WO2023187425A1

WO2023187425A1 - Actuator assembly

Info

Publication number: WO2023187425A1
Application number: PCT/GB2023/050879
Authority: WO
Inventors: Robin Eddington; Andreas FLOURIS; Konstantinos PANTELIDIS
Original assignee: Cambridge Mechatronics Limited
Priority date: 2022-03-31
Filing date: 2023-03-31
Publication date: 2023-10-05
Also published as: GB202204749D0

Abstract

An actuator assembly comprising: a support structure; a movable part that is movable relative to the support structure; an endstop component fixed relative to the movable part; wherein the endstop component comprises endstop surfaces configured to engage corresponding endstop surfaces of the support structure so as to limit axial translation of the movable part relative to the support structure in one or more directions perpendicular to the primary axis of the support structure; wherein the endstop surfaces extend from the main body of the endstop component and/or the corresponding endstop surfaces extend from a main body of the support structure in a direction at least partly along an axis parallel to the primary axis so that the endstop surfaces and the corresponding endstop surfaces overlap with each other along the primary axis; wherein the main body of the endstop component is disposed on a first side of the movable part and the main body of the support structure is disposed on a second opposite side of the movable part.

Description

ACTUATOR ASSEMBLY

Field

The present invention relates to optical image stabilisation (OIS) actuator assemblies (e.g. lens-shift actuator assemblies, or sensor-shift actuator assemblies) with endstops.

Background

SMA actuator assemblies may be used in a variety of applications for effecting movement of a movable part relative to a support structure, for example to effect optical image stabilization (OIS) in a camera apparatus.

For example, WO 2013/175197 Al describes a camera apparatus in which SMA actuator wires are arranged to move a lens element relative to an image sensor in a plane that is perpendicular to the optical axis of the lens element, thereby effecting OIS. WO2017072525 Al discloses an SMA actuation apparatus in which SMA actuator wires are used to provide OIS in a camera by driving planar movement of the image sensor.

Endstops may be provided in a camera apparatus to prevent damage to SMA wires or other sensitive elements of the actuator assembly due to abnormal loads (such as impact events/drops). In conventional OIS camera apparatuses, such endstops are provided between a lens module and camera can or between an image sensor assembly and camera can. So, the endstops are provided only when the camera apparatus is assembled in its entirety, including costly components such as lenses, AF modules and image sensors. Testing for stroke or manufacturing misalignment can thus only be performed in the final product. This may lead to a yield loss in manufacturing of the camera apparatus.

Summary

According to an aspect of the present invention, there is provided an actuator assembly comprising: a support structure; a movable part that is movable relative to the support structure; and an endstop component fixed relative to the movable part. The endstop component comprises endstop surfaces configured to engage/abut corresponding endstop surfaces of the support structure so as to limit axial translation of the movable part relative to the support structure in one or more directions perpendicular to the primary axis of the support structure. The endstop surfaces extend/protrude from the main body of the endstop component and/or the corresponding endstop surfaces extend/protrude from a main body of the support structure in a direction at least partly along an axis parallel to the primary axis (or generally in a direction parallel to the primary axis) so that the endstop surfaces and the corresponding endstop surfaces overlap with each other along the primary axis. The main body of the endstop component is disposed on a first side (e.g. upper side) of (the main body of) the movable part and the main body of the support structure is disposed on a second opposite side (e.g. lower side) of (the main body of) the movable part (along the primary axis).

Optionally, the main body of the support structure is a base plate of the support structure.

Optionally, the actuator assembly comprises a housing (e.g. a (screening) can) for covering the support structure, the movable part and the endstop component.

Optionally, the actuator assembly comprises an actuator arrangement configured to move the movable part relative to the support structure across a range of movement in two orthogonal directions perpendicular to the primary axis.

Optionally, the actuator arrangement comprises one or more SMA wires (e.g. four SMA wires) arranged, on contraction, to move the movable part relative to the support structure. In other words, optionally, the actuator assembly comprises one or more SMA wires arranged, on contraction, to move the movable part relative to the support structure across a range of movement in two orthogonal directions perpendicular to the primary axis.

Optionally, the endstop surfaces extend (downwards) towards the main body of the support structure. Optionally, (the main body of) the endstop component comprises outwardly extending portions that extend away from the primary axis and that extend beyond the periphery (or footprint) of the movable part as viewed along the primary axis.

Optionally, the endstop surfaces extend/protrude from ends of the outwardly extending portions (of the main body) of the endstop component that are located outside the periphery (or footprint) of the movable part as viewed along the primary axis.

Optionally, the outwardly extending portions (of the main body) of the endstop component bend over portions of the movable part so as to avoid interfering with the one or more SMA wires.

Optionally, the endstop component comprises one or more bent sheets of metal.

Optionally, the endstop surfaces face toward the primary axis. Where this is the case, the corresponding endstop surfaces may face away from the primary axis. Optionally, the corresponding endstop surfaces extend (upwards) towards the main body of the movable part.

Optionally, the corresponding endstop surfaces extend/protrude from portions (of the main body) of the support structure that are located outside the periphery (or footprint) of the movable part as viewed along the primary axis.

Optionally, the corresponding endstop surfaces face toward the primary axis. Where this is the case, the endstop surfaces face away from the primary axis.

