Field

The present application relates to electrical interconnects between a moving component and a support structure in an electronic device, for example a camera.

Background

Many electronic devices comprise a movable component which must be electrically connected to one or more other components in the device which do not move with the movable component. Such an electrical connection may be for the purposes of data and/or power transfer. Therefore, an electrical interconnect between the movable component and the non-moving component is required which does not hinder movement of the movable component.

An example of a device in which such an interconnect may be required is a camera. In a camera, various degrees of movement of a movable component may be required for example for the purposes of optical image stabilisation (OIS) and/or autofocus. The movable component in a camera may be, for example, a lens assembly, an image sensor, or a module comprising the image sensor and the lens assembly, as will now be described.

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. 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. Several techniques for adjusting the camera apparatus are known.

A number of actuator arrangements employing 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 space constraints for components in miniature camera apparatuses presents great difficulties in adding OIS actuators within the desired space.

In one type of OIS, a camera unit comprising an image sensor and a lens assembly for focussing an image on the image sensor is tilted relative to a support structure around two notional axes that are perpendicular to each other and parallel to the light-sensitive region of the image sensor (when untilted). Such a type of OIS will be referred to herein as "OlS-module-tilt". WO-2010/029316 and WO-2010/089529 each disclose actuator assemblies of this type in which a plurality of shape memory alloy (SMA) actuator wires are arranged to drive tilting of the camera unit.

In another type of OIS, a lens assembly is moved orthogonally to the optical axis thereof. Such a type of OIS will be referred to herein as "OlS-lens shift". WO-2013/175197 and WO-2014/083318 each disclose actuator assemblies of this type in which a plurality of SMA actuator wires are arranged to drive movement of the lens assembly.

WO-2017/072525 discloses an image sensor mounted on a carrier that is suspended on a support structure by a 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 arrangement comprising plural shape memory alloy 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. Such an arrangement, in which the image sensor is moved laterally will be referred to herein as "OIS sensor-shift". The image sensor may be moved along the optical axis, for example for the purpose of autofocus. This may be combined with OIS sensor-shift or may be used without OIS.

The present invention is concerned with an actuator assembly that can provide an electrical connection to a movable component without hindering movement of the movable component and whilst ensuring that the space occupied by the connection is kept small.

Summary

According to an aspect of the present invention, there is provided an actuator assembly comprising: a support structure defining a primary axis; a movable component movable relative to the support structure; and a flexible electrical connector connected between the movable component and the support structure.

The flexible electrical connector may be a flexible printed circuit (FPC) or any other type of flexible electrical connector or flexible interconnect. The flexible electrical connector may be electrically connected to the movable component and to the support structure, i.e. it may provide an electrical connection that is fixed relative to the support structure and an electrical connection that is fixed relative to the movable component. So, the flexible electrical connector is connected to the movable component and to the support structure. The flexible electrical connector is connected at one end to the movable component and at the other end to the support structure. The flexible electrical connector provides one or more electrical connections between its ends.

The flexible electrical connector comprises a first planar portion, a second planar portion and a bend between the first and second planar portions. The first and second planar portions and the bend lie in a first plane such that the flexible electrical connector allows movement of the movable component along two orthogonal axes parallel to the first plane and/or rotation of the movable part about the two orthogonal axes. For example, the actuator assembly could be used for OlS-sensor shift or module tilt (in which a module comprising an image sensor and a lens assembly is tilted about one or more axes parallel to the image sensor). OlS-sensor shift could involve lateral movement only (i.e. in the x-y plane, where the optical axis is aligned with the z-axis) or could optionally involve movement along the x, y and z axes (i.e. both lateral movement and movement along the optical axis). Module tilt may involve tilt about two orthogonal axes that are perpendicular to the primary axis.

The flexible electrical connector may be a section of FPC tape. The FPC may have a conventional construction, for example it may comprise a flexible substrate made of a suitable material, for example a plastic such as polyimide, PEEK or polyester and conductive (e.g. copper) tracks. The FPC may comprise four layers (i.e. four layers of conductive tracks, each layer separated by an insulating layer) or two layers, for example. Equally, any other number of one or more layers could be used.

A flexible electrical connector with first and second planar portions and a bend as described above means that the height of the flexible electrical connector and the actuator assembly generally may be reduced. This is particularly advantageous in scenarios in which space is limited, particularly in a direction perpendicular to the first plane.

The bend also means that the flexible electrical connector allows movement of the movable component along two orthogonal axes parallel to the first plane (and optionally a third axis perpendicular to the first plane). Taking the first plane to be the x-y plane, the movable component may move along the x and y axes. The bend may equally enable rotation of the movable component about the two orthogonal axes, for module tilt purposes.

In some embodiments, the flexible electrical connector may be connected at one end to the movable component and at the other end to the support structure. The flexible electrical connector provides an electrical connection between its ends. So, the flexible electrical connector may be electrically connected at one end to the movable component and at the other end to the support structure.

In some embodiments, the bend may be a 90-degree bend (or approximately 90 degrees). The bend may be about an axis which is perpendicular to the first plane.

The first and second planar portions may comprise most or all of the flexible electrical connector . In embodiments in which not all of the flexible electrical connector is planar, it will be appreciated that one or more end portions of the flexible electrical connector may extend outside of the first plane, for example for the purposes of connecting with other components of the assembly, e.g. a printed circuit board (PCB). Optionally, the respective extent along the primary axis of each of: the first planar portion; the second planar portion; and the movable component overlap. The movable component may lie in the first plane. For example, the movable component may be an image sensor and the extent of each of the first and second planar portions in a direction perpendicular to the first plane may overlap with the extent of the image sensor in that direction.

In some embodiments, the combined angular extent of the first and second planar portions about the primary axis may be greater than 90 degrees, greater than 180 degrees, greater than 270 degrees, or substantially equal to 360 degrees (for example within 10% or within 5% of 360 degrees). Such arrangements may provide a sufficient length of flexible electrical connector whilst keeping within a relatively small x-y footprint. Herein, the x-y plane is defined as the plane in which the planar portion of the flexible electrical connector lies and the z direction is perpendicular to the x-y plane. It will be appreciated that the second portion may comprise additional bends to accommodate a greater angular extent of the first and second portions.

In an example, the movable component may have four sides and the first and second planar portions of the flexible printed circuit may extend along two or more or three or more adjacent sides of the movable component. For example, the flexible electrical connector may extend along two adjacent sides of the movable component (forming an 'L' shape) or along three adjacent sides of the movable component (forming a 'C' shape).

Optionally a planar portion of the flexible printed circuit may extend in a loop around the movable component.

