WO2022089712A1

WO2022089712A1 - Optical image stabilization device and apparatus comprising such device

Info

Publication number: WO2022089712A1
Application number: PCT/EP2020/079981
Authority: WO
Inventors: Marko Eromaki
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2020-10-26
Filing date: 2020-10-26
Publication date: 2022-05-05
Also published as: EP4217783A1; CN116391152A

Abstract

An optical image stabilization device (1), said device comprising a first frame (2) configured to accommodate an imaging module (3) and a first actuation unit (4) comprising at least one actuator (5). Said actuator (5) comprises a bending arm (5a) and at least one shape memory alloy member (5b) configured to bend said bending arm (5a) such that a free end of said actuator (5) may fasten said first frame (2), thereby generating a pivoting movement of said first frame (2) around a first pivot axis (A1). Said device (1) may comprise a second frame (6), the second frame (6), the first frame (2), and the imaging module (3) being arranged in a nesting arrangement. By differentiating the pivot points for the second frame and the first frame, multi- axial rotational movement is facilitated.

Description

OPTICAL IMAGE STABILIZATION DEVICE AND APPARATUS COMPRISING SUCH DEVICE

TECHNICAL FIELD

The disclosure relates to an optical image stabilization device comprising an imaging module and a frame, the imaging module being accommodated with the frame.

BACKGROUND

Common prior art optical image stabilization systems, such as lens-shift based optical image stabilization, usually suspend the camera module using springs meaning low internal resonation frequencies must be considered. Externally excited vibrations cause suspension spring systems to vibrate since the native system force generation in mobile handset cameras is limited, due to, e.g., the small size of the actuators. Hence, common lens-shift optical image stabilization systems function best for anti-shake operations at lower frequencies, e.g. 2-8 Hz. In practice, this means only hand shaking can be corrected properly.

So called gimbal optical image stabilization, i.e. a rotational or pivoted tilt mechanism, is a highly efficient feature facilitating high quality images and video recordings to be made on mobile handsets, and which can be utilized more efficiently in various active lifestyle, action, or cinematographic situations requiring steady video recordings. Prior art gimbal based optical image stabilization systems typically provide operations around three axes, so called pitch, yaw, and roll movement. The system is usually implemented as an accessory product having separate and chained joints as well as relatively large sized voice coil stepper motors which are able to handle heavier masses.

Gimbal based optical image stabilization systems perform better, in this regard, since they usually do not suspend the camera using springs, wherefore there is no low internal resonation frequency to consider.

Furthermore, gimbal based optical image stabilization systems can also eliminate a significant disadvantage of the lens-shift system, namely the limited correction angle. Gimbal based optical image stabilization systems have no such limitation. Lens-shift optical image stabilization systems can usually only provide around ±1-1.5 degree horizontal and vertical angle correction, making the “wobbling” effect at the image corners less visible especially in video. This effect is caused by optical lens distortion and perspective errors.

Also, once a lens group arranged above an image sensor has been shifted and off-centered from the optical axis, a reduction in sharpness and resolution becomes visible in the images, especially in the corner areas. Lens systems perform best in the center area, and the performance level decreases gradually towards the side edges of the image. Additional error parameters are generated by the actuation system which introduces dynamical (tilt) errors during movement in an x-y plane, further reducing the sharpness and resolution of the image.

Prior art electromagnetic actuation of gimbal based optical image stabilization systems use two voice coil-based actuators for tilting the core camera module. Such actuators have relatively low efficiency, and thus low capability as regards handling relatively large moving masses and produces large angular displacement. Additionally, such systems are limited to movement in the one plane, i.e. two-dimensional movement.

SUMMARY

It is an object to provide an improved optical image stabilization device. 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 an optical image stabilization device, the device comprising a first frame configured to accommodate an imaging module and a first actuation unit comprising at least one actuator. The actuator comprises a bending arm and at least one shape memory alloy member configured to bend the bending arm such that a free end of the actuator may fasten the first frame, thereby generating a pivoting movement of the first frame around a first pivot axis.

This solution provides a miniaturized, simple, and modular rotational architecture for small camera modules, which can provide rotation around one or several rotation axes by means of identical features. The modularity provides a cost-effective system. Furthermore, the system can be divided into several functional parts which work independently or in combination. By utilizing a shape memory alloy member, relatively large angular displacement, > ±5 degrees, and large displacement forces achieved, allowing the architecture to function also with relatively large and heavy camera modules.

In a possible implementation form of the first aspect, the linear force generated by the bending arm onto the first frame pivots the first frame around the first pivot axis, the linear force being directed perpendicular to the first pivot axis. This change of from linear motion to rotational motion facilitates a compact system.

In a further_possible implementation form of the first aspect, the optical image stabilization device further comprises a second frame configured to accommodate the first frame, and/or the imaging module. This allows the optical image stabilization device to pivot around three pivot axes.

In a further possible implementation form of the first aspect, the second frame is configured to accommodate the first frame, and/or the second frame is configured to be accommodated in the first frame, providing maximum flexibility.

In a further possible implementation form of the first aspect, the second frame, the first frame, and the imaging module are arranged in a nesting arrangement, the first frame directly accommodating the imaging module, and the second frame accommodating the first frame and the imaging module, providing a spatially efficient device.