According to an aspect of the present invention, there is provided an actuator assembly comprising: a support structure, and a movable part that is movable relative to the support structure. The movable part comprises endstop surfaces configured to engage/abut corresponding endstop surfaces of the support structure so as to limit axial translation of the movable part relative to the support structure in one or more directions perpendicular to a primary axis of the support structure. The endstop surfaces extend/protrude from the main body of the movable part in a direction at least partly along an axis parallel to the primary axis so as to overlap with the corresponding endstop surfaces of the support structure along the primary axis.

Optionally, the actuator assembly comprises a housing (e.g. a (screening) can) for covering the support structure, and the movable part.

Optionally, the endstop component comprises one or more bent sheets of metal.

Optionally, the endstop surfaces face toward the primary axis. Optionally, the corresponding endstop surfaces face away from the primary axis.

Optionally, the actuator assemblies described herein comprise a lens assembly and/or an image sensor (wherein the actuator assembly is for providing optical image stabilisation).

Optionally, the movable part comprises the lens assembly.

Optionally, the primary axis is parallel to the optical axis of the lens assembly.

Optionally, the support structure comprises the image sensor.

Optionally, the movable part comprises the image sensor.

Optionally, the primary axis is perpendicular to the light sensitive surface/region of the image sensor.

Optionally, the movable part of the actuator assemblies described herein, comprise a display, an emitter, or a part thereof.

Optionally, the primary axis is parallel to the general direction in which radiation (e.g. light) is emitted (or projected) by the display or emitter. According to an aspect of the present invention, there is provided an apparatus comprising: an actuator assembly as described herein; and a further actuator assembly. The further actuator assembly is fixedly attached to the movable part so as to move with the movable part.

Optionally, the further actuator assembly comprises: a fixed part; a further movable part movable relative to the fixed part along an axis parallel to the primary axis; and a further actuator arrangement configured to move the further movable part along the primary axis.

Optionally, the actuator assembly comprises an image sensor; the further actuator assembly comprises a lens assembly configured to focus light on the image sensor; the further movable part comprises one or more lenses of the lens assembly. This configuration allows the one or more lenses to be moved along the primary axis relative to the image sensor for autofocussing.

Optionally, the endstop component is provided between the actuator assembly and the further actuator assembly.

According to the present invention, there is also provided an actuator assembly comprising: a support structure; a movable part that is movable relative to the support structure, the movable part comprising a region for fixedly connecting an image sensor assembly or a lens assembly; an actuator arrangement configured, on actuation, to drive movement of the movable part relative to the support structure; wherein the movable part comprises endstop surfaces configured to engage corresponding endstop surfaces of the support structure so as to limit axial translation of the movable part relative to the support structure in one or more directions perpendicular to a primary axis of the support structure.

In some embodiment, the actuator assembly further comprises an image sensor assembly or a lens assembly fixedly connected to the region of the movable part, wherein the endstop surfaces of the movable part are provided separately from the image sensor assembly or lens assembly.

In some embodiment, the support structure comprises a portion configured to fixedly connect to a housing configured to enclose the actuator arrangement and movable part. In some embodiment, the actuator assembly further comprises a housing fixed to the portion of the support structure, wherein the housing encloses the actuator arrangement and movable part, and wherein the endstop surfaces of the support structure are provided separately from the housing.

In some embodiment, the actuator arrangement is configured to drive movement of the movable part relative to the support structure in two orthogonal directions perpendicular to the primary axis.

In some embodiment, the endstop surfaces of the movable part extend from a main body of the movable part in a direction parallel to the primary axis and/or wherein the endstop surfaces of the support structure extend from a main body of the support structure in a direction parallel to the primary axis, such that the endstop surfaces of the movable part and of the support structure overlap with each other when viewed perpendicularly to 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:

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 of Figure 1;

Figure 3 is a perspective view of a moving plate of a carrier of the actuator assembly of Figure 1;

Figure 4 is a plan view of the actuator assembly of Figure 1;

Figure 5 is a plan view of the actuator assembly of Figure 1 with an endstop component;

Figure 6 is a plan view of an actuator assembly comprising an endstop component;

Figure 7 is a plan view of an actuator assembly comprising an endstop component;

Figure 8 is a plan view of the actuator assembly of Figure 7 with the endstop component illustrated as see-through;

Figure 9 is a perspective view of the actuator assembly of Figure 7 with the endstop component illustrated as see-through;

Figure 10 is a side view of an actuator assembly; and

Figure 11 is a side view of the actuator assembly of Figure 10 with a lens carriage and a can.

Detailed Description A camera apparatus 1 that incorporates an actuator assembly 2 is shown in Fig. 1, which is a cross- sectional view taken along the optical axis O. In the depicted embodiment, the actuator assembly 2 is a sensor shift assembly. The camera apparatus 1 is to be incorporated in a portable electronic device such as a mobile telephone, or tablet computer.

The actuator assembly 2 is shown in detail in Figs. 2 to 4, Fig. 2 being a side view of the actuator assembly 2, Fig. 3 being a perspective view of a moving plate 9 of a carrier 8 of the actuator assembly 2; and Fig. 4 being a plan view of the actuator assembly 2. For clarity, Figs. 2 and 4 omit the flexures 67 described below. The actuator assembly 2 may be manufactured first and then assembled with the other components of the camera apparatus 1.

