike fig. 10, the actuator device is connected between the intermediate member 30 and the stationary member 10.

The actuator assembly 4 of fig. 11 comprises a third support means 43 mechanically coupling the moving part 20 to the static part 10. The third support means 43 are configured to guide the movement Tx, ty, tz of the moving part 20 relative to the static part 10 along the first axis x, the second axis y and/or the third (predetermined) axis z, while limiting the rotation Rz of the moving part 20 relative to the static part 10 about the predetermined axis z. The third support means 43 may be, but is not limited to, any of the non-rotating universal supports described in relation to figures 10A, 10B, 11 and 12 of GB2005573.6, GB2005573.6 being incorporated herein by reference. Other supports may be used but need to be connected in series with another support allowing translation Tz along the main axis z.

The actuator assembly 4 of fig. 11 further comprises a first (e.g. planar) support means 41, the first (e.g. planar) support means 41 mechanically coupling the static component 10 to the intermediate component 30. The first support 41 is not shown in fig. 11. The intermediate member 30 is coupled to the static member 10 using four segments of SMA wires 51-1, 51-2, 51-3, 51-4, the four segments of SMA wires 51-1, 51-2, 51-3, 51-4 forming an actuator arrangement substantially similar to the actuator arrangement described with respect to fig. 10, although connected to the intermediate member 30 rather than the moving member 20.

The second support means 42 is a helical roller support 56, the helical roller support 56 comprising a ring 1101 and an outer periphery alternating between rectangular and circular profiles, the ring 1101 having a circular inner periphery defining a central aperture 1102. The ring 1101 supports four ramps 1103-1, 1103-2, 1103-3, 1103-4, with the four ramps 1103-1, 1103-2, 1103-3, 1103-4 being equally spaced in a ring around the central aperture 1102. Each ramp 1103-1, 1103-2, 1103-3, 1103-4 takes the form of a rectangular frame having an elongated aperture 1104-1, 1104-2, 1104-3, 1104-4 extending along the length of the ramp 1103-1, 1103-2, 1103-3, 1103-4. The inclined surfaces 1103-1, 1103-2, 1103-3, 1103-4 are all at substantially equal angles to the ring 1102 (which lies in a plane parallel to the first and second axes x, y). When assembled, each elongated aperture 1104-1, 1104-2, 1104-3, 1104-receives a respective ball bearing 1105-1, 1105-2, 1105-3, 1105-4.

The moving part 20 (which may be a lens carrier, not shown) supporting the lens element 21 comprises four protrusions 1106-1, 1106-2, 1106-3, 1106-4 extending radially outwards from the moving part 20. The first protrusion 1106-1 and the third protrusion 1106-3 each define a respective bearing surface 1107-1, 1107-2 in the form of a generally downwardly oriented V-shaped channel (the normal to the first bearing surface 1107-1/third bearing surface 1107-3 has a component that is generally in the negative z-direction along the predetermined axis z). The second and fourth protrusions 1106-2 and 1106-4 define the second and fourth bearing surfaces 1107-2 and 1107-4 as V-shaped channels. The second support surface 1107-2/fourth support surface 1107-4 is oriented generally upward (the normal to the second support surface 1107-2/fourth support surface 1107-4 has a component that is generally in the positive +z direction along the predetermined axis z).

When assembled, each bearing surface 1107-1, 1107-2, 1107-3, 1107-4 is in rolling contact with a respective ramp 1103-1, 1103-2, 1103-4 via a respective ball bearing 1105-1, 1105-2, 1103-3, 1103-4.

Note that the form of the second support 42 of fig. 11 may be used as a helical first support in the actuator assembly 4 of fig. 8 and 10. Similarly, the form of the first support of FIG. 10 (the form of flexible arms 41-1, 41-2, 41-3, 41-4) may be used as the second support 42 in the actuator assembly 4 of FIGS. 9 and 11.