In a further possible implementation form of the first aspect, the optical image stabilization device further comprises a second actuation unit comprising at least one actuator, the actuator comprising a bending arm and at least one shape memory alloy member configured to bend the bending arm such that a free end of the actuator may fasten the first frame or the second frame, thereby generating a pivoting movement of the first frame and/or the second frame around a second pivot axis. This solution provides a miniaturized and simple dual-axis gimbal-based architecture suitable for small camera modules.

In a further possible implementation form of the first aspect, the optical image stabilization device further comprises a third actuation unit comprising at least one actuator, the actuator comprising a bending arm and at least one shape memory alloy member configured to bend the bending arm such that a free end of the actuator may fasten the first frame or the second frame, thereby generating a pivoting movement of the first frame and/or the second frame around a third pivot axis, allowing the architecture to provide rotation around three axes.

In a further possible implementation form of the first aspect, the first pivot axis, the second pivot axis, and/or the third pivot axis extends perpendicular to, or parallel with, a main plane of the optical image stabilization device.

In a further possible implementation form of the first aspect, the second pivot axis extends perpendicular to the first pivot axis, and/or the third pivot axis extends perpendicular to the first pivot axis and the second pivot axis.

In a further possible implementation form of the first aspect, the first actuation unit may fasten the first frame, and thereby generate a pivoting movement of the first frame around the first pivot axis, the second actuation unit may fasten the first frame, and thereby generate a pivoting movement of the first frame around the second pivot axis, and the third actuation unit may fasten the second frame, and thereby generate a pivoting movement of the second frame and the first frame simultaneously around the third pivot axis, the first frame, the second frame the first actuation unit, and the second actuation unit being operably coupled to a first printed wiring board, the third actuation unit being operably coupled to a second printed wiring board. This allows for a compact device which can provide rotation in all directions.

In a further possible implementation form of the first aspect, the third pivot axis extends in parallel with an optical axis of the imaging module, and the first pivot axis and the second pivot axis extend in a first actuation plane perpendicular to the optical axis and the third pivot axis, the first actuation plane being parallel with a main plane of the second printed wiring board, the second frame being pivotally coupled to the second printed wiring board, allowing the pivoting movement can be individualized around one or several axes at once.

In a further possible implementation form of the first aspect, the first frame is pivotally connected to the second frame by means of a center pivot point, the center pivot point being aligned with the optical axis and comprising a protrusion extending from the first printed wiring board or extending from the first frame in the direction of the optical axis. Hence, dual-axis rotational movement is provided by means of a device is as simple and non-complex as possible. In a further possible implementation form of the first aspect, the second frame is pivotally connected to the second printed wiring board by means of an offset pivot point, the offset pivot point being arranged externally to the second frame such that the second frame is pivotable in the first actuation plane.

In a further possible implementation form of the first aspect, the optical image stabilization device further comprises a least one flexible interface between the first actuation unit, the second actuation unit, and/or the third actuation unit and one of the printed wiring boards, a flexible interface between the imaging module and one of the printed wiring boards, and/or current supply to the first actuation unit, the second actuation unit, and/or the third actuation unit.

In a further possible implementation form of the first aspect, the first actuation unit, the second actuation unit, and/or the third actuation unit comprises a first actuator and a second actuator, the actuators of each actuation unit being arranged on opposite sides of the pivot axis related to the actuation unit. This facilitates fully individual operation of the actuators while taking advantage of the modularity of the components.

In a further possible implementation form of the first aspect, the bending arm is electrically conductive and operatively coupled to the shape-memory alloy member, a first end of the bending arm being fixed, and a second end of the bending arm being arranged to move freely and to engage with the first frame and/or the second frame.

In a further possible implementation form of the first aspect, the bending arm is arranged between two shape-memory alloy members in the actuation plane, and wherein one end of the bending arm is arranged to move freely in the plane upon being pulled by one of the shapememory alloy members. This allows a reduction in the number of actuators since one actuator can operate in two directions.

In a further possible implementation form of the first aspect, the optical image stabilization device further comprises electric couplings connected to the actuation unit, the actuation unit being configured to conduct an amount of electric current through one of the shape-memory alloy members such that the shape-memory alloy member contracts along its length, bending the bending arm.

In a further possible implementation form of the first aspect, the at least one shape-memory alloy member is a wire, rod, or strip with a circular, triangular, rectangular, or polygonal crosssection.

In a further possible implementation form of the first aspect, the first actuator, the second actuator and/or the third actuator comprises a first shape memory alloy member and a second shape memory alloy member, the first shape memory alloy member being configured to bend the bending arm in a first direction, the second shape memory alloy member being configured to bend the bending arm in a second direction, the second direction being opposite to the first direction.

In a further possible implementation form of the first aspect, the first actuator and/or the second actuator comprises a third shape memory alloy member and a fourth shape memory alloy member, the third shape memory alloy member being configured to bend the bending arm in a third direction, the fourth shape memory alloy member being configured to bend the bending arm in a fourth direction, the first direction and the second direction extending in the first actuation plane, and the third direction and the fourth direction extending in a second actuation plane perpendicular to the first actuation plane. This allows one single actuator to generate rotational movement around two pivot axes, reducing the number of actuators needed.

In a further possible implementation form of the first aspect, the first frame and/or the second frame comprises at least one protrusion, the free end of the actuator fastening the first frame and/or the second frame by means of the protrusion. This allows for a simple and stable connection with the actuator.

