Field

The present application relates to an actuator assembly, particularly an actuator assembly for enabling optical image stabilisation (OIS) and/or autofocus (AF).

Background

In a camera, the purpose of OIS is to compensate for camera shake, that is vibration of the camera, typically caused by user hand movement, that degrades the quality of the image captured by the image sensor. Mechanical OIS typically involves detecting the vibration by a vibration sensor such as a gyroscope sensor, and controlling, on the basis of the detected vibration, an actuator arrangement that adjusts the camera apparatus to compensate for the vibration.

A number of actuator arrangements employing mechanical OIS techniques are known and applied successfully in relatively large camera apparatuses, such as digital still cameras, but are difficult to miniaturise. Cameras have become very common in a wide range of portable electronic equipment, for example mobile telephones and tablet computers, and in many such applications miniaturisation of the camera is important. The very tight packaging of components in miniature camera apparatuses presents great difficulties in adding OIS actuators within the desired package.

WO-2017/072525 discloses an image sensor mounted on a carrier that is suspended on a support structure by a plain bearing that allows movement of the carrier and the image sensor relative to a support structure in any direction laterally to the light-sensitive region of the image sensor. An actuator assembly comprising plural SMA wires is arranged to move the carrier and the image sensor relative to the support structure for providing OIS of the image captured by the image sensor.

Electrical paths are needed between the support structure and the carrier/image sensor, for example to transfer drive signals, control signals and/or data. The electrical interconnectors that form the electrical paths may have a minimum length so that they do not significantly restrict the relative movement between the support structure and the carrier/image sensor. The electrical paths take up space and can contribute to the overall size of the assembly. The present invention is concerned, amongst other things, with an actuator assembly that reduces the contribution of the electrical paths to the overall size of the assembly, particularly that helps reduce the two largest dimensions of the assembly or, in other words, helps reduces the footprint of the assembly. Summary

According to an aspect of the present invention, there is provided actuator assembly comprising: a support structure; a generally planar movable part, wherein the movable part is movable relative to the support structure; and a plurality of electrical interconnectors configured to electrically connect the support structure to the movable part; wherein at least two of the electrical interconnectors are spaced from each other when viewed in a direction parallel to the plane of the movable part.

By providing that at least two of the electrical interconnectors are spaced from each other when viewed in a direction parallel to the plane of the movable part, it may be possible to reduce the presence of the electrical interconnectors in positions where they may increase the overall volume of the apparatus. For example, it may be possible to reduce the length of the electrical interconnectors extending away from the movable part. This can help to reduce the area of the actuator assembly when viewed in a direction perpendicular to the plane of the movable part. As another example, it may be possible to reduce the length of the electrical interconnectors extending along the movable part. This can help to reduce the possibility of overlap between the electrical interconnectors and components of the movable part (particularly components that are thicker than the electrical interconnectors) when viewed in a direction perpendicular to the plane of the movable part. In turn this can help to reduce the dimension of the actuator assembly in the direction perpendicular to the plane of the movable part.

As will be appreciated, the spacing refers to spacing in a direction parallel to an axis (also referred to as the primary axis) which is perpendicular to the plane of the movable part. Hence, at least two of the electrical interconnectors are spaced from each other when projected onto the primary axis. Optionally, there is a gap between the extent of one electrical interconnector when projected onto the primary axis and the extent of another electrical interconnector when projected onto the primary axis. Optionally, equivalent regions (midpoints, for example) of at least two electrical interconnectors are spaced from each other when projected onto the primary axis.

Optionally, at least two of the electrical interconnectors overlap when viewed in a direction at least partly perpendicular to the plane of the movable part. Such a direction may be at an acute angle relative to a normal to the plane of the movable part. The acute angle may be less than 45°, less than 20° or less than 10°. The direction may be perpendicular to the plane of the movable part.

As will be appreciated, further (non-planar) components may be attached to the generally planar movable part. The movable part need not be generally planar but may be movable relative to the support structure in any direction in a movement plane and references herein to the plane of the movable part may refer to such a movement plane.

The at least two electrical interconnectors that are spaced from each other when viewed in a direction parallel to the plane of the movable part may be referred to as being "stacked".

Optionally, at least one of the electrical interconnectors has one end provided at a peripheral region of the movable part.

Optionally, at least part of at least one of the electrical interconnectors is integrally formed with at least part of the movable part and/or at least part of the support structure.

By providing that at least one of the electrical interconnectors has one end provided at a peripheral region of the movable part, the possibility of overlap between the electrical interconnectors and components in a central portion of the movable part can be reduced. In turn this can help to reduce the dimension of the actuator assembly in the direction perpendicular to the plane of the movable part.

Optionally, the support structure comprises a support plate that overlaps the movable part when viewed in a direction perpendicular to the plane of the movable part, and at least one of the electrical interconnectors is connected to a surface of the movable part facing the support plate. Optionally, at least one of the electrical interconnectors is embedded into the surface of the movable part facing the support plate such that a minimum distance between the embedded section of the electrical interconnector and the support plate is greater than or equal to a minimum distance between the movable part and the support plate.

By providing that at least one of the electrical interconnectors is embedded, the dimension of the actuator assembly in the direction perpendicular to the plane of the movable part can be reduced. The thickness of the electrical interconnector does not contribute to this dimension.

Optionally, the movable part is an image sensor assembly comprising an image sensor having a lightsensitive region.

The possibility of overlap between the electrical interconnectors and the image sensor can be reduced. In turn this can help to reduce the dimension of the actuator assembly in the direction perpendicular to the plane of the movable part. Optionally, the support structure comprises a printed circuit board, PCB, to which the electrical interconnectors are electrically connected. Optionally, the movable part comprises a PCB to which the electrical interconnectors are electrically connected.

The PCBs may form part of the electrical path to/from the image sensor. The electrical paths may be formed more reliably and/or robustly.

Optionally, the image sensor is mounted on the PCB of the image sensor assembly. Optionally, the image sensor and the PCB of the image sensor assembly overlap in a direction perpendicular to the plane of the image sensor assembly.

By providing that the image sensor and the PCB of the image sensor assembly overlap, the dimension of the apparatus in the direction perpendicular to the plane of the movable part can be reduced.

Optionally, at least one of the electrical interconnectors is connected between a side of the support structure facing in a first direction and a side of the movable part facing in the first direction. Optionally, a plurality of the electrical interconnectors are connected between the side of the support structure facing in the first direction and the side of the movable part facing in the first direction and are spaced from each other when viewed in a direction parallel to the plane of the movable part.

By providing stacked electrical interconnectors connected to the same side of the support structure and movable part, it is easier to assemble the actuator assembly. In particular, the level of access to the support structure and movable part necessary to apply the electrical interconnectors may be required for only one side of the actuator assembly. This may help reduce the cost of manufacturing the actuator assembly.

Optionally, the support structure is configured to electrically isolate at least two of the electrical interconnectors from each other.

By providing that the support structure is configured to electrically isolate at least two of the electrical interconnectors from each other, it may not be necessary to provide an additional component to prevent electrical breakdown between stacked electrical interconnectors. The properties of the existing support structure can be used to perform mechanical and electrical separation of the different layers of electrical interconnectors. Optionally, at least one of the electrical interconnectors is arranged to extend in a plane parallel to the plane of the movable part. Optionally, at least one of the electrical interconnectors comprises a first portion configured to extend in a first plane parallel to the plane of the movable part and a second portion configured to extend in a second plane parallel to and different from the first plane. Optionally, the first portion is connected to the support structure and the second portion is connected to the movable part.

By providing two planes for the electrical interconnectors, the design of the actuator assembly may be kept relatively simple while allowing the advantages of the stacked electrical interconnectors. The electrical interconnectors may be positioned on the same side of the movable part while remaining stacked. This can help make it easier to manufacture the actuator assembly.

Optionally, the first portion and the second portion are connected by a third portion configured to extend perpendicularly to the first plane.

By providing the third portion, the possibility of interference between the two planes of electrical interconnectors can be reduced.

Optionally, a plurality of the electrical interconnectors comprise respective diagonal portions, spaced from each other when viewed in a direction parallel to the plane of the movable part, that extend in a direction parallel to the plane of the movable part and in a direction perpendicular to the plane of the movable part. Optionally, the diagonal portions are parallel to each other.

By providing the diagonal portions, it may not be necessary to jog the material of the electrical interconnectors in order to provide stacked electrical interconnectors on the same side of the movable part. The design may make use of the surfaces of the movable part and the support structure being at different positions along the axis perpendicular to the movable part.

Optionally, at least one of the electrical interconnectors comprises a metallic flexure.

By providing that at least one of the electrical interconnectors comprises a metallic flexure, the design of the electrical interconnector may be relatively simple, for example not requiring an integrated insulator. The metallic flexure may be used to impart a force on the movable part or the support structure.

