TECHNICAL FIELD

The disclosure relates to a single-piece actuator for operating an adjustable aperture unit of a camera module, an actuator unit comprising the single-piece actuator, and a variable iris system comprising the actuator unit and an adjustable aperture unit, as well as a method of operating a variable iris system comprising an adjustable aperture unit.

BACKGROUND

Small electronic devices such as smart handsets are oftentimes provided with cameras. It is advantageous if the user of the device is able to adjust the size of the optical iris aperture of the camera, in order to adjust the amount of light reaching the image sensor. Under low illumination circumstances, e.g., a larger sized aperture can be used to shorten exposure time and increase sensitivity. Under higher illumination circumstances, a smaller sized aperture ensures increased depth-of-field and reduce oversaturation, while a large aperture helps to generate a photographic bokeh effect, i.e. a soft out-of-focus background.

Professional photography devices are provided with adjustable aperture units which have relatively large sizes and complex architecture, and which are expensive. When attempting to downscale such solutions for smaller devices such as smartphones, the complexity grows and becomes a limiting technical factor, affecting the weight, size, thickness, and reliability of the device, as well as production capability and unit cost. Therefore, small device cameras mainly comprise switchable, two-state blade systems in which a simple bi-stable (on-off type) actuator operates a single or dual blade mechanism to move a pre-defined smaller aperture shape (either uniform or segmented type) on top of a larger one, thus reducing its circular diameter while kept in switch-on state. Alternatively, the wing system may consist of multiple pivoted blades, typically operated with a circularly shaped common rotator element. An actuator inside the system is coupled to the rotator element for adjusting its angular position and thus changing the position of the aperture blades. Other forms of prior art implementations involve radial, linearly moving, multiple blades which are individually operated. However, the electrical operation of such blade systems via actuators is challenging, as the blade systems require a reasonably accurate, long stroke and strong actuator to generate enough controllable force (of several tens or few hundreds of millinewtons) to drive the blades and overcome frictional issues.

Furthermore, as the aperture unit is usually mounted on an optical lens barrel which is moved in vertical direction by another actuator (for Auto Focus, AF) and in horizontal direction by third actuator (for Optical Image Stabilization, OIS), the overall weight of the blade system and actuation structure needs to be very lightweight. All extra moving mass on the lens may hinder the AF and OIS movements.

One additional requirement for the actuator characteristics is the dual direction drive capability as the blades in the aperture system need to be closed and opened when needed.

SUMMARY

It is an object to provide an improved actuator unit and an improved variable iris system that overcomes the technical complexity of driving each aperture blade individually in at least two directions, while keeping the system lightweight. To achieve this, it is proposed that a common single-piece actuator is used to operate the mutual placement of moving blades via a shared system member, such as a rotating frame part, linear guide or cam element, having a mechanically dynamic connection for each blade.

By having a common single-piece actuator, the control and synchronized movement of the blades via a shared member can be implemented more easily.

For generating an actuator able to produce enough force and being small enough to be fitted inside a circular blade architecture, it is further proposed that shape memory alloy (SMA) based solution is used, especially sheet-type SMA, instead of much more common SMA wire-type.

The foregoing and other objects are achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description, and the figures.

According to a first aspect, there is provided a single-piece actuator for operating an adjustable aperture unit of a camera module by displacing at least one movable element. The single-piece actuator comprises a plurality of fastening areas configured to be fastened by means of at least one first fastening element, wherein such fastening enables the fastening areas to remain stationary during actuation; a displacement area configured to move during actuation with regards to the fastening areas; and a plurality of actuating arms, each actuating arm extending from one fastening area to the displacement area. Each actuating arm is configured to deform in response to electric activation, and the displacement area is moved in response to this deformation. The displacement area is further configured to be mechanically interconnected with a movable element.