In a further possible implementation form of the first aspect, the optical image stabilization device further comprises at least one housing arranged externally to the first frame and/or the second frame, one first actuation unit and/or one second actuation unit being connected to the printed wiring boards by means of the housing(s). Such a housing does not interfere with the rotational movement of any of the other components. In a further possible implementation form of the first aspect, the optical image stabilization device further comprises a position detection arrangement configured to detect an angular position of the second frame, the position detection arrangement optionally comprising at least one magnet arranged on the second frame and at least one hall-sensor arranged on the printed wiring board.

According to a second aspect, there is provided an apparatus comprising the optical image stabilization device according to the above, and an imaging module at least partially accommodated within the optical image stabilization device. By providing a miniaturized, simple, and modular rotational architecture to be used with small imaging modules, even small mobile handsets can be used to capture high quality images and video recordings.

In a possible implementation form of the second aspect, the imaging module comprises a gyroscope unit, allowing for an improved detection of the angular position of the imaging module.

According to a third aspect, there is provided a method for stabilizing an optical image, the method comprising the steps of providing a first frame configured to accommodate an imaging module, providing a first actuation unit comprising at least one actuator, the actuator comprising a bending arm and at least one shape memory alloy member, providing a current to the first actuation unit, the current being conducted through the shape memory alloy member such that the shape-memory alloy member contracts along its length, the contraction generating a bending of the bending arm such that a free end of the actuator may fasten the first frame, and thereby generating a pivoting movement of the first frame around a first pivot axis.

This method facilitates provision of a miniaturized, simple, and modular rotational architecture for small camera modules, which can provide rotation around at least one rotation axis by means of identical features. The modularity provides a cost-effective system. Furthermore, the system can be divided into several functional parts which work independently or in combination. By utilizing a shape memory alloy member, relatively large angular displacement, > ±5 degrees, and large displacement forces achieved, allowing the architecture to function also with relatively large and heavy camera modules. In a possible implementation form of the third aspect, the method further comprises the subsequent or simultaneous steps of providing a second frame configured to accommodate the first frame and/or the imaging module, providing a second actuation unit comprising at least one actuator, the actuator comprising a bending arm and at least one shape memory alloy member, providing a current to the second actuation unit, the current being conducted through the shape memory alloy member such that the shape-memory alloy member contracts along its length, the contraction generating a bending of the bending arm such that a free end of the actuator may fasten the first frame or the second frame, and thereby generating a pivoting movement of the first frame and/or the second frame around a second pivot axis. This solution provides a miniaturized and simple dual-axis gimbal-based architecture suitable for small camera modules.

In a further possible implementation form of the third aspect, the method further comprises the subsequent or simultaneous steps of providing a third actuation unit comprising at least one actuator, the actuator comprising a bending arm and at least one shape memory alloy member, providing a current to the third actuation unit, the current being conducted through the shape memory alloy member such that the shape-memory alloy member contracts along its length, the contraction generating a bending of the bending arm such that a free end of the actuator may fasten the first frame or the second frame, and thereby generating a pivoting movement of the first frame and/or the second frame around a third pivot axis. This allows the optical image stabilization device to pivot around three pivot axes.

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 perspective view of an apparatus comprising an optical image stabilization device according to an embodiment of the present invention;

Figs. 2a to 2c show perspective, side, and top views of an actuator of an optical image stabilization device according to an embodiment of the present invention; Figs. 3a and 3b show a perspective view and a side view of an actuator of an optical image stabilization device according to an embodiment of the present invention;

Figs. 4a to 4c show perspective and side views of an actuator of an optical image stabilization device according to an embodiment of the present invention;

Figs. 5a and 5b show a top view and a perspective view of an actuator of an optical image stabilization device according to an embodiment of the present invention;

Figs. 6a to 6c show a perspective view and exploded views of an optical image stabilization device according to an embodiment of the present invention;

Fig. 7a shows a perspective view of an apparatus comprising an optical image stabilization device according to an embodiment of the present invention;

Figs. 7b and 7c show top views of the embodiment of Fig. 7a, when the first and second frames of the optical image stabilization device are in a non-pivoted position as well as in a pivoted position;

Fig. 8 shows an exploded view of an optical image stabilization device according to an embodiment of the present invention;

Fig. 9 shows a perspective view of part of an optical image stabilization device according to an embodiment of the present invention;

Figs. 10a and 10b show perspective views of an optical image stabilization device according to an embodiment of the present invention;

Figs. I la and 11b show perspective views of an optical image stabilization device according to an embodiment of the present invention;

Figs. 12a and 12b show a top view and a perspective view of an apparatus comprising an optical image stabilization device according to an embodiment of the present invention; Figs. 13a and 13b show a perspective view and a side view of an apparatus comprising an optical image stabilization device according to an embodiment of the present invention.

DETAILED DESCRIPTION

Fig. 1 shows an apparatus 19 comprising an optical image stabilization device 1 and an imaging module 3 at least partially accommodated within the optical image stabilization device 1. The imaging module 3 may be any suitable type of conventional camera module, and the optical image stabilization device 1 is used for stabilizing (mainly) the imaging module 3 in view of, for example, externally excited vibrations. The imaging module 3 may be provided with a gyroscope unit 20, as shown in Fig 9, assisting in the control of the angular movement of the optical image stabilization device 1 and hence the imaging module 3. The apparatus 19 may furthermore comprise a flexible interface 14 connecting the imaging module 3 with at least one printed wiring board 1 la, 1 lb. The flexible interface 14 may be a flexible printed circuit (FPC) and may be provided with a longitudinal slit improving the flexibility of the interface 14 and hence reducing the stress applied onto the optical image stabilization device 1 and the imaging module 3 as they pivot during movement.

