CN116762029A

CN116762029A - Shape memory alloy actuator architecture for driving an adjustable aperture

Info

Publication number: CN116762029A
Application number: CN202180089642.1A
Authority: CN
Inventors: 马科·埃罗马基
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2021-01-14
Filing date: 2021-01-14
Publication date: 2023-09-15
Also published as: EP4244485A1; WO2022152375A1

Abstract

A curved-shape, lightweight, bi-directional actuator unit (11) is provided for operating a rotating portion of an adjustable aperture unit (12) to adjust blade position by mechanical coupling in an iris system (15) of a mobile camera module architecture. The actuator unit (11) comprises a sheet monolithic actuator (1), the sheet monolithic actuator (1) having a plurality of fastening regions (2), and a displacement region (3), the displacement region (3) being configured to be moved between the fastening regions (2) by an actuation arm (4) based on shape memory actuation, the actuation arm (4) being configured to selectively deform in response to electrical activation, thereby displacing the displacement region (3), the displacement region (3) in turn moving an actuation member (14) to adjust the size of the aperture region of the adjustable aperture unit (12).

Description

Shape memory alloy actuator architecture for driving an adjustable aperture

Technical Field

The present invention relates to a monolithic actuator for operating an adjustable aperture unit of a camera module, an actuator unit comprising a monolithic actuator, an iris system comprising an actuator unit and an adjustable aperture unit, and a method of operating an iris system comprising an adjustable aperture unit.

Background

Small electronic devices such as smartphones are typically equipped with cameras. It is advantageous if the user of the device is able to adjust the size of the diaphragm aperture of the camera in order to adjust the amount of light reaching the image sensor. In a low illumination environment, for example, a larger size aperture may be used to shorten the exposure time and increase the sensitivity. Under higher illumination conditions, a smaller size aperture can ensure increased depth of field and reduced oversaturation, while a large aperture helps to create a photographic scene effect, i.e., a soft out-of-focus background.

Professional photographic equipment is equipped with adjustable coil units that are relatively large in size, complex in architecture, and expensive. When attempting to scale down such solutions for smaller devices such as smartphones, the complexity increases and becomes a limiting technical factor, affecting the weight, size, thickness and reliability of the device, as well as the throughput and unit cost. Thus, small device cameras mainly comprise switchable two-state blade systems, wherein a simple bi-stable (on-off type) actuator operates a single-blade or two-blade mechanism to move a predefined smaller aperture shape (uniform or segmented type) on top of a larger aperture shape, thereby reducing its circular diameter while maintaining an open state. Alternatively, the wing system may be made up of a plurality of pivoting blades, typically operated with a circular common rotating element. An actuator within the system is coupled to the rotary element for adjusting its angular position, thereby changing the position of the aperture blade. Other forms of prior art implementations include radially, linearly moving individually operated multiple blades.

However, such blade systems are challenging to operate electrically by the actuator because the blade system requires a high precision, long stroke, and powerful actuator to generate enough controllable force (tens or hundreds of millinewtons) to drive the blade and overcome the friction problem.

Further, since the aperture unit is generally mounted on an optical lens barrel, which is moved in a vertical direction by another actuator (for Auto Focus (AF)) and in a horizontal direction by a third actuator (for optical anti-shake (optical image stabilization, OIS)), the total weight of the blade system and the actuation structure needs to be very light. All additional moving mass on the lens may hinder the movement of AF and OIS.

An additional requirement for the actuator characteristics is the bi-directional driving capability, as the blades in the aperture system need to be closed and opened when needed.

Disclosure of Invention

It is an object to provide an improved actuator unit and an improved iris system which overcome the technical complexity of driving each aperture blade individually in at least two directions while maintaining a light weight of the system. To achieve this, it is proposed to use a common monolithic actuator, operating the mutual placement of the moving blades by means of a shared system component (e.g. a rotating frame part, a linear guide rail or a cam element) with a mechanical dynamic connection of each blade.

Having a common monolithic actuator can more easily achieve control and synchronous movement of the blades by sharing components.

In order to create an actuator that is capable of generating sufficient force and small enough to fit within a circular blade architecture, it has also been proposed to use a shape memory alloy (shape memory alloy, SMA) based solution, in particular sheet SMA, rather than the more common SMA wires.

The above and other objects are achieved by the features as claimed in the independent claims. Other implementations are apparent in the dependent claims, the description and the drawings.

According to a first aspect, a monolithic actuator is provided for operating an adjustable aperture unit of a camera module by displacing at least one movable element. The monolithic actuator includes: a plurality of fastening regions configured to be fastened by at least one first fastening element, wherein such fastening causes the fastening regions to remain stationary during actuation; a displacement region configured to move relative to the fastening region during actuation, the displacement region configured to mechanically interconnect with a movable element; a plurality of actuator arms, each extending from one of the fastening regions to the displacement region. Each actuation arm is configured to deform in response to electrical activation, the displacement region moving in response to the deformation. The displacement region is also configured to mechanically interconnect with the movable element.