This solution provides an actuator suitable for operating an adjustable aperture unit of a camera module that is simple and comprises a minimum of components, making it cost efficient to produce, structurally lightweight, as well as reliable and effective in use. The single-piece actuator enables reasonable accuracy, sufficiently long stroke and strength for moving a connected movable element. The size of the actuator can be minimized due to the actuation being implemented electrically instead of mechanically. Furthermore, it allows displacement of several moving blades by means of only one actuator interconnected with a movable element, thereby reducing the number of components needed and hence freeing up space for other unrelated components and/or allowing the size of the device comprising the actuator to be reduced. Using an actuating arm that is configured to deform in response to electric activation allows for avoiding interference with other VCM actuators such as OIS and AF systems in the device.

In a possible implementation form of the first aspect, the actuating arm is configured to return to an at least partly non-deformed shape and/or deform further in response to a change in the electric activation. This keeps the amount of energy required to operate the actuator to a minimum while maximizing its flexibility.

In a further possible implementation form of the first aspect, the electric activation comprises supplying current to the actuating arm by means of the fastening area. This double purpose enables reducing the number of components needed and hence freeing up further space, allowing the size of the device comprising the actuator to be further reduced.

In a further possible implementation form of the first aspect, changing the electric activation comprises changing the strength of the current, i.e. increasing or reducing the strength of the current, and electric deactivation, which comprises not supplying any current at all to the fastening area. This allows for precise control of the single-piece actuator through the supply or non- supply of different currents. In a further possible implementation form of the first aspect, the single-piece actuator comprises a shape memory material, the shape memory material having a one-way shape memory effect or a two-way shape memory effect. This allows provision of a flexible, thin form factor actuator, capable of long movement generation for actuator applications. Using shape memory material further provides a lightweight actuator compared to other materials, while still enabling higher power efficiency in relation to the force generation. Another advantage is a silent operation compared to other types of actuators.

In a further possible implementation form of the first aspect, only the actuating arms comprise shape memory material, while the fastening areas and the displacement are configured not to deform in response to electric activation. This provides further precision and additional savings in costs of manufacture due to easier assembly and lower material costs.

In a further possible implementation form of the first aspect, the single-piece actuator is a sheetbased layer extending in at least 2 dimensions between the fastening areas. Such a sheet-based actuator enables easy and cost-effective manufacturing (due to formability, e.g. by etching or laser), thin form- factor, and allows the actuator to be constructed as two-directional type which enables an aperture system to be closed and opened via the actuator when needed.

In a further possible implementation form of the first aspect, the sheet-based layer is bent in a curved shape between the fastening areas, thereby enabling a thin and curved form-factor specifically adapted to be accommodated or integrated onto a variable iris system in compact way.

In an embodiment, the curved shape corresponds to an outer circumference of an adjustable aperture unit of a variable iris system in a camera module, which further increases the integrability of the actuator into a variable iris system in a camera module.

In a further possible implementation form of the first aspect, each of the plurality of actuating arms comprises a plurality of segments, each segment extending at an angle against adjacent segments, allowing deformation of the actuating arm resulting in displacement of the displacement area.

In possible embodiments, the angle is between 45 and 135 degrees, preferably around 90 degrees, when the actuating arms are in a non-deformed shape. In further possible embodiments, the segments are at least one of linear, curved, or free-form segments.

In a further possible implementation form of the first aspect, the single-piece actuator is a twodirectional actuator comprising two actuating arms extending from the displacement area in opposing directions, each actuating arm extending towards one of two fastening areas, the two actuating arms each configured to displace the displacement area in one of the two opposing directions, which enables an aperture system to be closed and opened via the actuator when needed.

According to a second aspect, there is provided an actuator unit comprising a main board comprising a structure for transmitting current; a single-piece actuator according to any of the preceding claims, and a movable element mechanically interconnected with the displacement area of the single-piece actuator. The single-piece actuator is connected to the main board by means of electrically conductive fastening means.