The actuator assembly 2 comprises a support structure 4. On the support structure 4 is supported an image sensor assembly 12 (herein also referred to as a movable part 12). In particular, the image sensor assembly 12 is supported in a manner allowing movement of the 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 printed circuit board (PCB) on which the image sensor 6 is mounted. When incorporated into the camera apparatus 1, the light-sensitive region 7 is 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 image sensor assembly 12 comprises a carrier 8 that comprises a moving plate 9. The image sensor 6 may be mounted on the carrier 8, in particular on the moving plate 9. The moving plate 9 may be formed from sheet material, which may be a metal for example steel such as stainless steel. The moving plate 9 is shown in isolation in Fig. 3 and includes flexures 67 that are described in more detail below.

Although the carrier 8 comprises a single moving plate 9 in this example, optionally the carrier 8 may comprise other layers which may be attached to or laminated with the moving plate 9.

The support structure 4 comprises a support plate 5 (herein also referred to as a base plate 5) which may be formed from sheet material, which may be a metal for example steel such as stainless steel. Although the support structure 4 comprises a single support plate 5 in this example, optionally the support structure 4 may comprise other layers which may be attached to or laminated with the support plate 5.

The support structure 4 further comprises a rim portion 10 fixed to the front side of the support plate 5 and extending around the support plate 5. The rim portion 10 has 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. A control circuit described further below 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 suppressing 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). The image sensor assembly 12 may be supported in a manner suppressing tilt or rotation of the image sensor assembly 12 about any axis parallel to the light-sensitive region 7.

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

As shown in Fig. 2, the bearing arrangement may comprise a rolling bearing 110. The rolling bearing 110 may, for example, be a ball bearing, a roller bearing or a rocker bearing. The rolling bearing 110 comprising a rolling element, for example a ball, a roller or a rocking element. The rolling element may be spherical or may in general be any rotary element with curved surfaces that bear against the image sensor assembly 12 and the support structure 4 and are able to roll back and forth and around in operation. The rolling element is disposed between the image sensor assembly 12 and the support structure 4. The image sensor assembly 12 is thus supported on the support structure 4 by the rolling element. The rolling bearing 110 may comprise plural rolling elements, for example three rolling elements.

In addition, the actuator assembly 2 may comprise a biasing arrangement. The biasing arrangement may provide a biasing force that biases the image sensor assembly 12 towards the bearing arrangement 110. An example of a biasing arrangement is schematically depicted in Fig. 3. Fig. 3 shows two flexures 67 connected between the support structure 4 and the carrier 8/moving plate 9 to act as a biasing arrangement, as well as providing an electrical connection to the image sensor assembly 12. In this example, the flexures 67 are formed integrally with the moving plate 9 at one end 68 thereof and are mounted to the support plate 5 of the support structure 4 at the other end 69 thereof. Alternatively, the flexures 67 could be formed integrally with a plate of the support structure 4 and mounted to the carrier 8, or else could be separate elements mounted to each of the support structure 4 and the carrier 8. In any of these examples, the mounting of the flexures 67 may be achieved e.g. by soldering which provides both mechanical and electrical connection.

The flexures 67 are arranged as follows to provide their mechanical function. Each flexure 67 is an elongate beam connected between the support structure 4 and carrier 8. The flexures 67, due to their intrinsic resilience, bias the support structure 4 and the image sensor assembly 12 together, the biasing force being applied parallel to the optical axis O. This may maintain the bearing arrangement 110, for example the bearing arrangement of Fig. 2. At the same time, the flexures 67 may be laterally deflected to permit lateral movement and rotation of the image sensor assembly 12 relative to the support structure 4 to permit the OIS function.

The flexures 67, again due to their intrinsic resilience, also provide a lateral biasing force that biases the image sensor assembly 12 towards a central position aligned with the optical axis O of the lens assembly 20 from any direction around that central position. As a result, in the absence of driving of the SMA wires 40, the image sensor assembly 12 will tend towards the central position. This ensures that the camera apparatus 1 remains functional to capture images, even in the absence of driving of the SMA wires 40.

The flexures 67 are designed as follows to provide a suitable retaining force along the optical axis O for the bearing arrangement 110, and also to permit lateral movement with a lateral biasing force. The magnitude of the lateral biasing force is kept low enough as not to hinder OIS, whilst being high enough to center the image sensor assembly 12 in the absence of driving. Each flexure 67 has a cross-section with an average width orthogonal to the optical axis O is that is greater than its average thickness parallel to the optical axis O. Each flexure 67 extends in an L-shape around the optical axis O, it in general being desirable that the angular extent is at least 90° as measured between the ends of the flexure 67.

In the assembled state of the actuator assembly 2, the flexures 67 are deflected from their relaxed state to provide a pre-loading force that biases the support structure 4 and the image sensor assembly 12 together.

The flexures 67 are made of a suitable material that provides the desired mechanical properties and is electrically conductive. Typically, the material is a metal having a relatively high yield, for example steel such as stainless steel.

Movement of the image sensor assembly 12 relative to the support structure 4 is driven by a lateral actuator arrangement that is arranged as follows, and seen most easily in Fig. 4. Particular advantage is achieved in the case that the actuator arrangement comprises plural SMA wires 40, as SMA provides a high actuation force compared to other forms of actuator. This may assist in accurate positioning of the image sensor assembly 12 relative to the support structure 4. In general, however, the actuator arrangement may comprise plural actuator components other than SMA wires 40.

The lateral actuator arrangement shown in Fig. 4 is formed by a total of four SMA wires 40 connected between the support structure 4 and the carrier 8. For attaching the SMA wires 40, the carrier 8 comprises crimp portions 41 fixed to the moving plate 9 and the support structure 4 comprises crimp portions 42 fixed to the rim portion 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 carrier 8. The crimp portions 41 fixed to the moving plate 9 are formed integrally from a sheet of metal so as to electrically connect the SMA wires 40 together at the carrier 8.