The solution provides an actuator suitable for operating an adjustable coil unit of a camera module, which actuator is simple and comprises a minimum of components, which makes it cost-effective to produce, light in construction and reliable and efficient to use. The monolithic actuator achieves sufficient precision, a long enough stroke and sufficient strength to move the connected movable element. Since actuation is achieved electrically rather than mechanically, the size of the actuator can be minimized. Furthermore, it is possible to displace several moving blades by means of only one actuator interconnected with the movable element, thereby reducing the number of components required, thereby making room for other unrelated components and/or possibly reducing the size of the device comprising the actuator. The use of an actuator arm configured to deform in response to electrical activation may avoid interference with other VCM actuators (e.g., OIS and AF systems) in the device.

In a possible implementation of the first aspect, the actuation arm is configured to return to an at least partially undeformed shape and/or to be further deformed in response to a change in the electrical activation. This keeps the energy required to operate the actuator to a minimum while maximizing its flexibility.

In another possible implementation of the first aspect, the electrically activating includes providing an electrical current to the actuation arm through the fastening region. This dual purpose allows to reduce the number of components required, thus freeing up more space, so that the size of the device comprising the actuator can be further reduced.

In another possible implementation of the first aspect, changing the electrical activation includes changing the intensity of the current, i.e. increasing or decreasing the intensity of the current, and electrically deactivating, which includes not providing any current to the fastening region at all. This supports precise control of the monolithic actuator with or without the supply of different currents.

In another possible implementation of the first aspect, the monolithic actuator comprises a shape memory material having a one-way shape memory effect or a two-way shape memory effect. This supports the provision of flexible, thin form factor actuators capable of producing long travel distances for actuator applications. The use of shape memory materials also provides a lightweight actuator, while still enabling higher energy efficiency associated with force generation, as compared to other materials. Another advantage is the silent operation compared to other types of actuators.

In another possible implementation of the first aspect, only the actuation arm comprises a shape memory material, and the fastening region and the displacement are configured to not deform in response to electrical activation. This further improves accuracy and additionally saves manufacturing costs due to easier assembly and lower material costs.

In another possible implementation of the first aspect, the monolithic actuator is a lamina extending in at least 2 dimensions between the fastening regions. Such a foil actuator is easy and cost-effective to manufacture (due to formability, e.g. by etching or laser) a thin form factor can be achieved and the actuator is supported to be constructed in a bi-directional type, which enables the aperture system to be closed and opened by the actuator when required.

In a further possible implementation of the first aspect, the foil layer is bent into a curved shape between the fastening regions, thereby realizing a thin and curved form factor which is particularly suitable for being accommodated or integrated onto an iris system in a compact manner.

In one embodiment, the curved shape corresponds to the outer circumference of the adjustable aperture unit of the iris system in the camera module, which further improves the integrability of the actuator to the iris system in the camera module.

In another possible implementation of the first aspect, each actuator arm of the plurality of actuator arms comprises a plurality of segments, each segment extending at an angle relative to an adjacent segment, supporting deforming the actuator arm to displace the displacement region.

In a possible embodiment, the angle is between 45 degrees and 135 degrees, preferably around 90 degrees, when the actuator arm is in the undeformed shape.

In other possible embodiments, the segment is at least one of a linear segment, a curved segment, or a free-form segment.

In another possible implementation of the first aspect, the monolithic actuator is a bi-directional actuator comprising two actuating arms extending in opposite directions from the displacement region, each actuating arm extending towards one of the two fastening regions, the two actuating arms each being configured to displace the displacement region in one of the two opposite directions, which enables the aperture system to be closed and opened by the actuator when required.

According to a second aspect, there is provided an actuator unit comprising: a main board including a structure for transmitting current; a monolithic actuator according to any preceding claim; a movable element mechanically interconnected with the displacement region of the monolithic actuator. The monolithic actuator is connected to the main board by an electrically conductive fastening member.

Such a solution of the actuator unit comprises the previously mentioned advantages over the prior art for monolithic actuators, furthermore, a minimum number of components is required as the actuator unit, which makes the actuator unit cost-effective to produce and reliable in terms of an adjustable light ring unit for operating the camera module. Due to the layered structure, the dimensions, in particular the thickness, of the actuator unit can be minimized, thereby achieving a thin form factor.

In a possible implementation manner of the second aspect, the conductive fastening member includes: a plurality of first fastening elements, each first fastening element connected to a fastening region, the first fastening elements configured to selectively transmit electrical current from the motherboard to each fastening region such that the fastening regions are electrically activated; a second fastening element connected to the displacement region, the second fastening element configured to receive current from the displacement region so as to be able to selectively electrically activate the actuation arm.

