Field

The present application relates to variable aperture assemblies.

Summary

According to an aspect of the present invention, there is provided a variable aperture assembly comprising: a base; a rotatable part; an actuator assembly configured to drive rotation of the rotatable part relative to the base about a primary axis to any rotational position within a range of movement; a plurality of blades connected (e.g. coupled) to the base via either a plurality of pivot protrusions (e.g. pivot pins) or a plurality of moving protrusions (e.g. moving pins), and connected (e.g. coupled) to the rotatable part via the other of the plurality of pivot protrusions (e.g. pivot pins) and the plurality of moving protrusions (e.g. moving pins), and arranged to define a variable aperture with a central axis which coincides with the primary axis; wherein said (relative) rotation of the rotatable part (i.e. the rotation of the rotatable part relative to the base) drives each moving protrusion to move along a circular path centred around a respective pivot protrusion (i.e. a pivot protrusion the moving protrusion is connected to via one of the plurality of blades) of the plurality of pivot protrusions (i.e. drives each moving protrusion to rotate around a respective pivot protrusion), which drives rotation of the plurality of blades about the pivot protrusions, wherein said rotation of the plurality of blades (i.e. the rotation of the plurality of blades about the pivot protrusions) changes the size of the variable aperture. In other words, the rotation of the rotatable part relative to the base drives relative movement between the pivot protrusions and the moving protrusions, which drives rotation of the plurality of blades about the pivot protrusions; wherein said rotation of the plurality of blades changes the size of the variable aperture; and wherein the moving protrusions are configured to rotate (e.g. move in a circular arc) around the pivot protrusions (when the rotatable part is rotated relative to the base).

The protrusions may be in the form of pins. The protrusions may be portions that extend from a sheet of material (e.g. sheet metal). For example, the protrusions may be etched portions that are bent up or down from a sheet of material. The protrusions may protrude from the base or the rotatable part in directions parallel to the primary axis.

The plurality of blades are arranged such that, throughout the range of movement, the (variable) aperture defined by the plurality of blades is continuously generally circular as viewed along the primary axis, and/or the shape of the (variable) aperture defined by the plurality of blades does not comprise any acute angles, and/or the shape of the (variable) aperture defined by the plurality of blades is continuously generally equilateral. By having the moving protrusions arranged to rotate around the pivot protrusions (i.e. by having the moving protrusions move along a circular paths centred around the pivot protrusions), a high-gain variable aperture mechanism (with e.g. a mechanical advantage of about 10:1) is provided that is suitable for use with low stroke (e.g. low displacement) high force actuators.

The variable aperture assembly may comprise a biasing arrangement configured to bias each moving protrusion towards or away from a respective pivot protrusion.

Optionally, each moving protrusion is biased (e.g. in a direction perpendicular to the primary axis) against a respective blade of the plurality of blades (i.e. the blade the moving protrusion is connected to) such that, throughout the range of movement, the moving protrusions are in constant (e.g. slidable) engagement with respective blades; and wherein the biasing of the moving protrusions against respective blades also biases (e.g. in a direction perpendicular to the primary axis) each blade against a respective pivot protrusion of the plurality of pivot protrusions (i.e. the pivot protrusion the blade is connected to) such that, throughout the range of movement, the blades are in constant (e.g. slidable) engagement with respective pivot protrusions. The biasing may be provided by spring-loaded connecting arms and/or by having the moving protrusions elastically/resiliently deformed. This is discussed in more detail below.

Each moving protrusion may be biased at least partially towards or away from the primary axis. Each moving protrusion may be biased at least partially towards or away from a respective pivot protrusion of the plurality of pivot protrusions (i.e. the pivot protrusion the moving protrusion is connected to via one of the blades).

Optionally, one or more (or all) of the moving protrusions are each connected to the base or the rotatable part via a connecting arm, wherein the connecting arm is configured to allow/accommodate (e.g. deform to allow/accommodate) rotation of the one or more moving protrusions around respective pivot protrusions of the plurality of pivot protrusions. In other words, the connecting arms may be configured to allow each of the one or more moving protrusions to rotate around the pivot protrusion it is connected to via one of the plurality of blades. In other words, one or more (or all) of the moving protrusions may each be connected to the base or the rotatable part via a connecting arm, wherein the connecting arm is configured to allow/accommodate (e.g. deform to allow/accommodate) movement of the one or more moving protrusions along circular paths centred around respective pivot protrusions of the plurality of pivot protrusions. The connecting arms may be flexure arms configured to allow/accommodate rotation of the one or more moving protrusions around respective pivot protrusions by elastically/resil iently deforming. In other words, the connecting arms may be flexure arms configured to allow/accommodate movement of the one or more moving protrusions along circular paths centred around respective pivot protrusions by elastically/resil iently deforming.

Optionally, the connecting arms comprise crank arms and/or flexure arms (which e.g. may be integrally formed with the base or the rotatable part).

Optionally, the connecting arms are configured to bias each of the moving protrusions into engagement with a respective blade of the plurality of blades. If the connecting arm comprises a crank arm, the crank arm may e.g. be spring-loaded so as to provide this biasing. If the connecting arm comprises a flexure arm, the flexure arm itself may be configured to provide this biasing.

Each connecting arm (e.g. each flexure arm) may be configured to act as a compression spring or as an extension spring throughout the range of movement.

Optionally, the connecting arms are configured to apply biasing forces (e.g. in directions at least partially towards respective pivot protrusions, and/or at least partially towards the primary axis), via the one or more moving protrusions, to respective blades of the plurality of blades (i.e. the blades connected to the connecting arms via the one or more moving protrusions) such that the respective blades are bistable. In other words, the connecting arms may be configured to bias the moving protrusions such that the plurality of blades are bistable, i.e. configured to cause the plurality of blades to have a first stable equilibrium position and a second stable equilibrium position. The first and second stable equilibrium positions may correspond to the ends of the range of movement of the plurality of blades.

Optionally, each of the connecting arms extend in a first sense (e.g. clockwise or anti-clockwise) around the primary axis. In other words, each of the connecting arms extend in the same sense (clockwise or anti-clockwise) around the primary axis.

Optionally, at least one (e.g. half, as in four out of eight) of the connecting arms extends in a first sense (e.g. clockwise) around the primary axis, and at least one (e.g. the other half, as in the other four of the eight) of the connecting arms extend in a second sense (e.g. anti-clockwise) around the primary axis, wherein the second sense is opposite to the first sense. Optionally, the one or more moving protrusions and the connecting arms are integrally formed with the base or the rotatable part. For example, the moving protrusions, the connecting arms and the base or the rotatable part are formed as a single part by injection moulding or sheet material fabrication. The moving protrusions, the connecting arms, and/or the rotatable part or the base may be etched portions of a sheet of material (e.g. sheet metal).

Optionally, at least one moving protrusion is configured to elastically deform to allow/accommodate rotation of the at least one moving protrusion around a respective pivot protrusion of the plurality of pivot protrusions (i.e. the pivot protrusion the moving protrusion is connected to via one of the blades). In other words, at least one moving protrusion is configured to elastically deform to allow/accommodate movement of the at least one moving protrusion along a circular path centred around a respective pivot protrusion of the plurality of pivot protrusions (i.e. the pivot protrusion the moving protrusion is connected to via one of the blades). This feature may be provided in addition to, or as an alternative to, the connecting arms.

Optionally, the at least one moving protrusion is configured to compliantly deform to ensure, throughout the range of movement, that the at least one moving protrusion is in constant engagement with a respective blade of the plurality of blades (i.e. the blade connected to the at least one moving protrusion).

Optionally, the at least one moving protrusion is configured to resiliently deform to apply a biasing force to a respective blade of the plurality of blades such that the respective blade is bistable.

The at least one moving protrusion may be configured to act as a compression spring or an extension spring throughout the range of movement.