Returning to fig. 11, in use, if the actuator device applies a lateral force (substantially perpendicular to the predetermined axis z), the second support 42 cannot respond by moving Tx and/or Ty in the direction of the applied lateral force. However, the third support means 43 may guide the movement Tx and/or Ty in the direction of the applied transversal force, allowing the movement of the moving part 20 transversally with respect to the stationary part 10. However, when the actuator means additionally or alternatively applies a torque about the main axis z, the third support means 43 limit the rotation Rz of the moving part 20 with respect to the static part 10. The response to the applied torque is that the intermediate member 30 will rotate. This rotation will cause the ball bearings 1105-1, 1105-2, 1105-3, 1105-4 to roll between the ramps 1103-1, 1103-2, 1103-3, 1103-4 and the bearing surfaces 1107-1, 1107-2, 1107-3, 1107-4, moving member 20 moving up or down (relative to the predetermined axis z) depending on the direction of torque and the corresponding rotation Rz. However, due to the constraint provided by the fourth support 54, the moving part 20 does not rotate Rz about the predetermined axis z. In this way, a single actuator device 11, 20 comprising a total of four SMA wires 51-1, 51-2, 51-3, 51-4 may be used to provide OIS and AF functions while also avoiding rotation Rz of any lens element 21 about the optical axis. This may improve image quality by, among other things, reducing the likelihood of aberrations caused by imperfect circular symmetry of one or more lenses 10.

Providing a spherical stop

Fig. 12A depicts another embodiment of the actuator assembly 2 described with respect to fig. 5. The actuator assembly 2 comprises a stationary part 10, a moving part 20 and an intermediate part 30. The actuator assembly 2 further comprises first and second support means 41, 42 and first and second actuator stages 51, 52, although these are not described for the sake of simplicity of illustration.

As already described with reference to fig. 5, the intermediate member 30 is movable with respect to the stationary member 10 by being tilted about two perpendicular axes. These two perpendicular axes may be orthogonal to the optical axis of the lens that is part of the actuator assembly 2. In some embodiments, additionally, the intermediate member 30 may be movable relative to the static member 10 by rotation about an optical axis. The movement of the intermediate member 30 relative to the stationary member 10 is guided by the first support means 41 and the first actuator stage 51. This will enable OIS in the camera.

The moving part 20 is translatable with respect to the intermediate part 30 along an axis orthogonal to the two perpendicular axes. This axis may correspond to the optical axis of a lens that is part of the actuator assembly 2. The movement of the moving part 20 relative to the intermediate part 30 is guided by the second bearing means 42 and the second actuator stage 52. This will enable auto-focusing in the camera.

The actuator assembly 2 includes a ball termination 64 located between the intermediate member 30 and the static member 10. The bulbous termination 64 surrounds the intermediate member 30. The spherical termination 64 may be designed such that the shortest distance between the static component 10 and the intermediate component 30 remains constant when the intermediate component 30 is tilted and/or rotated relative to the static component 10. One embodiment of the ball termination 64 is described in co-pending GB application number 2104391.4, which is incorporated herein by reference. Generally, the spherical termination comprises spherical surfaces on the static component 10 and the intermediate component 30. The centre of the spherical surface coincides with the point of inclination/rotation of the intermediate part 30 with respect to the static part.

One possible disadvantage of the spherical termination is that it allows the moving part 20 to experience a relatively large z-displacement in the event of a fall. This is due to the combination of the gap required for the tilting movement and the offset of the terminating surface from the optical axis. The relatively large z-displacement is also due to the intermediate member 30 moving along the optical axis to the extent allowed by the spherical terminator housing, combined with the extent to which the moving member 20 moves to its terminator housing. This results in a larger gap than the basically required lens-to-housing (camera-level) gap.

The actuator assembly 2 of fig. 12 aims to address this possible disadvantage by providing a universal termination 72. The universal termination 72 limits movement of the moving member 20 along the optical axis. The universal termination 72 is disposed between the moving part 20 and the stationary part 10.