Although in this example the crimp portions 41 and 42 are separate elements fixed to the moving plate 9 and the rim portion 10, as an alternative the crimp portions 41 could be formed integrally with the moving plate 9 and/or the crimp portions 42 could be formed integrally with the support plate 5.

The SMA wires 40 are arranged 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 light-sensitive region 7 and also of rotating the image sensor assembly 12 about an axis orthogonal to the lightsensitive region 7. Each of the SMA wires 40 is held in tension, thereby applying a force between the support structure 4 and the carrier 8.

The SMA wires 40 may be perpendicular to the optical axis O so that the force applied to the carrier 8 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 carrier 8 includes a component lateral to the light-sensitive region 7 and a component along the optical axis O that acts as a biasing force that biases the image sensor assembly 12 against the bearing arrangement 110. So, the SMA wires 40 may act as the biasing arrangement. The biasing arrangement may comprise plural actuator components that are inclined relative to the light-sensitive region 7 for applying a biasing force that biases image sensor assembly 12 towards the bearing arrangement 110.

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

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

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

On heating of one of the SMA wires 40, the stress therein increases and it contracts, causing movement of the image sensor assembly 12. A range of movement occurs as the temperature of the SMA increases over the range of temperature in which there occurs the transition of the SMA material from the Martensite phase to the Austenite phase. Conversely, on cooling of one of the SMA wires 40 so that the stress therein decreases, it expands under the force from opposing ones of the SMA wires 40. This causes the image sensor assembly 12 to move in the opposite direction. The carrier 8 and the image sensor assembly 12 are positioned axially within the aperture 11 of the rim portion 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 are of the same length and 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. 4) that is lateral to the light-sensitive region 7. However, the first pair of the SMA wires 40 are oppositely connected to the support structure 4 and the carrier 8 so that they apply forces in opposite directions along the first axis (vertically up and down in Fig. 4) . 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 (anti-clockwise in Fig. 4).

As viewed axially, a second pair of SMA wires 40 extend parallel to a second axis (horizontal in Fig. 4) 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 carrier 8 so that they apply forces in opposite directions along the second axis (horizontally left and right in Fig. 4). 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 and to rotate the image sensor assembly 612 about an axis parallel to the optical axis O. That is:

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

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

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

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

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

The camera apparatus 1 comprises a lens assembly 20 that is assembled with the actuator assembly 2 by being mounted to the support structure 4, in particular to the rim portion 10.

The lens assembly 20 comprises a lens carriage 21 in the form of a cylindrical body that is mounted to the rim portion 10 of the support structure 4. The lens carriage supports at least one lens 22 arranged along the optical axis O. In general any number of one or more lenses 22 may be provided. Without limitation to the invention, in this example the camera apparatus 1 is a miniature camera in which the at least one lens 22 (i.e. each lens 22 if plural lenses are provided) typically have a diameter of at most 10mm or 15mm or 20mm. The at least one lens 22 of the lens assembly 20 is arranged to focus an image onto the image sensor.

In this example, at least one lens 22 is supported on the lens carriage 21 in a manner in which at least one lens 22 is movable along the optical axis O relative to the lens carriage 21, for example to provide focusing or zoom, although that is not essential. In particular, the at least one lens is fixed to a lens holder 23 which is movable along the optical axis O relative to the lens carriage 21. Where there are plural lenses 22, any or all of the lenses 22 may be fixed to the lens holder 23 and/or one or more of the lenses 22 may be fixed to the lens carriage 21 and so not movable along the optical axis O relative to the lens carriage 21. An axial actuator arrangement 24 provided between the lens carriage 21 and the lens holder 23 is arranged to drive movement of the lens holder 21 and lenses 22 along the optical axis O relative to the lens carriage 21. The axial actuator arrangement 24 may be any suitable type, for example being a voice coil motor (VCM) or an arrangement of SMA wires, such as is described in WO-2019/243849 which is incorporated herein by reference.

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

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

Relative movement of the image sensor relative to the support structure 4 and hence also relative to the lens assembly 20 may be used to stabilise the image against tilting of the camera apparatus 1, i.e. rotation about axes extending laterally to the light-sensitive region 7. This occurs in a similar manner to a camera apparatus providing OlS-lens shift of the type disclosed in WO 2013/175197 and WO 2014/083318 which also involves relative lateral movement of the image sensor and lens assembly 20. In addition, rotation of the image sensor may be used to stabilise the image against rotation of the camera apparatus 1 around the optical axis O. This type of stabilisation is not achieved by a camera apparatus providing OlS-lens shift of the type disclosed in WO 2013/175197 and WO 2014/083318. The SMA wires 40 are driven by the control circuit implemented in the IC chip 30. In particular, the control circuit generates drive signals for each of the SMA wires 40 and supplies the drive signals to the SMA wires 40.