Optionally, the moving protrusions are connected to the blades in a manner that prevents or restricts relative translational movement between each connected moving protrusion and blade in directions perpendicular to the primary axis. However, the moving protrusions may be connected to the blades in a manner that allows each connected moving protrusion and blade to slidably rotate relative to each other, i.e. the moving protrusions are rotatably/slidably mounted within openings in the blades. Additionally or alternatively, the moving protrusions may be rotatably/slidably held by the connecting arms. Optionally, the moving protrusions and the pivot protrusions are configured (e.g. are close enough to each other) to provide, per degree of rotation of the rotatable part about the primary axis (relative to the base), at least 5, 10, or 20 degrees of rotation of the blades about the pivot protrusions.

Optionally, each blade is connected to the base and to the rotatable part via one (e.g. only one) pivot protrusion and one (e.g. only one) moving protrusion.

Optionally, the base (e.g. the main body of the base) is (at least partially or fully) provided/nested within a hole that extends through the rotatable part along the primary axis. Optionally, the rotatable part is provided/nested within a hole that extends through the base along the primary axis.

Optionally, the plurality of blades (at least partially) overlap with the base and/or the rotatable part as viewed along the primary axis.

Optionally, the plurality of blades (at least partially) overlap with each other as viewed along the primary axis.

Optionally, the plurality of blades generally lie in a plane perpendicular to the primary axis which sits on top of the rotatable part and the base (e.g. the plurality of blades (at least partially) cover or are provided at sides of the base and the movable part that generally face in the same direction).

Optionally, a bearing arrangement (e.g. comprising a sliding bearing) is provided between the base and the rotatable part. This bearing arrangement may guide, allow and/or facilitate the rotational movement of the rotatable part relative to the base.

Optionally, the variable aperture assembly comprises a holding arrangement configured to releasably hold the rotatable part at one or more positions within the range of positions that the rotatable part is capable of being driven to relative to the base by the actuator assembly.

Optionally, the variable aperture assembly comprises at least one biasing element configured to bias the rotatable part in a direction parallel to the primary axis so as to generate frictional forces that constrain the movement of the rotatable part relative to the base at any position within the range of movement (i.e. at any position within the range of positions that the rotatable part is capable of being driven to relative to the base by the actuator assembly) when the actuator assembly is not actuated. The frictional forces may by generated by engagement between the components provided between the rotatable part and the base. For example, engagement between surfaces of the rotatable part, surfaces of the blades, surfaces of the base, (if provided) surfaces of one or more washer/spacer plates provided between the blades and the rotatable part, and/or (if provided) surfaces of one or more washer/spacer plates provided between the blades and the base (e.g. an upper plate fixed to the base).

Optionally, the actuator assembly is configured such that the frictional forces remain substantially constant on actuation.

Optionally, the actuator assembly is configured to be capable of reducing the frictional forces on actuation. For example, the actuator assembly may be configured to be capable of reducing the frictional forces on actuation by applying a force to the rotatable part, on actuation, which acts against the bias (force) of the biasing element and is large enough to meaningfully reduce the bias (force).

Optionally, the plurality of blades comprises six or eight blades.

Optionally, the plurality of blades are stacked in layers of two blades on top of each other, and wherein the layers overlap when viewed along the primary axis.

Optionally, the actuator assembly comprises one or more shape memory alloy (SMA) elements configured to, upon contraction, (directly or indirectly) drive the rotation of the rotatable part relative to the base.

Optionally, the actuator assembly comprises: a support structure fixed to the base; and a movable part coupled to the rotatable part; wherein the one or more SMA elements are configured to, upon contraction, drive relative movement between the movable part and the support structure so as to drive the rotation of the rotatable part (relative to the base).

Optionally, the movable part is fixed to the rotatable part; and the one or more SMA elements are configured to, upon contraction, drive rotation of the movable part relative to the support structure (e.g. around the primary axis) so as to drive the rotation of the rotatable part (relative to the base).

Optionally, the variable aperture assembly comprises a holding arrangement configured to releasably hold the movable part at one or more positions within the range of positions that the movable part is capable of being driven to relative to the support structure.

Optionally, the one or more SMA elements comprise (e.g. a total of) four SMA elements configured to (directly, or indirectly via the movable part) drive the rotation of the rotatable part; wherein, optionally, the four SMA elements are arranged in a loop at different angular positions around the primary axis; and, optionally, wherein successive SMA elements around the primary axis are configured (on contraction) to apply a force to the rotatable part (directly or indirectly via the movable part) in alternate senses around the primary axis.

Optionally, the one or more SMA elements comprise: a first SMA element arranged to (directly, or indirectly via the movable part) rotate the rotatable part about the primary axis in a first sense; and a second SMA element arranged to (directly, or indirectly via the movable part) rotate the rotatable part about the primary axis in a second sense, wherein the second sense is opposite to the first sense.

Optionally, the one or more SMA elements comprise: a first pair of SMA elements, electrically connected together (in series or parallel), arranged to apply a torque to the rotatable part (directly, or indirectly via the movable part) for rotating the rotatable part about the primary axis in a first sense; and a second pair of SMA elements, electrically connected together (in series or parallel), arranged to apply a torque to the rotatable part (directly, or indirectly via the movable part) for rotating the rotatable part about the primary axis in a second sense, wherein the second sense is opposite to the first sense.

Optionally, the actuator assembly is configured to be controlled by a drive chip via two drive channels of the drive chip (only).

According to another aspect of the present invention, there is provided a camera assembly comprising: a variable aperture assembly as described above; a further actuator assembly; a (single) drive chip operatively connected to the actuator assembly and the further actuator assembly for controlling the actuator assembly and the further actuator assembly; wherein the drive chip comprises at least four drive channels; and wherein the actuator assembly is configured to be (fully) controlled (only) via a first channel and a second channel of the at least four drive channels, and the further actuator assembly is configured to be (fully) controlled (only) via a third channel and a fourth channel of at least four drive channels.

Optionally, the further actuator assembly is a focus (e.g. auto-focus (AF)) actuator assembly (e.g. configured to drive movement of one or more lenses along the primary axis, and, optionally, comprising one or more SMA elements configured to drive said movement).

According to another aspect of the present invention, there is provided a camera assembly comprising: a variable aperture assembly as described above; and a lens assembly; wherein the variable aperture assembly (e.g. the base of the variable aperture assembly) is mounted on the lens assembly, and the optical axis of the lens assembly coincides with the primary axis.

Optionally, the lens assembly is (at least partially) provided/nested within a (through) hole that extends through the base along the primary axis.

Optionally, more than 50%, 60%, 70%, 80%, or 90% of the variable aperture assembly overlaps with the lens assembly along the primary axis (i.e. as viewed across the primary axis).

Optionally, the actuator assembly fully overlaps with the lens assembly along the primary axis (i.e. as viewed across the primary axis).

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:

Fig. 1 is a schematic plan view of a variable aperture assembly with a rotatable part in a first position relative to a base;

Fig. 2 is a schematic plan view of the variable aperture assembly of Fig. 1 with a rotatable part in a second position relative to a base;

Fig. 3 is a schematic cross-sectional side view of the variable aperture assembly of Fig. 1 mounted on a lens assembly;

Fig. 4 is a schematic plan view of a variable aperture assembly;

Fig. 5 is a schematic cross-sectional side view of the variable aperture assembly of Fig. 4 mounted on a lens assembly;

Fig. 6 is a schematic perspective view of the variable aperture assembly of Fig. 4 mounted on a lens assembly;

Fig. 7 is a schematic plan view of an actuator assembly comprising four shape memory alloy (SMA) wires;

Fig. 8 is a schematic illustration of an eight-channel drivechip configured to control three actuator assemblies;

Fig. 9 is a schematic illustration of two four-channel drivechips configured to control three actuator assemblies;

Fig. 10 is a schematic illustration of an eight-channel drivechip and a four-channel drivechip configured to control three actuator assemblies;

Fig. 11 is a schematic plan view of a variable aperture assembly comprising folded SMA wires; Fig. 12 is a schematic plan view of a variable aperture assembly;

Fig. 13 is a schematic perspective view of a biasing element;

Fig. 14 is a schematic perspective view of a biasing element;

Figs. 15 to 20 are plan views of different stages of a method of assembling a variable aperture assembly;

Figs. 21 to 23 are schematic plan views of different stages of a method of forming blades for a variable aperture assembly;

Figs. 24 to 28 are schematic plan views of different stages of a method of forming blades for a variable aperture assembly;

Fig. 29 is a schematic plan view of a blade for a variable aperture assembly; and

Fig. 30 is a schematic plan view of a blade for a variable aperture assembly.