Optionally, at least one of metallic flexures is provided with a flexible electrical connector layered relative to it, the flexible electrical connector being another of the electrical interconnectors. By providing that at least one of metallic flexures is provided with a flexible electrical connector layered relative to it, additional electrical paths may be formed without significantly increasing the volume taken up by the electrical interconnectors.

Optionally, at least one of the electrical interconnectors comprises a flexible electrical connector.

By providing that at least one of the electrical interconnectors comprises a flexible electrical connector, the electrical interconnector can be compliant so as not to obstruct the free movement of the movable part. Meanwhile the flexible electrical connector may carry a plurality of electrical paths in a spaceefficient way.

Optionally, the actuator assembly comprises an insulator layer configured to electrically isolate a plurality of the electrical interconnectors from another plurality of the electrical interconnectors.

By providing the insulator layer it is possible to electrically isolate the electrical interconnectors from each other while providing the space-saving advantages of the stacked electrical interconnectors.

Optionally, within a group comprising a plurality of the electrical interconnectors, the longest electrical interconnector is at most 20%, and optionally at most 10% longer than the shortest electrical interconnector. Optionally, the group comprises all of the electrical interconnectors.

By providing that the electrical interconnectors have similar or the same lengths, the difference in time taken for electrical signals to pass through the electrical interconnectors may be reduced. This can help to synchronize signals. By providing that the electrical interconnectors have similar or the same lengths, the difference in impedance of the electrical interconnectors may be reduced. This can facilitate impedance matching.

Optionally, at least one of the electrical interconnectors is configured to flex when the support structure and the movable part move relative to each other. Optionally, at least one of the electrical interconnectors comprises at least one bend configured to facilitate flexing of the electrical interconnector during relative movement between the support structure and the movable part.

By providing the bend, the flexing of the electrical interconnector may be facilitated. This may help the electrical interconnectors to have compliance sufficient not to impede the stroke of the actuator driving them. Optionally, the actuator assembly comprises a bearing arrangement configured to support the movable part relative to the support structure, wherein the bearing arrangement is configured to allow the movement of the movable part and the support structure relative to each other. Optionally, the electrical interconnectors are configured to apply a force biasing the movable part against the bearing arrangement. Optionally, the electrical interconnectors act as the bearing arrangement.

By providing that the electrical interconnectors act as a biasing arrangement or as the bearing arrangement, it may not be necessary to provide separate components dedicated to these functions. This may reduce the cost of manufacturing the actuator assembly.

Optionally, the actuator assembly comprises an actuator arrangement capable of moving the movable part and the support structure relative to each other in any direction parallel to the plane of the movable part and/or rotating the movable part about an axis perpendicular to the plane of the movable part. Alternatively or additionally, the actuator assembly may comprise an actuator arrangement capable of moving the movable part and the support structure relative to each other in a direction perpendicular to the plane of the movable part. Alternatively or additionally, the actuator assembly may comprise an actuator arrangement capable of rotating (or, in other words, tilting) the movable part about any axis in a plane parallel to the plane of the movable part. Optionally, the actuator arrangement comprises plural shape memory alloy, SMA, elements (e.g. wires) arranged, on contraction, to move the movable part and the support structure relative to each other. Optionally, the SMA elements are fixed to the support structure and the movable part.

By providing that SMA elements drive the movements, the movements can be controlled in a particularly accurate and efficient way.

Generally, the electrical interconnectors are separate from (e.g. do not comprise and are not comprised in) the SMA elements. Generally, the electrical interconnectors are at least for making an electrical connection to components other than the actuator arrangement.

Brief description of the drawings

Certain embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a schematic cross-sectional view of a camera apparatus including an actuator assembly; Figure 2 is a cross-sectional view of the actuator assembly; Figure 3 is a plan view of the actuator assembly from above;

Figure 4 is a plan view of the electrical interconnectors of the actuator assembly;

Figure 5 is a cross-sectional view of the electrical interconnectors of the actuator assembly;

Figure 6 is a plan view of the electrical interconnectors of an actuator assembly;

Figure 7 is a cross-sectional view of the electrical interconnectors of the actuator assembly shown in Figure 6;

Figure 8 is a cross-sectional view of the electrical interconnectors of an actuator assembly of a comparative example;

Figure 9 is a perspective view of the electrical interconnectors of part of an actuator assembly;

Figure 10 is a plan view of the electrical interconnectors of the actuator assembly shown in Figure 9;

Figure 11 is a plan view of an actuator assembly;

Figure 12 is a cross-sectional view of two of the electrical interconnectors of the actuator assembly shown in Figure 11;

Figure 13 is a cross-sectional view of an electrical interconnector of the actuator assembly;

Figure 14 is a cross-sectional view of electrical interconnectors of the actuator assembly;

Figure 15 is a cross-sectional view of electrical interconnectors of the actuator assembly;

Figure 16 is a cross-sectional view of electrical interconnectors of the actuator assembly;

Figure 17 is a cross-sectional view of electrical interconnectors of the actuator assembly;

Figure 18 is a cross-sectional view of an actuator assembly;

Figure 19 is a plan view of the electrical interconnectors of an actuator assembly; and Figure 20 is a plan view of the electrical interconnectors of an actuator assembly.

Detailed description

Structure of actuator assembly

A camera apparatus 1 that incorporates an actuator assembly 2 in accordance with the present invention is shown in Figure 1, which is a cross-sectional view taken along the optical axis O. In the depicted embodiment, the actuator assembly 2 is a sensor shift assembly. The camera apparatus 1 is to be incorporated in a portable electronic device such as a mobile telephone, or tablet computer. Thus, miniaturisation is an important design criterion.

The actuator assembly 2 is shown in detail in Figures 2 to 4, Figure 2 being a side view of the actuator assembly 2, Figure 3 being a plan view of the actuator assembly 2; and Figure 4 being an alternative plan view of electrical interconnectors of the actuator assembly 2. For clarity, Figures 2 and 3 omit the electrical interconnector 51 described below. The line A-A shown in Figure 4 is the line along which the cross-sectional view shown in Figure 2 is taken. This line does not intersect with the electrical interconnector 51. Accordingly, the electrical interconnector 51 is not shown in Figure 2. The actuator assembly 2 may be manufactured first and then assembled with the other components of the camera apparatus 1.

The actuator assembly 2 comprises a support structure 4. The support structure 4 may comprise a first printed circuit board (PCB) 10. However, it is not essential that the support structure 4 comprises a PCB. Electrical paths through and/or across the support structure 4 may be formed by alternative electrically conductive elements such as wires, for example. Relative to the support structure 4 is supported a movable part. The movable part may be an image sensor assembly 12. However, it is not essential that the movable part is an image sensor assembly. The movable part may comprise one or more alternative components such as a lens or a light source, for example. The movable part may comprise a second PCB 9. However, it is not essential that the movable part comprises a PCB. Electrical paths through and/or across the movable part may be formed by alternative electrically conductive elements such as wires, for example.

The movable part is generally planar. When incorporated into the camera apparatus 1, the plane of the movable part is perpendicular to the optical axis O. For brevity, the invention is described mainly in the context of the support structure 4 comprising a first PCB 10, the movable part being an image sensor assembly and the movable part comprising a second PCB 9. However, none of these features is essential and any or all may be omitted from any of the variations described.

Optionally, the image sensor assembly 12 comprises an image sensor 6 having a light-sensitive region 7. The image sensor 6 is fixed relative to the second PCB 9. For example, the image sensor 6 may be mounted on the second PCB 9. When incorporated into the camera apparatus 1, the light-sensitive region 7 is aligned with the optical axis O and perpendicular to the optical axis O. The image sensor 6 captures an image and may be of any suitable type, for example a CCD (charge-coupled device) or a CMOS (complementary metal-oxide-semiconductor) device. As is conventional, the image sensor 6 has a rectangular light-sensitive region 7. The light-sensitive region 7 may comprise an array of pixels. Without limitation to the invention, in this example the camera apparatus 1 is a miniature camera in which the light-sensitive region 7 has a diagonal length of at most 12mm.

Optionally, the electrical connection between the image sensor 6 and the electrical interconnector 51 is at least partly formed by the second PCB 9. The second PCB is for transferring signals such as data signals and power signals between the image sensor 6 and the first PCB 10. Additionally, the second PCB 9 may comprise electronic components configured to act on signals output by the image sensor 6. For example, the second PCB 9 may comprise electrical components such as capacitors. It can be desirable to reduce as much as possible the distance between the image sensor 6 and such electronic components in which case it is desirable to provide such electronic components in the second PCB 9 rather than in the first PCB 10. The distance between the image sensor 6 and the second PCB 9 is smaller than the distance between the image sensor 6 and the first PCB 10.

The first PCB 10 is configured to collect the signals from the second PCB 9, and to provide signals to the second PCB 9. The first PCB 10 facilitates collection of signals for connection to an external device (e.g. a mobile phone).