Optionally the actuator assembly may comprise a second flexible electrical connector having one or more portions which are planar. The flexible electrical connector (hereinafter referred to as the first flexible electrical connector) and the second flexible electrical connector may connect to the same or different components. For example, the first flexible electrical connector may be connected at one end to a first PCB and at the other end to the support structure (e.g. a component fixed relative to the support structure) and the second flexible electrical connector may be connected at one end to a second PCB separate to the first and at the other end to the support structure (e.g. a component fixed relative to the support structure). In some embodiments the first and second planar portions of the first flexible printed circuit may be coplanar with the planar portions of the second flexible printed circuit. In this sense, two flexible electrical connector portions may extend in the same plane. In some embodiments, corresponding portions of the first and second flexible electrical connectors extend parallel to each other in one of the shapes (e.g. 'L', 'C' or the loop) described above. Using two flexible electrical connectors as described increases the flexibility of the flexible electrical connector but may lead to a larger x-y footprint, depending on the widths of the first and second flexible electrical connectors.

In other embodiments the one or more planar portions of the second flexible printed circuit may be parallel to and stacked on one or both of the first and second planar portions of the first flexible electrical connector in a direction perpendicular to the first plane. Stacking flexible electrical connectors in this way may reduce the x-y footprint of the flexible electrical connectors but will increase the z height of the flexible electrical connectors.

In some embodiments, the two stacked flexible electrical connectors may extend in a loop (for example along one, two, three or four sides of the movable component) in the same direction (i.e. clockwise or anticlockwise). In other embodiments, the two stacked flexible electrical connectors may extend in loops in opposite directions, i.e. one flexible electrical connector clockwise and one flexible electrical connector anticlockwise. For stacked flexible electrical connectors generally, any possible rubbing between flexible electrical connectors can be alleviated with a low-friction spacer.

Optionally the one or more planar portions of the second flexible electrical connector extend lengthways parallel to at the first and/or second planar portions of the first flexible electrical connector along at least part of their respective lengths. In other words, at least part of the planar portions of the second flexible electrical connector follows the same path in the x-y plane as the first and/or second planar portions of the first flexible electrical connector.

Optionally, the flexible electrical connector allows movement of the movable component along three orthogonal axes. This is advantageous as the movable component is able to move in more degrees of freedom. For example, the movable component could be a component of a camera, for example an image sensor, which is able to move in the x-y plane (for example for the purpose of optical image stabilisation) and also along the z axis (aligned with the optical axis), e.g. for autofocusing. In some embodiments, the flexible electrical connector may allow rotation of the movable component about two orthogonal axes which are parallel to the first plane. For example, such a flexible electrical connector could be used in an OlS-module-tilt camera assembly. The movable component may be rotatable relative to the support structure about the two orthogonal axis.

Optionally, the movable component may itself be planar (or may comprise a planar component).

Optionally, as mentioned above, the movable component may be an image sensor assembly comprising an image sensor having a light-sensitive region.

In some embodiments in which a flexible electrical connector is connected to a PCB, the flexible electrical connector may comprise a different number of layers to the PCB. For example, the flexible electrical connector may comprise four layers and the PCB may comprise five. In such embodiments in which the numbers of layers between the PCB and flexible electrical connector differ, the assembly may comprise a step-up feature which provides a connection between the flexible electrical connector and the PCB. The step-up feature may be part of the flexible electrical connector or it could equally be part of the PCB. Alternatively, it could be a separate component that is connected to the flexible electrical connector and the PCB.

In some embodiments, the flexible electrical connector may extend in a loop around the primary axis. Optionally, the actuator assembly may comprise one or more additional flexible electrical connector arms, each of which: comprises a first planar portion, a second planar portion and a bend between the first and second planar portions, wherein the first and second planar portions and the bend lie in the first plane; and extends in a loop about the axis.

In some embodiments, the actuator assembly comprises two such flexible electrical connectors. The two flexible electrical connectors may be mechanically connected, for example part-way along the length of each flexible electrical connector and may be electrically isolated from eachother.

In some embodiments, the or each flexible electrical connector may be electrically connected at one end to the movable component and at the other end to the support structure. Optionally, the or each flexible electrical connector may comprise a plurality of bends in the first plane (i.e. a plurality of bends, each about a respective bend axis which is perpendicular to the first plane), e.g. three or four such bends. Each bend may be through 90 degrees or approximately (e.g. within 10% of) 90 degrees. The angular extent of the or each flexible electrical connector may be equal to or greater than 270 degrees or may be 360 degrees or approximately (e.g. within 10% of) 360 degrees.

Optionally, in embodiments in which the actuator comprises a plurality of flexible electrical connectors and/or flexible electrical connector arms, the flexible electrical connectors (or flexible electrical connector arms) may each extend around the primary axis in the same direction (i.e. clockwise or anticlockwise about the axis). In some embodiments, the actuator assembly may comprise four such flexible electrical connectors (or flexible electrical connector arms) which each loop around the primary axis in the same direction (i.e. clockwise or anticlockwise about the axis).

In some embodiments, each flexible electrical connector may comprise a plurality of track layers, each track layer separated from adjacent track layers by a layer of insulating material.

The width of the or each flexible electrical connector in the first plane may be less than or equal to 1mm (for example less than or equal to 0.7mm). The height of each flexible electrical connector (in a direction perpendicular to the first plane) may be less than or equal to 0.5mm, for example less than or equal to 0.4mm.

Within the footprint of the interconnect (or flexible electrical connector), the proportion of the area taken up by flexible electrical connector(s) may be less than or equal to half or less than or equal to one third.

As used herein, the term 'loop' may refer to a partial or complete loop, e.g. it may refer to an angular extent of 360 degrees or less than 360 degrees.

According to another aspect of the present invention, there is provided an actuator assembly comprising: a support structure; a movable component movable relative to the support structure; and a flexible electrical connector connected at one end to the movable component and at the other end to the support structure.

The flexible electrical connector is disposed along a side (e.g. a single side) of the movable component and is folded back on itself such that the flexible electrical connector comprises a first portion, a second portion and a bend (or fold) between the first and second portions. The first portion extends from the movable object in a first direction to the bend (or fold) and the second portion extends from the bend (or fold) in a second direction having at least a component opposite to the first direction, such that the flexible electrical connector allows the movable component to move along two orthogonal axes and/or to rotate about the two orthogonal axes.

In some embodiments, the first and second direction may be parallel or substantially parallel. In other words, the first and second portions of the flexible electrical connector may be parallel or substantially parallel. In some embodiments the first and second portions may extend in substantially opposite directions. In some embodiments, an angle between the first portion and the second portion is acute.

An alternative arrangement is thus provided which allows the movable component to move along two orthogonal axes.

The bend may be a bend through 90 or more degrees, for example 120 or more degrees. For at least some of its length, the flexible electrical connector may extend widthwise in one direction, and the bend may be about an axis which is parallel to this direction.

In some embodiments, the actuator assembly may comprise one or more additional flexible electrical connectors, which may be as described above. Such additional flexible electrical connectors could be disposed on the same side on another side (e.g. the opposite side or an adjacent side) of the movable component.