Detailed description

First embodiment

Figs. 1 to 3 show a variable aperture (VA) assembly 1 comprising: a base 30, a rotatable part 20, a plurality of blades 40 which are connected to the base 30 and the rotatable part 20 via pins 21, 31 and which define a variable aperture and, and an actuator assembly 10 (only schematically illustrated in Fig. 3) configured to drive rotation of the rotatable part 20 relative to the base 30 about a primary axis 0 to any rotational position within a range of movement so as to change the size of the variable aperture defined by the blades 40.

As shown in Figure 3, the base 30 may be mounted onto a lens assembly 50. The base 30 is mounted such that the lens assembly 50 is nested or provided within a through hole or opening of the base 30 which extends along a primary axis O of the VA assembly 1. The primary axis O coincides with the optical axis of the lens assembly 50. The base 30 may be described as a hollow tube with a base plate, provided on the lower end of the base 30, which radially protrudes outwards from the main body of the base 30 away from the optical axis O. The base 30 comprises a plurality of pivot pins 31 (also referred to as pivot protrusions herein) protruding from an upper surface of the main body of the base 30 in an upward direction parallel to the primary axis O. The plurality of pivot pins 31 form a loop around the primary axis O and are equally distanced from each other and equally distanced from the primary axis O.

The main body of the base 30 is nested or provided within a hole or opening that extends through the rotatable part 20 along the primary axis O. The rotatable part 20 is mounted onto the base 30 such that it is capable of rotating relative to the base 30 about the primary axis O. The rotatable part 20 comprises a plurality of moving pins 21 (also referred to as moving protrusions herein) protruding from an upper surface of the rotatable part 20 in an upward direction parallel to the primary axis O. The plurality of moving pins 21 form a loop around the primary axis O and are equally distanced from each other and equally distanced from the primary axis O. The moving pins 21 are connected to the main body of the rotatable part 20 via connecting arms 22. The connecting arms 22 in the illustrated embodiments are flexure arms 22 configured to elastically deform so as to allow movement of the moving pins 21 relative to the main body of the rotatable part 20 in directions generally perpendicular to the extent/length of the flexure arms 22. In other words, given that the flexure arms 22 extend in a circular manner around the primary axis O (i.e. wrap around the primary axis O), the flexure arms 22 are configured to elastically deform to accommodate movement of the moving pins 21 relative to the main body of the rotatable part 20 generally towards and away from the primary axis O. In Figs. 1 and 2, the connecting arms 22 extend in the same sense (anti-clockwise) around the primary axis O. However, as shown in Fig. 12, some (e.g. half) of the connecting arms 22 may extend in a first sense (e.g. clockwise) around the primary axis O and some (e.g. the remaining half) of the connecting arms 22 may extend in a second opposite sense (e.g. anti-clockwise) around the primary axis O.

The plurality of blades 40 are arranged to define a variable aperture (VA) with a central axis which coincides with the primary axis O. The central axis of the VA also coincides with the optical axis of the lens assembly 50.

The plurality of blades 40 are connected to the base 30 via the plurality of pivot pins 31 and connected to the rotatable part 20 via the plurality of moving pins 21. The plurality of blades 40 are provided on the upper sides of the base 30 and the rotatable part 20. In other words, the plurality of blades 40 (at least partially) cover or are provided at sides of the base 30 and the movable part 20 that generally face in upwards. The plurality of blades 40 (at least partially) overlap with the base 30 and/or the rotatable part 20 as viewed along the primary axis O. The plurality of blades 40 (at least partially) overlap with each other as viewed along the primary axis O. The plurality of blades 40 generally lie in a plane perpendicular to the primary axis O which sits on top of the rotatable part 20 and the base 30. The plurality of blades 40 are provided at sides of the base 30 and the movable part 20 that generally face in the same direction (e.g. upwards).

Each blade 40 is connected to the base 30 via a single pivot pin 31 and connected to the rotatable part 20 via a single moving pin 21. The pivot pins 31 and the moving pins 21 extend through holes provided in the blades 40. The plurality of blades 40 are arranged such that, throughout the range of movement, the (variable) aperture defined by the plurality of blades 40 is continuously generally circular as viewed along the primary axis O, and/or the shape of the (variable) aperture defined by the plurality of blades 40 does not comprise any acute angles, and/or the shape of the (variable) aperture defined by the plurality of blades 40 is continuously an equilateral shape. The plurality of blades 40 are distributed around the primary axis O. In Figs. 1 and 2, the plurality of blades 40 comprises a total of six blades 40. The plurality of blades 40 are stacked in two layers of three blades 40 on top of each other, and the layers overlap when viewed along the primary axis O.

It will be appreciated that, the plurality of blades 40 may comprise any number of blades and any number of layers. For example, the plurality of blades may comprise six blades, the blades stacked in layers of two blades on top of each other wherein the layers overlap when viewed along the primary axis. For example, as shown in Fig 21, the plurality of blades may comprise eight blades, the blades stacked in layers of four blades on top of each other wherein the layers overlap when viewed along the primary axis.

The moving pins 21 are connected to the blades 40 in a manner that prevents or restricts (any significant amount of) relative translational movement between each connected moving pin 21 and blade 40 in directions perpendicular to the primary axis O. The pivot pins 31 are also connected to the blades 40 in a manner that prevents or restricts (any significant amount of) relative translational movement between each connected pivot pin 31 and blade 40 in directions perpendicular to the primary axis O.

In the illustrated embodiments, the moving pins 21 are fixed (e.g. integrally formed with, attached, welded, glued or soldered) to the connecting arms 22, and the moving pins 21 are connected to the blades 40 in a manner that allows each connected moving pin 21 and blade 40 to slidably rotate relative to each other, i.e. the moving pins 21 are rotatably/slidably mounted within openings in the blades 40. However, it will be appreciated that in alternative embodiments this may not be the case. For example, the moving pins 21 may instead be fixed to the blades 40 and connected to the connecting arms 22 in a manner that allows each connected moving pin 21 and connecting arm 22 to slidably rotate relative to each other, i.e. the moving pins 21 may be rotatably/slidably mounted within openings in the connecting arms 22. In another example, the moving pins 21 may be rotatably/slidably mounted within openings in the connecting arms 22 and also rotatably/slidably mounted within openings in the blades 40. In yet another example, the moving pins 21 may be fixed to the connecting arms 22 and fixed to the blades 40, and the moving pins 21 may be arranged to elastically deform to allow the moving pins 21 (i.e. at least the portions of the moving pins 21 engaging the blades 40) to rotate about the pivot pins 31.

In the illustrated embodiments, the pivot pins 31 are fixed (e.g. integrally formed with, attached, welded, glued or soldered) to the base 30, and the pivot pins 31 are connected to the blades 40 in a manner that allows each connected pivot pin 31 and blade 40 to slidably rotate relative to each other, i.e. the pivot pins 31 are rotatably/slidably mounted within openings in the blades 40. However, it will be appreciated that in alternative embodiments this may not be the case. For example, the pivot pins 31 may instead be fixed to the blades 40 and connected to the base 30 in a manner that allows the pivot pins 31 to slidably rotate (about their own axes) relative to the base 30, i.e. the pivot pins 31 may be rotatably/slidably mounted within openings in the base 30. In another example, the pivot pins 31 may be rotatably/slidable mounted within openings in the base 30 and also rotatably/slidable mounted within openings in the blade 40. In yet another example, the pivot pins 31 may be fixed to the base 30 and fixed to the blades 40, and the pivot pins 31 may be arranged to elastically deform to allow the moving pins 21 to rotate about the pivot pins 31.