The control circuit 30 receives the output signals of the gyroscope sensor 31 which acts as a vibration sensor. The gyroscope sensor 31 detects the vibrations that the camera apparatus 1 is experiencing and its output signals represent those vibrations, specifically as the angular velocity of the camera lens element 20 in three dimensions. The gyroscope sensor 31 is typically a pair of miniature gyroscopes, for detecting vibration around three axes, being two axes laterally of the light-sensitive region 7 and also the optical axis O. More generally, larger numbers of gyroscopes or other types of vibration sensor could be used. The drive signals are generated by the control circuit in response to the output signals of the gyroscope sensor 31 so as to drive movement of the image sensor assembly 12 to stabilise an image focused by the camera lens element 20 on the image sensor, thereby providing OIS. The drive signals may be generated using a resistance feedback control technique for example as disclosed in any of WO-2013/175197, WO- 2014/076463, WO 2012/066285, WO-2012/020212, WO-2011/104518, WO-2012/038703, WO 2010/089529 or WO-2010/029316, each of which is incorporated herein by reference.

The camera apparatus 1 may be incorporated into a portable electronic device, such as such as a mobile telephone or tablet computer. There is thus provided a portable electronic device comprising the camera apparatus 1. The portable electronic device may comprise a processor. Super-resolution imaging may be provided in the camera apparatus 1 and/or the portable electronic device. Superresolution imaging is achieved, for example, by combining two or more images that are captured at positions offset from one another by a sub-pixel distance.

In Figures 1 to 6, the actuator assembly 2 is a sensor shift assembly. Alternatively, as shown in Figures 7 to 11, the actuator assembly 2 may be a lens shift assembly in which the image sensor 6 is mounted to the support structure 4 and the lens assembly is part of the movable part 12.

Endstops

Endstops may be provided in a camera apparatus to prevent damage to SMA wires or other sensitive elements of the actuator assembly due to abnormal loads (such as impact events/drops). In a conventional OIS sensor-shift camera apparatus, such endstops are provided between the image sensor assembly 12 and the cam 15. In conventional OIS lens-shift camera apparatus, such endstops may be provided between the lens assembly 23 and the camera can 15. So, the endstops are provided only when the camera apparatus is assembled in its entirety, including costly components such as lenses, AF modules and image sensors. Testing for stroke or manufacturing misalignment can thus only be performed in the final product. This may lead to a yield loss in manufacturing of the camera apparatus.

According to the present invention, endstops are provided as part of the OIS actuator assembly. So, endstops are provided in the absence of a camera can 15 and image sensor assembly 12 or lens assembly 23.

Figures 5 to 11 show embodiments of the present invention. Figures 5 and 6 schematically show a sensor-shift actuator assembly 2 comprising an additional endstop component 200 compared to conventional sensor-shift actuator assemblies. Figures 7 to 9 schematically show a lens-shift actuator assembly 2 comprising an additional endstop component 200 compared to conventional lens-shift actuator assemblies.

As shown, the endstop component 200 may be fixed relative to the movable part 12 of the actuator assembly 2. The endstop component 200 may be fixed relative to the movable part 12 in the absence of an image sensor assembly or a lens assembly, for example.

There is thus provided an actuator assembly 2 comprising: a support structure 4; a movable part 12 that is movable relative to the support structure 4; and an endstop component 200 fixed relative to the movable part 12. The movable part 12 and the endstop component 200 may be different components, i.e. they may be initially provided separately, before being fixed relative to one another.

As perhaps best shown in Figures 9, 10 and 11, the endstop component 200 comprises endstop surfaces

201 configured to engage/abut corresponding endstop surfaces 202 of the support structure 4 so as to limit axial translation of the movable part 12 relative to the support structure 4 in one or more directions perpendicular to the primary axis of the support structure P. The endstop surfaces 201,202 may, in some embodiment, be configured not to engage during normal operation of the actuator assembly, i.e. not due to contraction or actuation of the SMA wires or other actuator. The endstop surfaces 201, 202 may engage due to abnormal loads acting on the actuator assembly, for example impact events such as drops.

The endstop surfaces 201 extend/protrude from the main body of the endstop component 200 and/or the corresponding endstop surfaces 202 extend/protrude from a main body of the support structure 4 in a direction at least partly along an axis parallel to the primary axis P (or generally in a direction parallel to the primary axis P) so that the endstop surfaces 201 and the corresponding endstop surfaces

202 overlap with each other along the primary axis P. The endstop surfaces 201, 202 overlap when viewed orthogonally to the primary axis P.

The main body of the endstop component 200 is disposed on a first side (e.g. upper side) of (the main body of) the movable part 12, i.e. on a first side along the primary axis P. The main body of the support structure 4 is disposed on a second opposite side (e.g. lower side) of (the main body of) the movable part 12 (along the primary axis P), i.e. on a second side along the primary axis P. The movable part 12 may be provided between the main body of the support structure 4 and the main body of the endstop component 200. Optionally, the main body of the support structure 4 is a base plate 5 of the support structure 4. The main body of the endstop component may be a plate, i.e. may be formed as a sheet of material. The base plate 5 and/or the main body of the endstop component 200 may be arranged to be orthogonal to the primary axis P.

Optionally, the actuator assembly 2 comprises a housing 15 (e.g. (screening) can 15) for covering the support structure 4, the movable part 12 and the endstop component 200. The housing/can 15 may be a component separate to the endstop component 200 and support structure 4.

Optionally, the actuator assembly 2 comprises an actuator arrangement configured to move the movable part 12 relative to the support structure 4 across a range of movement in two orthogonal directions perpendicular to the primary axis P. The actuator arrangement may comprise one or more SMA wires 40, for example in the arrangement described in relation to Figure 4. So, the actuator arrangement 2 may comprise one or more SMA wires 40 (e.g. four SMA wires) arranged, on contraction, to move the movable part 12 relative to the support structure 4. In other words, optionally, the actuator assembly 2 comprises one or more SMA wires 40 arranged, on contraction, to move the movable part 12 relative to the support structure 4 across a range of movement in two orthogonal directions perpendicular to the primary axis P.