Optionally, the movable component defines a plane and at least part of the second portion is displaced from at least part of the first portion in a direction perpendicular to the plane defined by the movable component. As such, the flexible electrical connector is folded back on itself and the second portion is stacked on top of the first portion, for example along the z axis. This may be advantageous depending on where around the movable component there is space for the flexible electrical connector, and also because the flexible electrical connector allows the movable component to move along the z axis. In some embodiments, a total height of the flexible electrical connector (along the z axis) may be less than or equal to 2mm, for example less than or equal to 1.6mm.

In such examples, the first and second portions are generally oriented ("horizontally") such that, for at some of their length, they extend widthwise in a direction parallel to the plane defined by the movable component. In some embodiments, the movable component defines a plane and at least part of the second portion is displaced from at least part of the first portion in a direction parallel to the plane defined by the movable component. In other words, the second portion is stacked on the first portion but in this case in a direction parallel to the plane of the movable component (e.g. the x or y direction). This alternative arrangement may be advantageous depending on the space requirements and the other components present in the device. Also, greater flexibility in the x-y plane may be afforded by such embodiments (as opposed to the 'vertically stacked' arrangement described above).

In such examples, the first and second portions are generally oriented ("vertically") such that, for at least some of their length, they extend widthwise in a direction perpendicular to the plane defined by the movable component.

Optionally, the first portion may comprise two (separate) sections which extend parallel to each other and along the first direction and the second portion may comprise two sections which extend parallel to each other and along the second direction. In other words, the flexible electrical connector of the arrangement described above may comprise a longitudinal slit such that the flexible electrical connector is separated into two longitudinal sections. Such a slit may afford greater flexibility of the flexible electrical connector . In some embodiments, the flexible electrical connector may comprise more than two (e.g. three or four or more) longitudinal sections (i.e. the flexible electrical connector may comprise two or three or more longitudinal slits).

In some embodiments the flexible electrical connector is folded back on itself a second time such that the flexible electrical connector comprises a third portion separated from the second portion by a second bend. At least part of the third portion may extend in a third direction having at least a component along the first direction. The flexible electrical connector may therefore have a concertina or 'zig-zag' arrangement comprising two bends. In some embodiments, the flexible electrical connector may comprise more bends (e.g. three or four or more) separating further sections of the flexible electrical connector . By providing more bends, greater flexibility of the flexible electrical connector is afforded.

In some embodiments the third portion may comprise two sections which extend parallel to each other and along the third direction. In other words, the third section may also comprise a longitudinal slit as described above with reference to the first and second sections. In some embodiments, the first portion of the flexible electrical connector may extend along the full length or substantially the full length of one side of the movable component. Optionally, the second portion (and third portion if there is one) may extend along the full length or substantially the full length of one side of the moveable component.

Optionally the flexible electrical connector may be disposed on one side only of the movable component.

In the case of a generally planar movable component, for example an image sensor, the term 'side' as used herein is intended to refer to an edge of the movable component when viewed in a direction perpendicular to the plane of the movable component.

In some embodiments the movable component is an image sensor assembly comprising an image sensor having a light-sensitive region. The light-sensitive region may extend in the plane.

In some embodiments, the flexible electrical connector allows movement of the movable component along three orthogonal axes (e.g. x, y and z).

According to another aspect of the present invention, there is provided an actuator assembly comprising: a support structure; a movable component movable relative to the support structure; and a flexible electrical connector connected at one end to the movable component and at the other end to the support structure.

The flexible electrical connector is disposed along a first side of the movable component and comprises a fold line part way along the side of the movable component such that in use, when the movable component moves relative to the support structure the flexible electrical connector folds along the fold line.

Optionally, the movable component defines a plane and both the fold line and a portion of the flexible electrical connector on which the fold line is disposed are perpendicular to the plane defined by the movable component such that the flexible electrical connector allows movement of the movable component along two orthogonal axes in the plane defined by the movable component. This configuration may be advantageous depending on space requirements are where the flexible electrical connector needs to fit in around other components of the device. Alternatively, in some embodiments both the fold line and a portion of the flexible electrical connector on which the fold line is disposed are parallel to the plane defined by the movable component This configuration may be advantageous depending on space requirements (e.g. where the flexible electrical connector needs to fit in around other components of the device) and also facilitates movement of the movable component e.g. perpendicular to the plane defined by the movable component.

In some embodiments, the flexible electrical connector may comprise a bend such that the flexible electrical connector also extends along a second side of the movable component adjacent to the first side. This facilitates movement along a second axis in the plane defined by the movable component such that the movable component can move in two orthogonal axes in the plane defined by the movable component. The portions of the flexible electrical connector that extend along the first and second sides may be respectively perpendicular and parallel to the plane defined by the movable component.

Optionally the movable component is an image sensor assembly comprising an image sensor having a light-sensitive region.

The term 'bend' as used herein is intended to refer to any change in direction of an flexible electrical connector . It could refer to a bend in the plane of the flexible electrical connector, i.e. such that two portions either side of the bend may be in the same plane, or it could refer to a bend such that two portions either side of the bend are in different planes. Equally, the terms 'corner' or 'fold' could be used instead of 'bend' (and vice versa).

According to a further aspect there is provided a camera (or device comprising a camera) comprising any of the actuator assemblies described herein, wherein the movable component is or comprises an image sensor assembly.

Optionally, any of the actuator assemblies described herein may comprise one or more shape memory alloy, SMA, wires configured to move the moveable component.

Any of the actuator assemblies described herein may comprise an actuator comprising eight SMA wires for moving the moveable component in three dimensions and tilting the movable component about one or more axes, for example two axes perpendicular to each other and parallel to the movable component. Such an actuator is described in W02011/104518A1, which is incorporated herein by reference in its entirety. Any of the features described herein with reference to one embodiment may be applied to other embodiments. Equally, any definitions made in the context of one embodiment may also apply to other embodiments.

Herein, reference to two elements lying in the same plane or being coplanar is intended to refer to at least an overlap of the elements in a direction perpendicular to the plane.