The actuator assembly 10 is provided between the base 30 and the rotatable part 20. In Fig. 3, the actuator assembly 10 is mounted onto the base plate of the base 30 but it will be appreciated that this may not necessarily be the case. The actuator assembly 10 is configured to, on actuation, drive rotation of the rotatable part 20 relative to the base 30 about a primary axis O in both clockwise and anticlockwise directions. As shown in e.g. Fig. 7 and 11, the actuator assembly 10 may be a shape memory alloy (SMA) actuator assembly. However, it will be appreciated that the actuator assembly 10 may be any suitable actuator assembly, for example, be a voice coil motor (VCM) actuator assembly or a piezoelectric actuator assembly, instead of a SMA actuator assembly.

The VA assembly 1 is configured such that rotation of the rotatable part 20 relative to the base 30 about the primary axis O, drives relative movement between the pivot pins 31 and the moving pins 21, more specifically drives rotation of the moving pins 21 around the pivot pins 31. In other words, rotation of the rotatable part 20 relative to the base 30 about the primary axis O drives the moving pins 21 to move along circular paths centred around the pivot pins 31 (i.e. drives each moving pin 21 to move along a circular path centred around a respective pivot pin 31). In other words, the relative rotation of the rotatable part 20 about the primary axis O drives each moving protrusion 21 to rotate around a respective pivot protrusion 31 (i.e. the pivot protrusion 31 the moving protrusion 21 is connected to via one of the plurality of blades 40). In other words, the moving pins 21 are configured to rotate (e.g. move in a circular arc) around the pivot pins 31 (when the rotatable part 20 is rotated relative to the base 30).

This in turn drives rotation of the plurality of blades 40 about the pivot pins 31. The rotation of the plurality of blades 40 changes the size of the variable aperture. In other words, the rotation of the moving pins 21 around the pivot pins 31 drives rotation of the plurality of blades 40 about the pivot pins 31, and the rotation of the plurality of blades 40 about the pivot pins 31 changes the size of the variable aperture. By having the moving protrusions 21 arranged to rotate around the pivot protrusions 31, a high-gain variable aperture mechanism (with e.g. a mechanical advantage of about 10:1) is provided that is suitable for use with low stroke (e.g. low displacement) high force actuators.

The moving pins 21 and the pivot pins 31 may be configured (e.g. are close enough to each other) to provide, per degree of rotation of the rotatable part 20 about the primary axis O (relative to the base), at least 5, 10, or 20 degrees of rotation of the blades 40 about the pivot pins 31.

Optionally, the variable aperture assembly comprises a holding arrangement configured to releasably hold the rotatable part at one or more positions within the range of positions that the rotatable part is capable of being driven to relative to the base by the actuator assembly.

Second embodiment

As illustrated in Figs. 4 to 6, instead of having the base 30 nested within the rotatable part 20, the rotatable part 20 may be nested within the base 30. In other words, the rotatable part 20 may be provided within an opening/hole extending along the primary axis O through the base 30. Where this is the case, as shown, the rotatable part 20 may be rotatably/slidably mounted onto the lens assembly 50 such that the rotatable part 20 can rotate relative to the lens assembly 50 about the primary axis O.

The variable aperture assembly 1 of Figs. 1 to 3 and the variable aperture assembly 1 of Figs. 4 to 6 mainly differ only in that the variable aperture assembly 1 of Figs. 1 to 3 has the base 30 nested within the rotatable part 20, whereas the variable aperture assembly 1 of Figs. 4 to 6 has the rotatable part 20 nested within the base 30.

Third embodiment

In the illustrated embodiments, the moving pins 21 comprise part of the rotatable part 20 and the pivot pins 31 comprise part of the base 30. However, the rotatable part 20 may instead comprise the pivot pins 31, and the base 30 may instead comprise the moving pins 21 and the connecting arms 22, wherein the moving pins 21 are pins configured to rotate around the pivot pins 31 (as described above). In other words, each blade 40 may be connected to the base 30 via a single moving pin 21 and connected to the rotatable part 20 via a single pivot pin 31 and the connecting arms 22.

In other words, in the illustrated embodiments, the moving pins 21 are connected to the rotatable part 20 via connecting arms 22, wherein the connecting arms 22 are configured to allow (e.g. deform to allow) rotation of the moving pins 21 around the pivot pins 31. However, in alternative embodiments, the moving pins 21 may be connected to the base 30 via connecting arms 22, wherein the connecting arms 22 are configured to allow (e.g. deform to allow) rotation of the moving pins 21 around the pivot pins 31.

In other words, although Figs. 1 to 3 only show the plurality of blades 40 being connected to the base 30 via the plurality of pivot pins 31 and connected to the rotatable part 20 via the plurality of moving pins 21, in alternative embodiments the plurality of blades 40 could instead be connected to the base 30 via a plurality of moving pins 21 and connected to the rotatable part 20 via the plurality of pivot pins 31.

Addition/alternative to connecting arms

In the above described embodiments, the moving pins 21 are connected to the rotatable part 20 or to the base 30 via connecting arms 22 which are configured to allow/accommodate rotational movement of the moving pins 21 about the pivot pins 31. Additionally or alternatively, the rotational movement of the moving pins 21 about the pivot pins 31 may be (e.g. further) allowed/accommodated by having the moving pins 21 configured to elastically deform. In other words, additionally or alternatively, at least one moving protrusion 21 may be configured to elastically deform to (e.g. further) allow/accommodate rotation of the at least one moving protrusion 21 around a respective pivot protrusion 31 of the plurality of pivot protrusions 31 (i.e. the pivot protrusion 31 the at least one moving protrusion 21 is connected to via one of the blades 40). As such, the connecting arms 22 may or may not be provided. It will be appreciated that some of the moving pins 21 may be connected to the rotatable part 2 or to the base 30 via connecting arms 22 and some of the moving pins 21 may be connected to the rotatable part 2 or to the base 30 with no connecting arms 22 (e.g. if the latter moving pins 21 are configured to elastically deform as just mentioned). It will be appreciated that the moving pins 21 may be elongate in shape and extend primarily in a direction parallel to the primary axis O in order to be sufficiently compliant in directions perpendicular to the primary axis O and thus to be capable of elastically deforming as just discussed.

Optional biasing / bistability

The connecting arms 22 and the elastically-deformable moving pins 21 (i.e. the just-mentioned moving pins 21 configured to elastically deform to accommodate rotation of the moving pins 21 relative to the pivot pins 31) may be configured to bias the moving pins 21 (more specifically, at least the portions of the moving pins 21 engaging the blades 40) against the blades 40. In other words, the connecting arms 22 and the elastically-deformable moving pins 21 may be configured to bias each of the moving protrusions 21 into engagement with a respective blade 40 of the plurality of blades 40. If the connecting arm 22 comprises a crank arm, the crank arm may e.g. be spring-loaded so as to provide this biasing. If the connecting arm 22 comprises a flexure arm, the flexure arm itself may be configured to provide this biasing. This biasing may ensure that the moving pins 21 are in constant engagement with the blades 40 throughout the range of movement, e.g. wherein the moving pins 21 are not fixed to the blades 40. In other words, each moving protrusion 21 may be biased (e.g. in a direction perpendicular to the primary axis 0) against a respective blade 40 of the plurality of blades 40 (i.e. the blade the moving protrusion 21 is connected to) such that, throughout the range of movement, the moving protrusions 21 are in constant (e.g. slidable) engagement with respective blades 40.

This biasing may also bias the blades 40 into engagement with the pivot pins 31 such that the blades 40 are in constant engagement with the pivot protrusions 31 throughout the range of movement, e.g. wherein the pivot pins 31 are not fixed to the blades 40. In other words, the biasing of the moving protrusions 21 against respective blades 40 may also bias (e.g. in a direction perpendicular to the primary axis O) each blade 40 against a respective pivot protrusion 31 of the plurality of pivot protrusions 31 (i.e. the pivot protrusion 31 the blade 40 is connected to) such that, throughout the range of movement, the blades 40 are in constant (e.g. slidable) engagement with respective pivot protrusions 31.