In a possible embodiment, the first fastening element comprises at least one of a rivet, a conductive glue or a spring like member.

In another possible implementation of the second aspect, the monolithic actuator is a first monolithic actuator, the movable element being mechanically interconnected with a first displacement region of the first monolithic actuator; the second fastening element is a second monolithic actuator comprising a second displacement region electrically connected to the first displacement region; the second monolithic actuator is configured to receive current from the first displacement region to enable selective electrical activation of the actuation arm of the first monolithic actuator.

In another possible implementation of the second aspect, the second fastening element is an electrically conductive, elongated elastic element arranged parallel to the displacement axis of the movable element; the second fastening element is configured to exert a force on the displacement region to oppose any displacement due to deformation of the actuation arm upon electrical activation, so that the displacement region may be returned to a rest position upon termination of the electrical activation.

In another possible implementation of the second aspect, the second fastening element is connected to the main plate by a second grounding member arranged at an end of the second fastening element, and the second fastening element comprises a first grounding member arranged between the second grounding members for connection to the displacement region for achieving selective electrical activation of the actuation arm.

In one possible embodiment, the displacement region comprises a hole and the first ground member comprises a clip arranged to interlock with the hole.

In other possible embodiments, the second ground member comprises at least one of a weld, a melt, a rivet, or a conductive paste.

In another possible implementation of the second aspect, the main plate comprises an elongated hole arranged between the first fastening elements. The movable element includes a protruding coupling member and is configured to mechanically interconnect with an actuation component of an adjustable coil unit disposed on an opposite side of the main plate relative to any monolithic actuator. The protruding coupling member is arranged in the elongated hole and is shaped to be movable along the elongated hole between its two shorter sides while being guided by its longer sides, thereby supporting an accurate and guided movement of the movable element.

In another possible implementation manner of the second aspect, the actuator unit further includes a housing adjacent to the main board and having a shape corresponding to the main board. The main plate is arranged between the housing and any monolithic actuator, providing additional mechanical stability to the actuator unit.

In one possible embodiment, the housing is made of sheet metal.

In another possible embodiment, the main board is connected to the housing by arranging adhesive material between its respective adjacent surfaces.

In another possible embodiment, the plurality of first fastening elements are configured to interconnect the housing, the motherboard, and any monolithic actuator.

In another possible implementation manner of the second aspect, the motherboard further comprises an electrical terminal for connecting to a current supply. This supports direct, simple and reliable actuation of the monolithic actuator.

In a possible embodiment, the motherboard is a printed wiring board, such as a flexible printed circuit board.

According to a third aspect, there is provided an iris system comprising: an actuator unit according to any one of the possible implementations of the second aspect;

An adjustable aperture unit includes an actuation 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 actuation part.

This solution of the iris system comprises the advantages previously mentioned for the actuator unit compared to the prior art and allows a very compact assembly with respect to the iris system and simple and direct actuation by a single-piece actuator by means of a movable element. This in turn makes room for other unrelated components and/or may reduce the size of the electronic device.

In a possible implementation of the third aspect, the movable element is connected to the actuation part by a protruding coupling member, thereby achieving a secure connection.

In another possible implementation manner of the third aspect, the adjustable coil unit has a circular periphery; and the actuator unit is bent into a curved shape having a radius corresponding to a radius of the outer circumference of the adjustable coil unit. This may allow the assembly to have as small overall dimensions as possible.

According to a fourth aspect, a method of operating an iris system comprising an adjustable aperture unit and an actuator unit is provided. The adjustable aperture unit comprises an actuation member for adjusting the size of the aperture area of the adjustable aperture unit, wherein the actuator unit comprises a monolithic actuator and a movable element; the movable element is connected to the actuation part of the adjustable coil unit. The method comprises the following steps: a first portion of the monolithic actuator is activated such that a first deformation of the monolithic actuator is produced, the first deformation displacing the movable element from a first position to a second position.

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

Such a method includes operating the iris system with minimal components, making it cost-effective and reliable in use. The deformation-based actuation provides ease of shaping, a thin form factor, generates large forces and long travel distances for actuator applications, and silences operation, and does not interfere with other VCM actuators, such as OIS and AF systems, in the vicinity of the electromagnetic field. Furthermore, due to the flexible movement of the movable element, the aperture area can be flexibly adjusted.

In a possible implementation manner of the fourth aspect, the method further includes the following steps: a second portion of the monolithic actuator is activated such that a second deformation of the monolithic actuator is produced that moves the movable element from the second position to a third position in an opposite direction relative to the first deformation. The aperture area having a third size and/or a third shape when the movable element is in the third position; and the third position likelihood includes the first position.

This supports the bi-directional driving capability of the system by which the aperture blades in the iris system can be closed and opened to a certain extent when required.