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 comprising a roller bearing;

Figure 3 is a plan view of the actuator assembly from above;

Figure 4 is plan view (from above, i.e. along the primary axis) of an interconnect arrangement;

Figure 5 is plan view (from above, i.e. along the primary axis) of an alternative interconnect arrangement;

Figure 6 is perspective view of an alternative interconnect arrangement;

Figure 7A is a plan view (from above, i.e. along the primary axis) of an alternative interconnect arrangement;

Figure 7B is a perspective view of the arrangement shown in Figure 7A;

Figure 8A is a perspective view of an alternative interconnect arrangement;

Figure 8B is a plan view (from above, i.e. along the primary axis) of the arrangement shown in Figure 8A;

Figure 9A is a perspective view of an alternative interconnect arrangement;

Figure 10 is a perspective view of an alternative interconnect arrangement;

Figure 11 is a perspective view of an alternative interconnect arrangement;

Figure 12 is a perspective view of an alternative interconnect arrangement;

Figure 13A is a perspective view of an alternative interconnect arrangement;

Figure 13B is a side-on view (i.e. from a direction perpendicular to the primary axis) of an alternative interconnect arrangement; Figure 14 is a perspective view of an alternative interconnect arrangement;

Figure 15 is a perspective view of an alternative interconnect arrangement;

Figure 16 is a perspective view of an alternative interconnect arrangement;

Figure 17A is a perspective view of an alternative interconnect arrangement;

Figure 17B is a different perspective view of the arrangement shown in Figure 17A;

Figure 17C is a perspective view of an alternative interconnect arrangement;

Figure 18 is a plan view (from above, i.e. along the primary axis) of an alternative interconnect arrangement;

Figure 19 is a plan view (from above, i.e. along the primary axis) of an alternative interconnect arrangement;

Figure 20 is a plan view (from above, i.e. along the primary axis) of an alternative interconnect arrangement;

Figure 21 is a plan view (from above, i.e. along the primary axis) of an alternative interconnect arrangement;

Figure 22 is a cross-sectional view of a set of three FPC sections;

Figure 23 is a perspective view of an alternative interconnect arrangement;

Figure 24 is a cross-sectional view of an interconnect connected to a moveable component; and

Figure 25 is a perspective view of an alternative interconnect arrangement;

Detailed description

Actuator assembly

A camera apparatus 1 that incorporates an actuator assembly 2 in accordance with the present invention is shown in Fig. 1. Figure 1 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 Figs. 2 and 3, Fig. 2 being a side view of the actuator assembly 2 and Fig. 3 being a plan view of the actuator assembly 2. For clarity, Figs. 2 and 3 omit the electrical interconnect which will be described below. The actuator assembly 2 comprises a support structure 4. The support structure 4 comprises a rim portion 10 (see Figure 2). On the support structure 4 is supported an image sensor assembly 12. The image sensor assembly 12 comprises an image sensor 6 having a light-sensitive region 7 and generally further comprises a movable plate 9. The image sensor 6 is fixed relative to the movable plate 9. For example, the image sensor 6 may be mounted on the movable plate 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 movable plate 9 comprises a printed circuit board, PCB, which may be called the moving PCB. The movable plate 9 may be the moving PCB. Alternatively, the movable plate 9 may comprise the moving PCB and at least one other layer or element such as a metal sheet which may be attached to or laminated with the moving PCB. The image sensor 6 may be mounted on the moving PCB of the movable plate 9.

The moving PCB of the movable plate 9 of the image sensor assembly 12 is electrically connected to another PCB by an electrical interconnector which will be described below. The other PCB may be called the static PCB and may be part of (or fixed relative to) the support structure 4.

Optionally, the rim portion 10 comprises the static PCB. The rim portion 10 may be at least partly, and optionally fully, formed by the static PCB. In the description below, the rim portion 10 is formed by the static PCB. However, in an alternative arrangement, the static PCB may be positioned between the image sensor assembly 12 and the support plate 5 (described below) of the support structure 4. The static PCB may be located directly below the image sensor 6.

Optionally, the electrical connection between the image sensor 6 and the electrical interconnector is at least partly formed by the moving PCB. The moving PCB is for transferring signals such as data signals and power signals between the image sensor 6 and the static PCB. Additionally, the moving PCB may comprise electronic components configured to act on such signals. For example, the moving PCB may comprise electrical components such as capacitors.

The static PCB is configured to collect the signals from the moving PCB, and to provide signals to the moving PCB. The static PCB facilitates collection of signals for connection to a device (e.g. a mobile phone). 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.

As mentioned above, the support structure 4 comprises the rim portion 10. The rim portion 10 may be fixed to the front side of the support plate 5 and extend at least partly around the support plate 5. The rim portion 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 is implemented in the IC chip 30.

The image sensor assembly 12 is supported on the support structure 4 in a manner allowing movement of the image sensor assembly 12 relative to the support structure 4 in any direction laterally to the lightsensitive region 7 (i.e. laterally of the optical axis O and parallel to the plane in which the light-sensitive region 7 extends). So, the image sensor assembly 12 may be supported in a manner supressing movement of the image sensor assembly 12 in a direction perpendicular to the light-sensitive region 7. The image sensor assembly 12 is further supported on the support structure 4 in a manner allowing rotation of the image sensor assembly about any axis parallel to the optical axis O (i.e. parallel to any axis orthogonal to the plane in which the light-sensitive region extends). So, the image sensor assembly 12 may be supported in a manner supressing tilt or rotation of the image sensor assembly 12 about any axis parallel to the light-sensitive region 7.

WO-2017/072525 discloses the use of plain bearings 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 ball bearing arrangement 110. In general, any type of bearing arrangement may be used instead, for example a plain bearing or sliding bearing in which a bearing surface of the movable component bears directly on a bearing surface of the support structure, or a flexure bearing comprising a plurality of flexures for suitably constraining movement of the movable component relative to the support structure.

The actuator arrangement shown in Fig. 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 moving PCB 9 and the support structure 4 comprises crimp portions 42 fixed to the static 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.

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 ball bearing arrangement 110. So, the SMA wires 40 may act as a biasing arrangement. Alternatively or additionally, the apparatus 1 may comprise a separate biasing arrangement for applying a biasing force that biases the image sensor assembly 12 towards the ball bearing arrangement 110. Such a biasing arrangement may comprise one or more resilient elements (e.g. flexures) connected between the image sensor assembly 12 and the support structure 4 or interacting magnetic components on the image sensor assembly 12 and the support structure 4.

The overall arrangement of the SMA wires 40 will now be described, being similar to that described in WO-2014/083318 (which is incorporated herein by reference in its entirety).

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 static 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 Fig. 3) 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 Fig. 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 Fig. 3).

As viewed axially, a second pair of SMA wires 40 extend parallel to a second axis (horizontal in Fig. 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 Fig. 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 Fig. 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 range of movement and rotation depends on the geometry and the range of contraction of the SMA wires 40 within their normal operating parameters.

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.

The actuator described above with reference to Figure 3 provides for lateral movement of the image sensor assembly and rotation of the image sensor assembly in a plane perpendicular to the optical axis. In some embodiments, however, the image sensor assembly (and optionally other components of the camera apparatus 1) may be supported on the support structure 4 in a manner allowing movement of the image sensor assembly relative to the support structure in alternative or additional directions, for example movement along the optical axis (e.g. for the purpose of autofocus) and/or rotation about one or more axes parallel to the light-sensitive region 7 (e.g. for module-tilt optical image stabilisation). An appropriate actuator for driving such movement may be used. An example of such an actuator mechanism is disclosed in W02011/104518A1, which is incorporated herein by reference in its entirety.