This solution for an actuator unit comprises the previously mentioned advantages over the prior art with respect to the single-piece actuator, and furthermore requires a minimum number of components as an actuator unit, making it cost efficient to produce and reliable in use for operating an adjustable aperture unit of a camera module. The size of the actuator unit, in particular the thickness, can be minimized due to the layered structure, thereby allowing for a thin form-factor.

In a possible implementation form of the second aspect, the electrically conductive fastening means comprise a plurality of first fastening elements, each first fastening element being connected to a fastening area, the first fastening elements being configured to selectively transmit current from the main board to each fastening area, such that the fastening area is electrically activated; and a second fastening element being connected to the displacement area, the second fastening element being configured to receive current from the displacement area and thus enabling selective electric activation of the actuating arms.

In possible embodiments the first fastening elements comprise at least one of rivets, conductive glue, or spring-based members. In a further possible implementation form of the second aspect, the single-piece actuator is a first single-piece actuator, the movable element being mechanically interconnected with a first displacement area of the first single-piece actuator; the second fastening element is a second single-piece actuator comprising a second displacement area electrically connected to the first displacement area; and the second single-piece actuator is configured to receive current from the first displacement area and thus enabling selective electric activation of the actuating arms of the first single-piece actuator.

In a further possible implementation form of the second aspect, the second fastening element is an electrically conductive, elongated resilient element arranged in parallel to an axis of displacement of the movable element; the second fastening element being configured to exert force on the displacement area opposing any displacement thereof resulting from deformation of an actuating arm upon electric activation, thereby allowing to return the displacement area to a resting position upon termination of the electric activation.

In a further possible implementation form of the second aspect, the second fastening element is connected to the main board by second grounding means arranged at extreme ends of the second fastening element, and the second fastening element comprises first grounding means, arranged between the second grounding means, for connecting to the displacement area, thus enabling selective electric activation of the actuating arms.

In a possible embodiment, the displacement area comprises a hole and the first grounding means comprise a clip hook arranged to interlock with the hole.

In further possible embodiments, the second grounding means comprise at least one of soldering, fusing, rivets, or conductive glue.

In a further possible implementation form of the second aspect, the main board comprises an elongated hole arranged between the first fastening elements. The movable element comprises protruding coupling means and configured to be mechanically interconnected with an actuating member of an adjustable aperture unit arranged on an opposite side of the main board with respect to any single-piece actuator. The protruding coupling means are arranged in the elongated hole and being shaped to be movable along the elongated hole between its two shorter sides while being guided by its longer sides, thereby allowing precise and guided movement of the movable element. In a further possible implementation form of the second aspect, the actuator unit further comprises a housing adjoining the main board and having a shape corresponding to the main board. The main board is arranged between the housing and any single-piece actuator, thereby providing additional mechanical stability for the actuator unit.

In a possible embodiment the housing is made of sheet metal.

In a further possible embodiment, the main board is attached to the housing by arranging adhesive material between their corresponding adjoining surfaces.

In a further possible embodiment, the plurality of first fastening elements are configured to interconnect the housing, the main board and any single-piece actuator.

In a further possible implementation form of the second aspect, the main board further comprises electrical terminals for connection to a supply of current. This allows for direct, simple, and reliable actuation of the single-piece actuator.

In possible embodiments the main board is a printed wiring board, such as a Flexible Printed Circuit board.

According to a third aspect, there is provided a variable iris system comprising an actuator unit according to any one of the possible implementation forms of the second aspect, and an adjustable aperture unit comprising an actuating member for adjusting a size of an aperture area of the adjustable aperture unit. The movable element of the actuator unit is connected to the actuating member.

This solution for a variable iris system comprises the previously mentioned advantages over the prior art with respect to the actuator unit and allows for a very compact assembly with respect to the variable iris system, as well as simple and direct actuation by the single-piece actuator via the movable element. This, in turn, frees up space for other unrelated components and/or allows the size of the electronic device to be reduced.