Figs. 7a to 7c, 12a, 13a, and 13b show embodiments of the above-mentioned apparatus 19, the features of which will be discussed in more detail below.

The optical image stabilization device 1, shown in more detail in Figs. 6a to 6c, 8, 10a, 10b, I la, 11b, and 12b, comprises at least a first frame 2 configured to accommodate the imaging module 3, and a first actuation unit 4 comprising at least one actuator 5. The optical image stabilization device 1 may further comprise a second actuation unit 7 comprising at least one actuator 8. The optical image stabilization device 1 may also comprise a third actuation unit 9 comprising at least one actuator 10. Fig. 6c shows a first actuation unit 4 and a second actuation unit 7, while Fig. 8 shows a third actuation unit 9.

The optical image stabilization device 1 may comprise a second frame 6 configured to accommodate the first frame 2, and/or the imaging module 3. The second frame 6 may be configured to accommodate the first frame 2, or the second frame 6 may be configured to be accommodated in the first frame 2. The second frame 6, the first frame 2, and the imaging module 3 may be arranged in a nesting arrangement, for example the first frame 2 directly accommodating the imaging module 3, and the second frame accommodating the first frame 2 and the imaging module 3. For ease of reading, the following description will presuppose this specific configuration even though other configurations, including use of only one frame 2, 6, are equally possible.

The first frame 2 and the second frame 6 may comprise a sheet metal material such as stainless steel. The first frame 2 may have a bottom and a rim, such that the frame 2 has a bowl-shape accommodating the imaging module 3. The second frame 6 may comprise a rim fixed to a printed wiring board I la, such that the frame 6 and the printed wiring board I la together have a bowl-shape accommodating the first frame 2 and the imaging module 3.

As shown in Figs. 2a, 2b, 3a, 3b, 4a, 4b, 4c, 5a and 5b, the actuator 5 comprises a flexible bending arm 5a and at least one shape memory alloy member 5b configured to bend the bending arm 5 a such that a free end of the actuator 5 may fasten the first frame 2.

By using the term “fasten”, any temporary or constant physical contact is included. For example, the fastening of a free end of an actuator to a frame may comprise transfer of linear force, from the actuator to the frame, via direct engagement. The fastening may be unidirectional, such that there is a fastening and application of force in one actuation direction, or bidirectional, such that there is fastening an application of force in two opposite actuation directions.

The bending of the bending arm 5a generates a linear force applied onto the first frame 2 at the point of fastening, which in turn generates a pivoting movement of the first frame 2 around a first pivot axis Al.

Correspondingly, the actuator 8 may comprise a bending arm 8a and at least one shape memory alloy member 8b configured to bend the bending arm 8a such that a free end of the actuator 8 may fasten the first frame 2 or the second frame 6. The Figs, show the actuator 8 fastening, i.e. engaging, the first frame 2. The bending of the bending arm 8a generates a linear force applied onto the first frame 2, and/or the second frame 6, at the point of fastening, which in turn generates a pivoting movement of the first frame 2 which in turn generates a pivoting movement of at least the first frame 2 around a second pivot axis A2. Furthermore, the actuator 10 may comprise a bending arm 10a and at least one shape memory alloy member 10b configured to bend the bending arm such that a free end of the actuator 10 may fasten the first frame 2 or the second frame 6. The Figs, show the actuator 10 fastening, i.e. engaging, the second frame 6. The bending of the bending arm 10a generates a linear force applied onto the second frame 6, or the first frame 2, at the point of fastening, which in turn generates a pivoting movement of the first frame 2 and/or the second frame 6 around a third pivot axis A3.

Even though the Figs, and the description describes a first frame 2 accommodating an imaging module 3, a first actuation unit 4 and a second actuation unit 7 generating pivoting movement of the first frame 2, as well as a second frame 6 accommodating the first frame 2 and the imaging module 3, and a third actuation unit 9 generating pivoting movement of the second frame 6, any combination of frame and actuation units is possible. For example, a first actuation unit 4 and a third actuation unit 9 may be utilized to pivot a first frame 2 only. A first actuation unit 4 may be utilized to pivot a first frame 2, while a third actuation unit 9 may be utilized to pivot a second frame 6. A first actuation unit 4 and a second actuation unit 7 may be utilized to pivot a first frame 2.

As shown in Fig. 8, the first actuation unit 4 may comprise two actuators 5, the second actuation unit 7 may comprise two actuators 8, and the third actuation unit 9 may comprise two actuators 10. As shown in Figs. 10a and 10b, the optical image stabilization device 1 may comprise a first actuation unit 4 comprising one actuator 5, a second actuation unit 7 comprising one actuator 8, and a third actuation unit 9 comprising one actuator 10. Any combination of one and two actuators is also possible.

The relatively small contraction of the shape memory alloy member 5b, 8b produces a relatively large displacement of the free end of the bending arm 5a, 8a. This large linear displacement is subsequently converted into angular movement around a first pivot point located under, or rather aligned with, the imaging module 3. The first pivot point allows pivoting around the first pivot axis Al and the second pivot axis A2, in other words x-tilt and y-tilt, also referred to as pitch and yaw. Correspondingly, the relatively small contraction of the shape memory alloy member 10b produces a relatively large displacement of the free end of the bending arm 10a. In order to achieve pivoting around the third pivot axis A3, i.e. a so-called roll effect, a second pivot point is placed outside the pitch and yaw system, i.e. not aligned with the imaging module 3. The second pivot point coincides with the third pivot axis A3.