12B schematically depicts another modification of the actuator assembly 2 described in relation to fig. 12A. In fig. 12B, the universal termination 72 is provided on the portion 10B of the static component 10 that is movable between the use position and the non-use position. The portion 10b may be implemented, for example, in a retractable camera bump on a smart phone. When the camera is in use, the portion 10b may be extended to a use position, allowing movement of the moving member 20 and intermediate member 30 as described above, and providing a universal termination 72. When the camera is not in use, the portion 10b may be retracted to a non-use position, which may reduce or even eliminate any clearance allowed by the universal termination 72.

Ball bearing with reduced dishing

As described herein, the first support 41 and/or the second support 42 may comprise ball bearings or other rolling bearings. In particular, the first support means 41 and/or the second support means 42 may comprise two support surfaces, located on the static part 10 and the intermediate part 30, respectively, or on the intermediate part 30 and the moving part 20. Rolling bearing elements, such as ball bearing elements, may be disposed between the two bearing surfaces. Thus, the two bearing surfaces are movable relative to each other by the rolling bearing element rolling on the two bearing surfaces.

The actuator assembly described with respect to fig. 11 is only one example of a rolling bearing. Other actuator assemblies including rolling bearings are disclosed, for example, in WO2007113478, WO2017134456 or WO2019243849, each of which is incorporated herein by reference. For example, WO2019243849 describes an actuator assembly for providing AF in a camera. In any of the foregoing embodiments, the actuator assembly may be provided as a second actuator stage 52. The actuator assembly includes: a support structure (the support structure may correspond to the intermediate member 30); a movable element (the movable element may correspond to the moving part 20); screw bearing means (which may correspond to the second bearing means 42) supporting the movable element on the support structure and arranged to guide a screw movement of the movable element relative to the support structure about a screw axis; and at least one shape memory alloy actuator wire (which may correspond to the second actuator stage 52) connected between the support structure and the movable element, the at least one shape memory alloy actuator wire being in a plane perpendicular to the helical axis or at an acute angle to the helical axis and being arranged to drive rotation of the movable element about the helical axis upon contraction, the helical support means converting the rotation into said helical movement. The screw support means may comprise one or more screw supports, such as ball supports, as rolling supports.

During impact events such as a drop, the rolling bearing may be damaged by the bearing surface sagging. This may reduce the accuracy and/or reliability of the movement guided by the rolling bearing.

As described herein, providing a universal termination reduces the risk of damage due to bearing surface dishing.

Another concept for reducing the risk of damage due to bearing surface depressions in a rolling bearing is described herein. These concepts may be applied to any actuator assembly described herein and may be used without a universal termination.

A first concept for reducing the risk of damage due to bearing surface depressions in the rolling bearing is to introduce flexibility in one or both of the bearing surfaces. For example, one or both of the bearing surfaces may be formed of a flexible material (such as sheet metal). Flexibility may also be achieved by, for example, manufacturing a separate bearing race molding and spring loading it with a flexible system. The rolling bearing may thus be a spring-loaded bearing. The stiffness of the bearing surface may be selected such that the bearing surface does not deflect or deflects only minimally under normal operation, but does deflect under impact events. Thus, the impact may be absorbed by the elasticity of the support surface, rather than causing a depression. Examples of spring-loaded supports are described with respect to fig. 11-15 of WO2014/083318A1, WO2014/083318A1 being incorporated herein by reference. The resilient member described in WO2014/083318A1 may be applied to any rolling bearing described herein.

According to a second concept, the flexibility may also be more generally provided in the body of the support structure (e.g. the intermediate part 30) or the movable element (e.g. the movable part 20). For example, as depicted in fig. 13A, a support structure (e.g., intermediate component 30) may include a first portion 30a and a second portion 30b that are coupled to each other by a resilient element (in fig. 13A, the resilient element is implemented by flexibility in the first portion 30 a). The first portion 30a may provide a second support means 42. The second portion 30b may be coupled to the first support device 41. In fig. 13A, the first portion 30a is bonded to the second portion 30b in the region 30c, but not to the second portion 30b in the region 30c', so that the corners of the first portion 30a (where the helical rolling bearings are located) are allowed to flex relative to the second portion 30 b. The stiffness of the resilient element may be selected such that the bearing surface does not deflect or deflects only minimally under normal operation, but does deflect under impact events. Thus, the impact may be absorbed by the elasticity of the support surface, rather than causing a depression.