In a possible implementation form of the third aspect, the movable element is connected to the actuating member by protruding coupling means, enabling a secure connection.

In a further possible implementation form of the third aspect, the adjustable aperture unit has a circular outer circumference, and the actuator unit is bent in a curved shape, the curved shape having a radius corresponding to a radius of the outer circumference of the adjustable aperture unit. This allows for an assembly having as small overall dimensions as possible.

According to a fourth aspect, there is provided a method of operating a variable iris system comprising an adjustable aperture unit and an actuator unit. The adjustable aperture unit comprises an actuating member for adjusting a size of an aperture area of the adjustable aperture unit, wherein the actuator unit comprises a single-piece actuator and a movable element; the movable element being connected to the actuating member of the adjustable aperture unit. The method comprises the step of activating a first part of the single-piece actuator such that a first deformation of the single-piece actuator is generated, the first deformation displacing the movable element from a first position to a second position.

The aperture area has a first size and/or a first shape when the movable element is in the first position, and the aperture area has a second size and/or second shape when the movable element is in the second position.

This method comprises operating a variable iris system using a minimum of components, making it cost efficient and reliable in use. The deformation-based actuation provides easy shape formability, thin form factor, high force and long movement generation for actuator applications, as well as silent operation, and no interference with other VCM actuators such as OIS and AF systems nearby with electromagnetic fields. Furthermore, the adjustment of the aperture area is flexible due to the flexible movement of the movable element.

In a possible implementation form of the fourth aspect, the method further comprises the steps of activating a second part of the single-piece actuator such that a second deformation of the single-piece actuator is generated, the second deformation displacing the movable element in an opposite direction with respect to the first deformation, from the second position to a third position. The aperture area has a third size and/or a third shape when the movable element is in the third position; and the possibilities for the third position comprise the first position.

This allows for dual-direction drive capability of the system, through which aperture blades in the variable iris system can be closed and opened when needed, to a specific extent.

In a further possible implementation form of the fourth aspect, the method further comprises the step of deactivating the single-piece actuator, the deactivation generating a return of the single-piece actuator to a non-deformed shape, the return generating movement of the movable element from the second or third position to the first position, such that there is no need for separate return control or return inducing components.

In a further possible implementation form of the fourth aspect, the method further comprises the step of changing the activation of the first part or the second part of the single-piece actuator such that a change in deformation of the single-piece actuator is generated, the change in deformation displacing the movable element, allowing the single-piece actuator to generate step-wise displacement of the movable element.

In a further possible implementation form of the fourth aspect, the activation comprises supplying a first current to at least one actuating arm of the single-piece actuator, the deactivation comprises not supplying the first current to the actuating arm, and the change in activation comprises supplying a second current to the actuating arm, the second current having a different strength than the first current, thereby allowing precise control of the actuator through the supply of different currents.

These and other aspects will be apparent from the embodiments described below.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following detailed portion of the present disclosure, the aspects, embodiments and implementations will be explained in more detail with reference to the example embodiments shown in the drawings, in which:

Fig. 1 shows a front view of a single-piece actuator according to an example of the embodiments of the disclosure;

Fig. 2 shows a front view of an actuator unit comprising the single-piece actuator when assembled, according to an example of the embodiments of the disclosure;

Fig. 3 shows a top view of a curved sheet-based actuator unit comprising the single-piece actuator when assembled, according to an example of the embodiments of the disclosure; Fig. 4 shows a perspective view from the back of a curved sheet-based actuator unit comprising the single-piece actuator when assembled, according to an example of the embodiments of the disclosure;

Fig. 5 shows a perspective view from the front of a curved sheet-based actuator unit comprising the single-piece actuator when assembled, according to an example of the embodiments of the disclosure;

Fig. 6 shows an exploded view of the actuator unit comprising the single-piece actuator, the main board and the housing, as well as further components according to an example of the embodiments of the disclosure;