The first frame 2 and/or the second frame 6 may comprise at least one protrusion 16, the free end of the actuator fastening the first frame 2 and/or the second frame 6 by means of the protrusion 16. The protrusions 16 are shown in Figs. 6c and 10a to 11b. As the bending arm 5a, 8a, 10a bends, it may engage, i.e. push downwards or laterally onto the protrusion 16 in one actuation direction, generating a pivoting movement of the frame 2, 6 in question. The protrusion 16 may also comprise a loop or similar, such that as the bending arm 5a, 8a, 10a bends in an opposite direction, or returns to the initial unbent position, it may engage, i.e. push upwards or laterally onto an opposite section of the protrusion 16 in an opposite actuation direction, also generating a pivoting movement of the frame 2, 6. The protrusion may have any suitable shape as long as it is configured to engage the free end of an actuator.

The bending arm 5a, 8a, 10a may be electrically conductive and operatively coupled to the shape-memory alloy member 5b, 8b, 10b, such that a first end of the bending arm 5a, 8a, 10a is fixed, and a second end of the bending arm, i.e. the free end of the actuator, is arranged to move freely, as indicated with arrows in Figs. 2b, 2c, 3a, and 5b, and is arranged to engage with the first frame 2 and/or the second frame 6.

The optical image stabilization device 1 may further comprise electric couplings connected to first actuation unit 4, the second actuation unit 7, and/or the third actuation unit 9, each actuation unit 4, 7, 9 being configured to conduct an amount of electric current to its shapememory alloy member(s) 5b, 8b, 10b, such that the shape-memory alloy member 5b, 8b, 10b contracts along its length, subsequently bending the bending arm 5a, 8a, 10a. The shapememory alloy member 5b, 8b, 10b may be a wire, a rod, or a strip with a circular, a triangular, a rectangular, or a polygonal cross-section.

Fig. 1 shows an apparatus 19 wherein the optical image stabilization device 1 can generate rotation around as much as three pivot axes, i.e. a first pivot axis Al, a second pivot axis A2, and a third pivot axis A3. The second pivot axis A2 may extend perpendicular to the first pivot axis Al, and the third pivot axis A3 may extend perpendicular to the first pivot axis Al and the second pivot axis A2. The first pivot axis Al, the second pivot axis A2, and/or the third pivot axis A3 may extend perpendicular to, or parallel with, a main plane of the optical image stabilization device.

The linear force generated by a bending arm 5a, 8a onto the first frame 2 may pivot the first frame 2 around the first pivot axis Al or the second pivot axis A2, the linear force being directed perpendicular to the first pivot axis Al or the second pivot axis A2. Correspondingly, the linear force generated by the bending arm 10a onto the second frame 6 may pivot the second frame 6 around the third pivot axis A3, the linear force being directed perpendicular to the third pivot axis A3.

In Fig. 1, the axes are shown in a specific configuration, nevertheless this is merely an example embodiment. The first pivot axis Al may be any one of the axes shown and, correspondingly, the second pivot axis A2 and the third pivot axis A3 can be any of the other axes. The pivot axes Al, A2, A3 usually extend perpendicular to each other, however, there may be some deviation such that they extend at other angles than exactly 90° to each other.

As mentioned, the first actuation unit 4 may fasten the first frame 2, and thereby generate a pivoting movement of the first frame 2 around the first pivot axis Al . The second actuation unit 7 may also fasten the first frame 2 and generate a pivoting movement of the first frame 2 around the second pivot axis A2. The third actuation unit 9 may fasten the second frame 6, and thereby generate a pivoting movement of the second frame 6 and the first frame 2 simultaneously around the third pivot axis A3. Figs. 7a and 7b shows the first frame 2 and the second frame 6 in a non-rotated position. Fig. 7c shows the first frame 2 and the second frame 6 rotated concurrently around one of the pivot axes Al, A2, A3. The top drawing of Fig. 6b shows the first frame 2 and the second frame 6 in a non-rotated position, while the bottom drawing of Fig. 6b shows the first frame 2 rotated around one of the pivot axes Al, A2, A3 with regards to the second frame 6.

The first frame 2, the second frame 6, the first actuation unit 4, and the second actuation unit 7 may be operably coupled to a first printed wiring board I la, while the third actuation unit 9 may be operably coupled to a second printed wiring board 1 lb. This is shown in more detail in Figs. 6c and 8. The first printed wiring board I la may be connected to the bottom of the second frame 6, such that the first printed wiring board I la and the second frame 6 together enclose the first frame 2. The second printed wring board 1 lb may form the base of the device, onto which the first printed wiring board I la, the frames 2, 6 and the third actuation unit 9 are provided.

The optical image stabilization device 1 may further comprise at least one housing 17, as shown in Figs. 2a to 5b and 10a to 11b. The housing(s) 17 may be arranged externally to the first frame 2 and/or the second frame 6, and the first actuation unit 4 and/or the second actuation unit 6 may be connected to one of the printed wiring boards I la, 1 lb by means of the housings 17. The housing(s) 17 may comprise of plastic and be provided with at least one wire crimp element which also functions as an electric coupling, i.e. power connection terminal, through which current is provided to the shape-memory alloy member 5b, 8b, 10b.