Optionally, the second PCB 9 of the image sensor assembly 12 functions as a moving plate. The image sensor 6 may be mounted on the moving plate.

Although the moving plate may comprise only the second PCB 9, optionally the moving plate may comprise other layers which may be attached to or laminated with the second PCB 9.

Optionally, the support structure 4 comprises a support plate 5 which may be formed from sheet material, which may be a metal for example steel such as stainless steel or copper or a copper alloy. Although the support structure 4 comprises a single support plate 5 in this example, optionally the support structure 4 may comprise other layers which may be attached to or laminated with the support plate 5.

The support structure 4 may further comprise the first PCB 10 which may form a rim portion. The first PCB 10 may be fixed to the front side of the support plate 5 and extend at least partly around the support plate 5. The first PCB 10 may have a central aperture 11.

The camera apparatus 1, and/or the portable electronic device in which the camera apparatus 1 is integrated, comprises an integrated circuit (IC) chip 30 and a gyroscope sensor 31 which, in the illustrated example, are fixed on the rear side of the support plate 5. Control circuitry described further below is implemented in the IC chip 30.

The movable part is supported relative to the support structure 4 in a manner allowing movement of the movable part relative to the support structure 4. Optionally, the movable part is supported relative to the support structure 4 in a manner allowing movement of the movable part relative to the support structure 4 in any direction laterally to plane of the movable part (e.g. laterally of the optical axis O and parallel to the plane in which the light-sensitive region 7 extends). Additionally or alternatively, the movable part is supported relative to the support structure 4 in a manner allowing movement of the movable part in a direction perpendicular to the plane of the movable part. Additionally or alternatively, the movable part is supported relative to the support structure 4 in a manner allowing rotation of the movable part about any axis perpendicular to the plane of the movable part (e.g. parallel to any axis orthogonal to the plane in which the light-sensitive region 7 extends). Additionally or alternatively, the movable part is supported relative to the support structure 4 in a manner allowing tilt or rotation of the movable part about any axis parallel plane of the movable part.

Optionally, the movable part may be supported in a manner suppressing one or more forms of movement of the movable part. For example, the movable part may be supported in a manner suppressing movement in a direction perpendicular to the plane of the movable part. As another example, the movable part may be supported in a manner suppressing tilt or rotation of the movable part about any axis parallel to the plane of the movable part.

WO-2017/072525 discloses use of a plain bearing for supporting an image sensor assembly on a support structure in a manner allowing the above-described movement. Such a plain bearing comprises two bearing surfaces that bear on each other, permitting relative sliding motion. Such a plain bearing may be compact and facilitate heat transfer between the image sensor assembly and the support structure. However, in certain applications it may be desirable to reduce friction between the image sensor assembly and the support structure compared to an arrangement in which a plain bearing is provided.

In the illustrated embodiments, the image sensor assembly 12 is supported on the support structure 4 by a bearing arrangement 110 (described below) such that a gap 104 is formed between the image sensor assembly 12 and the support structure 4. The gap 104 is formed on a side of the image sensor assembly 12 facing away from the light-sensitive region 7, in particular in a direction perpendicular to the light-sensitive region 7. The gap 104 is formed, in particular, between the image sensor assembly 12 and the support plate 5.

Electrical interconnection

Figure 4 is a plan view of one side (either the underside or the top side) of the first PCB 10 and the second PCB 9. Figure 4 may be a view of the actuator assembly 2 shown in Figure 2 with the support plate 5 and the bearing arrangement 110 removed.

As shown in Figure 4, the actuator assembly 2 comprises a plurality of electrical interconnectors 51. The electrical interconnectors 51 are configured to electrically connect the support structure 4 to the movable part. For example, when PCBs are present, the electrical interconnectors 51 may be configured to electrically connect the first PCB 10 to the second PCB 9. The electrical interconnectors 51 may be configured to transfer data between the support structure 4 and the movable part. For example, image data acquired by the image sensor 6 may be transferred from the second PCB 9 to the first PCB 10 via the electrical interconnectors 51. The electrical interconnectors 51 may be configured to supply power for the image sensor 6 from the first PCB 10 to the second PCB 9. In general, the electrical interconnectors 51 are configured to transfer electrical signals such as power and data in either direction between the support structure 4 and the movable part. The electrical interconnectors 51 may also be configured to transfer (or provide a common return path for) signals for driving the SMA wires 40 from the support structure 4 to the movable part.

Optionally a plurality of groups of electrical interconnectors 51 are provided. For example, Figure 4 shows four groups of electrical interconnectors 51. Each group of electrical interconnectors 51 is generally for providing electrical connection between the second PCB 9 and a respective side or corner of the first PCB 10. The number of groups of electrical interconnectors 51 may alternatively be one, two, three, or more than four, for example. For example, in an alternative arrangement the first PCB 10 may extend around only two sides of the second PCB 9. In such an arrangement, there may be only two groups of electrical interconnectors 51.

Figure 19 is a plan view of electrical interconnectors 51 according to an arrangement different from that shown in Figure 4. As shown in Figure 4, optionally each group of electrical interconnectors 51 is generally for providing electrical connection between the support structure 4 and a respective side or corner of the movable part. As shown in Figure 19, optionally a plurality of groups of electrical interconnectors 51 are provided on the same side of the movable part. For example, two groups may extend from one edge of the movable part and another two groups may extend from another (e.g. opposite) edge of the movable part when viewed in plan view. In alternative arrangements there may be three or more groups of electrical interconnectors 51 extending from the same edge of the movable part. As shown in Figure 19, optionally the electrical interconnectors 51 of different groups extending from the same edge of the movable part comprise bends 55 in opposite senses adjacent to the support structure 4. As shown in Figure 19, optionally each group comprises four electrical interconnectors 51. Alternatively there may be two, three or more than four electrical connectors 51 in each group.

Optionally, the electrical interconnectors 51 generally extend in a plane parallel to the plane of the movable part (which may correspond to the plane in which the first PCB 10 extends). The electrical interconnectors 51 may generally extend in a plane perpendicular to the primary axis of the actuator assembly 2. The primary axis of the actuator assembly 2 is perpendicular to the plane in which the support plate 5 extends. The primary axis is perpendicular to the plane in which the light-sensitive regions 7 of the image sensor 6 extends when the image sensor 6 is in its neutral (i.e. untitled) position relative to the support structure 4. The primary axis may correspond to the optical axis O shown in Figure 1.

The electrical interconnectors 51 may be configured to flex when the movable part moves relative to the support structure 4. The electrical connection between the support structure 4 and the movable part is maintained during movement of the movable part relative to the support structure 4. For example, the electrical interconnectors 51 may flex in the plane parallel to the plane of the movable part, i.e. in the plane perpendicular to the primary axis of the actuator assembly 2. Each electrical interconnector 51 may comprise at least one bend 55. The bend 55 is configured to facilitate flexing of the electrical interconnector 51 during relative movement between the support structure 4 and the movable part.

Optionally, the electrical interconnectors 51 remain essentially in the plane perpendicular to the primary axis during movement of the movable part relative to the support structure 4. Alternatively, the electrical interconnector 51 may flex at least partly in a direction parallel to the primary axis. For example, the electrical interconnector 51 may extend into the gap 104 towards the support plate 5. There is a possibility that the electrical interconnector 51 may come in to contact with the support plate 5 during movement of the image sensor assembly 12 relative to the support structure 4. Optionally, the support structure 4 comprises an electrically insulating surface facing the gap 104. For example, the upper surface of the support plate 5 may be electrically insulating. The support plate 5 may comprise an electrically insulating coating at its side facing the image sensor assembly 12. The electrically insulating surface can reduce the possibility of an undesirable electrical connection being formed between the electrical interconnector 51 and the support plate 5. This reduces the possibility of an undesirable short circuit occurring.

As shown in Figure 2, for example, optionally the electrical interconnectors 51 are located in the gap 104. For example, the electrical interconnectors 51 may be attached to the sides (also referred to as the undersides) of the first and second PCBs 9, 10 facing the gap 104. This can help to reduce the extent of the actuator assembly 2 in the direction of the primary axis.

In an alternative arrangement, the electrical interconnectors 51 are provided on the side of the first PCB 10 and/or the second PCB 9 facing away from the gap 104. For example, the electrical interconnectors 51 may be attached to the lower side of the first PCB 10 and the upper side of the second PCB 9. The electrical interconnectors 51 may alternatively be attached to the upper side of the first PCB 10 and the lower side of the second PCB 9. Alternatively, the electrical interconnectors 51 may be attached to the upper side of the first PCB 10 and the upper side of the second PCB 9. Figure 4 is a plan view of the electrical interconnectors 51 of the actuator assembly 2. Figure 5 is a cross- sectional view of the electrical interconnectors 51 of the actuator assembly 2. As shown in Figure 5, optionally at least two of the electrical interconnectors 51 overlap when viewed in a direction perpendicular to the plane of the movable part. In the view shown in Figure 5, the plane of the movable part extends horizontally. The direction perpendicular to the plane of the movable part is vertical in the view of Figure 5. An imaginary vertical line could be added to Figure 5, with the imaginary vertical lines passing through at least two of the electrical interconnectors 51. The electrical interconnectors 51 may fully overlap, or may only partially overlap. Optionally, at least one of the electrical interconnectors 51 does not overlap any of the other electrical interconnectors 51. Alternatively, all of the electrical interconnectors 51 may at least partially overlap at least one of the other electrical interconnectors 51.