Details of the electrical interconnector

As mentioned above, the moving PCB of the movable plate 9 of the image sensor assembly 12 is electrically connected to a static PCB by an electrical interconnector, for example a flexible electrical connector such as a flexible printed circuit (FPC). Various FPC arrangements for use with an actuator such as that described above with reference to Figure 3 will now be described with reference to Figures 5 to 22. Such FPC arrangements may also be used with other actuators such as those described in the previous paragraph. In such other actuators, the electrical interconnector may be used for making electrical connections between any support structure and any movable component.

Fig. 4 is a view of such an electrical interconnector (specifically an FPC), looking along the optical axis O (aligned with the z-axis). Fig. 4 shows parts of the sensor shift assembly that provide an electrical connection for the image sensor assembly 12. As mentioned above, the electrical connection may be for connecting the image sensor to the portable electronic device such as a mobile telephone, or tablet computer. The electrical connection may be for providing power from the device to the image sensor. The electrical connection may be for allowing transfer of data such as image data from the image sensor to the device. The electrical connection may be for other purposes, for example providing control signals for autofocus and/or OIS, as will be described below.

As shown in Fig. 4, the interconnect 13 comprises a flexible printed circuit (FPC) 50. The FPC 50 is a section of FPC tape. The FPC 50 may have a conventional construction, for example it may comprise a flexible substrate made of a suitable material, for example a plastic such as polyimide, PEEK or polyester with copper tracks. The FPC 50 may comprise a single layer of tracks or more than one layer of copper tracks (for example two, three, four or more), with each layer of tracks separated by an insulator e.g. polyimide.

In the example shown in Fig. 4, the actuator assembly comprises one FPC 50. However, more than one FPC 50 may be provided, for example, two (as shown in figure 9, for example), three or four may be provided. The FPC 50 is connected at one end 51 to the image sensor assembly 12, specifically a PCB 40 on which the image sensor 6 is mounted (i.e. the moving PCB). In particular, the FPC 50 may be electrically and mechanically connected to (or may be an extension of) the moving PCB 40. For brevity, the moving PCB 40 is hereinafter referred to as simply the PCB 40. The FPC 50 may be electrically connected to the image sensor such that power can be provided to the image sensor and/or image data can be read from the image sensor. The FPC 50 comprises two layers but in other embodiments it may equally comprise a different number of layers (e.g. four).

As shown in Fig. 4, portions of the FPC 50 are planar. In the embodiment shown in Figure 4, the FPC 50 comprises a first planar portion 60a, a second planar portion 60b, a third planar portion 60c and a fourth planar portion 60d. Each of the first, second, third and fourth planar portions lie in a first plane (the x-y plane as labelled in Figure 4). The FPC also comprises: a first bend 61 between the first and second planar portions 60a, 60b; a second bend 62 between the second and third planar portions 60b, 60c; and a third bend 63 between the third and fourth planar portions 60c, 60d.

Each of the bends 61, 62 and 63 also lies in the first plane.

The FPC 50 also comprises: a fifth planar portion 60e, a fourth bend 64, a sixth planar portion 60f and a fifth bend 65.

The fourth bend 64 is between the fourth planar portion 60d and the fifth planar portion 60e and the fifth bend 65 is between the fifth planar portion and the sixth planar portion 60f.

The image sensor assembly 12, in particular the image sensor itself or the PCB 40, also lies in the first plane. The planar arrangement of the FPC 50 is advantageous for a number of reasons. Firstly, the FPC 50 does not add any additional height (or adds minimal height) in the direction along the optical axis (otherwise referred to as z height) because it is coplanar with at least a portion of the image sensor assembly (for example the PCB). This may be particularly useful in devices in which z height is limited.

Further, the FPC 50 also has a small footprint in the x-y plane (i.e. the first plane), thus taking up only limited space in the x-y plane. A further advantage is that the material for manufacturing the FPC 50 can be used more efficiently compared to FPCs that require large patterns of FPC tape which then must be folded into shape. The manufacturing itself is also simplified in comparison to FPCs which require folding because the folding step(s) are avoided.

As shown in Fig. 4, the FPC 50 bends around the PCB 40 (and hence the image sensor assembly 12). The FPC 50 extends from the end 51 connected to the image sensor assembly 12, alongside the PCB 40, and is then bent around bends (otherwise referred to as corners) 61, 62 and 63, extending to the other end 52 of the FPC 50, where it is connected to the device in which the FPC 50 is disposed. This may be the support structure or a component fixed relative to the support structure (e.g. a static PCB).

As the FCP 50 is arranged bent around a number of corners, it accommodates the motion of the image sensor assembly 12 relative to the support structure 4 in any direction in the first plane (including rotation of the image sensor assembly 6 about an axis parallel to the optical axis O). In particular, the FPC 50 will bend in a direction perpendicular to its length. Accordingly, the portions of the FPC on sides A and C of the assembly (the first and third planar portions 60a and 60c) will accommodate motion in the y direction (see axis labels in Figure 4) (although portions 60b and 60d will also flex to some extent) and the portions of the FPC on sides B and D (the second and fourth planar portions 60b and 60d) will accommodate motion in the x direction (although portions 60a and 60c will also flex to some extent).

The FPC can also accommodate motion along the optical axis, O, for example for the purposes of autofocussing. The FPC will give in the manner of a helical spring being extended. In such embodiments, the FPC in Figure 4 may be used in conjunction with an actuator providing for motion in the x, y and z directions. For example, the actuator described in W02011/104518A1 (incorporated herein by reference in its entirety) may be used.

The FPC can also accommodate tilting e.g. about any axis in a plane parallel to the X-Y plane. As will be appreciated, the above-described features that enable the FPC 50 to accommodate e.g. translational motion in x, y and z directions also enable the FPC 50 to accommodate such tilting.

With reference to Figure 5, a further embodiment is described. Figure 5 depicts a view along the optical axis. The embodiment shown in Figure 5 has a number of similarities with the embodiment shown in Figure 4 and only the differences will be described here. In the embodiment shown in Figure 5, the FPC 50 comprises two portions, 50a and 50b, which extend parallel to one another. An advantage of having two such portions 50a and 50b is that the flexibility of the FPC 50 in at least the x and y directions is improved (as compared to a single FPC, as in Figure 4). In simple terms, this is due to e.g. the reduced width of each of the portions 50a, 50b. The flexibility of the FPC 50 in the z direction may also be improved but, depending on the total width (e.g. in the x direction on sides B and D) of the FPC portions 50a and 50b the z-direction flexibility may decrease (if, for example, the total width of the two portions 50a and 50b exceeds the width of the FPC 50 in Figure 4 then the flexibility in the z direction will be less). The two FPC portions 50a and 50b are at least substantially coplanar with each other and with the PCB 40. The two FPC portions 50a and 50b follow the same path as the FPC 50 in Figure 4, i.e. they both loop round the PCB 40. The two FPC portions, 50a and 50b can be considered as being formed by providing the FPC 50 of Figure 4 with a (lengthways) slit.