The first actuator 5 and the second actuator 8 may be attached to the same housing 17, as shown in Figs. I la and 1 lb, the housing 17 preferably being arranged adjacent a corner of the second frame 6 and the first actuator 5 and the second actuator 8 extending perpendicular to each other along one side of the second frame 6 each.

Each actuator 5, 8, 10 may also be attached to individual housings 17, as shown in Figs. 2a to 5b, 10a, and 10b.

The optical image stabilization device 1 may further comprise a position detection arrangement 18 configured to detect an angular position of the second frame 6, and subsequently the first frame 2 and imaging module 3.

The position detection arrangement 18 may be any suitable arrangement. In one embodiment, the position detection arrangement 18 comprises at least one magnet 18a arranged on the second frame 6 and at least one hall-sensor 18b arranged on the printed wiring board 1 la as indicated in Fig. 6c. One position detection arrangement 18 may be aligned with each protrusion 16. Additional monitoring, i.e. self-sensing, of the behavior of the shape-memory alloy member 5b, 8b, 10b can be performed by using its own characteristics, e.g. open loop control can be implemented by measuring wire resistance during activation.

The third pivot axis A3 may extend in parallel with an optical axis O of the imaging module 3, and the first pivot axis Al and the second pivot axis A2 extend in a first actuation plane Pl perpendicular to the optical axis O and the third pivot axis A3. The first actuation plane Pl may be parallel with a main plane of the second printed wiring board 1 lb, and the second frame 6 may be pivotally coupled to the second printed wiring board 1 lb as shown in Fig. 8.

The first frame 2 may be pivotally connected to the second frame 6 by means of a center pivot point, the center pivot point being aligned with the optical axis O and/or the first actuation plane Pl. The center pivot point may comprise a protrusion 12 extending from the first printed wiring board I la, not shown, or extending from the bottom of the first frame 2 in the direction of the optical axis O, as shown in Figs. 6c, 7b, 7c, and 8.

The second frame 6 may be pivotally connected to the second printed wiring board 1 lb by means of an offset pivot point, the offset pivot point being arranged externally to the second frame 6 as shown in Figs. 7b to 8. This allows the second frame 6 to be pivoted in the first actuation plane Pl.

The optical image stabilization device 1 may further comprise a least one flexible interface 13a, 13b extending between the first actuation unit 4, the second actuation unit 6, and/or the third actuation unit 9 and one of the printed wiring boards 1 la, 1 lb, as shown in Figs. 6a to 6c, 8, and 10a to 13a. The flexible interface 13a, 13b may comprise stainless steel or titanium copper and is configured to allow partial rotational movement around the first pivot axis Al, the second pivot axis A2, and/or the third pivot axis A3. The optical image stabilization device 1 may also comprise a flexible interface 14 between the imaging module 3 and one of the printed wiring boards I la, 11b, as shown in Figs. 9 and 13b. The optical image stabilization device 1 may also comprise a current supply 15 to the first actuation unit 4, the second actuation unit 6, and/or the third actuation unit 9, as shown in Fig. 6c. The flexible interfaces 13a, 13b, and/or 14 may comprise a flexible printed circuit (FPC) provided with a longitudinal slit improving the flexibility of the interface 13a, 13b, 14 and hence reducing the stress applied onto the first frame 2, the second frame 6, and/or the imaging module 3 as they move.

The first actuation unit 4, the second actuation unit 6, and/or the third actuation unit 9 may comprise a pair of actuators, i.e. a first actuator 5, 8, 10 and a second actuator 5, 8, 10. The two actuators 5, 8, 10 of each such actuation unit 4, 7, 9 are arranged on diametrically opposite sides of the pivot axis Al, A2, A3 related to the respective actuation unit 4, 7, 9. This is shown in best detail in Figs. 6c, 7b to 8, 12a, and 12b. Each actuator 5, 8, 10 may be configured to actuate in only one direction, as shown in Figs. 2b, 2c. For example, the one actuator 5, 8, 10 may be configured to actuate in a first actuation direction, while a further actuator 5, 8, 10, in a pair of actuators, may be configured to actuate in a second actuation direction. Each actuator 5, 8, 10 may also be configured to actuate in both actuation directions, as shown in Figs. 3a and 5b.

The first actuator 5, the second actuator 8, and/or the third actuator 10 may comprise a first shape memory alloy member 5b, 8b, 10b and a second shape memory alloy member 5b, 8b, 10b, i.e. a pair of shape memory alloy members as show in Figs. 3a, 3b, 5a, and 5b. The first shape memory alloy member 5b, 8b, 10b may be configured to bend the bending arm 5a, 8a, 10a in the first actuation direction, while the second shape memory alloy member 5b, 8b, 10b may be configured to bend the bending arm 5a, 8a, 10a in the second actuation direction, the second direction being opposite to the first direction. The bending arm 5a, 8a, 10a may be arranged between two shape-memory alloy members 5b, 8b, 10b, in a second actuation plane P2, and one end of the bending arm 5a, 8a, 10a may be arranged to move freely in the second actuation plane P2 upon being pulled by one of the shape-memory alloy members 5b, 8b, 10b.

In one embodiment (not shown), the first actuator 5 and/or the second actuator 8 comprises also a third shape memory alloy member 5b, 8b and a fourth shape memory alloy member 5b, 8b, the third shape memory alloy member 5b, 8b being configured to bend the bending arm 5a, 8a in a third actuation direction and the fourth shape memory alloy member 5b, 8b being configured to bend the bending arm 5a, 8a in a fourth actuation direction. The third direction and the fourth direction extend in the first actuation plane Pl, and the first direction and the second direction extend in the second actuation plane P2 perpendicular to the first actuation plane Pl, as shown in Figs. 3a and 5b.