By providing that at least two of the electrical interconnectors 51 overlap when viewed in a direction perpendicular to the plane of the movable part, it may be possible to reduce the presence of the electrical interconnectors 51 in positions where they may increase the overall volume of the actuator assembly 2. For example, it may be possible to reduce the extent to which the electrical interconnectors 51 extend away from the movable part in plan view. This can be seen from a comparison between Figure 5 and Figure 6.

As shown in Figure 4 and Figure 5, optionally at least two of the electrical interconnectors 51 overlap when viewed in a direction perpendicular to the plane of the movable part. However, it is not essential for the electrical interconnectors 51 to overlap. Figure 20 shows a plan view of electrical interconnectors 51 in an actuator assembly 2. The cross-sectional view of the actuator assembly 2 shown in Figure 20 may be the arrangement shown in Figure 5. The actuator assembly 2 comprises two layers 57, 58 of electrical interconnectors 51. Figure 20 shows four groups of electrical interconnectors 51, each group comprising four electrical interconnectors 51. Within each group, alternate electrical interconnectors 51 are in the same layer 57, 58. Within each group two electrical interconnectors 51 are in a first layer 57 on the near side of the actuator assembly 2 in the view shown in Figure 20. Substantially the whole of these electrical interconnectors 51 can be seen in Figure 20. Within each group two electrical interconnectors 51 are in a second layer 58 on the far side of the actuator assembly 2 in the view shown in Figure 20. Only the part of these electrical interconnectors 51 that extends between the movable part and the support structure 4 can be seen in Figure 20. The rest of these electrical interconnectors 51 is obscured by the movable part and the support structure 4.

The electrical interconnectors 51 of the different layers 57, 58 do not overlap. Instead the electrical interconnectors 51 of different layers 57, 58 are spaced from each other in plan view. The electrical interconnectors 51 of different layers 57, 58 are spaced from each other when viewed in a direction parallel to the plane of the movable part (or, in other words, the electrical interconnectors 51 may be stacked). By providing the electrical interconnectors 51 in different layers 57, 58, the electrical interconnectors 51 may be located closer together in plan view without unduly increasing the risk of electrical shorting between the electrical interconnectors 51, e.g. when the movable part moves relative to the support structure 4 and the electrical interconnectors 51 flex. In some examples, regions associated with the electrical interconnectors 51 of the different layers 57, 58 overlap in plan view, wherein each region has a width equal to the width of the electrical interconnector 51 plus an additional width equal to e.g. 200% or 100% or 50% of the width of the electrical interconnector 51.

The same principle, i.e. that electrically interconnectors may be stacked without necessarily overlapping in plan view, also applies to the electrical interconnectors 51 of Figures 9-10, 11-12 and 19.

Figure 6 is a plan view of the electrical interconnectors 51 of an actuator assembly 2. Figure 7 is a cross- sectional view of the electrical interconnectors 51 of the actuator assembly 2 shown in Figure 6. The actuator assembly 2 shown in Figure 6 has a different arrangement of electrical interconnectors 51 compared to the actuator assembly 2 shown in Figure 5. Other features of the actuator assembly 2 shown in Figure 6 may be the same as the actuator assembly 2 shown in Figures 1-5. For brevity, a description of these features is not repeated below.

As shown in Figure 7, optionally the electrical interconnectors 51 do not overlap each other. As shown in Figure 6, the electrical interconnectors 51 are spaced from each other when viewed in the direction perpendicular to the plane of the movable part. In the arrangement shown in Figure 6, there are four groups of electrical interconnectors 51. Each group consists of six electrical interconnectors 51. Similarly, in the arrangement shown in Figure 4 and Figure 5, there are four groups of electrical interconnectors 51, each group consisting of six electrical interconnectors 51.

From a comparison between Figure 5 and Figure 6, it can be seen that in the arrangement of Figure 5, the electrical interconnectors 51 do not laterally extend as far from the edge of the movable part compared to the arrangement of Figure 6. The support structure 4 of the actuator assembly 2 shown in Figure 5 may be narrower than the support structure 4 of the actuator assembly 2 shown in Figure 6. This can help to reduce the area of the actuator assembly 2 (sometimes referred to as the footprint of the actuator assembly 2) when viewed in a direction perpendicular to the plane of the movable part.

As another example of the benefit of overlapping or stacking, it may be possible to reduce the length of the electrical interconnectors 51 extending along the movable part. This can be seen from a comparison between Figure 5 and Figure 8. Figure 8 is a cross-sectional view of the electrical interconnectors of an actuator assembly of a comparative example.

As shown in Figure 8, in the comparative example, the electrical interconnectors 51 extend further across the movable part compared to the arrangement shown in Figure 5. The electrical interconnectors 51 extend to overlap a central region of the movable part. The electrical interconnectors 51 overlap the image sensor 6.

In contrast in the arrangement of Figure 5, providing overlapping or stacked electrical interconnectors 51 can help to reduce the possibility of overlap between the electrical interconnectors 51 and components of the movable part (particularly components that are thicker than the electrical interconnectors 51 such as the image sensor 6) when viewed in a direction perpendicular to the plane of the movable part. In turn this can help to reduce the dimension of the actuator assembly 2 in the direction perpendicular to the plane of the movable part.

Periphery of movable part

As shown in Figures 4-7, optionally at least one of the electrical interconnectors 51 has one end provided at a peripheral region of the movable part. No part of the electrical interconnector 51 extends beyond the peripheral region to a central region of the movable part. The peripheral region is a region near the edge of the movable part. For example, the peripheral region may correspond to a region that extends at most 20%, and optionally at most 10%, of the width of the movable part from the edge of the movable part. If the movable part is generally a square having sides of 10mm, say, then the peripheral region may have a width of at most 2mm, or optionally at most 10mm from the edge of the movable part.

By providing that at least one of the electrical interconnectors 51 has one end provided at a peripheral region of the movable part, the possibility of overlap between the electrical interconnectors 51 and components in a central portion of the movable part can be reduced. In turn this can help to reduce the dimension of the actuator assembly 2 in the direction perpendicular to the plane of the movable part. A smaller total thickness of components is required to be accommodated in the direction perpendicular to the lane of the movable part.

Optionally the electrical interconnectors 51 comprise connector pads 56. The connector pads 56 are for electrically connecting the electrical interconnectors 51 to the support structure 4 and the movable part. The connector pads 56 form the terminals of the electrical interconnectors 51. The connectors pads 56 are wider than the length of the electrical interconnector 51 extending from the connector pads 56. As shown in Figure 6, optionally most of the length of the electrical interconnector 51 that extends across the movable part is the connector pad 56.

As shown in Figures 2, 5 and 7, for example, optionally the support structure 4 comprises a support plate 5 that overlaps the movable part when viewed in a direction perpendicular to the plane of the movable part. Optionally, at least one of the electrical interconnectors 51 is connected to a surface of the movable part facing the support plate 5. This surface may be referred to as the underside of the movable part. However, during use of the actuator assembly 2, the orientation may change.

As shown in Figure 7, optionally at least one of the electrical interconnectors 51 is embedded into the surface of the movable part facing the support plate 5. Optionally, a minimum distance between the embedded section of the electrical interconnector 51 and the support plate 5 is greater than or equal to a minimum distance between the movable part and the support plate 5. The electrical interconnector 51 extends no further down (in the orientation shown in Figure 7) towards the support plate 5 than the movable part (e.g. the second PCB 9). The embedded section is the end part of the electrical connector 51. The embedded section may be mostly (or completely) formed by the connector pad 56. The movable part (e.g. the second PCB 9) may comprise a notch for accommodating the embedded section.

By providing that at least one of the electrical interconnectors 51 is embedded, the dimension of the actuator assembly in the direction perpendicular to the plane of the movable part can be reduced. The thickness of the electrical interconnector 51 does not contribute to this dimension. The thickness of the electrical interconnector 51 is not the limiting factor of how compactly the actuator assembly 2 can be manufactured.

As explained above, optionally the movable part is an image sensor assembly 12 comprising an image sensor 6 having a light-sensitive region 7. The possibility of overlap between the electrical interconnectors 51 and the image sensor 6 can be reduced. In turn this can help to reduce the dimension of the actuator assembly 2 in the direction perpendicular to the plane of the movable part.

