Drive device and system for providing a movement of an image sensor for image stabilization

Abstract

The invention relates to a drive device (10) for providing a movement of an image sensor (5) for image stabilization, comprising: – a beam (30) designed to be deflectable at least in one plane, – at least two piezoelectric strips (20) formed on the beam (30) so that the surface (25) of said strips lies in the plane, the latter being substantially parallel to the image sensor plane.

Description

[0001] Description

[0002] title

[0003] Drive device and system for providing movement of an image sensor for image stabilization

[0004] The invention relates to a drive device for providing movement of an image sensor for image stabilization. Furthermore, the invention relates to a system for this purpose.

[0005] State of the art

[0006] It is known from the prior art, particularly in the context of smartphone camera modules, that image stabilization can be achieved by shifting the image chip instead of the lens. Voice coil and S MA drives are used in combination with mechanical spring elements for this purpose. However, these mechanical combinations can lead to structures with high tolerances, which increases the technical complexity and reduces the yield.

[0007] An alternative solution is MEMS, which combines a capacitive actuator and a spring system. However, manufacturing is technologically challenging and more expensive due to the large area required.

[0008] Generic solutions are also known from the documents EP 1 719 012 B9, EP 3 745 482 B1, US 11 ,635,632 B2 and WO 2023 / 277958 A1.

[0009] Disclosure of the invention

[0010] The subject matter of the invention is a drive device having the features of claim 1 and a system having the features of claim 6. Further features and details of the invention emerge from the respective subclaims, the description, and the drawings. Features and details described in connection with the drive device according to the invention naturally also apply in connection with the system according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is always made to each other.

[0011] The invention particularly relates to a drive device for providing movement of an image sensor for image stabilization. Image stabilization can be used for cameras, e.g., those of smartphones, to compensate for camera movements by mechanically changing the image section. For this purpose, sensors in the camera or smartphone can be used, for example, to detect camera movements and adjust the image stabilization accordingly. This prevents blurred images and achieves better image quality.

[0012] The drive device can comprise a beam that is designed to be deflectable, preferably in at least one plane. The beam, or one of these at least one planes, can be (substantially) parallel to an image sensor plane of the image sensor. Accordingly, the surface of the image sensor can lie in the image sensor plane. The drive device can provide a drive for the deflection of the image sensor via the beam.

[0013] For the purposes of this invention, "parallel" also means "essentially parallel." This means that the protection naturally extends to insignificant, minor deviations from a perfect parallel alignment.

[0014] Furthermore, the drive device can have at least or exactly two piezoelectric strips. The strips can each be formed and / or arranged on the beam so that their surface lies in the or a plane that is (substantially) parallel to the or an image sensor plane of the image sensor. In other words, the strips can be formed and / or arranged such that their surface lies in the plane parallel to the image sensor plane when used for image stabilization in the installed state. Preferably, the described orientation, in which the surfaces of the strips lie in a plane parallel to the image sensor plane, can be provided in a resting state of the strips.

[0015] By controlling the stripes, it may be possible for the stripes to change mechanically - especially outside the resting state -, for example to contract or lengthen, and thereby set the bar in motion in at least one direction within a plane parallel to the image sensor plane.

[0016] The area of ​​the respective strips can be defined, in particular, as the area that occupies the largest part of the strip and is, if applicable, bounded by the surrounding areas. The area of ​​the image sensor can be defined in the same way.

[0017] Furthermore, the piezoelectric strips can be provided on the deflectable beam to effect the deflection of the beam in a plane, and in particular limited to the plane parallel to the image sensor plane and / or parallel to the plane in which the surfaces of the strips lie, and thus generate the movement of the image sensor as a planar movement of the image sensor. This provides the advantage of providing greater accuracy with improved driving force for an image stabilization system. The planar movement can also be referred to as movement within the image sensor plane or in directions within the image sensor plane.

[0018] Furthermore, within the scope of the invention, it can be provided that the drive device is designed as a micromechanical drive device, preferably for integration into a micromechanical system and / or into a system according to the invention. The piezoelectric strips can each be formed as a thin film on the beam, in particular produced by a coating on the surface of the beam. This has the advantage that the high precision of MEMS can be combined with the powerful drive of piezo technology. MEMS stands for "Micro-Electro-Mechanical Systems" and refers in particular to microscopically small mechanical components that are generally used in electronic devices and systems. Within the scope of the invention, MEMS can be used, for example, for camera systems for optical image stabilization.