The connecting arms 22 and the elastically-deformable moving pins 21 may be configured to act as a compression springs (i.e. be under compression) or as extension springs (i.e. be under tension) throughout the range of movement.

The biasing forces provided may generally be inwardly, i.e. in directions towards the primary axis O. Alternatively, the biasing forces provided may generally be outwardly, i.e. in directions away from the primary axis O. In other words, each moving protrusion 21 may be biased at least partially towards or away from the primary axis O.

The biasing forces applied to the moving pins 21 may generally be towards respective pivot pins 31. Alternatively, the biasing forces applied to the moving pins 21 may generally be in directions away from respective pivot pins 31. In other words, each moving protrusion 21 may be biased at least partially towards or away from a respective pivot protrusion 31 of the plurality of pivot protrusions 31 (i.e. the pivot protrusion 31 the moving protrusion 21 is connected to via one of the blades 40).

The connecting arms 22 and the elastically-deformable moving pins 21 may be configured to apply biasing forces (e.g. in directions at least partially towards respective pivot pins 31, and/or at least partially towards the primary axis O), via the moving pins 21, to respective blades 40 such that the respective blades 40 are bistable, i.e. configured to cause the plurality of blades 40 to have a first stable equilibrium position and a second stable equilibrium position. In other words, the connecting arms 22 and the elastically-deformable moving pins 21 may be configured to bias the moving protrusions 21 such that the plurality of blades 40 are bistable. The first and second stable equilibrium positions may correspond to the ends of the range of movement of the plurality of blades 40 (which e.g. may be defined by endstops).

The VA assembly 1 may further comprise at least one biasing element 60 configured to help bias the moving pins 21 at least partially towards respective pivot pins 31, e.g. throughout the range of movement. As shown in Figure 13, the biasing element 60 may comprise a ring-shaped body 62, and a plurality of flexure arms 61 wrapping around the body 62, each configured to engage a moving pin 21 and each configured to bias the moving pins 21 inwardly towards or outwardly away from the primary axis O. These flexure arms 61 may be configured to act as a compression springs (i.e. be under compression) or as extension springs (i.e. be under tension).

Optional biasing element for friction

The VA assembly 1 may comprise at least one biasing element 70 (an example of which is shown in Figure 14) configured to bias the rotatable part 20 in a direction parallel to the primary axis O so as to generate frictional forces that constrain the movement of the rotatable part 20 relative to the base 30 at any position within the range of movement (i.e. at any position within the range of positions that the rotatable part 20 is capable of being driven to relative to the base 30 by the actuator assembly 10) when the actuator assembly 10 is not actuated. The frictional forces may by generated by engagement between the components provided between the rotatable part 20 and the base 30. For example, engagement between surfaces of the rotatable part 20, surfaces of the blades 40, surfaces of the base 30, (if provided) surfaces of one or more washer/spacer plates provided between the blades 40 and the rotatable part 20, and/or (if provided) surfaces of one or more washer/spacer plates provided between the blades 40 and the base 30 (e.g. an upper plate fixed to the base 30).

The biasing element 70 may comprise a ring-shaped main body 71 which may be pre-deformed so as to provide the biasing force for generating the frictional forces. The biasing element 70 may also comprise radially extending portions 72 for attaching the biasing element 70 to e.g. the base 30 or the rotatable part 20.

The actuator assembly 10 may be configured such that the frictional forces remain substantially constant on actuation. The actuator assembly 10 may be configured to be capable of reducing the frictional forces on actuation. For example, the actuator assembly may be configured to be capable of reducing the frictional forces on actuation by applying a force to the rotatable part, on actuation, which acts against the bias (force) of the biasing element and is large enough to meaningfully reduce the bias (force).

Optional holding arrangement

The variable aperture assembly 1 may comprise a holding arrangement (not shown) configured to releasably hold the rotatable part 20 at one or more positions within the range of positions that the rotatable part 20 is capable of being driven to relative to the base 30 by the actuator assembly 10. The holding arrangement may, for example, be any suitable latch or catch arrangement known in the art, such as a roller ball catch arrangement.

SMA actuator assembly

The actuator assembly 10 may be an SMA actuator assembly 10 comprising one or more SMA elements configured to, upon contraction (e.g. upon heating the SMA elements by passing a current through them), (directly or indirectly) drive the rotation of the rotatable part 20 relative to the base 30.

An example of an SMA actuator assembly 10 is shown in Fig. 7. Similar actuator assemblies are described in detail in WO2013175197 which is incorporated herein by reference. The actuator assembly 10 of Fig. 7 comprises a total of four SMA elements 11, 12, 13, 14; a support structure 4 fixed to the base 30; and a movable part 3 coupled to the rotatable part 20. The SMA elements 11, 12, 13, 14 are configured to, upon contraction, drive relative movement between the movable part 3 and the support structure 4 so as to drive the rotation of the rotatable part 20 relative to the base 30.

The movable part 3 is fixed to the rotatable part 20; and the one or more SMA elements 11, 12, 13, 14 are configured to, upon contraction, drive rotation of the movable part 3 relative to the support structure 4 (e.g. around the primary axis O) so as to drive the rotation of the rotatable part 20 relative to the base 30.

The variable aperture assembly 1 may comprise a holding arrangement (not shown) configured to releasably hold the movable part 3 at one or more positions within the range of positions that the movable part 3 is capable of being driven to relative to the support structure 4, e.g. by the one or more SMA elements 11, 12, 13, 14. The holding arrangement may be any suitable latch or catch arrangement known in the art, such as a roller ball catch arrangement. The four SMA elements 11, 12, 13, 14 are configured to, indirectly via the movable part 3, drive the rotation of the rotatable part 20 relative to the base 30. The four SMA elements 11, 12, 13, 14 are arranged in a loop at different angular positions around the primary axis O. Successive SMA elements 11, 12, 13, 14 around the primary axis O are configured, on contraction, to, indirectly via the movable part 3, apply a force to the rotatable part 20 in alternate senses around the primary axis O.

In an alternative embodiment, the four SMA elements 11, 12, 13, 14 may be configured to directly drive the rotation of the rotatable part 20 relative to the base 30. Successive SMA elements 11, 12, 13, 14 around the primary axis O may be configured, on contraction, to directly apply a force to the rotatable part 20 in alternate senses around the primary axis O.

A first pair of SMA elements 11, 13 may be electrically connected together (in series or parallel), and arranged to apply a torque to the rotatable part 20 (directly, or indirectly via the movable part 3) for rotating the rotatable part 20 about the primary axis O in a first sense (e.g. anticlockwise); and a second pair of SMA elements 12, 14 may be electrically connected together (in series or parallel) and arranged to apply a torque to the rotatable part 20 (directly, or indirectly via the movable part 3) for rotating the rotatable part 20 about the primary axis O in a second sense (e.g. clockwise), wherein the second sense is opposite to the first sense.

An alternative example of an SMA actuator assembly 10 is shown in Fig. 11. As shown in Fig. 11, the actuator assembly 10 may comprise: a first SMA element 11' arranged to (directly, or indirectly via the movable part) rotate the rotatable part 20 about the primary axis O in a first sense relative to the base 30; and a second SMA element 12' arranged to (directly, or indirectly via the movable part) rotate the rotatable part 20 about the primary axis O in a second sense relative to the base 30, wherein the second sense is opposite to the first sense.

As shown in Fig. 11, the actuator assembly 10 may comprise one or more SMA elements 11', 12' (e.g. a total of two SMA elements 11', 12') that are wound around (i.e. bent or folded around) corner elements 300' which may be flexures, pulley wheels, posts and/or rocking arms.