In another possible implementation manner of the fourth aspect, the method further includes the following steps: deactivating the monolithic actuator, the deactivating returning the monolithic actuator to an undeformed shape, the returning moving the movable element from the second position or the third position to the first position such that no separate return control or return inducing assembly is required.

In another possible implementation manner of the fourth aspect, the method further includes the following steps: changing the activation of the first or second portion of the monolithic actuator causes a change in deformation of the monolithic actuator, the change in deformation displacing the movable element, thereby causing a stepwise displacement of the movable element by the monolithic actuator.

In another possible implementation of the fourth aspect, the activating comprises providing a first current to at least one actuation arm of the monolithic actuator, the deactivating comprises not providing the first current to the actuation arm, and the varying of the actuation comprises providing a second current to the actuation arm, the second current having a different intensity than the first current, thereby supporting precise control of the actuator by providing a different current.

These and other aspects will be apparent from and elucidated with reference to the embodiments described hereinafter.

Drawings

In the following detailed description of the invention, aspects, embodiments and implementations are explained in detail with reference to exemplary embodiments shown in the drawings, in which:

FIG. 1 illustrates a front view of a monolithic actuator provided by an example of an embodiment of the present invention;

FIG. 2 illustrates a front view of an actuator unit including a monolithic actuator when assembled as provided by an example of an embodiment of the present invention;

FIG. 3 illustrates a top view of a curved sheet actuator unit including a monolithic actuator when assembled as provided by an example of an embodiment of the present invention;

FIG. 4 illustrates a perspective view of the back of a curved sheet actuator unit including a monolithic actuator when assembled as provided by an example of an embodiment of the present invention;

FIG. 5 illustrates a front perspective view of a curved sheet actuator unit including a monolithic actuator when assembled as provided by an example of an embodiment of the present invention;

FIG. 6 shows an exploded view of an actuator unit including a monolithic actuator, a main board, and a housing, as well as other components, provided by an example of an embodiment of the present invention;

FIG. 7A illustrates a top view of an iris system prior to assembly, including an actuator unit and an adjustable aperture unit, provided by an example of an embodiment of the invention;

FIG. 7B illustrates a top view of an assembled iris system including an actuator unit and an adjustable aperture unit provided by an example of an embodiment of the invention;

FIG. 8 illustrates a top view of an assembled iris system including an actuator unit and an adjustable aperture unit provided by various examples of embodiments of the invention;

FIG. 9 illustrates a front view of a portion of an actuator unit including two monolithic actuators provided by another example of an embodiment of the invention;

FIG. 10A illustrates a perspective view of a portion of an actuator unit including two monolithic actuators prior to assembly provided by an example of an embodiment of the present invention;

fig. 10B shows a perspective view of a portion of an actuator unit comprising two monolithic actuators when assembled, as provided by an example of an embodiment of the invention.

Detailed Description

Fig. 7A and 7B illustrate one example of an iris system 15 provided by the present invention. The iris system 15 includes: an actuator unit 11 comprising a movable element 8; and an adjustable aperture unit 12 including an actuating member 14 for adjusting the size of the 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 actuation part 14 by means of a protruding coupling member 13. The actuator unit 11 will be described in detail below.

As shown in the examples of fig. 7A and 7B to 8, the adjustable aperture unit 12 may have a circular outer periphery, and the actuator unit 11 may be bent into a curved shape having a radius corresponding to the outer peripheral radius of the adjustable aperture unit 12, which allows the iris system 15 to have an overall size as small as possible.

The adjustable coil unit 12 itself may include a plurality (e.g., between 3-12) of pivoting blades 18, operated by shared system components configured for mutual placement of the blades 18. The shared system components may be arranged as, for example, circular rotating elements 19, linear guides or cam elements, with a mechanically dynamic connection for each blade 18. This dynamic connection may be based on pivoting, sliding or deforming, which supports radial movement of the blade 18 toward and out of the center point C. Having such shared components allows for easier control and synchronous movement of the vanes 18.

In the example shown, adjusting the angular position of the circular rotating element 19 by moving the actuating member 14 (as indicated by the arrow in fig. 7B) through the movable element 8 of the actuator unit 11 changes the position of the aperture blade 18, thereby adjusting the lens aperture.

The adjustable iris unit 12 may also comprise any known iris diaphragm blade structure with an external coupling connection, whereby the actuator unit 11 may be connected to such coupling connection by the movable element 8, for example by means of the protruding coupling member 13 described above.

Alternatively, as shown in fig. 8, the adjustable aperture unit 12 may house the actuator unit 11 within the outline, resulting in an integrated and non-split architecture of the iris system 15.