Layered interconnectors

Figure 9 is a perspective view of the electrical interconnectors 51 of part of an actuator assembly 2. Figure 9 is a view that may be from either the underside or the top side of the actuator assembly 2. Figure 10 is a plan view of the electrical interconnectors 51 of the actuator assembly 2 shown in Figure 9. Optionally, at least one of the electrical interconnectors 51 is connected between a side of the support structure 4 facing in a first direction and a side of the movable part facing in the first direction. The first direction may be, for example, a direction facing upwards (i.e. the direction that the light-sensitive region 7 faces) in the orientation shown in Figure 2. Alternatively, the first direction may be, for example, a direction facing downwards in the orientation shown in Figure 2. The electrical interconnector 51 is connected to the same side of both the movable part and the support structure 4.

As shown in Figure 9, optionally a plurality of the electrical interconnectors 51 are connected between the side of the support structure 4 facing in the first direction and the side of the movable part facing in the first direction. This plurality of the electrical interconnectors 51 overlap when viewed in a direction perpendicular to the plane of the movable part. There is a plurality of layers of electrical interconnectors 51 on the same side of the movable part and support structure 4. At least a first layer 57 and a second layer 58 may be provided. The second layer 58 of electrical interconnectors 51 may be located between the first layer 57 and the support structure 4. Optionally, each layer 57, 58 corresponds generally to a plane parallel to the plane of the movable part.

By providing overlapping or stacked electrical interconnectors 51 on the same side of the support structure 4 and movable part, it is easier to assemble the actuator assembly 2. In particular, the level of access to the support structure 4 and movable part necessary to apply the electrical interconnectors 51 may be required for only one side of the actuator assembly 2. This may help reduce the cost of manufacturing the actuator assembly 2.

As shown in Figures 4-7, for example, optionally at least one of the electrical interconnectors 51 is arranged to extend in a plane parallel to the plane of the movable part. However, it is not essential for the electrical interconnectors 51 to be formed within a plane. For example, as shown in Figure 9, optionally at least one of the electrical interconnectors 51 comprises a first portion 52 configured to extend in a first plane parallel to the plane of the movable part and a second portion 53 configured to extend in a second plane parallel to and different from the first plane. The first plane may correspond to the location of the first layer 57. The second plane may correspond to the location of the second layer 58.

Optionally one of the first portion 52 and the second portion 53 is connected to the support structure 4, while the other of the first portion 52 and the second portion 53 is connected to the movable part. As shown in Figure 9, optionally the first portion 52 is connected to the support structure 4 and the second portion 53 is connected to the movable part. By providing two planes for the electrical interconnectors 51, the design of the actuator assembly 2 may be kept relatively simple while allowing the advantages of the overlapping or stacked electrical interconnectors 51. The electrical interconnectors 51 may be positioned on the same side of the movable part while remaining overlapping or stacked. This can help make it easier to manufacture the actuator assembly 2.

As shown in Figure 9, optionally the first portion 52 and the second portion 53 are connected by a third portion 54 configured to extend perpendicularly to the first plane. The third portion 54 may alternatively be diagonal, extending both between the planes and also laterally. By providing the third portion 54, the possibility of interference between the two planes of electrical interconnectors 51 can be reduced. The length of the third portion 54 may be selected so as to appropriately reduce the possibility of electrical breakdown between the layers 57, 58 of the electrical interconnectors 51.

As shown in Figure 9, optionally the electrical interconnectors 51 are jogged so as to bridge the two layers 57, 58 of electrical interconnectors 51. The jogs are shown in Figure 9 by a dashed line and an arrow. Jogging provides a relatively simple way to manufacture the appropriate arrangement of electrical interconnectors 51.

As shown in Figure 9, optionally most of the length of one or more of the electrical interconnectors 51 is overlapped with another electrical interconnector 51 in another layer. The extent of overlap may be at least 20%, optionally at least 50%, optionally at least 80%, and optionally at least 90% of the length of the electrical interconnector 51. As shown in Figure 9, optionally the bends 55 are provided in the overlapping positions for the different layers 57, 58. As shown in Figure 10, the paths of the electrical interconnectors 51 may be selected so that different layers 57, 58 follow the same path generally.

However, it is not essential for a plurality of layers of electrical interconnectors 51 to be provided on the same side of the support structure 4 and movable part. As shown in Figure 5, optionally one layer is provided on either side. Optionally, the support structure 4 is configured to electrically isolate at least two of the electrical interconnectors 51 from each other.

By providing that the support structure 4 is configured to electrically isolate at least two of the electrical interconnectors 51 from each other, it may not be necessary to provide an additional component to prevent electrical shorting between overlapping or stacked electrical interconnectors 51. The properties of the existing support structure 4 can be used to perform mechanical and electrical separation of the different layers of electrical interconnectors 51. As a further alternative, there may be a plurality of layers 57, 58 on one side of the movable part and support structure 4, while also providing one or more layers of electrical interconnectors 51 on the other side. The number of layers of electrical interconnectors 51 on either side may be selected based on the number of electrical paths required and space constraints. For example, either side may be provided with zero, one, two, three or more than three layers.

'3D' interconnectors

Figure 11 is a plan view of an actuator assembly 2. Figure 12 is a cross-sectional view of two of the electrical interconnectors 51 of the actuator assembly 2 shown in Figure 11. Figure 11 shows three electrical interconnectors 51 extending from each of the four sides of the movable part. The support structure 4 is not depicted.

Figure 12 shows a first diagonal portion 59a of a first electrical interconnector 51, which is one of the three electrical interconnectors 51 shown extending from the left hand side of the second PCB 9 in the view of Figure 11. Figure 12 shows a second diagonal portion 59b of a second electrical interconnector 51, which is one of the three electrical interconnectors 51 shown extending from the upper side of the second PCB 9 in the view of Figure 11. Other electrical interconnectors 51 are omitted from Figure 12 for clarity.

As shown in Figure 12, optionally a plurality of the electrical interconnectors 51 comprise respective diagonal portions 59. The diagonal portions 59 overlap each other when viewed in a direction perpendicular to the plane of the movable part. The diagonal portions 59 extend in a direction parallel to the plane of the movable part and in a direction perpendicular to the plane of the movable part. In general the diagonal portions 59 may extend parallel to edges of the movable part when viewed perpendicularly to the plane of the movable part.

By providing the diagonal portions 59, it may not be necessary to jog the material of the electrical interconnectors 51 in order to provide overlapping or stacked electrical interconnectors 51 on the same side of the movable part. The design may make use of the surfaces of the movable part and the support structure 4 being at different positions (i.e. different heights) along the axis perpendicular to the movable part.

In the view shown in Figure 12, the first diagonal portion 59a is shown above the second diagonal portion 59b. In a view of the edge of the movable part shown at the bottom of Figure 11, the first diagonal portion 59a would be below a diagonal portion of one of the electrical interconnectors 51 that extends from the bottom edge shown in Figure 11. The electrical interconnectors 51 spiral around the edges of the movable part.

As shown in Figure 11 and Figure 12, optionally, the diagonal portions 59 are parallel to each other. However, it is not essential for them to be parallel. It may be that the diagonal portions 59 are parallel to each other when viewed perpendicularly to the plane of the movable part (i.e. in the view shown in Figure 11) but are not parallel in a side on view (i.e. the view shown in Figure 12). The extent to which the diagonal portions 59 are parallel may be limited by the extent to which the diagonal portions form straight, taut lines.

Types of interconnector

Different types of electrical interconnector 51 may be used. All of the electrical interconnectors 51 may be of the same type. Alternatively, multiple different types of electrical interconnector 51 may be combined in the actuator assembly 2.

Figure 13 is a cross-sectional view of an electrical interconnector 51 of the actuator assembly 2. As shown in Figure 13, optionally at least one of the electrical interconnectors 51 comprises a metallic flexure 61. The electrical interconnector 51 may consist of a metallic flexure 61. Optionally a plurality of (e.g. all of) the electrical interconnectors 51 comprise respective metallic flexures 61.

By providing that at least one of the electrical interconnectors 51 comprises a metallic flexure 61, the design of the electrical interconnector 51 may be relatively simple, for example not requiring an integrated insulator. The metallic flexure 61 may be used to impart a force on the movable part or the support structure 4.

As shown in Figure 13, optionally the metallic flexure 61 has a rectangular cross-section. The metallic flexure 61 may have a width (i.e. its longest dimension in cross-section) of at least 20pm and optionally at least 50pm. The metallic flexure 61 may have a width of at most 100pm and optionally at most 50pm. The metallic flexure 61 may have a height (i.e. its shortest dimension in cross-section) of at least 10pm and optionally at least 20pm. The metallic flexure 61 may have a height of at most 100pm and optionally at most 50pm. For example the metallic flexure 61 may have a height of about 40pm.

Figure 14 is a cross-sectional view of electrical interconnectors 51 of the actuator assembly 2.