As a further improvement of this second concept, OIS termination 63 may be provided to location 63 instead of location 63', as shown in fig. 13B. Thus, OIS termination 63 may preferably be located at the center of the actuator assembly rather than at the corners. This also allows the corners of the moving part 20 to flex in order to absorb impact events, reducing the risk of damage due to bearing surface depressions in the rolling bearing.

The actuator assembly includes an SMA wire. The term "shape memory alloy (shape memory alloy, SMA) wire" may refer to any element comprising SMA. The SMA wire may have any shape suitable for the purposes described herein. The SMA wire may be elongate and may have a circular cross-section or any other shape. The cross-section may vary along the length of the SMA wire. It is also possible that the length of the SMA wire (defined in any case) may be similar to one or more of its other dimensions. The SMA wire may be pliable or, in other words, may be flexible. In some examples, when connected in a straight line between two elements, the SMA wire can only apply a tensioning force that pushes the two elements together. In other examples, the SMA wire may bend around the element and may apply a force to the element as the SMA wire tends to straighten out under tension. The SMA wires may be beam-like or rigid and are capable of applying different forces (e.g., non-tensile) to the element. The SMA wire may or may not include materials and/or components that are not SMA. For example, the SMA wire may include a core of SMA and a coating of non-SMA material. Unless the context requires otherwise, the term "SMA wire" may refer to any configuration of SMA wire that acts as a single actuation element, e.g., the single actuation element may be individually controlled to generate a force acting on the element. For example, the SMA wire may comprise two or more portions of SMA wire arranged mechanically in parallel and/or in series. In some arrangements, the SMA wire may be part of a larger length of SMA wire. Such a larger length of SMA wire may comprise two or more sections that are individually controllable, thereby forming two or more SMA wires.

Those skilled in the art will appreciate that the present disclosure should not be limited to the specific configurations and methods disclosed in this description of the preferred embodiments. Those skilled in the art will recognize that the invention has a wide range of applications and that the embodiments can be modified in a wide range without departing from the scope defined by the appended claims.

Claims (26)

1. An actuator assembly, comprising:

a static component;

a moving member;

an intermediate member;

a first support means guiding movement of the intermediate member relative to the stationary member;

a second support device guiding movement of the moving member relative to the intermediate member; and

an actuator means arranged to drive movement of the moving part relative to the static part; and

at least one universal termination located between the static component and the moving component, the universal termination being arranged such that the moving component contacts the static component at a limit of movement of the moving component relative to the static component.

2. The actuator assembly of claim 1, further comprising at least one intermediate movement termination located between the intermediate member and the moving member and arranged such that the moving member contacts the intermediate member at a limit of movement of the moving member relative to the intermediate member.

3. An actuator assembly according to claim 1 or claim 2, wherein the actuator device comprises:

an actuator stage arranged to drive movement of the moving part relative to the intermediate part guided by the second support means.

4. An actuator assembly according to claim 3, wherein the actuator device further comprises a second actuator stage arranged to drive movement of the intermediate member relative to the stationary member guided by the first support means.

5. The actuator assembly of claim 3 wherein,

the actuator assembly further comprises biasing means arranged to bias movement of the intermediate member relative to the stationary member, guided by the first support member, towards a central position.

6. An actuator assembly according to any preceding claim, wherein the movement of the moving member relative to the intermediate member guided by the second support means comprises translational movement along a predetermined axis or translational movement along a predetermined axis.