Optionally, as shown in Figures 5 to 9, the endstop surfaces 201 extend (downwards) towards the main body of the support structure 4. The endstop surfaces 201 may be parallel to the primary axis P.

Optionally, (the main body of) the endstop component 200 comprises outwardly extending portions 210 that extend away from the primary axis P and that extend beyond the periphery (or footprint) of the movable part 12 as viewed along the primary axis P.

Optionally, as shown in Figures 5 to 9, the endstop surfaces 201 extend/protrude from ends of the outwardly extending portions 210 (of the main body) of the endstop component that are located outside the periphery (or footprint) of the movable part 12 as viewed along the primary axis P.

Optionally, the outwardly extending portions 210 (of the main body) of the endstop component bend over portions of the movable part 12 so as to avoid interfering with the one or more SMA wires 40.

Optionally, the endstop component 200 comprises one or more bent sheets of metal. The endstop component 200 may comprise sheet metal. The main body of the endstop component 200 may Optionally, as shown in Figures 5 to 9, the endstop surfaces 201 face toward the primary axis P. Where this is the case, the corresponding endstop surfaces 202 may face away from the primary axis P.

Optionally, as shown in Figures 10 and 11, the corresponding endstop surfaces 201 extend (upwards) towards the main body of the movable part 12.

Optionally, as shown in Figures 10 and 11, the corresponding endstop surfaces 202 extend/protrude from portions (of the main body) of the support structure 4 that are located outside the periphery (or footprint) of the movable part 12 as viewed along the primary axis P.

Optionally, as shown in Figures 10 and 11, the corresponding endstop surfaces 202 face toward the primary axis P. Where this is the case, the endstop surfaces 201 may face away from the primary axis P.

An advantage of the configuration shown in Figures 10 and 11 is that when a can 15 is provided it can provide mechanical support to the portions of the support structure 4 / base plate 5 that comprise the endstop surfaces 202.

As shown in Figures 5 to 9, according to an aspect of the present invention, there is provided an actuator assembly 2 comprising: a support structure 4, and a movable part 12 that is movable relative to the support structure 4. The movable part 4 comprises endstop surfaces 201 configured to engage/abut corresponding endstop surfaces 202 of the support structure 4 so as to limit axial translation of the movable part 12 relative to the support structure 4 in one or more directions perpendicular to a primary axis P of the support structure 4. The endstop surfaces 201 extend/protrude from the main body of the movable part 12 in a direction at least partly along an axis parallel to the primary axis P so as to overlap with the corresponding endstop surfaces 202 of the support structure 4 along the primary axis P.

Optionally, the main body of the support structure 4 is a base plate 5 of the support structure 4.

Optionally, the actuator assembly 2 comprises a housing 15 (e.g. a (screening) can 15) for covering the support structure 4, and the movable part 12.

Optionally, the actuator assembly 2 comprises an actuator arrangement configured to move the movable part 12 relative to the support structure 4 across a range of movement in two orthogonal directions perpendicular to the primary axis P. Optionally, the actuator arrangement 2 comprises one or more SMA wires 40 (e.g. four SMA wires) arranged, on contraction, to move the movable part 12 relative to the support structure 4. In other words, optionally, the actuator assembly 2 comprises one or more SMA wires 40 arranged, on contraction, to move the movable part 12 relative to the support structure 4 across a range of movement in two orthogonal directions perpendicular to the primary axis P.

Optionally, as shown in Figures 5 to 9, the endstop surfaces 201 extend (downwards) towards the main body of the support structure 4.

Optionally, (the main body of) the endstop component 201 comprises outwardly extending portions 210 that extend away from the primary axis P and that extend beyond the periphery (or footprint) of the movable part 4 as viewed along the primary axis P.

Optionally, as shown in Figures 5 to 9, the endstop surfaces 201 extend/protrude from ends of the outwardly extending portions 210 (of the main body) of the endstop component 200 that are located outside the periphery (or footprint) of the movable part 12 as viewed along the primary axis P.

Optionally, the outwardly extending portions 210 (of the main body) of the endstop component 200 bend over portions of the movable part 12 so as to avoid interfering with the one or more SMA wires 40.

Optionally, the endstop component 200 comprises one or more bent sheets of metal.

Optionally, as shown in Figures 5 to 9, the endstop surfaces 201 face toward the primary axis P; and, optionally, the corresponding endstop surfaces 202 face away from the primary axis P.

Optionally, the actuator assemblies 2 described herein comprise a lens assembly (not shown) and/or an image sensor 6 (wherein the actuator assembly 2 is for providing OIS).

Optionally, the movable part 12 comprises the lens assembly. Where this is the case, the support structure may comprise the image sensor 6. Also, as shown in Figures 7 to 9, an aperture is provided on the movable part 12 to allow light passing through the lens assembly to reach the image sensor 6.

Optionally, the primary axis P is parallel to the optical axis O of the lens assembly.

Optionally, the support structure 4 comprises the image sensor 6. Optionally, as shown in Figure 5, the movable part 12 comprises the image sensor 6. Optionally, as shown in Figure 6, the image sensor 6 is mounted onto the endstop component 200.

Optionally, the primary axis P is perpendicular to the light sensitive surface/region 7 of the image sensor 6.