The actuator unit 11 (shown in detail in the examples of fig. 2 to 6) may comprise a monolithic actuator 1 (described in further detail below), and a main board 9 comprising a structure for transmitting electric current. In these examples, the monolithic actuator 1 is connected to the main plate 9 by means of an electrically conductive fastening member, and the actuator unit 11 further comprises a movable element 8 mechanically interconnected with the displacement region 3 of the monolithic actuator 1.

These conductive fastening members may comprise a plurality of first fastening elements 5, each first fastening element 5 being connected to a fastening region 2 of the monolithic actuator 1 and configured to selectively transmit an electric current from the main plate 9 to each fastening region 2 such that the fastening region 2 is electrically activated. The first fastening element 5 may comprise rivets, conductive glue and/or spring-like parts.

The electrically conductive fastening member may further comprise a second fastening element 6 connected to the displacement region 3 of the monolithic actuator 1, the second fastening element 6 being configured to receive an electrical current from the displacement region 3, thereby enabling selective electrical activation of the actuation arm 4 of the monolithic actuator 1, as will be described in further detail below.

In the example shown in fig. 2 to 6, the second fastening element 6 is connected to the main plate 9 by means of second grounding members 7B arranged at the ends of the second fastening element 6, the second fastening element 6 further comprising first grounding members 7A arranged between the second grounding members 7B for connection to the displacement region 3 of the monolithic actuator 1. The second grounding member 7B may include a weld, a fuse, a rivet, and/or a conductive paste.

In one example, as shown, the displacement region 3 comprises a hole and the first ground member 7A comprises a clip arranged to interlock with the hole.

As further shown in fig. 4-6, the main plate 9 may comprise elongated holes 17 arranged between the first fastening elements 5. The movable element 8 may further comprise a protruding coupling member 13 and may be configured to mechanically interconnect with an actuation part 14 of an adjustable coil unit 12, said adjustable coil unit 12 being arranged on the opposite side of the main plate 9 with respect to the monolithic actuator 1, as shown in fig. 7A and 7B and fig. 8.

The protruding coupling member 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 shown in fig. 4.

As further shown in fig. 4 to 6, the actuator unit 11 may further include a housing 10 adjacent to the main plate 9 and having a shape corresponding to the main plate 9; the main plate 9 is arranged between the housing 10 and the monolithic actuator 1. The housing 10 may be made of sheet metal.

The main board 9 may be connected to the housing 10 by arranging an adhesive material between its respective adjacent surfaces.

As shown in fig. 3-6, the first fastening element 5 may be configured to interconnect the housing 10, the motherboard 9, and the monolithic actuator 1.

According to the illustrated example of fig. 2 to 6, the motherboard 9 may further comprise electrical terminals 16 for connection to a current supply. The main board 9 may be a printed wiring board, such as a flexible printed circuit (flexible printed circuit, FPC) board.

An example of a monolithic actuator 1 provided by the present invention is shown in fig. 1. The monolithic actuator 1 comprises a plurality of fastening regions 2, which fastening regions 2 are configured to be fastened to a fixation element by means of at least one first fastening element 5, such that the fastening regions 2 can remain stationary during actuation. The monolithic actuator 1 further comprises a displacement region 3, which displacement region 3 is configured to move relative to the fastening region 2 during actuation. The displacement region 3 is configured to mechanically interconnect with the movable element 8. The monolithic actuator 1 further comprises a plurality of actuating arms 4, each actuating arm 4 extending from one fastening region 2 to a displacement region 3. Each actuating arm 4 is configured to deform in response to electrical activation by one of the fastening regions 2. In response to the deformation, the displacement region 3 is moved.

In the example shown in fig. 1 to 6, the displacement region 3 is located between two fastening regions 2, and the two actuating arms 4 extend from the displacement region 3 in different directions, such that each actuating arm 4 extends towards one of the two fastening regions 2. However, in other examples there may be more fastening areas 2 and actuating arms 4.

By providing an equal voltage to a pair of oppositely arranged first fastening elements 5, a symmetrical displacement of the movable element 8 can be produced by moving the displacement region 3 of the monolithic actuator 1 from the centre point shown in fig. 2 to one of the fastening regions 2.

Each actuator arm 4 may also be configured to return to an at least partially undeformed shape and/or further deformed in response to a change in electrical activation, wherein the electrical activation includes providing current to the actuator arm 4 through the fastening region 2, and the change in electrical activation may include changing the intensity of the current, and the electrical deactivation includes not providing current to the fastening region 2.

As shown in fig. 6, the movable element 8 may include one or more protrusions extending from the movable element 8. Correspondingly, the displacement region 3 may comprise a recess, e.g. an annular portion, configured to accommodate one or more protrusions, such that a movement of the displacement region 3 of the monolithic actuator 1 causes a corresponding movement of the corresponding movable element 8 and, subsequently, as shown in fig. 7B, a corresponding movement of the actuation part 14 of the iris system 15.