Fig. 7A shows a top view of a variable iris system comprising an actuator unit and an adjustable aperture unit, before assembly, according to an example of the embodiments of the disclosure;

Fig. 7B shows a top view of a variable iris system comprising an actuator unit and an adjustable aperture unit, when assembled, according to an example of the embodiments of the disclosure;

Fig. 8 shows a top view of a variable iris system comprising an actuator unit and an adjustable aperture unit, when assembled, according to a different example of the embodiments of the disclosure;

Fig. 9 shows a front view of a portion of an actuator unit comprising two single-piece actuators, according to another example of the embodiments of the disclosure;

Fig. 10A shows a perspective view of a portion of an actuator unit comprising two single-piece actuators, before assembly, according to an example of the embodiments of the disclosure; and

Fig. 10B shows a perspective view of a portion of an actuator unit comprising two single-piece actuators, when assembled, according to an example of the embodiments of the disclosure.

DETAILED DESCRIPTION

Figs. 7A and 7B show one example of a variable iris system 15 according to the present disclosure. The variable iris system 15 comprises an actuator unit 11 comprising a movable element 8, and an adjustable aperture unit 12 comprising an actuating member 14 for adjusting a size of an aperture area of the adjustable aperture unit 12. The movable element 8 of the actuator unit 11 may be a plastic slider element connected to the actuating member 14 by protruding coupling means 13. The actuator unit 11 will be described in more detail further below.

As shown in the examples of Figs. 7 through 8, the adjustable aperture unit 12 may have a circular outer circumference, and the actuator unit 11 may be bent in a curved shape, this curved shape having a radius corresponding to a radius of the outer circumference of the adjustable aperture unit 12, which allows for a variable iris system 15 having as small overall dimensions as possible.

The adjustable aperture unit 12 itself may comprise multiple (such as between 3-12) pivoted blades 18, operated via a shared system member configured for mutual placement of the blades 18. The shared system member can be arranged, for example, as a circularly shaped rotator element 19, a linear guide, or a cam element, having mechanically dynamic connection for each blade 18. This dynamic connection can be pivoting, sliding or deforming-based, which allows the blades 18 to move radially towards and outwards from a center point C. By having such a shared member, the control and synchronized movement of the blades 18 can be implemented more easily.

In the illustrated example, adjusting the angular position of a circularly shaped rotator element 19 by moving the actuating member 14 (as shown by the arrows in Fig. 7B) through the movable element 8 of the actuator unit 11 changes the position of the aperture blades 18, thereby adjusting the lens aperture.

The adjustable aperture unit 12 may further comprise any known iris diaphragm blade structure with external coupling connection, whereby the actuator unit 11 may connect to such coupling connection via the movable element 8, for example by the above-mentioned protruding coupling means 13.

Alternatively, as illustrated in Fig. 8, the adjustable aperture unit 12 may accommodate the actuator unit 11 inside the outline, resulting in an integrated and non-separated architecture for the variable iris system 15. The actuator unit 11, shown in detail in the examples of Figs. 2 through 6, may comprise a single-piece actuator 1, which will be described in more detail further below, and a main board 9 comprising a structure for transmitting current. In these examples, the single-piece actuator 1 is connected to the main board 9 by means of electrically conductive fastening means, and the actuator unit 11 further comprises a movable element 8 mechanically interconnected with a displacement area 3 of the single-piece actuator 1.

These electrically conductive fastening means may comprise a plurality of first fastening elements 5, each first fastening element 5 being connected to a fastening area 2 of the singlepiece actuator 1 and configured to selectively transmit current from the main board 9 to each fastening area 2, such that the fastening area 2 is electrically activated. The first fastening elements 5 may comprise rivets, conductive glue, and/or spring-based members.

The electrically conductive fastening means may further comprise a second fastening element 6 connected to the displacement area 3 of the single-piece actuator 1, the second fastening element 6 being configured to receive current from the displacement area 3 and thus enabling selective electric activation of the actuating arms 4 of the single-piece actuator 1, as will be described in more detail further below.