Optionally, the movable part 12 of the actuator assemblies 2 described herein, comprise a display, an emitter, or a part thereof.

Optionally, the primary axis P is parallel to the general direction in which radiation (e.g. light) is emitted (or projected) by the display or emitter.

According to an aspect of the present invention, there is provided an apparatus comprising: an actuator assembly 2 as described herein; and a further actuator assembly 20'. The further actuator assembly 20' is fixedly attached to the movable part 12 so as to move with the movable part 12.

Optionally, the further actuator assembly 20' comprises: a fixed part; a further movable part movable relative to the fixed part along an axis parallel to the primary axis P; and a further actuator arrangement configured to move the further movable part along the primary axis P.

Optionally, the actuator assembly 2 comprises an image sensor 6; the further actuator assembly 20' comprises a lens assembly configured to focus light on the image sensor 6; the further movable part comprises one or more lenses of the lens assembly. This configuration allows the one or more lenses to be moved along the primary axis P relative to the image sensor 6 for autofocussing.

Optionally, the endstop component 200 is provided between the actuator assembly 2 and the further actuator assembly 20'.

SMA wire

The above-described SMA actuator assemblies may comprise one or more SMA wires. 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.

AR

The actuator assemblies described herein may correspond to (part of) an illumination source which may be for use in a 3D sensing system such as described in W02020/030916 or in an augmented reality (AR) display system.

Where the movable part comprises an emitter or a display (or a part thereof), the movable part may be moved to achieve wobulation, for example for the display of a super-resolution image (i.e. an image having a resolution higher than that of the intrinsic resolution of the emitter or display). In this case, a high-resolution image is displayed (or projected) by displaying a number of lower-resolution images at different positions in rapid succession. The image displayed at each position is a lower-resolution image formed of a subset of pixels of the high-resolution image. The movable part may be moved between the positions in a repeated pattern at a high frequency, for example greater than 30 Hz, preferably greater than 60 Hz, further preferably greater than 120 Hz. The succession of lower-resolution images is thus perceived by the human eye as one high-resolution image.

The display may be a display panel, for example a LCOS (liquid crystal on silicon) display, a MicroLED display, a digital micromirror device (DMD) or a laser beam scanning (LBS) system.

The emitter is configured to emit radiation (visible light or non-visible radiation, e.g. near infrared (NIR) light, short-wave infrared (SWIR) light). The emitter may comprise one or more LEDs or lasers, for example VCSELs (vertical-cavity surface-emitting lasers) or edge-emitting lasers. The emitter may comprise a VCSEL array. The emitter may otherwise be referred to as an illumination source and/or may comprise an image projector.

In the case that the movable part comprises a display, the display may define a plane and the primary axis may be perpendicular to the plane defined by the display. In any case, the primary axis may be aligned with a general direction in which light is emitted from the display. In the case that the movable part comprises an emitter, the emitter may define a plane and the primary axis may be perpendicular to the plane defined by the emitter. For example, the emitter may comprise a VCSEL array and the primary axis may be perpendicular to the plane of the VCSEL array. In any case, the primary axis may be aligned with a general direction in which radiation is emitted by the emitter.

Claims

1. An actuator assembly comprising: a support structure; a movable part that is movable relative to the support structure; an endstop component fixed relative to the movable part; wherein the endstop component comprises endstop surfaces configured to engage corresponding endstop surfaces of the support structure so as to limit axial translation of the movable part relative to the support structure in one or more directions perpendicular to the primary axis of the support structure; wherein the endstop surfaces extend from the main body of the endstop component and/or the corresponding endstop surfaces extend from a main body of the support structure in a direction at least partly along an axis parallel to the primary axis so that the endstop surfaces and the corresponding endstop surfaces overlap with each other along the primary axis; wherein the main body of the endstop component is disposed on a first side of the movable part and the main body of the support structure is disposed on a second opposite side of the movable part.

2. An actuator assembly according to claim 1, wherein the main body of the support structure is a base plate of the support structure.

3. An actuator assembly according to claim 1 or 2, comprising a housing for covering the support structure, the movable part and the endstop component.

4. An actuator assembly according to any preceding claim, comprising an actuator arrangement configured to move the movable part relative to the support structure across a range of movement in two orthogonal directions perpendicular to the primary axis.

5. An actuator assembly according to claim 4, wherein the actuator arrangement comprises one or more SMA wires arranged, on contraction, to move the movable part relative to the support structure.

6. An actuator assembly according to any preceding claim, wherein the endstop surfaces extend towards the main body of the support structure.

7. An actuator assembly according to any preceding claim, wherein the endstop component comprises outwardly extending portions that extend away from the primary axis and that extend beyond the periphery of the movable part as viewed along the primary axis.

8. An actuator assembly according to claim 7, wherein the endstop surfaces extend from ends of the outwardly extending portions of the endstop component that are located outside the periphery of the movable part as viewed along the primary axis.

9. An actuator assembly according to claim 7 or 8 when dependent on claim 5, wherein the outwardly extending portions of the endstop component bend over portions of the movable part so as to avoid interfering with the one or more SMA wires.

10. An actuator assembly according to any preceding claim, wherein the endstop component comprises one or more bent sheets of metal.

11. An actuator assembly according to any preceding claim, wherein the endstop surfaces face toward the primary axis.

12. An actuator assembly according to any preceding claim, wherein the corresponding endstop surfaces extend towards the main body of the movable part.