As mentioned above, the first fastening element 5 may comprise rivets, conductive glue and/or spring-like parts, and the fastening region 2 is preferably directly connected to the main board 9 by the first fastening element 5. The fastening region 2 may comprise an annular portion configured to receive the first fastening element/rivet 5.

The monolithic actuator 1 may be configured to move the shared system component (e.g., as shown in fig. 7A and 7B and 8) of the adjustable coil unit 12 by moving a movable element (e.g., the movable element 8 described above as shown in fig. 2-6) that may mechanically couple the shared system components of the adjustable coil unit 12 through the actuation component 14 as shown in fig. 7A and 7B. The movable element 8 of the actuator unit 11 may be connected to the actuation part 14 by means of a protruding coupling member 13, as shown in fig. 4.

The monolithic actuator 1 may comprise a shape memory material having a one-way shape memory effect or a two-way shape memory effect. The actuation arm 4 may be configured to return to an at least partially undeformed shape, i.e., having a one-way shape memory effect, and/or to be further deformed, i.e., having a two-way shape memory effect, in response to a change in electrical or magnetic activation. The shape memory material may be a shape memory alloy. The bi-directional effect may be achieved by the material responding differently at two different temperatures, the different temperatures being generated by actuation with different intensities.

Thus, the monolithic actuator 1 may be a bi-directional actuator comprising two actuating arms 4 extending in opposite directions from the displacement region 3, each actuating arm 4 extending towards one of the two fastening regions 2, the two actuating arms 4 each being configured to displace the displacement region 3 in one of the two opposite directions.

In a possible example, only the actuation arm 4 comprises a shape memory material, while the fastening region 2 and the displacement may be configured to not deform in response to electrical activation.

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

In one example, the monolithic actuator 1 is a sheet layer extending in at least 2 dimensions between the fastening regions 4, as shown in fig. 2.

Fig. 3 to 6 show examples in which the sheet layer of the monolithic actuator 1 is bent into a curved shape between the fastening regions 2. Such a curved shape is represented by a radius R, which represents the difference in curvature with respect to a straight line between the fastening regions 2. As shown in the examples in fig. 7A and 7B to 8, the curved shape (and thus the radius R) may correspond to the outer circumference (radius) of the adjustable aperture unit 12 of the iris system 15 in a camera module, thereby making the thin and curved form factor particularly suitable for accommodating or integrating onto the iris system in a compact manner.

The actuator arm 4 may comprise a plurality of segments, each extending at an angle relative to an adjacent segment to support deformation of the actuator arm 4 to result in a volute, curve, meandering overall shape. The segments may vary in dimension or in angular placement relative to each other, resulting in displacement of the displacement region 3. The initial angle may be between 45 degrees and 135 degrees, preferably around 90 degrees, when the actuator arm 4 is in the undeformed shape. The segments may be linear, curved, and/or free form segments.

As described above, the monolithic actuator 1 may be connected to the main plate 9 by electrically conductive fastening members, such as a plurality of first fastening elements 5, the plurality of first fastening elements 5 being configured to selectively transmit electrical current from the main plate 9 to each fastening region 2 of the monolithic actuator 1 as described above; and a second fastening element 6 connected to the displacement region 3 and configured to receive an electric current from the displacement region 3, thereby enabling selective electrical activation of the actuation arm 4.

As shown in fig. 2, 5 and 6, the second fastening element 6 may be an electrically conductive, elongated elastic element (e.g. a metal spring) arranged parallel to the displacement axis of the movable element 8 and configured to exert a force on the displacement region 3 against any displacement due to deformation of the actuation arm 4 upon electrical activation, so as to return the displacement region 3 to the rest position at the end of the electrical activation.

According to another example shown in fig. 9 to 10A and 10B, the actuator unit 11 may comprise two monolithic actuators, namely a first monolithic actuator 1A and a second monolithic actuator 1B. In this example, the first monolithic actuator 1A acts as a monolithic actuator, the movable element 8 being mechanically interconnected with the first displacement region 3A of the first monolithic actuator 1A; wherein the second monolithic actuator 1B acts as a second fastening element 6, which second fastening element 6 comprises a second displacement zone 3B electrically connected to the first displacement zone 3A by a compression connection, as shown in fig. 10A. This compressive connection over the displacement area between the layers (two monolithic actuators) can be created with hot pin plastic ribs or conductive glue. In this example, the second monolithic actuator 1B is connected to the main plate 9 by a second grounding member 7B arranged at its extremity (at its fastening region) and is also configured to receive a current from the first displacement region 3A, so as to achieve selective electrical activation of the actuation arm 4 of the first monolithic actuator 1A.

The invention also relates to a method of operating an iris system 15 as shown in fig. 7B, the iris system 15 comprising an adjustable aperture unit 12, the adjustable aperture unit 12 comprising an actuation member 14 for adjusting the size of the aperture area of the adjustable aperture unit 12 and an actuator unit 11 comprising a monolithic actuator 1 and a movable element 8, the movable element 8 being connected to the actuation member 14 as described above.