[0019] According to the invention, the drive device can advantageously be designed as a piezoelectric drive for a planar movement, i.e., in particular, for a movement within the image sensor plane or a plane parallel thereto. The drive device can be designed such that the movement is essentially limited to the plane. In other words, by limiting it to a planar movement, movement in other directions (out of the plane) can be essentially excluded and / or prevented.

[0020] The drive device can be designed, in particular manufactured, based on a thin-film technology, preferably PZT (abbreviated for lead zirconate titanate), for providing lateral movement. Thin-film technology is understood in particular to be a process for producing thin layers of materials such as metals, semiconductors, or insulators on a substrate. The layers can be created in a vacuum by vapor deposition or sputtering. The advantages of this technology lie in the possibility of specifically influencing the properties of the layers through the selection of materials and thickness. PZT thin-film technology is in particular a process for producing thin layers of piezoceramics, in particular of lead zirconate titanate.

[0021] Furthermore, within the scope of the invention, it is conceivable for the beam to be designed to be deflectable in multiple planes. The deflection of the beam caused by the piezoelectric strips in the / a plane parallel to the image sensor plane can be maximum, at least five times, at least 10 times, or at least 20 times greater than a deflection of the beam in a direction orthogonal to the plane. Accordingly, the movement in the orthogonal direction can be insignificant and can therefore be referred to as a planar movement overall. Optionally, it is conceivable for the piezoelectric strips to be designed as double beams, in particular exactly two, manufactured using PZT thin-film technology. Alternatively or additionally, the strips can be arranged next to one another parallel to the longitudinal direction of the beam in order to reduce the deflection of the beam essentially to the plane parallel to the image sensor plane.This has the advantage that a particularly efficient drive for image stabilization can be provided.

[0022] Furthermore, it is conceivable that the piezoelectric strips are designed to be controlled differently in order to, for example, enlarge and / or shorten the strips and thus deflect the beam. The at least or exactly two piezoelectric strips can preferably be structured on the beam and controlled differently in order to generate the deflection of the beam and thus a movement. The movement can cause the deflection of the beam, for example, in the range from 10 pm to 200 pm, preferably 50 pm to 150 pm. The beam can, for example, have a length in the range from 1 mm to 5 mm, preferably 2 mm to 4 mm. Furthermore, the deflection can be transmitted to a movable element, in particular a sensor carrier, which then carries an imager chip or a part thereof.

[0023] The invention also relates to a system for optical image stabilization in an image sensor. The system can comprise a movably arranged sensor carrier, in particular a stage, which is moved or driven by the beam, in order to hold the image sensor with its surface in the image sensor plane. Furthermore, the system can comprise at least one or more drive devices, preferably according to the invention, for providing movement of the image sensor for image stabilization. The respective drive device can be designed as a micromechanical element for this purpose, preferably for integration into the micromechanical system.

[0024] Furthermore, the respective drive device can have a beam, which is preferably designed to be deflectable and preferably deflectable at least in one plane that is in particular parallel to an image sensor plane of the image sensor. Furthermore, at least two piezoelectric strips can be provided in the respective drive device, which are preferably designed to lie with their surface in or in a plane that is parallel to the image sensor plane. The piezoelectric strips can be provided on the deflectable beam in order to effect the deflection of the beam in a / the plane that is parallel to the image sensor plane, and thus to generate the movement of the image sensor as a planar movement of the image sensor. The system according to the invention thus brings with it the same advantages as have been described in detail with reference to a drive device according to the invention.

[0025] Optionally, it can be provided that a resilient suspension of and / or for the sensor carrier is provided, which has a higher rigidity in a direction orthogonal to a plane that is parallel to the image sensor plane than in at least one direction within the plane. To enable this, the suspension can, for example, have a spring system, e.g. with one or more leaf springs. According to a further possibility, it can be provided that the system is designed as a micromechanical system, preferably as a micro-electro-mechanical system, into which the plurality of drive devices, preferably at least two or at least four or at least six drive devices, are integrated in order to move the image sensor attached to the sensor carrier. The surface of the image sensor can lie in the image sensor plane.This means, in particular, that the sensor carrier can be designed such that it holds the image sensor with its surface in the image sensor plane. The respective drive device can also be designed as a micromechanical drive element. In other words, the respective drive device can be designed such that it can be integrated into a MEMS structure. The MEMS (microelectromechanical system) can improve the accuracy of a spring system and thus the positioning, and in particular, simultaneously realize contacting. Furthermore, the drive function can also be integrated into the MEMS.