As shown in Figs. 3, 5 and 6, the variable aperture assembly 1 (e.g. the base 30 of the variable aperture assembly 1) may be mounted on a lens assembly 50 of a camera assembly, such that the optical axis of the lens assembly 50 coincides with the primary axis O. The lens assembly 50 may be (at least partially) provided/nested within a (through) hole that extends through the base 30 along the primary axis O. More than 50%, 60%, 70%, 80%, or 90% of the variable aperture assembly 1 may overlap with the lens assembly 50 along the primary axis O, i.e. as viewed across the primary axis O. The actuator assembly 10 may fully overlap with the lens assembly 50 along the primary axis O, i.e. as viewed across the primary axis.

Drive channels

The actuator assembly 10 may be driven/controlled using two drive channels only (and a common). As such, as shown in Fig. 8, a single 8-channel drive chip 101 could be used to drive: (i) the actuator assembly 10, (ii) an optical image stabilisation (OIS) actuator assembly 51 requiring four drive channels (and a common), and (iii) a focus (e.g. auto-focus (AF)) actuator assembly 52 requiring two drive channels (and a common). If the 8-channel drive chip 101 has two common channels C, as shown in Fig.

8, one of the common channels C may be shared by e.g. the AF actuator assembly 52 and the actuator assembly 10.

Alternatively, as shown in Fig. 9, a single 4-channel drive chip 102' could be used to drive: (i) the actuator assembly 10, and (ii) the AF actuator assembly 52; and another single 4-channel drive chip 102 could be used to drive the OIS actuator assembly 51. If the 4-channel drive chip 102' has a single common channel C, as shown in Fig. 9, the single common channel C may be shared by the AF actuator assembly 52 and the actuator assembly 10.

Alternatively, as shown in Fig. 10, where a camera assembly comprises a module tilt actuator assembly 53 which requires 8-channels (and a common) to provide OIS, a single 4-channel drive chip 102' could be used to drive: (i) the actuator assembly 10, and (ii) the AF actuator assembly 52; and a single 8-channel drive chip 101 could be used to drive the module tilt actuator assembly 53. If the 4-channel drive chip 102' has a single common channel C, as shown in Fig. 10, the single common channel C may be shared by the AF actuator assembly 52 and the actuator assembly 10.

The above-mentioned OIS actuator assembly 51 may be an actuator assembly comprising (a total of) four SMA elements such as the one disclosed in WO 2013/175197 or WO 2017/072525. The above- mentioned AF actuator assembly 52 may be an actuator assembly comprising (a total of) two SMA elements such as the one disclosed in WO 2019/243849. The above-mentioned module tilt actuator assembly 53 may be an actuator assembly comprising (a total of) eight SMA elements such as the one disclosed in WO 2011/104518.

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 or deposition and/or other forming process(es). 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.

Blade mounting

Figs. 15 to 20 show different stages of a method of assembling the blades 40 onto the rotatable part 20 and base 30 of a version of the VA assembly 1 comprising two layers of four blades 40.

As illustrated in Fig. 15, the first stage involves providing a first sub-assembly 41 comprising a sacrificial body 42 and a first plurality of blades 40 (four blades 40 in the illustrated example). The first plurality of blades 40 are fixed to the sacrificial body 42. The sacrificial body 42 holds the first plurality of blades 40 in pre-determined positions and orientations relative to each other, and such that the first plurality of blades 40 cannot move relative to each other and to the sacrificial body 42. The sacrificial body 42 comprise a central support 43 provided at a central position between the blades 40.

As illustrated in Fig. 16, the second stage involves detaching the central support 43 from the first subassembly 41 and removing the central support 43 from the first sub-assembly 41. The central support 43 may be detached from the first plurality of blades 40 by any suitable means such as e.g. by using a laser or a blade to cut the connections (e.g. sprues) between the central support 43 and the first plurality of blades 40. It will be appreciated that the central support 43 may not be provided to begin with in which case the second stage could be considered the first stage of this method of assembly.

As illustrated in Fig. 17, the third stage involves mounting/loading the first sub-assembly 41 onto the rotatable part 20 and the base 30 such that the pins 21, 31 of the rotatable part 20 and the base 30 are inserted into respective openings of the first plurality of blades 40. It will be appreciated that the actuator assembly 10 may or may not already be assembled with the rotatable part 20 and the base 30 before this stage.

As illustrated in Fig. 18, the fourth stage involves detaching the sacrificial body 42 from the first plurality of blades 40 and removing the sacrificial body 42 such that the first plurality of blades 40 are no longer held relative to each other by the sacrificial body 42. The sacrificial body 42 may be detached from the first plurality of blades 40 by any suitable means such as e.g. by using a laser or a blade to cut the connections (e.g. sprues) between the sacrificial body 42 and the first plurality of blades 40. This stage completes the mounting/assembly of the first plurality of blades 40 (forming the first layer) onto the rotatable part 20 and the base 30. It will be appreciated that the central support 43, if provided, may not need to be removed before this stage, and may instead be detached and removed after the mounting/loading of the first sub-assembly 41 e.g. at the same time that the sacrificial body 42 is detached and removed from the first plurality of blades 40.

As illustrated in Figs. 19 and 20, to assemble/mount a second plurality of blades 40 to the rotatable part 20 and the base 30 (i.e. to assemble/mount the second layer of blades 40), the above-described stages can be repeated with a second sub-assembly 41' (instead of the first sub-assembly 41) comprising a sacrificial body 42' and a second plurality of blades 40. As shown in Fig. 19, the second sub-assembly 41' may be almost identical to the first sub-assembly 41 but differ only in that the sacrificial body 42' holds the second plurality of blades 40 at pre-determined positions that are different from the predetermined positions in which the sacrificial body 42 holds the first plurality of blades 40, as the second plurality of blades 40 are mounted onto a set of pins that are different from the pins the first plurality of blades 40 are mounted onto.

It will be appreciated that the detaching and removing of sacrificial bodies 42, 42' and/or central supports 43 may only occur (e.g. simultaneously) after two or more (or all) layers of blades 40 have been mounted/assembled onto the rotatable part 20 and the base 30. Each sub-assembly 41, 41' may be an etched or stamped part, e.g. made of a sheet of material (e.g. sheet metal). The pins may have fillet or chamfer edges to allow easy loading of the blades 40.

During loading of the blades 40, the rotatable part 20 may be rotated about the primary axis O against an endstop (e.g. provided on the base 30 or provided by a jig) to ensure that the pins are aligned with the openings in the blades 40 during loading.

It will be appreciated that further layers of blades 40 may be provided by repeating the above-described stages with further sub-assemblies. In the illustrated example each layer comprises four blades 40 but it will be appreciated that each layer may comprise a different number of blades 40, e.g. 1, 2 or 3 blades.

It will be appreciated that different methods of assembling the blades 40 onto the rotatable part 20 and base 30 may be used. For example, the blades 40 could be loaded individually manually or using an automated 'pick-and-place' system.

The blades 40 provided with the sub-assemblies 41, 41' may be fully formed before loading onto the rotatable part 20 and base 30, as illustrated in Figs. 15 to 20. Alternatively, the blades 40 provided with the sub-assemblies 41, 41' may be fully formed after loading, as described below in relation to Figs. 21 to 23 and Figs. 24 to 28.

Two-part blades for circularity and concentricity

Figs. 21 to 23 show different stages of a method of forming a blade 40. One or more blades 40 of the VA assembly 1 (e.g. each blade 40 of the VA assembly 1) may be formed in this manner. This method of forming blades may help achieve good circularity and concentricity of the VA defined by the blades 40.

This method involves providing a two-part blade 40 comprising a first part 40a and a second part 40b fixed together, wherein the first part 40a comprises the openings for the pins 21, 31, and wherein the second part 40b comprises the part of the blade 40 configured to define (at least part of) the VA.

As illustrated in Fig. 21, the first stage involves loading/mounting the first part 40a of the two-part blade 40 onto the pins 21, 31 of the rotatable part 20 and the base 30. This stage may correspond to e.g. the third stage of the method of assembly mentioned above and described in relation to Fig. 17.