With reference to Figure 6, a further embodiment is described. This has a number of similarities with the embodiment shown in Figure 5 and only the differences will be described here. Figure 6 is a perspective view of an interconnect 13. In the embodiment shown in Figure 6, the FPC 50 comprises two portions, 50a and 50b, with portion 50b being stacked on top of portion 50a (i.e. 50b is stacked on 50a along the optical axis). An advantage of having two such stacked portions 50a and 50b is that the footprint of the FPC in the x-y plane is reduced (as compared to the embodiment shown in Figures 4 and 5), but the area of FPC tape is maintained.

With reference to Figures 7A and 7B, a further embodiment is described. This has a number of similarities with the embodiment shown in Figure 6 and only the differences will be described here. The embodiment shown in Figures 7A and 7B comprises two PCBs 40s and 40b and also comprises two FPC portions 50a and 50b. Instead of being aligned and stacked one on top of the other along the z axis (as in Figure 6), FPCs 50a and 50b loop around the PCBs 40a, 40b in different directions. Specifically, FPC 50a is connected to PCB 40a and extends around the PCBs 40a, 40b in a clockwise direction. FPC 50b is connected to PCB 40b and extends around the PCBs 40a, 40b in an anticlockwise direction. FPC 50b is stacked on top of FPC 50a along the z-axis. Accordingly, the x-y footprint of the FPC arrangement is reduced as compared to the side-by-side arrangement shown in Figure 5. In the illustrated embodiment the FPCs 50a and 50b are each connected to a separate PCB (40b and 40a respectively) but they could equally be connected to the same PCB. With reference to Figure 8A and 8B, a further interconnect arrangement is described. Figure 8a is a perspective view of the FPC 50 and, in Figure 8b, the FPC 50 is viewed along the optical axis. The arrangement in Figures 8A and 8B shares a number of features with that shown in Figure 4 and only the differences will be described here. In this embodiment, the PCB 40 comprises a different number of layers to the FPC 50. For example, the PCB 40 may comprise four layers and the FPC 50 may comprise five layers (although in other embodiments one or both of the FPC 50 and PCB 40 may have a different number of layers). Accordingly, the arrangement comprises a step-up feature 41 which provides a connection between the FPC 50 and the PCB 40. The step-up feature in this embodiment is part of the FPC 50 but it could equally be part of the PCB 40 or could be a separate component that is connected to the FPC 50 and the PCB 40.

With reference to Figure 23, a further interconnect arrangement is described. Figure 23 is a perspective view of the interconnect 13. The interconnect 13 comprises four FPC arms: first FPC arm 50a, second FPC arm 50b, third FPC arm 50c and fourth FPC arm 50d. The interconnect 13 is connected to a moveable component 100 (see Figure 24). As shown in Figure 24, the moveable component sits above the interconnect 13 and connects to the interconnect via connection portions 112 (one of which is shown schematically in Figure 24). A bearing arrangement 104 is in contact with the moveable component 100, as shown in Figure 24.

Each of the first to fourth FPCs arms (50a, 50b, 50c and 50d) lies in a first plane and each has a first end (114a, 114b, 114c and 114d respectively). Each FPC arm connects to a central FPC portion 102 and extends in a loop around the primary axis (which extends through the central FPC portion 102 and is perpendicular to the first plane). The central FPC portion 102 has four sides and one FPC arm is disposed on each of the four sides. Each FPC arm 50a, 50b, 50c and 50d extends from the central FPC portion 102 in a different direction, perpendicular to the side of the central FPC portion 102 on which the FPC is disposed. The points at which the four FPCs connect to the central FPC portion 102 are offset such that none of the directions are colinear.

The second and fourth FPC arms 50b and 50d are connected to a support structure of the actuator assembly (not shown in Figure 23) at their respective ends 114b and 114d. Specifically, the second and fourth FPC arms 50b and 50d are connected to a component of the device which is fixed relative to the support structure. The first and third FPC arms 50a and 50c are connected to the moveable component 100. The central FPC portion 102 is free to move. The connection portions 112 of the movable component are shown in Figure 24 as being part way along a side of the interconnect 13 but they could be disposed on the corners of the interconnect 13 as described above (i.e. at ends 114a and 114c of FPCs 50a and 50c) or elsewhere along FPC arms 50a and 50c. In some embodiments, FPC arms 50b and 50d may be connected to the moveable component and FPC arms 50a and 50c may be connected to the support structure. In some embodiments, adjacent (as opposed to opposite, as described above) corners of the interconnect could be connected to the same component. For example, ends 114a and 114b could be connected to the moveable component and ends 114c and 114d to the support structure or vice versa.

The four FPC arms 50a, 50b, 50c and 50d each extend in a loop around the primary axis. In particular, the angular extent of each FPC arm is 360 degrees. The loops are nested such that on each side of the central connection FPC 102 there is a set of four parallel FPC portions, one from each of the FPC arms 50a, 50b, 50c and 50d. The parallel FPC portions are separated by gaps. The width of each FPC portion (in the first plane) may be approximately equal to (e.g. within 10% of) the width of the gaps between adjacent FPC portions.

Each FPC arm comprises conductive tracks for providing an electrical connection between the moveable component 100 and the support structure. In terms of electrical connection, the interconnect 13 comprises two separate FPCs. The first FPC comprises FPC arms 50a and 50b and is connected at a first end 114a to the moveable component 100 and at a second end 114b to the support structure. The second FPC comprises FPC arms 50c and 50d and is connected at a first end 114c to the moveable component 100 and at a second end 114d to the support structure. Each FPC also comprises a portion of central FPC portion 102. There is no electrical connection between the first and second FPCs at central FPC portion 102 but there is a physical connection between the first and second FPCs provided by the central FPC portion 102. The electrical separation between the first and second FPCs is shown in Figure 23 with dashed line 122.

It will be appreciated that a different number of FPCs may be provided by the interconnect shown in Figure 23 and electrical connections may be routed differently according to different connection requirements. The FPC arms 50a, 50b, 50c, 50d and the central FPC portion 102 may be part of a single FPC.

Each FPC (and hence each FPC arm) comprises multiple layers of conductive tracks, each track layer separated from each adjacent track layer by a layer of insulating material. For example, each FPC may comprise 2, 3, 4 or 5 layers of tracks. An advantage of multiple layers of tracks is that the width of FPC tape used can be reduced (in comparison to a scenario in which a single layer of tracks is used, which would require a greater width of FPC tape to allow for the same number of tracks). By using narrower FPC tape, the flexibility of the interconnect in the first plane (i.e. the plane which each of the FPCs lie in) is increased. This is particularly advantageous in the spiral configurations shown in Figures 23 and 25 because when the moveable component is displaced (and hence the interconnect is displaced), the interconnect can act as a spring and impart a tilting force onto the moveable component, as will now be explained with reference to Figure 24.