The method at least comprises the following steps: the first part of the monolithic actuator 1 is activated such that a first deformation of the monolithic actuator 1 is produced, said first deformation displacing the movable element 8 from the first position to the 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 a second size and/or a second shape when the movable element 8 is in the second position.

The method may comprise additional steps. The second part of the monolithic actuator 1 may be activated such that a second deformation of the monolithic actuator 1 is produced, which moves the movable element 8 in the opposite direction (as indicated by the opposite arrow in fig. 7B) with respect to the first deformation 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 third position possibilities include the first position.

The method may further comprise subsequently deactivating the monolithic actuator 1. Deactivation returns the monolithic actuator 1 to the at least partially undeformed shape and the return moves the movable element 8 from the second or third position to the first position.

Correspondingly, the method may further comprise varying the activation of the monolithic actuator 1, for example by varying the intensity of the supplied current, such that a deformation change of the monolithic actuator 1 is produced instead of returning to the undeformed shape. In other words, if the activating comprises providing a first current to at least one actuating arm 4 of the monolithic actuator 1, the deactivating may comprise not providing a first current to the actuating arm 4. Similarly, the variation of activation may include providing a second current to the actuator arm 4, the second current having a different intensity than the first current.

Various aspects and implementations have been described herein in connection with various embodiments. 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 "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 measures 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 (e.g., cross-hatching, arrangement of parts, proportion, degree, etc.) should be read together with the specification, and should be considered a portion of the entire written description of this invention. As used in this description, the terms "horizontal," "vertical," "left," "right," "upward" and "downward," as well as adjectives and derivatives of words such as "horizontal," "right," "upward," etc., refer only to the orientation of the structure as shown when the particular drawing figures are oriented toward 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 the case may be.

Claims

1. A monolithic actuator (1) for operating an adjustable light ring unit of a camera module by displacing a movable element (8), the monolithic actuator (1) comprising:

-a plurality of fastening areas (2) configured to be fastened by at least one first fastening element (5), wherein such fastening causes the fastening areas (2) to remain stationary during actuation;

-a displacement region (3) configured to move relative to the fastening region (2) during actuation, the displacement region (3) being configured to mechanically interconnect with a movable element (8);

-a plurality of actuation arms (4), each actuation arm (4) extending from one fastening region (2) to the displacement region (3);

each actuation arm (4) is configured to deform in response to electrical activation, the displacement region (3) moving in response to the deformation to displace the movable element (8).

2. Monolithic actuator (1) according to claim 1, characterized in that each actuation arm (4) is configured to return to an at least partially undeformed shape and/or to be further deformed in response to a change in the electrical activation.

3. Monolithic actuator (1) according to claim 1 or 2, characterized in that the electrical activation comprises supplying an electrical current to the actuation arm (4) through the fastening region (2).

4. A monolithic actuator (1) according to any one of claims 1 to 3, characterized in that it comprises a shape memory material having a one-way shape memory effect or a two-way shape memory effect.

5. The monolithic actuator (1) according to any one of claims 1 to 4, characterized in that the monolithic actuator (1) is a sheet layer extending in at least 2 dimensions between the fastening regions (4).

6. Monolithic actuator (1) according to claim 5, wherein the foil layer is bent into a curved shape between the fastening areas (2).

7. Monolithic actuator (1) according to any one of claims 1 to 6, wherein each of said plurality of actuating arms (4) comprises a plurality of segments, each extending at an angle to an adjacent segment, supporting deforming said actuating arm (4) so as to displace said displacement region (3).

8. The monolithic actuator (1) according to any one of claims 1 to 7, wherein the monolithic actuator (1) is a bi-directional actuator comprising two actuation arms (4), the two actuation arms (4) extending in opposite directions from the displacement region (3), each actuation arm (4) extending towards one of two fastening regions (2), the two actuation arms (4) each being configured to displace the displacement region (3) in one of the two opposite directions.

9. An actuator unit (11), characterized by comprising:

-a main board (9) comprising a structure for transmitting electric current;

the monolithic actuator (1) according to any one of the preceding claims, the monolithic actuator (1) being connected to the main plate (9) by means of an electrically conductive fastening member;

-a movable element (8) mechanically interconnected with said displacement zone (3) of said monolithic actuator (1).

10. The actuator unit (11) according to claim 9, wherein the electrically conductive fastening member comprises:

-a plurality of first fastening elements (5), each first fastening element (5) being connected to a fastening region (2), the first fastening elements (5) being configured to selectively transmit an electric current from the main board (9) to each fastening region (2) such that the fastening regions (2) are electrically activated;

-a second fastening element (6) connected to the displacement region (3), the second fastening element (6) being configured to receive an electric current from the displacement region (3) so as to be able to selectively electrically activate the actuation arm (4).