[0026] Furthermore, within the scope of the invention, it can be provided that the piezoelectric strips are designed such that the deflection of the beam is essentially limited to the / a plane that is parallel to the image sensor plane in order to generate the planar movement of the image sensor attached to the sensor carrier as a movement in the image sensor plane.

[0027] Further advantages, features, and details of the invention will become apparent from the following description, which describes embodiments of the invention in detail with reference to the drawings. The features mentioned in the claims and in the description may be essential to the invention individually or in any combination. They show:

[0028] Fig. 1 Parts of a drive device according to embodiments of the invention in a plan view.

[0029] Fig. 2 Parts of a drive device according to embodiments of the invention in a side view.

[0030] Fig. 3 Parts of a drive device according to embodiments of the invention in a perspective view.

[0031] Fig. 4 Parts of a drive device according to embodiments of the invention in a schematic plan view.

[0032] Fig. 5 Parts of a system according to embodiments of the invention.

[0033] Fig. 1 illustrates, according to embodiments of the invention, a drive device 10 for providing a movement of an image sensor 5 for image stabilization. In this case, a beam 30 is shown on a substrate 50, which is designed to be deflectable in at least one plane. This plane can be substantially parallel to an image sensor plane of the image sensor 5 - shown only schematically in Fig. 5. Furthermore, at least two piezoelectric strips 20 are shown, which are formed on the beam 30 so that their surface 25 also lies in a plane that is substantially parallel to the image sensor plane. The piezoelectric strips 20 can be provided on the deflectable beam 30, preferably as a layer on the beam 30, in order to effect the deflection 60 of the beam 30 in a plane that is substantially parallel to the image sensor plane, in order to thereby generate a planar movement of the image sensor 5. The strips 20 are, for example,formed as a thin layer on the beam 30, which is preferably achieved by a coating on the surface of the beam 30. This has the advantage that an improved, in particular low-torsion movement of the beam is enabled and movement out of the plane can be minimized.

[0034] Fig. 2 shows a side view of the described design of the drive device 10. In conjunction with Fig. 1, a basic idea becomes clear: two piezoelectric strips 20 are structured on a thin beam 30, which can be controlled differently. For example, the piezoelectric strips can be enlarged in the direction of arrow a and contracted in the direction of arrow b. In particular, the piezoelectric strips 20 can be designed so that, in a rest state, their surface 25 lies in the plane that is essentially parallel to the image sensor plane, and can be controlled differently from the rest state for enlargement a and shortening b.

[0035] Fig. 3 shows further exemplary details of the drive device 10. The strips can have a width w in the range from 1 pm to 100 pm, preferably 8 pm to 80 pm, more preferably 10 pm to 40 pm. The width w refers in particular to the extent of the strips in the direction x indicated by an arrow in Fig. 3. In this case, x can also indicate the direction of the "desired movement", i.e. in particular the direction of the deflection of the bar 30. A plane that is essentially parallel to the image sensor plane can extend in the directions x and y.

[0036] Furthermore, a thickness tp of the strips 20 can be in the range from 0.1 pm to 8 pm, preferably 1 pm to 4 pm, more preferably 2 pm to 4 pm. The thickness tb of the beam 30 can be in the range from 1 pm to 4 pm, preferably substantially 2 pm. An edge distance d marked in Fig. 3 is, for example, substantially 10 pm. An extension b of the substrate 50 in the y-direction is, for example, substantially 80 pm, although other dimensions are also conceivable. In tests, the described embodiments have each proven advantageous in achieving a possible deflection of the beam 30 in the range from 150 µm to 300 µm. One aim here is to minimize the difference in the z-direction (|UZmax - Uzmin|), i.e., the torsional component. In the present case, this can, for example, be in the range from 7 pm to 288 pm.In this way, a drive device 10 is obtained in which the piezoelectric strips 20 are formed on the deflectable beam 30 such that the deflection 60 of the beam 30 is effected in a plane that is substantially parallel to the image sensor plane, thereby generating a planar movement of the image sensor 5. In particular, this enables the deflection 60 of the beam 30 in a plane that is substantially parallel to the image sensor plane to be maximal, at least five times, at least 10 times, or at least 20 times greater, compared to a deflection of the beam 30 in a direction orthogonal to this plane.