Optionally, at least one of the electrical interconnectors 51 comprises a flexible electrical connector. The flexible electrical connector may be a flexible printed circuit or a rigid-flex circuit, for example. The flexible electrical connector may comprise a plurality of electrical paths (or electrical traces), for example two, three, four or more. Alternatively, the flexible electrical connector may comprise only one electrical path.

By providing that at least one of the electrical interconnectors 51 comprises a flexible electrical connector, the electrical interconnector 51 can be compliant so as not to obstruct the free movement of the movable part. Meanwhile the flexible electrical connector may carry a plurality of electrical paths in a space-efficient way.

As shown in Figure 14, optionally the flexible electrical connector comprises a conductive trace 62. The conductive trace 62 is the transmission line that transfers the electrical current signal. The conductive trace 62 may be formed of copper, for example. A different conductive material other than copper may be used as the conductive trace 62.

As shown in Figure 14, optionally the flexible electrical connector comprises an insulating cover 63. The insulating cover 63 is configured to electrically isolate the conductive trace 62 from other conductors, for example other electrical connectors 51. As shown in Figure 14, optionally the insulating cover 63 covers a plurality of sides of the conductive trace 62 when the conductive trace 62 is viewed in crosssection. In the arrangement shown in Figure 14, the insulating cover 63 covers three of the four sides of the conductive trace 62, with the fourth side covered by an insulating layer 64. The insulating cover 63 may also cover the exposed area of the insulating layer 64.

As shown in Figure 14, optionally an insulating layer 64 is provided so as to electrically isolate electrical interconnectors 51 from each other. In the example shown in Figure 14, the insulating layer 64 is configured to electrically isolate the metallic flexure 61 from the conductive trace 62 of the flexible electrical connector. As shown in Figure 14, optionally the metallic flexure 61 is greater in cross- sectional area than the flexible electrical connector. As shown in Figure 14, optionally the insulating layer 64 extends across the whole width of the widest of the isolated electrical connectors 51 when viewed in cross-section. In the arrangement shown in Figure 14, the widest electrical connector 51 is the metallic flexure 61. The insulating layer 64 is as wide as the metallic flexure 61. This can help to reduce the possibility of undesirable electrical breakdown.

By providing the insulator layer 64 it is possible to electrically isolate the electrical interconnectors 51 from each other while providing the space-saving advantages of the electrical interconnectors 51 overlapping each other or being stacked. In some examples, the insulating layer 64 (and/or the insulating cover 63) may be made wider than the flexure 61. This can provide a standoff feature to prevent flexures 61 within the same plane electrically shorting to one another.

Figure 14 shows a flexure with a single insulated trace. Such an arrangement may comprise a flexible electrical connector (e.g. a flexible printed circuit) bonded to a metallic flexure 61. Alternatively, the arrangement may be formed by a trace suspension assembly. The trace suspension assembly comprises the metallic flexure 61, the insulating layer 64 and the conductive trace 62. The insulating cover 63 may be provided or may be omitted.

As shown in Figure 14, optionally, at least one of metallic flexures 61 is provided with a flexible electrical connector layered relative to it. By providing that at least one of metallic flexures 61 is provided with a flexible electrical connector layered relative to it, additional electrical paths may be formed without significantly increasing the volume taken up by the electrical interconnectors 51. The flexible plastic substrate (e.g. the insulating layer 64) of the flexible electrical connector may prevent electrical breakdown between the metallic flexure 61 and the flexible electrical connector.

Figure 15 is a cross-sectional view of electrical interconnectors 51 of the actuator assembly 2. Figure 15 shows an arrangement of a flexure with multiple insulated traces. As shown in Figure 15, optionally an insulating layer 64 is provided so as to electrically isolate the metallic flexure 61 from a plurality of (e.g. two) conductive traces 62. The conductive traces 62 may be comprised in a flexible electrical connector. As shown in Figure 14, optionally the insulating cover 63 covers a plurality of conductive traces 62.

Figure 16 is a cross-sectional view of electrical interconnectors of the actuator assembly. Optionally, the insulator layer 64 configured to electrically isolate a plurality of the electrical interconnectors 51 from another plurality of the electrical interconnectors 51. The insulator layer 64 may be formed by the flexible plastic substrate of one or more flexible electrical connectors. Alternatively, a separate layer of electrically insulating material may be provided between layers 57, 58 of the electrical interconnectors 51.

Figure 16 shows an arrangement of a flexure with multi-layer insulated traces. Such an arrangement may comprise a flexible electrical connector (e.g. a flexible printed circuit) bonded to a metallic flexure 61. The flexible electrical connector comprises a plurality of layers of conductive traces 62. In the arrangement shown in Figure 16, the flexible electrical connector comprises two layers of conductive traces 62. However, the number of layers is not limited to two. In an alternative arrangement the flexible electrical connector may comprise three, four or more layers of conductive traces. In the arrangement shown in Figure 16, each layer of conductive traces 62 comprises two conductive traces 62. However, the number of conductive traces 62 is not limited to two. In an alternative arrangement each layer of conductive traces 62 may comprise one, three, four or more conductive traces 62. Different layers may comprise different numbers of conductive traces 62.

As shown in Figure 16, optionally an insulating layer 64 is provided between layers of conductive traces. Part of an insulating cover 63 electrically isolates the flexible electrical connector from the metallic flexure 61.

Figure 17 is a cross-sectional view of electrical interconnectors 51 of the actuator assembly 2. As shown in Figure 17, optionally the electrical interconnectors 51 are all formed as one or more flexible electrical connectors. Such a connector 51 may be equivalent to the arrangement described above with reference to Figure 16 but without the flexure 61.

Optionally, within a group comprising a plurality of the electrical interconnectors 51, the longest electrical interconnector 51 is at most 20%, and optionally at most 10% longer than the shortest electrical interconnector 51. By providing that the electrical interconnectors 51 have similar or the same lengths, the difference in time taken for electrical signals to pass through the electrical interconnectors 51 may be reduced. This can help to synchronize signals. By providing that the electrical interconnectors 51 have similar or the same lengths, the difference in impedance of the electrical interconnectors 51 may be reduced. This can facilitate impedance matching.

Optionally, the group comprises all of the electrical interconnectors 51. All of the electrical interconnectors 51 may have similar lengths. Alternatively, the group may be a subset of the electrical interconnectors 51. For example, the group having similar lengths may correspond to one or more of the groups of electrical interconnectors described above (e.g. a group of electrical interconnectors 51 extending from the same side of the movable part).

Bearing arrangement

In the illustrated embodiments, the actuator assembly 2 further comprises a bearing arrangement 110. The bearing arrangement 110 supports the image sensor assembly 12 relative to the support structure 4. Optionally, the bearing arrangement 110 supports the image sensor assembly 12 on the support structure 4 so as to form the gap 104. The bearing arrangement 110 allows movement of the image sensor assembly 12 relative to the support structure 4, for example in a manner allowing movement of the image sensor assembly 12 relative to the support structure 4 in any direction laterally to the light- sensitive region 7 and/or in a manner allowing rotation of the image sensor assembly 12 about any axis perpendicular to the light-sensitive region 7.

As shown in Figure 2, the bearing arrangement may comprise a rolling bearing 110. The rolling bearing 110 may, for example, be a ball bearing or a roller bearing. The rolling bearing 110 comprising a rolling element, for example a ball, a roller or a rocking element. The rolling element may be spherical or may in general be any rotary element with curved surfaces that bear against the image sensor assembly 12 and the support structure 4 and are able to roll back and forth and around in operation.

The rolling element is disposed between the image sensor assembly 12 and the support structure 4. The image sensor assembly 12 is thus supported on the support structure 4 by the rolling element. The rolling bearing 110 may comprise plural rolling elements, for example three rolling elements. Although in general any number of rolling elements could be provided, it is preferable to provide at least three rolling elements to prevent relative tilting of the image sensor assembly 12 and the support structure 4. Three rolling elements are sufficient to support the image sensor assembly 12 without tilting, and the provision of three rolling elements has the advantage of easing the tolerances required to maintain point contact with each rolling element in a common plane.

In the embodiment of Figure 2, the rolling bearing 110 is disposed on the same side of the image sensor assembly 12 as the gap 104, as shown in Figure 2. This may ensure that the height of the gap 104 remains constant even when large forces act upon the image sensor assembly 12. The extent of the rolling element may be larger than the extent of the gap 104 in the direction perpendicular to the lightsensitive region 7, for example by way of a recess in the underside of the image sensor assembly 12 to accommodate the rolling element. This may allow the height of the gap 104 to be reduced compared to a situation in which the rolling element is arranged in the gap 104.

In an alternative embodiment, the rolling bearing 110 is disposed on the side of the image sensor assembly 12 that is opposite to the gap 104. The rolling bearing 110 is disposed on the same side of the image sensor assembly 12 as the light-sensitive region 7, in particular laterally to the light-sensitive region 7.