The present invention also relates to a method for stabilizing an optical image by means of an optical image stabilization device 1. The method comprises the steps of providing a first frame 2 configured to accommodate an imaging module 3 and providing a first actuation unit 4 comprising at least one actuator 5, the actuator 5 comprising a bending arm 5a and at least one shape memory alloy member 5b. Current is provided to the first actuation unit 4, the current being conducted through the shape memory alloy member 5b such that the shape-memory alloy member 5b contracts along its length. The contraction generates a bending of the bending arm 5 a such that the free end of the actuator 5 may fasten the first frame 2, and thereby generate a pivoting movement of the first frame 2 around the first pivot axis Al.

The method may comprise the subsequent, or simultaneous, steps of providing a second frame 6 configured to accommodate the first frame 2 and/or the imaging module 3, and providing a second actuation unit 7 comprising at least one actuator 8, the actuator 8 comprising a bending arm 8a and at least one shape memory alloy member 8b. Current is provided to the second actuation unit 7, the current being conducted through the shape memory alloy member 8b such that the shape-memory alloy member 8b contracts along its length. The contraction generates a bending of the bending arm 8a such that the free end of the actuator 8 may fasten the first frame 2 or the second frame 6, and thereby generate a pivoting movement of the first frame 2 and/or the second frame 6 around the second pivot axis A2.

The method may further comprise the subsequent or simultaneous steps of providing a third actuation unit 9 comprising at least one actuator 10, the actuator 10 comprising a bending arm 10a and at least one shape memory alloy member 10b. Current is provided to the third actuation unit 9, the current being conducted through the shape memory alloy member 10b such that the shape-memory alloy member 10b contracts along its length. The contraction generates a bending of the bending arm 10a such that the free end of the actuator 10 may fasten the first frame 2 or the second frame 6, and thereby generate a pivoting movement of the first frame 2 and/or the second frame 6 around the third pivot axis A3.

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. 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.

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.

Claims

1. An optical image stabilization device (1), said device comprising

-a first frame (2) configured to accommodate an imaging module (3);

-a first actuation unit (4) comprising at least one actuator (5); said actuator (5) comprising a bending arm (5a) and at least one shape memory alloy member (5b) configured to bend said bending arm (5a) such that a free end of said actuator (5) may fasten said first frame (2), thereby generating a pivoting movement of said first frame (2) around a first pivot axis (Al).

2. The optical image stabilization device (1) according to claim 1, further comprising a second frame (6) configured to accommodate said first frame (2), and/or said imaging module (3).

3. The optical image stabilization device (1) according to claim 1 or 2, further comprising a second actuation unit (7) comprising at least one actuator (8), said actuator (8) comprising a bending arm (8a) and at least one shape memory alloy member (8b) configured to bend said bending arm (8a) such that a free end of said actuator (8) may fasten said first frame (2) or said second frame (6), thereby generating a pivoting movement of said first frame (2) and/or said second frame (6) around a second pivot axis (A2).

4. The optical image stabilization device (1) according to claim 3, further comprising a third actuation unit (9) comprising at least one actuator (10), said actuator (10) comprising a bending arm (10a) and at least one shape memory alloy member (10b) configured to bend said bending arm such that a free end of said actuator (10) may fasten said first frame (2) or said second frame (6), thereby generating a pivoting movement of said first frame (2) and/or said second frame (6) around a third pivot axis (A3).

5. The optical image stabilization device (1) according to claim 3 or 4, wherein said second pivot axis (A2) extends perpendicular to said first pivot axis (Al), and/or said third pivot axis (A3) extends perpendicular to said first pivot axis (Al) and said second pivot axis (A2).

6. The optical image stabilization device (1) according to any one of claims 2 to 5, wherein said first actuation unit (4) may fasten said first frame (2), and thereby generate a pivoting movement of said first frame (2) around said first pivot axis (Al), said second actuation unit (7) may fasten said first frame (2), and thereby generate a pivoting movement of said first frame (2) around said second pivot axis (A2), and said third actuation unit (9) may fasten said second frame (6), and thereby generate a pivoting movement of said second frame (6) and said first frame (2) simultaneously around said third pivot axis (A3), said first frame (2), said second frame (6), said first actuation unit (4), and said second actuation unit (7) being operably coupled to a first printed wiring board (I la), said third actuation unit (9) being operably coupled to a second printed wiring board (1 lb).

7. The optical image stabilization device (1) according to any one of the previous claims, wherein said third pivot axis (A3) extends in parallel with an optical axis (O) of said imaging module (3), and said first pivot axis (Al) and said second pivot axis (A2) extend in a first actuation plane (Pl) perpendicular to said optical axis (O) and said third pivot axis (A3), said first actuation plane (Pl) being parallel with a main plane of said second printed wiring board (1 lb), said second frame (6) being pivotally coupled to said second printed wiring board (1 lb).

8. The optical image stabilization device (1) according to claim 7, wherein said first frame (2) is pivotally connected to said second frame (6) by means of a center pivot point, said center pivot point being aligned with said optical axis (O) and comprising a protrusion (12) extending from said first printed wiring board (I la) or extending from said first frame (2) in the direction of said optical axis (O).