7. The actuator assembly of claim 6, wherein the movement of the intermediate member relative to the stationary member guided by the first support means is a translational movement perpendicular to the predetermined axis.

8. The actuator assembly of claim 6, wherein the movement of the intermediate member relative to the stationary member guided by the first support means is a rotational movement about two orthogonal axes perpendicular to the predetermined axis.

9. An actuator assembly according to claim 1 or claim 2, wherein the actuator arrangement comprises a single actuator stage arranged to drive relative movement between any two of the moving, intermediate and static components.

10. The actuator assembly of claim 10, wherein the single actuator stage is configured to independently drive movement of the moving component relative to the intermediate component guided by the second support means and movement of the intermediate component relative to the stationary component guided by the first support means.

11. An actuator assembly according to claim 9 or 10, wherein the actuator assembly further comprises a third bearing means guiding movement of the moving part relative to the stationary part.

12. The actuator assembly of claim 11, wherein,

The movement of the moving part relative to the intermediate part guided by the second support means is a helical movement about a predetermined axis,

the movement of the intermediate part relative to the static part, guided by the first support means, is a translational movement orthogonal to the predetermined axis and/or a rotational movement about a line parallel to the predetermined axis, and

the movement of the moving part relative to the static part guided by the third support means is a translational movement along the predetermined axis and/or a translational movement orthogonal to the predetermined axis.

13. The actuator assembly of claim 10 or 11, wherein,

the movement of the moving part relative to the intermediate part, guided by the second support means, is a translational movement orthogonal to the predetermined axis, and

the movement of the intermediate part relative to the static part, guided by the first support means, is a helical movement about the predetermined axis.

14. An actuator assembly according to any preceding claim, wherein the actuator device comprises at least one shape memory alloy wire.

15. An actuator assembly according to any one of claims 3 to 14 wherein the or each actuator stage comprises at least one shape memory alloy wire.

16. The actuator assembly according to any of the preceding claims, wherein the universal termination is configured to limit a three-dimensional translational movement of the moving part relative to the static part and/or to limit a rotational movement of the moving part relative to the static part about a line parallel to a predetermined axis.

17. The actuator assembly of any one of the preceding claims, wherein the universal termination comprises at least one surface on the static component configured to engage with a substantially conformal surface on the moving component, thereby limiting the movement.

18. An actuator assembly according to any preceding claim, wherein the moving part comprises a lens element having an optical axis.

19. The actuator assembly of any one of claims 6-8, 12, 13 or 16, wherein the moving member comprises a lens element having an optical axis, the optical axis being the predetermined axis.

20. An actuator assembly according to claim 18 or 19, wherein,

the static part comprises a shield extending around the lens element, the intermediate part and the actuator device, and

The at least one universal termination is at least partially provided by the shield.

21. An actuator assembly according to any preceding claim, wherein the mass of the intermediate member is less than the mass of the moving member.

22. An actuator assembly, comprising:

a static component;

a moving member;

an intermediate member;

a first support means guiding movement of the intermediate member relative to the stationary member;

a biasing means arranged to bias movement of the intermediate member relative to the static member guided by the first support member towards a central position;

a second support device guiding movement of the moving member relative to the intermediate member; and

an actuator device arranged to drive movement of the moving member relative to the intermediate member.

23. The actuator assembly of claim 22, wherein the actuator device comprises at least one shape memory alloy wire.

24. An actuator assembly according to claim 22 or 23, wherein the moving part comprises a lens element.

25. An actuator assembly according to any of claims 22 to 24, wherein the lens element has an optical axis,

the second support means guides the movement of the moving member relative to the intermediate member along the optical axis, an

The first support means guides the movement of the intermediate member perpendicular to the optical axis.

26. An actuator assembly according to claim 24 or 25, wherein the static part comprises a shield extending around the lens element, the intermediate part and the actuator device, and at least one universal termination is provided between the shield and the moving part, the at least one universal termination being arranged such that the moving part contacts the shield at a limit of movement of the moving part relative to the static part.