The bearing arrangement 110 may, alternatively or additionally, comprise a flexure arrangement. The flexure arrangement is disposed between the image sensor assembly 12 and the support structure 4. The image sensor assembly 12 is thus supported on the support structure 4 by the flexure arrangement. Alternatively or additionally, the bearing arrangement 110 may comprise a plain bearing, such as a structured plain bearing. The plain bearing comprises a bearing surface on each of the image sensor assembly 12 and the support structure 4. The plain bearing may comprise steel, polymer or ceramic. The bearing surfaces may each be planar. The bearing surfaces bear on each other so as to support the image sensor assembly 12 on the support structure 4, permitting relative sliding motion. The plain bearing thus allows movement of the image sensor assembly 12 relative to the support structure 4, in particular in said manner allowing movement or rotation of the image sensor assembly 12 relative to the support structure 4 in any direction laterally to the light-sensitive region 7.

Additionally or alternatively, the electrical interconnectors 51 may act as the bearing arrangement 110. For example, flexures forming the electrical interconnectors 51 may be configured to support the image sensor assembly 12 on the support structure 4 so as to form the gap 104. The flexures are configured to allow the movement of the image sensor assembly 12 relative to the support structure 4. The image sensor assembly 12 may be suspended in space using the electrical interconnectors 51. The electrical interconnectors 51 may comprises a flexure type arrangement configured to hold the movable part in a plane as the movable part moves relative to the support structure 4. This can help to reduce friction and reduce the number of parts required to form the actuator assembly 2.

The bearing arrangement 110 is configured to constrain the image sensor 6 in a plane. This can help to improve or maintain the quality of images obtained by the image sensor 6.

Optionally, the actuator assembly 2 comprises a biasing arrangement for providing a force acting on the image sensor assembly 12 to ensure that it remains engaged with the bearing surfaces, preferably in all postures. As shown in Figure 2, optionally the actuator assembly 2 comprises a magnet arrangement configured to apply a force biasing the image sensor assembly 12 against the bearing arrangement 110. For example, the image sensor assembly 12 may comprise at least one magnet 22. The magnets 22 may be fixed relative to the second PCB 9. The number of magnets may be one, two, three, four or more than four. The magnets 22 may be embedded in the second PCB 9, or may be attached to a side of the second PCB 9, for example.

Optionally, the support structure 4 comprises a ferrous material. For example, the support plate 5 may be formed of a ferrous material such as steel. The magnetic attraction between the magnets 22 and the support plate 5 biases the image sensor assembly 12 against the bearing arrangement 110.

Optionally, the electrical interconnectors 51 are preformed to provide the biasing force urging the image sensor assembly 12 against the bearing arrangement 110. For example, the electrical interconnectors 51 may be shaped so as to provide such a biasing force. Optionally the electrical interconnectors 51 are formed into a particular shape before the actuator assembly 2 is assembled (i.e. before the image sensor assembly 12 is assembled with the support plate 5). For example, the electrical interconnectors 51 may comprise a jog. The electrical interconnectors 51 may be formed such that the mounting position of the second PCB 9 relative to the first PCB 10 is lower (i.e. further in the direction facing away from the light sensitive region 7) than the intended position of the second PCB 9 in the actuator assembly 2 once it has been fully assembled. When the second PCB is assembled with the support plate 5, the bearing arrangement 110 may force the second PCB 9 to take its intended position. The initial shape of the flexures of the electrical interconnector 51 causes the electrical interconnector 51 to apply a spring force urging the image sensor assembly 12 onto the bearing arrangement 110.

Actuator arrangement

Movement of the movable part relative to the support structure 4 is driven by an actuator arrangement that is arranged as follows, and seen most easily in Figure 3. Particular advantage is achieved in the case that the actuator arrangement comprises plural SMA wires 40, as SMA provides a high actuation force compared to other forms of actuator. This may assist in accurate positioning of the movable part relative to the support structure 4. In general, however, the actuator arrangement may comprise actuator components other than SMA wires 40.

The actuator arrangement shown in Figure 3 is formed by a total of four SMA wires 40 connected between the support structure 4 and the image sensor assembly 12. For attaching the SMA wires 40, the image sensor assembly 12 comprises crimp portions 41 fixed to the second PCB 9 and the support structure 4 comprises crimp portions 42 fixed to the first PCB 10. The crimp portions 41 and 42 crimp the four SMA wires 40 so as to connect them to the support structure 4 and the image sensor assembly 12.

As shown in Figure3, optionally the SMA wires 40 are fixed to the first PCB 10 and the second PCB 9. The crimp portions 41 may be mounted directly onto the second PCB 9. The crimp portions 42 may be mounted directly onto the first PCB 10.

The SMA wires 40 are arranged as follows so that they are capable, on selective driving, of moving the image sensor assembly 12 relative to the support structure 4 in any direction laterally to the lightsensitive region 7 and also of rotating the image sensor assembly 12 about an axis orthogonal to the light-sensitive region 7.

In use, each of the SMA wires 40 is held in tension, thereby applying a force between the support structure 4 and the image sensor assembly 12. The SMA wires 40 may be perpendicular to the optical axis O so that the force applied to the image sensor assembly 12 is lateral to the light-sensitive region 7. Alternatively, the SMA wires 40 may be inclined at a small angle to the light-sensitive region 7 so that the force applied to the image sensor assembly 12 includes a component lateral to the light-sensitive region 7 and a component along the optical axis O that acts as a biasing force that biases the image sensor assembly 12 against the bearing arrangement 110. So, the SMA wires 40 may act as the biasing arrangement. The biasing arrangement may comprise actuator components for applying a biasing force that biases the image sensor assembly 12 towards the bearing arrangement 110.

The overall arrangement of the SMA wires 40 will now be described, being similar to that described in WO-2014/083318.

SMA material has the property that on heating it undergoes a solid-state phase change which causes the SMA material to contract. At low temperatures, the SMA material enters the Martensite phase. At high temperatures, the SMA enters the Austenite phase which induces a deformation causing the SMA material to contract. The phase change occurs over a range of temperature due to the statistical spread of transition temperature in the SMA crystal structure. Thus heating of the SMA wires 40 causes them to decrease in length.

The SMA wires 40 may be made of any suitable SMA material, for example Nitinol or another Titanium- alloy SMA material. Advantageously, the material composition and pre-treatment of the SMA wires 40 is chosen to provide phase change over a range of temperature that is above the expected ambient temperature during normal operation and as wide as possible to maximise the degree of positional control.

On heating of one of the SMA wires 40, the stress therein increases and it contracts, causing movement of the image sensor assembly 12. A range of movement occurs as the temperature of the SMA increases over the range of temperature in which there occurs the transition of the SMA material from the Martensite phase to the Austenite phase. Conversely, on cooling of one of the SMA wires 40 so that the stress therein decreases, it expands under the force from opposing ones of the SMA wires 40. This causes the image sensor assembly 12 to move in the opposite direction.

The image sensor assembly 12 is positioned axially within the aperture 11 of the first PCB 10 of the support structure 4. The four SMA wires 40 are arranged on four sides of the image sensor assembly 12.

The SMA wires 40 may be of the same length and may have a rotationally symmetrical arrangement. As viewed axially, a first pair of the SMA wires 40 extend parallel to a first axis (vertical in Figure 4) that is lateral to the light-sensitive region 7. However, the first pair of the SMA wires 40 are oppositely connected to the support structure 4 and the image sensor assembly 12 so that they apply forces in opposite directions along the first axis (vertically up and down in Figure 3) . The forces applied by the SMA wires 40 of the first pair balance in the event that the tension in each SMA wire 40 is equal. This means that the first pair of the SMA wires 40 apply a first torque to the image sensor assembly 12 (anticlockwise in Figure 3).

As viewed axially, a second pair of SMA wires 40 extend parallel to a second axis (horizontal in Figure 3) that is lateral to the light-sensitive region 7. However, the second pair of SMA wires 40 are oppositely connected to the support structure 4 and the image sensor assembly 12 so that they apply forces in opposite directions along the second axis (horizontally left and right in Figure 3). The forces applied by the SMA wires 40 of the second pair balance in the event that the tension in each SMA wire 40 is equal. This means that the second pair of the SMA wires 40 apply a second torque (clockwise in Figure 3) to the image sensor assembly 12 that is arranged to be in an opposite sense to the first torque. Thus, the first and second torques balance in the event that tension in each SMA wire 40 is the same.

As a result, the SMA wires 40 may be selectively driven to move the image sensor assembly 12 in any direction laterally relative to the optical axis O and to rotate the image sensor assembly 12 about an axis parallel to the optical axis O. That is:

• movement of the image sensor assembly 12 in either direction along the first axis may be achieved by driving the first pair of SMA wires 40 to contract differentially, due to them applying forces in opposite directions;

• movement of the image sensor assembly 12 in either direction along the second axis may be achieved by driving the second pair of SMA wires 40 to contract differentially, due to them applying forces in opposite directions; and

• rotation of the image sensor assembly 12 may be achieved by driving the first pair of SMA wires 40 and the second pair of SMA wires 40 to contract differentially, due to the first and second torques being in opposite senses.