9. The optical image stabilization device (1) according to claim 7 or 8, wherein said second frame (6) is pivotally connected to said second printed wiring board (1 lb) by means of an offset pivot point, said offset pivot point being arranged externally to said second frame (6) such that said second frame (6) is pivotable in said first actuation plane (Pl).

10. The optical image stabilization device (1) according to any one of the previous claims, further comprising a least one flexible interface (13a, 13b) between said first actuation unit (4), said second actuation unit (6), and/or said third actuation unit (9) and one of said printed wiring boards (I la, 11b), a flexible interface (14) between said imaging module (3) and one of said printed wiring boards (I la, 1 lb), and/or current supply (15) to said first actuation unit (4), said second actuation unit (6), and/or said third actuation unit (9).

11. The optical image stabilization device (1) according to any one of the previous claims, wherein said first actuation unit (4), said second actuation unit (6), and/or said third actuation unit (9) comprises a first actuator (5, 8, 10) and a second actuator (5, 8, 10), the actuators (5, 8, 10) of each actuation unit (4, 7, 9) being arranged on opposite sides of the pivot axis (Al, A2, A3) related to said actuation unit (4, 7, 9).

12. The optical image stabilization device (1) according to any one of the previous claims, wherein said first actuator (5), said second actuator (8) and/or said third actuator (10) comprises a first shape memory alloy member (5b, 8b, 10b) and a second shape memory alloy member (5b, 8b, 10b), said first shape memory alloy member (5b, 8b, 10b) being configured to bend the bending arm (5a, 8a, 10a) in a first direction, said second shape memory alloy member (5b, 8b, 10b) being configured to bend said bending arm (5a, 8a, 10a) in a second direction, said second direction being opposite to said first direction.

13. The optical image stabilization device (1) according to claim 12, wherein said first actuator (5) and/or said second actuator (8) comprises a third shape memory alloy member (5b, 8b) and a fourth shape memory alloy member(5b, 8b), said third shape memory alloy member (5b, 8b) being configured to bend the bending arm (5a, 8a) in a third direction, said fourth shape memory alloy member (5b, 8b) being configured to bend said bending arm (5a, 8a) in a fourth direction, said third direction and said fourth direction extending in said first actuation plane (Pl), and said first direction and said second direction extending in a second actuation plane perpendicular to said first actuation plane (Pl).

14. The optical image stabilization device (1) according to any one of the previous claims, wherein said first frame (2) and/or said second frame (6) comprises at least one protrusion (16), said free end of said actuator fastening said first frame (2) and/or said second frame (6) by means of said protrusion (16).

15. The optical image stabilization device (1) according to any one of the previous claims, further comprising at least one housing (17) arranged externally to said first frame (2) and/or said second frame (6), one first actuation unit (4) and/or one second actuation unit (6) being connected to one of said printed wiring boards (I la, 1 lb) by means of said housing(s) (17).

16. The optical image stabilization device (1) according to any one of claims 2 to 15, further comprising a position detection arrangement (18) configured to detect an angular position of said second frame (6), said position detection arrangement (18) optionally comprising at least one magnet (18a) arranged on said second frame (6) and at least one hall-sensor (18b) arranged on said printed wiring board (I la).

17. An apparatus (19) comprising the optical image stabilization device (1) according to any one of claims 1 to 16, and an imaging module (3) at least partially accommodated within said optical image stabilization device (1).

18. The apparatus (19) according to claim 17, wherein said imaging module (3) comprises a gyroscope unit (20).

19. A method for stabilizing an optical image, said method comprising the steps of: -providing a first frame (2) configured to accommodate an imaging module (3);

-providing a first actuation unit (4) comprising at least one actuator (5), said actuator (5) comprising a bending arm (5a) and at least one shape memory alloy member (5b);

-providing a current to said first actuation unit (4), said current being conducted through said shape memory alloy member (5b) such that said shape-memory alloy member (5b) contracts along its length, said contraction generating a bending of said bending arm (5a) such that a free end of said actuator (5) may fasten said first frame (2), and thereby generating a pivoting movement of said first frame (2) around a first pivot axis (Al).

20. The method according to claim 19, further comprising the subsequent or simultaneous steps of

-providing a second frame (6) configured to accommodate said first frame (2) and/or said imaging module (3);

-providing a second actuation unit (7) comprising at least one actuator (8), said actuator (8) comprising a bending arm (8a) and at least one shape memory alloy member (8b);

-providing a current to said second actuation unit (7), said current being conducted through said shape memory alloy member (8b) such that said shape-memory alloy member (8b) contracts along its length, said contraction generating a bending of said bending arm (8a) such that a free end of said actuator (8) may fasten said first frame (2) or said second frame (6), and thereby generating a pivoting movement of said first frame (2) and/or said second frame (6) around a second pivot axis (A2).

21. The method according to claim 20, further comprising the subsequent or simultaneous steps of

-providing a third actuation unit (9) comprising at least one actuator (10), said actuator (10) comprising a bending arm (10a) and at least one shape memory alloy member (10b);

-providing a current to said third actuation unit (9), said current being conducted through said shape memory alloy member (10b) such that said shape-memory alloy member (10b) contracts along its length, said contraction generating a bending of said bending arm (10a) such that a free end of said actuator (10) may fasten said first frame (2) or said second frame (6), and thereby generating a pivoting movement of said first frame (2) and/or said second frame (6) around a third pivot axis (A3).