As illustrated in Figs. 22 and 23, the second stage involves placing the second part 40b of the two-part blade 40 adjacent (e.g. in contact with) the first part 40a, and fixing the second part 40b to the first part 40a. The second part 40b may be positioned and held adjacent to the first part 40a by a frame or a clamp for accurate positioning. The second part 40b may be held against one or more endstop surfaces (e.g. provided by a jig) for accurate positioning. The fixing may be carried out by any suitable means, e.g. welding, gluing, or soldering at one or more locations W. The fixing may involve attaching an additional part 40d to the first and second parts 40a, 40b by any suitable means, e.g. welding, gluing, or soldering. Having the second part 40b loaded/mounted onto the first part 40a after the first part 40a has been loaded onto the pins 21, 31 may help ensure that the VA defined by the blades 40 has good circularity and concentricity irrespective of the (in)accuracy of the positioning of the first part 40a.

If any sacrificial bodies and/or central supports connected to the first part 40a are present, the next stage could involve detaching and removing the sacrificial bodies and/or central supports connected to the first part 40a of the two-part blades 40. This stage may correspond to e.g. the fourth stage of the method of assembly mentioned above and described in relation to Fig. 18. Additionally or alternatively, this stage may involve releasing/disengaging/detaching the second part 40b from the frame or clamp or endstop surfaces mentioned above.

Flexing blades for circularity and concentricity

Figs. 24 to 28 show different stages of an alternative method of forming a blade 40. One or more blades 40 of the VA assembly 1 (e.g. each blade 40 of the VA assembly 1) may be formed in this manner. This method of forming blades may also help achieve good circularity and concentricity of the VA defined by the blades 40.

This method involves providing a blade 40 comprising: a first part 40a, a second part 40b, and a connection point 40c (mechanically) connecting the first and second parts 40a, 40b. The first and second parts 40a, 40b and the connection point 40c may be integrally formed as shown, but it will be appreciated that this may not be the case. The connection point 40c may be the only part of the blade 40 connecting the first and second parts 40a, 40b together, but it will be appreciated that this may not be the case. The first part 40a comprises the openings for the pins 21, 31, and the second part 40b comprises the part of the blade 40 configured to define (at least part of) the VA. The connection point 40c is configured to allow the second part 40b to move relative to the first part 40a (e.g. move the second part 40b towards the first part 40a) when the first and second parts 40a, 40b are not fixed relative to each other. The connection point 40c is configured to allow the second part 40b to move relative to the first part 40a by pivoting about the connection point 40c.

As illustrated in Fig. 24, the first stage involves loading/mounting the first part 40a onto the pins 21, 31 of the rotatable part 20 and the base 30. This stage may correspond to e.g. the third stage of the method of assembly mentioned above and described in relation to Fig. 17. As illustrated in Fig. 25, the second stage involves driving rotation of the rotatable part 20 about the primary axis 0 relative to the base 30 to drive the blade 40 (or blades 40 if more than one have been mounted onto the pins 21, 31) into engagement with an endstop 100, which e.g. may form part of an external jig. The endstop 100 is circular in cross-section and is shaped to accurately define a target VA size. The central axis (e.g. longitudinal axis) of the endstop 100 is configured to coincide with the primary axis O of the VA assembly 1 throughout the entire process of forming the blades 40. The relative rotation of the rotatable part 20 about the primary axis O may be driven by the actuator assembly 10 (if already operably assembled to the base 30 and the rotatable part 20) or driven by an external actuator assembly or driven manually.

As illustrated in Fig. 26, the third stage involves driving further rotation of the rotatable part 20 about the primary axis O relative to the base 30 to drive the blade 40 further against the endstop 100 such that the second part 40b is moved towards the first part 40a by pivoting about the connection point 40c. It will be appreciated that in the illustrated example this requires the blade 40 to deform. This deformation may be elastic or plastic. The rotatable part 20 may be driven against another endstop, which e.g. may form part of an external jig or the base 30.

As illustrated in Fig. 27, the fourth stage involves fixing the second part 40b to the first part 40a. The fixing may be carried out by any suitable means, e.g. welding, gluing, or soldering at one or more locations W. The fixing may involve attaching an additional part 40d to the first and second parts 40a, 40b by any suitable means, e.g. welding, gluing, or soldering.

As illustrated in Fig. 28, the next stage involves disengaging the blade(s) 40 from the endstop 100. Additionally, if any sacrificial bodies and/or central supports connected to the first part 40a are present, this stage may also involve detaching and removing the sacrificial bodies and/or central supports connected to the first part 40a. This stage may correspond to e.g. the fourth stage of the method of assembly mentioned above and described in relation to Fig. 18.

Large non-circular pins

As illustrated in Fig. 29, the pins 21, 31 may be quite large in size relative to the overall size of the blades 40. This may help with manufacturability and fragility of the pins 21, 31. As illustrated in Fig. 29, the pins 21, 31 may also be non-circular in cross-section - e.g. non-circular as viewed along the primary axis O. Sensitivity optimisation

As illustrated in Fig. 30, the moving pins 21 and the pivot pins 31 may be configured such that the mechanical advantage provided by these pins 21, 31 is at a minimum (e.g. 1) when the VA defined by the blades 40 is smallest, and the mechanical advantage provided by these pins 21, 31 is at a maximum (e.g. 10) when the VA defined by the blades 40 is largest. As illustrated in Fig. 30, the moving pin 21 and the pivot pin 31 may be configured such that when the VA is smallest, the moving pin 21 and the pivot 31 are aligned with the optical axis O such that the mechanical advantage provided is at a minimum of 1.

When the mechanical advantage is low, control la bi I ity/sensitivity of the rotation of the blades 40 by the actuator assembly 10 may be high. When the mechanical advantage is high, controllability/sensitivity of the rotation of the blades 40 by the actuator assembly 10 may be low. It may be desirable to have high controllability when the VA is small.

Other

The primary axis O may be the longitudinal axis of the variable aperture assembly 1. The primary axis O may be the longitudinal axis of the actuator assembly 10.

A bearing arrangement (e.g. a sliding/plain bearing, ball bearing, or a roller bearing) may be provided between the base 30 and the rotatable part 20. This bearing arrangement may guide, allow and/or facilitate the rotational movement of the rotatable part 20 relative to the base 30.

The connecting arms 22 may be integrally formed with the base 30 or the rotatable part 20. For example, the moving protrusions 21, the connecting arms 22, and the base 30 or the rotatable part 20 may be formed as a single part by injection moulding or sheet material fabrication. The moving protrusions 21, the connecting arms 22, and the rotatable part 20 or the base 30 may be etched portions of a single sheet of material (e.g. sheet metal).

The plurality of blades 40 may, for example, comprise five or six blades 40.

Other variations

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

It will be appreciated that the moving pins 21 and the pivot pins 31 may be replaced with any suitable protrusions, such as protrusions that protrude from a sheet of material (e.g. sheet metal) especially wherein the base 30 or the rotatable part 20 comprises, or is formed of, said sheet of material. The protrusions may be etched portions of the sheet of material that are bent upwards or downwards from the sheet of material. The protrusions may protrude from the base 30 or the rotatable part 20 in directions parallel to the primary axis O.

Wherein the base 30 or the rotatable part 20 comprises or is formed of a sheet of material, such as sheet metal, at least some of the electrical connections required for the operation of the actuator assembly 10 may be laid (e.g. printed or attached) onto a (coated or non-coated) surface (e.g. the top surface) of the sheet of material in the form of electrical tracks.

In the illustrated embodiments, the VA assembly 1 is only described as being for use with a lens assembly and/or a camera assembly. However, it will be appreciated that the VA assembly 1 may instead be used for other applications and with other devices. For example, the VA assembly 1 may be used to control the flow of liquids or gases in a flow control device.

It will be appreciated that the moving pins 21 and/or the connecting arms 22 may be e.g. insert molded into the rotatable part 20 or the base 30.

It will be appreciated that any electrical connections required for the actuator assembly 10 may be e.g. insert molded into the rotatable part 20 and/or the base 30. It will also be appreciated that any electrical connections required for the actuator assembly 10 may be e.g. laid (e.g. printed or attached) onto a (coated or non-coated) surface (e.g. the top surface) of the rotatable part 20 and/or the base 30.