The magnitude of the range of movement and rotation depends on the geometry and the range of contraction of the SMA wires 40 within their normal operating parameters.

This particular arrangement of the SMA wires 40 is advantageous because it can drive the desired lateral movement and rotation with a minimum number of SMA wires. However, other arrangements of SMA wires 40 could be applied. To provide three degrees of motion (two degrees of lateral motion and one degree of rotational motion), then a minimum of four SMA wires 40 are provided. Other arrangements could apply a different number of SMA wires 40. Less SMA wires 40 could be provided for lateral motion, but not rotation. Arrangements with more than four SMA wires 40 are also possible, and may have advantages in allowing additional parameters to be controlled in addition to motion, for example the degree of stress in the SMA wires 40.

The lateral position and orientation of the image sensor assembly 12 relative to the support structure 4 is controlled by selectively varying the temperature of the SMA wires 40. This driving of the SMA wires 40 is achieved by passing selective drive signals through the SMA wires 40 to provide resistive heating. Heating is provided directly by the current of the drive signals. Cooling is provided by reducing or ceasing the current of the drive signals to allow the SMA wire 40 to cool by conduction, convection and radiation to its surroundings.

Camera apparatus

The camera apparatus 1 comprises a lens assembly 20 that is assembled with the actuator assembly 2 by being mounted to the support structure 4, for example to the rim portion formed at least partly by the first PCB 10.

The lens assembly 20 comprises a lens carriage 21 in the form of a cylindrical body that is mounted to the rim portion of the support structure 4. The lens carriage supports at least one lens arranged along the optical axis O. In general any number of one or more lenses may be provided. Without limitation to the invention, in this example the camera apparatus 1 is a miniature camera in which the at least one lens (i.e. each lens if plural lenses are provided) typically have a diameter of at most 10mm or 15mm or 20mm. The at least one lens of the lens assembly 20 is arranged to focus an image onto the image sensor.

In this example, at least one lens is supported on the lens carriage 21 in a manner in which at least one lens is movable along the optical axis O relative to the lens carriage 21, for example to provide focussing or zoom, although that is not essential. In particular, the at least one lens is fixed to a lens holder 23 which is movable along the optical axis O relative to the lens carriage 21. Where there are plural lenses, any or all of the lenses may be fixed to the lens holder 23 and/or one or more of the lenses may be fixed to the lens carriage 21 and so not movable along the optical axis O relative to the lens carriage 21.

An axial actuator arrangement 24 provided between the lens carriage 21 and the lens holder 23 is arranged to drive movement of the lens holder 21 and lenses along the optical axis O relative to the lens carriage 21. The axial actuator arrangement 24 may be any suitable type, for example being a voice coil motor (VCM) or an arrangement of SMA wires, such as is described in WO-2019/243849 which is incorporated herein by reference.

In addition, the camera apparatus 1 may comprise a can 15 fixed to the support structure 4 and protruding forwardly therefrom to encase and protect the other components of the camera apparatus 1.

As discussed above, in operation the SMA wires 40 are selectively driven to move the image sensor assembly 12 in any direction laterally and/or to rotate the image sensor assembly 12 about an axis parallel to the optical axis O. This is used to provide OIS, compensating for image movement of the camera apparatus 1, caused by for example hand shake.

Relative movement of the image sensor 6 relative to the support structure 4 and hence also relative to the lens assembly 20 may be used to stabilise the image against tilting of the camera apparatus 1, i.e. rotation about axes extending laterally to the light-sensitive region 7. In addition, rotation of the image sensor 6 may be used to stabilise the image against rotation of the camera apparatus 1 around the optical axis O.

The SMA wires 40 are driven by the control circuit implemented in the IC chip 30. In particular, the control circuit generates drive signals for each of the SMA wires 40 and supplies the drive signals to the SMA wires 40.

The control circuit 30 receives the output signals of the gyroscope sensor 31 which acts as a vibration sensor. The gyroscope sensor 31 detects the vibrations that the camera apparatus 1 is experiencing and its output signals represent those vibrations, specifically as the angular velocity of the camera lens element 20 in three dimensions. More generally, larger numbers of gyroscopes or other types of vibration sensor could be used.

The drive signals are generated by the control circuit in response to the output signals of the gyroscope sensor 31 so as to drive movement of the image sensor assembly 12 to stabilise an image focused by the camera lens element 20 on the image sensor, thereby providing OIS. The drive signals may be generated using a resistance feedback control technique for example as disclosed in any of WO-2013/175197, WO- 2014/076463, WO 2012/066285, WO-2012/020212, WO-2011/104518, WO-2012/038703, WO 2010/089529 or WO-2010/029316, each of which is incorporated herein by reference. The camera apparatus 1 may be incorporated into a portable electronic device, such as such as a mobile telephone or tablet computer.

Variations

The above-described SMA actuator assemblies comprise at least one SMA element. The term 'shape memory alloy (SMA) element' may refer to any element comprising SMA. The SMA element may be described as an SMA wire. The SMA element may have any shape that is suitable for the purposes described herein. The SMA element may be elongate and may have a round cross section or any other shape cross section. The cross section may vary along the length of the SMA element. The SMA element might have a relatively complex shape such as a helical spring. It is also possible that the length of the SMA element (however defined) may be similar to one or more of its other dimensions. The SMA element may be sheet-like, and such a sheet may be planar or non-planar. The SMA element may be pliant or, in other words, flexible. In some examples, when connected in a straight line between two components, the SMA element can apply only a tensile force which urges the two components together. In other examples, the SMA element may be bent around a component and can apply a force to the component as the SMA element tends to straighten under tension. The SMA element may be beam-like or rigid and may be able to apply different (e.g. non-tensile) forces to elements. The SMA element may or may not include material(s) and/or component(s) that are not SMA. For example, the SMA element may comprise a core of SMA and a coating of non-SMA material. Unless the context requires otherwise, the term 'SMA element' may refer to any configuration of SMA material acting as a single actuating element which, for example, can be individually controlled to produce a force on an element. For example, the SMA element may comprise two or more portions of SMA material that are arranged mechanically in parallel and/or in series. In some arrangements, the SMA element may be part of a larger SMA element. Such a larger SMA element might comprise two or more parts that are individually controllable, thereby forming two or more SMA elements. The SMA element may comprise an SMA wire, SMA foil, SMA film or any other configuration of SMA material. The SMA element may be manufactured using any suitable method, for example by a method involving drawing, rolling, deposition, sintering or powder fusion. The SMA element may exhibit any shape memory effect, e.g. a thermal shape memory effect or a magnetic shape memory effect, and may be controlled in any suitable way, e.g. by Joule heating, another heating technique or by applying a magnetic field.

It will be appreciated that there may be many other variations of the above-described examples. For example, the second PCB 9 may be replaced by a plate that does not have integrated electrical paths, for example a metal plate. As another example, the first PCB 10 may be replaced by an alternative rigid material such as a metal plate, or the support plate 5 may comprise an integral rim around the movable part. As another example, the gap 104 may not be provided. Instead the movable part may be configured to slide on the support plate 5.

As another example of a variation, optionally there is no overlap between electrical interconnectors 51 when viewed perpendicularly to the plane of the movable part. Instead, as shown in Figure 5 and Figure 7, for example, the electrical interconnectors 51 do not extend into a central region of the movable part. Where the electrical interconnectors 51 extend across the movable part, the electrical interconnectors 51 are provided only in a peripheral region (i.e. near the edge) of the movable part. This may help reduce the height of the actuator assembly 2 as explained above.

As shown in Figure 2, optionally the image sensor 6 is mounted on the second PCB 9. Alternatively, as shown in Figure 18 the image sensor 6 and the second PCB 9 (i.e. the PCB of the image sensor assembly 12) overlap in a direction perpendicular to the plane of the image sensor assembly 12. When viewed in a lateral direction (i.e. a direction parallel to the plane of the movable part), the image sensor 6 and the second PCB 9 overlap. As shown in Figure 18, optionally the image sensor 6 is mounted on a sensor support member 58. The sensor support member 58 may be essentially planar, for example it may be a plate. The sensor support member 58 may be a metal for example steel (e.g. stainless steel) or copper or beryllium copper. Optionally, the second PCB 9 is mounted on the sensor support member 58. By providing that the image sensor 6 and the second PCB 9 overlap, the dimension of the actuator assembly 2 in the direction perpendicular to the plane of the movable part can be reduced.

The bearing arrangement 110 may comprise any combination of the above-described bearing arrangements 110. The roller bearing 110 may comprise rolling elements on both sides of the image sensor assembly 12 in a direction perpendicular to the light-sensitive region 7. The bearing arrangement 110 may comprise one or more rolling bearings and one or more flexure arrangements.