[0037] Figs. 4 and 5 illustrate a system 1 for optical image stabilization in an image sensor 5 according to embodiments of the invention. In addition to one or more of the described drive devices 10, a movably arranged sensor carrier 6 may be provided to hold the image sensor 5. Furthermore, a resilient suspension 40 of the sensor carrier 6 may be provided, which has a higher rigidity in a direction orthogonal to the plane than in at least one direction within the plane.

[0038] In Fig. 4, a rigid force transmission is further indicated by two arrows 401 for the beam drive. A movable frame 402 and a spring-loaded suspension 40 are also shown. The suspension can be rigid in the z-direction, but flexible in the direction of the desired movement. This allows for a two-dimensionally movable stage to be provided.

[0039] The above explanation of the embodiments describes the present invention exclusively by way of examples.

[0040] Of course, individual features of the embodiments can be freely combined with one another, provided that this is technically reasonable, without departing from the scope of the present invention.

Claims

Claims 1 . Drive device (10) for providing a movement of an image sensor (5) for image stabilization, comprising: a beam (30) which is designed to be deflectable at least in one plane, at least two piezoelectric strips (20) which are designed on the beam (30) in order to lie with their surface (25) in a plane which is substantially parallel to an image sensor plane of the image sensor (5), characterized in that the piezoelectric strips (20) are provided on the deflectable beam (30) in order to effect the deflection (60) of the beam (30) in a plane which is substantially parallel to the image sensor plane in order to thereby generate the movement of the image sensor (5) as a planar movement of the image sensor (5).

2. Drive device (10) according to claim 1, characterized in that the drive device (10) is designed as a micromechanical drive device (10) in order to be integrated into a micromechanical system (1), wherein the piezoelectric strips (20) are each formed as a thin film on the beam (30).

3. Drive device (10) according to one of the preceding claims, characterized in that the beam (30) is designed to be deflectable in several planes, wherein the deflection (60) of the beam (30) caused by the piezoelectric strips (20) in the plane which is substantially parallel to the image sensor plane, in comparison to a deflection of the beam (30) in a direction orthogonal to this plane is maximum, at least five times or at least 10 times or at least 20 times as large.

4. Drive device (10) according to one of the preceding claims, characterized in that the piezoelectric strips (20) are designed as two double beams produced on the basis of a PZT thin-film technology, which are arranged next to one another substantially parallel to the longitudinal direction of the beam (30) in order to reduce the deflection (60) of the beam (30) substantially to a plane which is substantially parallel to the image sensor plane.

5. Drive device (10) according to one of the preceding claims, characterized in that the piezoelectric strips (20) are designed to lie in a rest state with their surface (25) in a plane which is substantially parallel to the image sensor plane, and to be controlled differently from the rest state in order to enlarge and / or shorten the strips (20) respectively and thus deflect the beam (30).

6. A system (1) for optical image stabilization in an image sensor (5), comprising: a movably arranged sensor carrier (6) for holding the image sensor (5) with its surface in an image sensor plane, at least one or more drive devices (10) for providing a movement of the image sensor (5) for image stabilization, wherein the respective drive device (10) is designed for this purpose as a micromechanical element, wherein the respective drive device (10) further comprises: a beam (30) which is designed to be deflectable at least in one plane, at least two piezoelectric strips (20) which are formed on the beam (30) in order to lie with their surface (25) in a plane which is substantially parallel to the image sensor plane of the image sensor (5), characterized in that the piezoelectric strips (20) are provided on the deflectable beam (30) to cause the deflection (60) of the beam (30) in a plane which is substantially parallel to the image sensor plane, in order to thereby generate the movement of the image sensor (5) as a planar movement of the image sensor (5).

7. System (1) according to one of the preceding claims, characterized in that the system (1) is designed as a micromechanical system (1) into which the plurality of drive devices (10), namely at least two or at least four or at least six drive devices (10), are integrated in order to move the image sensor (5) fastened to the sensor carrier (6).

8. System (1) according to one of the preceding claims, characterized in that the piezoelectric strips (20) are designed such that the deflection (60) of the beam (30) is substantially limited to a plane which is substantially parallel to the image sensor plane in order to generate the planar movement of the image sensor (5) attached to the sensor carrier (6) as a movement in the image sensor plane.

9. System (1) according to one of the preceding claims, characterized in that a resilient suspension (40) of the sensor carrier (6) is provided, which has a higher rigidity in a direction orthogonal to a plane which is substantially parallel to the image sensor plane than in at least one direction within the plane.

10. System (1) according to one of the preceding claims, characterized in that the respective drive device (10) is designed according to one of claims 1 to 5.

Images