In the examples illustrated in Figs. 2 through 6, the second fastening element 6 is connected to the main board 9 by second grounding means 7B arranged at extreme ends of the second fastening element 6, and the second fastening element 6 further comprises first grounding means 7A, arranged between the second grounding means 7B, for connecting to the displacement area 3 of the single-piece actuator 1. The second grounding means 7B may comprise soldering, fusing, rivets, and/or conductive glue.

In an example, as illustrated, the displacement area 3 comprises a hole and the first grounding means 7A comprise a clip hook arranged to interlock with the hole.

As further illustrated in Figs. 4 through 6, the main board 9 may comprise an elongated hole 17 arranged between the first fastening elements 5. The movable element 8 may further comprise protruding coupling means 13 and may be configured to be mechanically interconnected with an actuating member 14 of an adjustable aperture unit 12 arranged on an opposite side of the main board 9 with respect to a single-piece actuator 1, as illustrated in Figs. 7-8.

The protruding coupling means 13 may be arranged in the elongated hole 17 and may be shaped to be movable along the elongated hole 17 between its two shorter sides while being guided by its longer sides, as can be best seen in Fig. 4. As further illustrated in Figs. 4 through 6, the actuator unit 11 may further comprise a housing 10 adjoining the main board 9 and having a shape corresponding to the main board 9; the main board 9 being arranged between the housing 10 and the single-piece actuator 1. The housing 10 may be made of sheet metal.

The main board 9 may be attached to the housing 10 by arranging adhesive material between their corresponding adjoining surfaces.

As illustrated in Figs. 3-6, the first fastening elements 5 may be configured to interconnect the housing 10, the main board 9 and the single-piece actuator 1.

According to the illustrated examples of Figs. 2-6, the main board 9 may further comprise electrical terminals 16 for connecting to a supply of current. The main board 9 may be a printed wiring board, such as a Flexible Printed Circuit (FPC) board.

One example of the single-piece actuator 1 according to the present disclosure is shown in Fig. 1. The single-piece actuator 1 comprises a plurality of fastening areas 2 configured to be fastened, to a stationary element, by means of at least one first fastening element 5, enabling the fastening areas 2 to remain stationary during actuation. The single-piece actuator 1 furthermore comprises a displacement area 3 configured to move during actuation with regards to the fastening areas 2. The displacement area 3 is configured to be mechanically interconnected with a movable element 8. The single-piece actuator 1 furthermore comprises a plurality of actuating arms 4, each actuating arm 4 extending from one fastening area 2 to the displacement area 3. Each actuating arm 4 is configured to deform in response to electric activation by means of one fastening area 2. In response to the deformation, the displacement area 3 is moved.

In the example as illustrated in Figs. 1-6, the displacement area 3 is located between two fastening areas 2, two actuating arms 4 extending from the displacement area 3 in different directions such that each actuating arm 4 extends towards one of the two fastening areas 2. However, further examples are also possible with more fastening areas 2 and actuating arms 4.

By supplying equal voltage, to one pair of oppositely arranged first fastening elements 5, symmetrical displacement of the movable element 8 may be generated by causing a displacement area 3 of the single-piece actuator 1 to move towards one of the fastening areas 2 from the center point as shown in Fig. 2.

Each actuating arm 4 may further be configured to return to an at least partly non-deformed shape and/or deform further in response to a change in the electric activation, wherein this electric activation comprises supplying current to the actuating arms 4 by means of the fastening area 2, and wherein the change in electric activation may comprise changing the strength of the current, and electric deactivation comprising not supplying the current to the fastening area 2.

As shown in Fig. 6, the movable element 8 may comprise (a) protrusion(s), extending from the movable element 8. Correspondingly, the displacement area 3 may comprise recesses, e.g. annular sections, configured to receive the protrusion(s), such that movement of the displacement area 3 of the single-piece actuator 1 generates corresponding movement of the corresponding movable element 8 and, subsequently, corresponding movement of the actuating member 14 of a variable iris system 15 as shown in Fig. 7B.