11. Actuator unit (11) according to claim 10, wherein,

-the monolithic actuator (1) is a first monolithic actuator (1A) according to claim 8, the movable element (8) being mechanically interconnected with a first displacement region (3A) of the first monolithic actuator (1A); wherein the method comprises the steps of

-the second fastening element (6) is a second monolithic actuator (1B) according to claim 8, comprising a second displacement zone (3B) electrically connected to the first displacement zone (3A); and is also provided with

The second monolithic actuator (1B) is configured to receive a current from the first displacement region (3A) so as to be able to selectively electrically activate the actuation arm (4) of the first monolithic actuator (1A).

12. Actuator unit (11) according to claim 10, wherein said second fastening element (6) is an electrically conductive, elongated elastic element arranged parallel to the displacement axis of said movable element (8); the second fastening element (6) is configured to exert a force on the displacement zone (3) against any displacement due to deformation of the actuation arm (4) upon electrical activation, so as to return the displacement zone (3) to a rest position upon termination of the electrical activation.

13. Actuator unit (11) according to any of the claims 10 or 12, characterized in that,

the second fastening element (6) is connected to the main board (9) by a second grounding member (7B) arranged at the end of the second fastening element (6), and

the second fastening element (6) comprises a first grounding member (7A) arranged between the second grounding members (7B) for connection to the displacement region (3).

14. Actuator unit (11) according to any of the claims 10 to 13, characterized in that,

-the main plate (9) comprises an elongated hole (17) arranged between the first fastening elements (5); wherein the method comprises the steps of

The movable element (8) comprises a protruding coupling member (13) and is configured to mechanically interconnect with an actuation part (14) of an adjustable coil unit (12), the adjustable coil unit (12) being arranged on the opposite side of the main plate (9) with respect to any monolithic actuator (1, 1A, 1B);

the protruding coupling member (13) is arranged in the elongated hole (17) and is shaped to be movable along the elongated hole (17) between its two shorter sides while being guided by its longer sides.

15. The actuator unit (11) according to any of claims 9 to 14, wherein the actuator unit (11) further comprises a housing (10) adjacent to the main plate (9) and having a shape corresponding to the main plate (9); the main plate (9) is arranged between the housing (10) and any monolithic actuator (1, 1A, 1B).

16. An iris system (15), characterized by comprising:

the actuator unit (11) according to any of claims 9 to 15;

an adjustable aperture unit (12) comprising an actuation member (14) for adjusting the size of an aperture area of the adjustable aperture unit (12); wherein the movable element (8) of the actuator unit (11) is connected to the actuation part (14).

17. Iris system (15) according to claim 16, comprising an actuator unit (11) according to claim 14, wherein the movable element (8) is connected to the actuation means (14) by the protruding coupling member (13).

18. The iris system (15) according to any of claims 16 or 17, wherein the adjustable aperture unit (12) has a circular periphery; and the actuator unit (11) is bent into a curved shape having a radius corresponding to a radius of the outer circumference of the adjustable coil unit (12).

19. A method of operating an iris system (15), characterized in that the iris system (15) comprises:

an adjustable aperture unit (12) comprising an actuation member (14) for adjusting the size of an aperture area of the adjustable aperture unit (12);

an actuator unit (11) comprising a monolithic actuator (1) and a movable element (8);

-said movable element (8) is connected to said actuation member (14);

the method comprises the following steps:

-activating a first portion of the monolithic actuator (1) such that a first deformation of the monolithic actuator (1) is produced, said 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 a second size and/or a second shape when the movable element (8) is in the second position.

20. The method of claim 19, further comprising the step of:

-activating a second portion of the monolithic actuator (1) such that a second deformation of the monolithic actuator (1) is produced, the second deformation moving the movable element (8) from the second position to a third position in an opposite direction with respect to the first deformation, the aperture area having a third size and/or a third shape when the movable element (8) is in the third position; wherein the third position likelihood comprises the first position.

21. The method according to claim 19 or 20, further comprising the step of:

-deactivating the monolithic actuator (1), said deactivating returning the monolithic actuator (1) to an undeformed shape, said returning moving the movable element (8) from the second or third position to the first position.

22. The method according to any one of claims 19 to 21, further comprising the step of:

-changing the activation of the first or second part of the monolithic actuator (1) such that a deformation of the monolithic actuator (1) changes, which changes the deformation displacing the movable element (8).

23. The method according to any one of claims 19 to 22, wherein the activating comprises providing a first current to at least one actuation arm (4) of the monolithic actuator (1), the deactivating comprises not providing the first current to the actuation arm (4), and the varying of the actuation comprises providing a second current to the actuation arm (4), the second current having a different intensity than the first current.