Clauses

Also disclosed herein is what is described in the following clauses:

Clause 1. A variable aperture assembly comprising: a base; a rotatable part; an actuator assembly configured to drive rotation of the rotatable part relative to the base about a primary axis to any rotational position within a range of movement; a plurality of blades connected to the base via either a plurality of pivot pins or a plurality of moving pins, and connected to the rotatable part via the other of the plurality of pivot pins and the plurality of moving pins, and arranged to define a variable aperture with a central axis which coincides with the primary axis; wherein said rotation of the rotatable part drives relative movement between the pivot pins and the moving pins, which drives rotation of the plurality of blades about the pivot pins; wherein said rotation of the plurality of blades changes the size of the variable aperture. 1

Clause 2. A variable aperture assembly according to clause 1, wherein the moving pins are configured to rotate around the pivot pins.

Clause 3. A variable aperture assembly according to clause 1 or 2, wherein the moving pins are connected to the base or the rotatable part via connecting arms, wherein the connecting arms are configured to allow rotation of the moving pins around the pivot pins.

Clause 4. A variable aperture assembly according to clause 3, wherein the connecting arms comprise crank arms and/or flexure arms.

Clause 5. A variable aperture assembly according to clause 3 or 4, wherein the connecting arms are configured to bias the moving pins at least partially towards the pivot pins.

Clause 6. A variable aperture assembly according to clause 5, comprising at least one biasing element configured to help bias the moving pins at least partially towards the pivot pins.

Clause 7. A variable aperture assembly according to any of clauses 3 to 6, wherein the connecting arms are configured to bias the moving pins such that the plurality of blades are bistable.

Clause 8. A variable aperture assembly according to any of clauses 3 to 7, wherein each of the connecting arms extend in the same sense around the primary axis.

Clause 9. A variable aperture assembly according to any of clauses 3 to 7, wherein half of the connecting arms extend in a first sense around the primary axis, and the other half of the connecting arms extend in a second sense around the primary axis, wherein the second sense is opposite to the first sense.

Clause 10. A variable aperture assembly according to any of clauses 3 to 9, wherein the moving pins and the connecting arms are integrally formed with the base or the rotatable part.

Clause 11. A variable aperture assembly according to any preceding clause, wherein the moving pins are connected to the blades in a manner that prevents relative translational movement between each connected moving pin and blade. Clause 12. A variable aperture assembly according to any preceding clause, wherein the moving pins and the pivot pins are configured to provide, per degree of rotation of the rotatable part about the primary axis, at least 5, 10, or 20 degrees of rotation of the blades about the pivot pins.

Clause 13. A variable aperture assembly according to any preceding clause, wherein each blade is connected with the base and the rotatable part via one pivot pin and one moving pin.

Clause 14. A variable aperture assembly according to any preceding clause, wherein the base is provided within a hole that extends through the rotatable part along the primary axis, or the rotatable part is provided within a hole that extends through the base along the primary axis.

Clause 15. A variable aperture assembly according to any preceding clause, wherein the plurality of blades overlap with the connecting arms and/or the rotatable part as viewed along the primary axis.

Clause 16. A variable aperture assembly according to any preceding clause, wherein the plurality of blades overlap with each other as viewed along the primary axis.

Clause 17. A variable aperture assembly according to any preceding clause, wherein the plurality of blades generally lie in a plane perpendicular to the primary axis which sits on top of the rotatable part and the base.

Clause 18. A variable aperture assembly according to any preceding clause, wherein a bearing is provided between the base and the rotatable part.

Clause 19. A variable aperture assembly according to any preceding clause, comprising a holding arrangement configured to releasably hold the rotatable part at one or more positions within the range of positions that the rotatable part is capable of being driven to relative to the base by the actuator assembly.

Clause 20. A variable aperture assembly according to any preceding clause, comprising at least one biasing element configured to bias the rotatable part in a direction parallel to the primary axis so as to generate frictional forces that constrain the movement of the rotatable part relative to the base at any position within the range of movement when the actuator assembly is not actuated.

Clause 21. A variable aperture assembly according to clause 20, wherein the actuator assembly is configured such that the frictional forces remain substantially constant on actuation. Clause 22. A variable aperture assembly according to clause 20, wherein the actuator assembly is configured to be capable of reducing the frictional forces on actuation.

Clause 23. A variable aperture assembly according to any preceding clause, wherein the plurality of blades comprises six or eight blades.

Clause 24. A variable aperture assembly according to clause 23, wherein the plurality of blades are stacked in layers of two blades on top of each other, and wherein the layers overlap when viewed along the primary axis.

Clause 25. A variable aperture assembly according to any preceding clause, wherein the actuator assembly comprises one or more shape memory alloy (SMA) elements configured to, upon contraction, drive the rotation of the rotatable part relative to the base.

Clause 26. A variable aperture assembly according to clause 25, wherein the actuator assembly comprises: a support structure fixed to the base; and a movable part coupled to the rotatable part; wherein the one or more SMA elements are configured to, upon contraction, drive relative movement between the movable part and the support structure so as to drive the rotation of the rotatable part.

Clause 27. A variable aperture assembly according to clause 26, wherein the movable part is fixed to the rotatable part; and the one or more SMA elements are configured to, upon contraction, drive rotation of the movable part relative to the support structure so as to drive the rotation of the rotatable part.

Clause 28. A variable aperture assembly according to clause 26 or 27, comprising a holding arrangement configured to releasably hold the movable part at one or more positions within the range of positions that the movable part is capable of being driven to relative to the support structure.

Clause 29. A variable aperture assembly according to any of clauses 25 to 28, wherein the one or more SMA elements comprise four SMA elements configured to drive the rotation of the rotatable part; wherein, optionally, the four SMA elements are arranged in a loop at different angular positions around the primary axis; and, optionally, wherein successive SMA elements around the primary axis are configured to apply a force to the rotatable part in alternate senses around the primary axis. Clause 30. A variable aperture according to any of clauses 25 to 29, wherein the one or more SMA elements comprise: a first SMA element arranged to rotate the rotatable part about the primary axis in a first sense; and a second SMA element arranged to rotate the rotatable part about the primary axis in a second sense, wherein the second sense is opposite to the first sense.

Clause 31. A variable aperture according to any of clauses 25 to 30, wherein the one or more SMA elements comprise: a first pair of SMA elements, electrically connected together, arranged to apply a torque to the rotatable part for rotating the rotatable part about the primary axis in a first sense; and a second pair of SMA elements, electrically connected together, arranged to apply a torque to the rotatable part for rotating the rotatable part about the primary axis in a second sense, wherein the second sense is opposite to the first sense.

Clause 32. A variable aperture assembly according to any preceding clause, wherein the actuator assembly is configured to be controlled by a drive chip via two drive channels of the drive chip.

Clause 33. A camera assembly comprising: a variable aperture assembly according to any preceding clause; a further actuator assembly; a drive chip operatively connected to the actuator assembly and the further actuator assembly for controlling the actuator assembly and the further actuator assembly; wherein the drive chip comprises at least four drive channels; and wherein the actuator assembly is configured to be controlled via a first channel and a second channel of the at least four drive channels, and the further actuator assembly is configured to be controlled via a third channel and a fourth channel of at least four drive channels.

Clause 34. A camera assembly according to clause 33, wherein the further actuator assembly is a focus actuator assembly.

Clause 35. A camera assembly comprising: a variable aperture assembly according to any preceding clause; and a lens assembly; wherein the variable aperture assembly is mounted on the lens assembly, and the optical axis of the lens assembly coincides with the primary axis.

Clause 36. A camera assembly according to clause 35, wherein the lens assembly is provided within a hole that extends through the base along the primary axis.

Clause 37. A camera assembly according to clause 35 or 36, wherein more than 50%, 60%, 70%, 80%, or 90% of the variable aperture assembly overlaps with the lens assembly along the primary axis.

Clause 38. A camera assembly according to any of clauses 35 to 37, wherein the actuator assembly fully overlaps with the lens assembly along the primary axis.