As mentioned above, the first fastening element 5 may comprise rivets, conductive glue, and/or spring-based members, and the fastening areas 2 are preferably directly connected to the main board 9 by means of the first fastening elements 5 first. The fastening areas 2 may comprise annular sections configured to receive the first fastening elements/rivets 5.

The single-piece actuator 1 may be configured to move a shared system member of an adjustable aperture unit 12, such as the one illustrated in Figs. 7-8, by displacing a movable element, such as the above-mentioned movable element 8 illustrated in Figs 2-6, which may be mechanically coupled the shared system member of the adjustable aperture unit 12 via an actuating member 14 as illustrated in Figs. 7A and 7B. The movable element 8 of the actuator unit 11 may be connected to the actuating member 14 by protruding coupling means 13 as shown in Fig. 4.

The single-piece actuator 1 may comprise a shape memory material, the shape memory material having a one-way shape memory effect or a two-way shape memory effect. The actuating arm 4 may be configured to return to an at least partly non-deformed shape, i.e. have a one-way shape memory effect, and/or deform further, i.e. have a two-way shape memory effect, in response to a change in the electric or magnetic activation. The shape memory material may be a shape memory alloy. The two-way effect may be achieved by a material responding differently at two different temperatures, the different temperatures being generated by the actuation having different strengths.

Accordingly, the single-piece actuator 1 may be a two-directional actuator comprising two actuating arms 4 extending from the displacement area 3 in opposing directions, each actuating arm 4 extending towards one of two fastening areas 2, the two actuating arms 4 each configured to displace the displacement area 3 in one of the two opposing directions.

In possible examples, only the actuating arms 4 comprise shape memory material, while the fastening areas 2 and the displacement may be configured not to deform in response to electric activation.

The single-piece actuator 1 may have any suitable shape. The main extent of the single-piece actuator may lie in one plane, resulting in a flat, sheet-like configuration, or may be curved as will be described later.

In an example the single-piece actuator 1 is a sheet-based layer extending in at least 2 dimensions between the fastening areas 4, as shown in Fig. 2.

Figs. 3-6 show an example wherein the sheet-based layer of the single-piece actuator 1 is bent in a curved shape between the fastening areas 2. This curved shape is illustrated by the radius R, which represents the difference in the curvature with respect to a straight line between the fastening areas 2. As illustrated in the examples in Figs. 7-8, the curved shape (and thus the radius R) may correspond to (the radius of) an outer circumference of an adjustable aperture unit 12 of a variable iris system 15 in a camera module, thereby enabling a thin and curved form-factor specifically adapted to be accommodated or integrated onto a variable iris system in compact way.

The actuating arm 4 may comprise a plurality of segments, each segment extending at an angle relative adjacent segments, allowing deformation of the actuating arm 4, and thereby resulting in a wormy, curvy, zig-zag overall shape. The segments may change in dimensions, or in angular placement relative each other, thereby resulting in displacement of the displacement area 3. The initial angle may be between 45 and 135 degrees, preferably around 90 degrees, when the actuating arms 4 are in a non-deformed shape. The segments may be linear, curved, and/or free-form segments. As indicated above, the single-piece actuator 1 may be connected to the main board 9 by means of electrically conductive fastening means, such as a plurality of first fastening elements 5 configured to selectively transmit current from the main board 9 to each fastening area 2 of the single-piece actuator 1 as described before; and a second fastening element 6 connected to the displacement area 3 and configured to receive current from the displacement area 3 and thus enabling selective electric activation of the actuating arms 4.