13. An actuator assembly according to any preceding claim, wherein the corresponding endstop surfaces extend from portions of the support structure that are located outside the periphery of the movable part as viewed along the primary axis.

14. An actuator assembly according to any of claims 1 to 10, 12 or 13, wherein the corresponding endstop surfaces face toward the primary axis.

15. An actuator assembly comprising: a support structure; a movable part that is movable relative to the support structure; wherein the movable part comprises endstop surfaces configured to engage corresponding endstop surfaces of the support structure so as to limit axial translation of the movable part relative to the support structure in one or more directions perpendicular to a primary axis of the support structure; wherein the endstop surfaces extend from the main body of the movable part in a direction at least partly along an axis parallel to the primary axis so as to overlap with the corresponding endstop surfaces of the support structure along the primary axis.

16. An actuator assembly according to claim 15, wherein the main body of the support structure is a base plate of the support structure.

17. An actuator assembly according to claim 15 or 16, comprising a housing for covering the support structure, and the movable part.

18. An actuator assembly according to any of claims 15 to 17, comprising an actuator arrangement configured to move the movable part relative to the support structure across a range of movement in two orthogonal directions perpendicular to the primary axis.

19. An actuator assembly according to claim 18, wherein the actuator arrangement comprises one or more SMA wires arranged, on contraction, to move the movable part relative to the support structure.

20. An actuator assembly according to any of claims 15 to 19, wherein the endstop surfaces extend towards the main body of the support structure.

21. An actuator assembly according to any of claims 15 to 20, wherein the endstop component comprises outwardly extending portions that extend away from the primary axis and that extend beyond the periphery of the movable part as viewed along the primary axis.

22. An actuator assembly according to claim 21, wherein the endstop surfaces extend from ends of the outwardly extending portions of the endstop component that are located outside the periphery of the movable part as viewed along the primary axis.

23. An actuator assembly according to claim 21 or 22 when dependent on claim 19, wherein the outwardly extending portions of the endstop component bend over portions of the movable part so as to avoid interfering with the one or more SMA wires.

24. An actuator assembly according to any of claims 15 to 23, wherein the endstop component comprises one or more bent sheets of metal.

25. An actuator assembly according any of claims 15 to 23, wherein the endstop surfaces face toward the primary axis.

26. An actuator assembly according to any preceding claim, comprising a lens assembly and/or an image sensor.

27. An actuator assembly according to claim 26, wherein the movable part comprises the lens assembly.

28. An actuator assembly according to claim 26 or 27, wherein the primary axis is parallel to the optical axis of the lens assembly.

29. An actuator assembly according to any of claims 26 to 28, wherein the support structure comprises the image sensor.

30. An actuator assembly according to any of claims 26 to 28, wherein the movable part comprises the image sensor.

31. An actuator assembly according to any of claims 26 to 30, wherein the primary axis is perpendicular to the light sensitive surface of the image sensor.

32. An actuator assembly according to any of claims 1 to 25, wherein the movable part comprises a display, an emitter, or a part thereof.

33. An actuator assembly according to claim 32, wherein the primary axis is parallel to the general direction in which radiation is emitted by the display or emitter.

34. An apparatus comprising: an actuator assembly according to any of claims 1 to 25; and a further actuator assembly; wherein the further actuator assembly is fixedly attached to the movable part so as to move with the movable part.

35. An apparatus according to claim 34, wherein the further actuator assembly comprises: a fixed part; a further movable part movable relative to the fixed part along an axis parallel to the primary axis; and a further actuator arrangement configured to move the further movable part along the primary axis. An apparatus according to claim 35, wherein: the actuator assembly comprises an image sensor; the further actuator assembly comprises a lens assembly configured to focus light on the image sensor; the further movable part comprises one or more lenses of the lens assembly. An apparatus according to any of claims 34 to 36, wherein the endstop component is provided between the actuator assembly and the further actuator assembly. An actuator assembly comprising: a support structure; a movable part that is movable relative to the support structure, the movable part comprising a region for fixedly connecting an image sensor assembly or a lens assembly; an actuator arrangement configured, on actuation, to drive movement of the movable part relative to the support structure; wherein the movable part comprises endstop surfaces configured to engage corresponding endstop surfaces of the support structure so as to limit axial translation of the movable part relative to the support structure in one or more directions perpendicular to a primary axis of the support structure. An actuator assembly according to claim 38, further comprising an image sensor assembly or a lens assembly fixedly connected to the region of the movable part, wherein the endstop surfaces of the movable part are provided separately from the image sensor assembly or lens assembly. An actuator assembly according to claim 38 or 39, wherein the support structure comprises a portion configured to fixedly connect to a housing configured to enclose the actuator arrangement and movable part. An actuator assembly according to any one of claims 38 to 40, further comprising a housing fixed to the portion of the support structure, wherein the housing encloses the actuator arrangement and movable part, and wherein the endstop surfaces of the support structure are provided separately from the housing. An actuator assembly according to any one of claims 38 to 41, wherein the actuator arrangement is configured to drive movement of the movable part relative to the support structure in two orthogonal directions perpendicular to the primary axis. An actuator assembly according to any one of claims 38 to 42, wherein the endstop surfaces of the movable part extend from a main body of the movable part in a direction parallel to the primary axis and/or wherein the endstop surfaces of the support structure extend from a main body of the support structure in a direction parallel to the primary axis, such that the endstop surfaces of the movable part and of the support structure overlap with each other when viewed perpendicularly to the primary axis.