As shown in part A of figure 24, when the moveable component is in a neutral position (i.e. with no displacement), the FPC is not displaced and no tilting force is imparted by the interconnect 13 on the movable component 100.

As shown in part B of Figure 24, when there is motion in the plane of the FPCs (referred to herein as the first plane), for example in the direction indicated by arrow 106, the interconnect 13 acts like a spring and generates a force that causes a moment on the moveable component 100, thus reducing the load on the bearing arrangement 104 (as indicated by arrows 108). This force increases as the displacement of the moveable component (as indicated by the 'X' label in Figure 24) increases.

If the force becomes high enough, the load on the bearing arrangement reduces to zero, resulting in tilting motion of the moveable component (as shown in part C of Figure 24, indicated by arrow 110).

This bearing instability can be reduced by increasing the flexibility of the interconnect in the first plane (which can be achieved by reducing the width of each FPC in the first plane, which in turn is facilitated by stacking multiple layers of tracks on top of each other, in a direction perpendicular to the first plane).

A further advantage of stacking layers in this way is that the footprint of the interconnect in the first plane may be reduced (as compared to a single-layer embodiment). The electrical path length is also reduced.

The width of each FPC in the first plane may be 0.7mm. The height of each FPC (in a direction perpendicular to the first plane) may 0.4mm.

With reference to Figure 25, a further interconnect arrangement is described. The embodiment shown in Figure 25 has a number of similarities with the embodiment shown in Figure 23 and only the differences will be described here. In the embodiment of Figure 25, the angular extent of each of the FPC arms 50a, 50b, 50c and 50d is 270 degrees. This means that on each side of the central FPC portion 102 there is a set of three parallel FPC portions, each from a different one of the FPC arms. The width of each FPC portion (in the first plane) may be approximately equal to (e.g. within 10% of) the width of the gaps between adjacent FPC portions. The footprint of the embodiment shown in Figure 25 is smaller than that of the Figure 23 embodiment but the flexibility of the interconnect is also reduced relative to the Figure 23 embodiment. It will be appreciated that the angular extent of the FPC arms 50a, 50b, 50c and 50d may be different such that on each side of the central FPC portion 102 there is a different number of parallel FPC portions (e.g. two). Equally, the central FPC portions may have a different number of sides (e.g. three or five) and the interconnect may have a corresponding number of FPC arms (i.e. three or five respectively).

With reference to Figure 9, a further interconnect arrangement is described. The interconnect 13 comprises a PCB 40 (on which an image sensor assembly may be mounted, for example as described above) and two FPCS 50a and 50b. Each FPC 50a and 50b is arranged along a side A of the PCB 40. The first FPC 50a is folded back on itself such that the first FPC 50a comprises a first portion 53a and a second portion 54a. The FPC 50a further comprises a first bend 55a between the first and second portions. The first portion 53a extends from the PCB 40 in a first direction and the second portion 54a extends in a second direction having at least a component opposite to the first direction. In this way the FPC 50a allows the PCB 40 to move along two orthogonal axes in the plane of the PCB 40 (in simple terms, with movement in the x direction being facilitated by e.g. each FPC 50a, 50b being bent back as described, and with movement in the y direction being facilitated by e.g. the relatively long length of each FPC 50a, 50b running perpendicular to the y-axis).

In the illustrated embodiment, the first portion 53a is angled relative to the second portion 54b. Specifically, the angle between the first and second portions is acute and may be less than or equal to 20 degrees or less than or equal to 10 degrees. In some embodiments the second portion 54a may be parallel to the first portion 53a. In such embodiments, for example, each of the first and second potions 53a, 54a may be substantially planar and may lie in a plane parallel to the x-y plane.

The second FPC 50b is arranged in a similar manner to the first FPC 50a and is a reflection of the first FPC 50a along the y axis (see Figure 9). The second FPC 50b has corresponding first and second portions (53b and 54b respectively) and a first bend 55b.

The first and second FPCs 50a and 50b are each connected to the PCB 40 by respective connecting portions 56a and 56b which extend in a direction perpendicular to the length of each of FPCs 50a and 50b. Ends 52a and 52b of the first and second FPCs respectively are connected to a support structure (e.g. support structure 4 described above). Specifically, the ends 52a and 52b may be connected to a component which is fixed relative to the support structure, for example a static PCB.

The configuration of the FPCs 50a and 50b as described allows the PCB 40 to move relative to the support structure along two perpendicular axes in the plane of the PCB 40 (i.e. x and y) but also along the z direction, perpendicular to the x and y axes.

Figure 9 illustrates two FPCs 50a and 50b but the interconnect 13 could equally comprise a different number of FPCs, for example one, three, four or more. In embodiments comprising more than one FPC, the FPCs could be disposed on different sides of the movable component. Examples include: two FPCs wherein each FPC is on an opposite side of the movable component; three FPCs, one on each of three on adjacent sides of the movable component, four FPCs, one on each of four sides of a movable component. .

An embodiment in which the interconnect 13 comprises only one FPC 50 is illustrated in Figure 10. The FPC 50 comprises a first portion 53 and a second portion 54 separated by a bend 55. FPC 50 is configured in an equivalent manner to FPC 50b in Figure 9 (but extends over a larger proportion of the side A of the PCB 40) and the relevant description will not be repeated here. As compared to the Figure 9 embodiment, the arrangement shown in Figure 10 may be easier to manufacture.

The FPC 50 also comprises a slit such that the FPC 50 comprises two sections 73a and 73b which extend parallel to each other and along the length of the FPC. Providing a slit in the FPC 50 in this way provides for greater flexibility (particularly in the y direction) but may increase the x-y footprint of the FPC (since the slit takes up space in the y direction).

Such a slit configuration may also be applied to embodiments with two FPCs (such as that illustrated in Figure 9). Such an embodiment is illustrated in Figure 11. Like reference numerals are used. Each FPC 50a and 50b comprises two sections which extend parallel to each other and along the length of the FPC. Specifically, FPC 50a comprises two sections 76a and 77a and FPC 50b comprises two sections 76b and 77b.

Furthermore, two slits may be provided in one or more of the FPCs. An embodiment equivalent to that shown in Figure 9 except with two slits in each of the FPCs 50a and 50b is shown in Figure 12. In this way, each of the first and second FPCs 50a and 50b comprise three sections (76a, 77a and 78a in the case of FPC 50a and 76b, 77b and 78b in the case of FPC 50b) which extend parallel to each other and along the length of the FPC. As explained above, this may provide greater flexibility but may also increase the footprint in the x-y plane (depending on the width of FPC tape used).