As illustrated in Figs. 2, 5 and 6, the second fastening element 6 may be an electrically conductive, elongated resilient element (such as a metal spring) arranged in parallel to an axis of displacement of the movable element 8 and configured to exert force on the displacement area 3 opposing any displacement thereof resulting from deformation of an actuating arm 4 upon electric activation, in order to return the displacement area 3 to a resting position upon termination of the electric activation.

According to another example illustrated in Figs. 9 through 10A and 10B, the actuator unit 11 may comprise two single-piece actuators, a first single-piece actuator 1 A and a second singlepiece actuator IB. In this example, first single-piece actuator 1A acts as the single-piece actuator, the movable element 8 being mechanically interconnected with a first displacement area 3A of the first single-piece actuator 1 A; wherein the second single-piece actuator IB acts as second fastening element 6 comprising a second displacement area 3B that is electrically connected to the first displacement area 3 A, as shown in Fig. 10A, through compression connection. Such compression connection on the displacement areas between the layers (two single-piece actuators) can be generated with heat staked plastic rib or conductive glue. In this example, the second single-piece actuator IB is connected to the main board 9 by second grounding means 7B arranged at its extreme ends (at the fastening areas thereof), and is further configured to receive current from the first displacement area 3A and thus enabling selective electric activation of the actuating arms 4 of the first single-piece actuator 1 A.

The present disclosure also relates to a method operating a variable iris system 15 as shown in Fig. 7B, the variable iris system 15 comprising an adjustable aperture unit 12 comprising an actuating member 14 for adjusting a size of an aperture area of the adjustable aperture unit 12 and an actuator unit 11 comprising a single-piece actuator 1 and a movable element 8, the movable element 8 being connected to the actuating member 14 as described above. The method comprises at least the step of activating a first part of the single-piece actuator 1 such that a first deformation of the single-piece actuator 1 is generated, the first deformation displacing the movable element 8 from a first position to a second position. The aperture area has a first size and/or a first shape when the movable element 8 is in the first position, and the aperture area having a second size and/or second shape when the movable element 8 is in the second position.

The method may comprise additional steps. A second part of the single-piece actuator 1 may be activated such that a second deformation of the single-piece actuator 1 is generated, the second deformation displacing the movable element 8 in an opposite direction with respect to the first deformation, as shown in Fig. 7B by the opposing arrows, from the second position to a third position, the aperture area having a third size and/or a third shape when the movable element 8 is in the third position; wherein the possibilities for the third position comprise the first position.

The method may also comprise subsequently deactivating the single-piece actuator 1. The deactivation generates a return of the single-piece actuator 1 to an at least partial non-deformed shape, and the return generates movement of the movable element 8 from the second or third position to the first position.

Correspondingly, the method may also comprise changing the activation of the single-piece actuator 1, e.g. by changing the strength of current supplied, such that a change in deformation, rather than a return to a non-deformed shape, of the single-piece actuator 1 is generated. In other words, if the activation comprises supplying a first current to at least one actuating arm 4 of the single-piece actuator 1, the deactivation may comprise not supplying the first current to the actuating arm 4. Similarly, the change in activation may comprise supplying a second current to the actuating arm 4, the second current having a different strength than the first current.

The various aspects and implementations have been described in conjunction with various embodiments herein. However, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed subject-matter, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. A computer program may be stored/distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

The reference signs used in the claims shall not be construed as limiting the scope. Unless otherwise indicated, the drawings are intended to be read (e.g., cross-hatching, arrangement of parts, proportion, degree, etc.) together with the specification, and are to be considered a portion of the entire written description of this disclosure. As used in the description, the terms “horizontal”, “vertical”, “left”, “right”, “up” and “down”, as well as adjectival and adverbial derivatives thereof (e.g., “horizontally”, “rightwardly”, “upwardly”, etc.), simply refer to the orientation of the illustrated structure as the particular drawing figure faces the reader.

Similarly, the terms “inwardly” and “outwardly” generally refer to the orientation of a surface relative to its axis of elongation, or axis of rotation, as appropriate.