In some embodiments, one or more FPCs may comprise additional bends, as described with reference to Figures 13A (which is a perspective view) and 13B (which is a side-on view of the interconnect viewed from a direction perpendicular to the z direction). An interconnect 13 with two FPCs 50a and 50b each having one bend was described above with reference to Figure 9. The embodiment illustrated in Figures 13A and 13B is equivalent to that in Figure 9 except that each of the FPCs 50a and 50b comprise a second bend. In this way, each FPC is folded back on itself a second time such that each FPC comprises a third portion (57a and 57b respectively) and a second bend (58a and 58b respectively) between the second and third portions. At least part of the third portion extends in a third direction having at least a component along the first direction. By providing additional bends in this way, the flexibility of each FPC may be increased (e.g.in the x direction - see figures 13A and 13B) but the z-height of the FPCs may also be increased.

The single-FPC arrangement shown in Figure 10 may be modified to have three bends in an analogous way to the Figure 13 embodiment. Equally, any embodiment may have a greater number of bends (for example 4 or 5).

Equally, the slit concept described with reference to Figures 10 to 12 may be applied to FPCs with three or more bends, as is shown in Figures 14 (one slit) and 15 (two slits).

In some embodiments, the interconnect 13 may comprise one or more folded FPCs (as described above with reference to Figures 9 to 15) in which the FPCs are generally perpendicular to the plane of the PCB 40 (rather than being generally parallel to the plane of the PCB 40 as they are in Figures 9 to 15). Specifically, Figure 16 illustrates an embodiment in which the first and second portions of the FPCs 50a and 50b are perpendicular (or approximately perpendicular) to the PCB 40. This may be advantageous in devices where space is limited in one direction but less limited in another. Accordingly, the "concertina" arrangements of Figures 9 to 15 can be oriented in either a parallel or a perpendicular way, depending on the device requirements.

With reference to Figures 17A and 17B a further FPC arrangement is described. In this arrangement, the interconnect 13 comprises an FPC 50 along a first side A of a PCB 40. The FPC 50 is perpendicular to the PCB 40 and comprises a fold line 70. The fold line 70 is along an axis which is perpendicular to the PCB 40. In use, when the PCB is moved laterally, the FPC 50 folds along the fold line 70. In this way, the FPC and the fold line facilitate movement of the PCB 40 in two orthogonal axes parallel to the PCB 40. The FPC 50 is connected to the PCB 40 by connecting element 72, which may be an extension of the FPC 50, the PCB 40 or a separate connecting element. Depending on the length of the connecting element 72, the interconnect 13 may also allow movement of the PCB in a direction perpendicular to the PCB 40, (e.g. along the optical axis).

With reference to Figure 17c, in some embodiments the FPC 50 may comprise a second FPC 74 connected to the connecting element 72. The second FPC 74 is parallel to the PCB 40 and thus allows for motion of the PCB 40 in a direction perpendicular to the PCB 40 (e.g. along the optical axis). The second FPC 40 extends along a second side B of the PCB 40. The second side B of the PCB 40 is adjacent to the first side A. Both the connecting element 72 and the second FPC 74 may be an extension of (e.g. may be integral with) the FPC 50.

The points at which the above-described FPC(s) connect to the PCB may also be chosen according to device requirements. For example, the start and end points of the FPCs may be varied according to Figures 18, 19, 20 and 21, in which FPCs 50a, 50b, 50c and 50d are shown schematically by lines. Alternative arrangements are also possible. For example, in Figure 18 one or more of the FPCs 50a, 50b, 50c or 50d may be omitted (for example FPCs 50a and 50b). Various advantages can be achieved by selecting the start and end points of the FPCs relative to each other and also to other components in the device. For example, reducing the length of an FPC may help in reducing image noise (in embodiments were the FPC is employed in a camera) and selective the positions of the start and end points could help in impedance matching.

Other considerations may also dictate the placement of the start and end points of an FPC, for example the relative positioning of the driver integrated circuit (IC) and the terminals of an image sensor assembly (they should be adjacent).

With reference to Figure 22, a cross-sectional view of a series of three parallel FPC sections are described. Specifically, three sections 76a, 77a and 78a of the embodiment shown in Figure 13 are shown in Figure 22. It will be appreciated that one or two of the FPC sections may be omitted and the structure shown in Figure 22 may be employed in embodiments requiring a different number of FPCs or FPC sections.

As shown in Figure 22, each FPC section (otherwise referred to as an FPC) comprises two layers: a first layer comprising two copper tracks 80 and 82 surrounded (on their upper and side edges) by insulation 88 and a second layer, comprising two copper tracks 84 and 86 surrounded (on their lower and side edges) by insulation 90.

A layer of insulation 92 is disposed between the first and second layers.

FPC sections 77a and 78a have the same structure.

One of more of the FPC sections may comprise additional layers comprising tracks and separated from the adjacent layer(s) by a layer of insulation. Further, one or more of the layers may comprise a different number of tracks.

Any FPC or portion of FPC disclosed herein may comprise any number of layers, for example one, two, three, four, five or more.

Instead of being flexible printed circuits per se, the FPCs described herein may correspond to other types of flexible electrical connectors, e.g. connectors made using techniques other than photolithographic techniques, connectors with metallic substrates, etc.. For example, the flexible electrical connectors may comprise a flexure (e.g. made from metal) having layered thereon one or more electrical tracks (e.g. separated by an insulating layer).

The electrical interconnects described herein may be used with various actuator types. For example, actuation may be achieved using shape memory alloy (SMA) wire, voice coil motors, piezoelectric actuators, ultrasonic motors, and/or microelectromechanical systems (MEMS).

Some of the above-described actuators are SMA actuator assemblies which comprise an SMA wire. The term 'shape memory alloy (SMA) wire' may refer to any element comprising SMA. The SMA wire may have any shape that is suitable for the purposes described herein. The SMA wire 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 wire. It is also possible that the length of the SMA wire (however defined) may be similar to one or more of its other dimensions. The SMA wire may be pliant or, in other words, flexible. In some examples, when connected in a straight line between two elements, the SMA wire can apply only a tensile force which urges the two elements together. In other examples, the SMA wire may be bent around an element and can apply a force to the element as the SMA wire tends to straighten under tension. The SMA wire may be beam-like or rigid and may be able to apply different (e.g. non-tensile) forces to elements. The SMA wire may or may not include material(s) and/or component(s) that are not SMA. For example, the SMA wire may comprise 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 acting as a single actuating element which, for example, can be individually controlled to produce a force on an element. For example, the SMA wire may comprise two or more portions of SMA wire that are arranged mechanically in parallel and/or in series. In some arrangements, the SMA wire may be part of a larger piece of SMA wire. Such a larger piece of SMA wire might comprise two or more parts that are individually controllable, thereby forming two or more SMA wires.

Applications

Although many of the above examples relate to use of the disclosed actuator assemblies in a camera, the actuator assemblies may equally be used in any application in which a movable electronic component must be moved relative to a static component. For example, the actuator assemblies could be used to connect an illumination source that is moved, for example for the purposes of 3D scanning.

It will be appreciated that there may be many other variations of the above-described examples.