Optical device for carrying an optical element, particularly for pixel shifting

Abstract

The present invention relates to an optical device (1) for carrying an optical element (2), particularly for pixel shifting, the optical device (1) comprising: an optical axis (3), a carrier (4), a frame (5) supported on the carrier via at least one pivot joint (6) allowing the frame to be pivoted about two axes (A, A'), an optical element (2) connected to the frame (5), the optical element comprising a clear aperture (CA), a spring structure (7) connecting the frame to the carrier, and an actuator (M1, M2, C1, C2) configured to generate forces parallel to the optical axis (3) for pivoting the frame (5), wherein the pivot joint (6) is arranged outside the clear aperture (CA) of the optical element (2).

Description

[0001] Optical device for carrying an optical element, particularly for pixel shifting

[0002] The present invention relates to an optical device allowing to tilt an optical element, particularly for pixel shifting.

[0003] Such devices are particularly used to carry and tilt an optical element, e.g. a flat transparent plate with two opposing parallel optical surfaces, between at least two positions. One important application of such a device is a so-called pixel shifter (often abbreviated as XPR) that can be used to increase the resolution of an image projected through the tilting glass plate of the pixel shifter.

[0004] Particularly resolution of an image can be enhanced by moving the image e.g. half of a pixel between image capture and combining the images into a resulting image. The shifting can be accomplished by letting light used to project the image on an image sensor pass through said optical element, e.g., plate, and tilting the latter about a defined axis by a defined angle corresponding, e.g., to the half pixel shift.

[0005] However, for many applications such an optical device must have a particularly small footprint. In particular, often, there is not an isotropic I space available around the optical aperture, i.e., the space available around the optical aperture is different on different sides. Often it is limited on one specific side due to constraints from the optical system of the application.

[0006] Particularly, US 2021 / 0278661 A1 discloses an out-of-plane actuator, i.e., coils and magnets are stacked along the z-direction, wherein a symmetric arrangement of coils and magnets around an optical aperture is provided. The support of the optical element is based on springs that do not provide a fixed Z-position which can lead to a parasitic piston mode of the optical element

[0007] Based on the above, the problem to be solved by the present invention is to provide an optical device that reduces a parasitic piston more of the optical element and particularly allows for omitting an actuator at least along one side of the optical element to allow application of the optical device in case there is no symmetrical space available around the optical aperture.

[0008] The problem underlying the present invention is solved by an optical device having the features of claim 1. Preferred embodiments of this aspect of the present invention are stated in the dependent claims and are described below. According to claim 1 an optical device for carrying an optical element, particularly for pixel shifting, is disclosed, the optical device comprising: an optical axis, a carrier, wherein particularly the optical axis extends perpendicular to the carrier, a frame supported on the carrier via at least one pivot joint allowing the frame to be pivoted about two axes, wherein the frame comprises a fixed position in a direction parallel to the optical axis at the pivot joint, an optical element connected to the frame, the optical element comprising a clear aperture and being pivotable together with the frame, a spring structure connecting the frame to the carrier so as to allow said tilting of the frame and optical element with respect to the carrier about said two axes, and an actuator configured to generate forces parallel to the optical axis for pivoting the frame, wherein the pivot joint is arranged outside the clear aperture of the optical element. Particularly, the pivot joint is arranged further out in a lateral direction running perpendicular to the optical axis than a contour defining the clear aperture.

[0009] Furthermore, according to a preferred embodiment, the axes about which the frame can be pivoted run through the at least one pivot joint.

[0010] According to a preferred embodiment of the present invention, the actuator comprises a first magnet and a second magnet, as well as a first coil and a second coil, wherein the first magnet faces the first coil in the direction of an optical axis of the optical device, and wherein the second magnet faces the second coil in said direction of the optical axis, wherein the first magnet and the second magnet are arranged on the frame, respectively, and the first coil and the second coil are arranged on the carrier, respectively. However, in a preferred embodiment, the first magnet and the second magnet are arranged on the carrier, respectively, and the first coil and the second coil are arranged on the frame, respectively. This interchange of positions of coil and associated magnet can also apply to the embodiments described further below.

[0011] Furthermore, according to a preferred embodiment of the present invention, the clear aperture comprises a contour comprising at least two sections connected by an intermediate section that runs obliquely with respect to said at least two sections.

[0012] According to yet another a preferred embodiment of the present invention, the at least one pivot joint is a single pivot joint, i.e. the optical device comprises only one pivot joint for pivoting the frame. Further, in a preferred embodiment of the present invention, the carrier comprises a first leg having a first end section and an opposing second end section, and wherein the carrier comprises a second leg protruding from the first end section and a third leg protruding from the second end section, wherein the second and the third leg each comprise a free end so that the three legs define a recess for the carrier for the passage of light therethrough, wherein the optical element is arranged in front of the recess or at least partially in the recess. In other words, the carrier essentially comprises a C- shape.

[0013] According to a further preferred embodiment of the present invention, the first coil is arranged on the second leg, and wherein the second coil is arranged on the third leg, and wherein the pivot joint is arranged on the first leg, wherein particularly the spring structure connects the frame to the second leg, and wherein particularly the spring structure connects the frame to the third leg. For this, the spring structure can comprise a first spring element connecting the frame to the second leg, and a further second spring element connecting the frame to the third leg. The spring elements can be integrally formed with the frame.

[0014] According to yet another preferred embodiment of the present invention, the pivot joint is connected to the first leg of the carrier via a first standoff. In addition, or alternatively, the spring structure, particularly the first spring element, is connected to the second leg of the carrier via a (second) standoff. Further, preferably, the spring structure, particularly the second spring element, is connected to the third leg of the carrier via a (third) standoff.

[0015] Furthermore, according to a preferred embodiment of the present invention, the respective standoff is a surface-mounted device (SMD) standoff soldered to the carrier. Alternatively, the standoff can be integrally formed with the frame and / or the carrier.

[0016] According to another preferred embodiment of the present invention, the magnets, coils and the optical element are arranged on the same side of the at least one pivot joint, wherein particularly the at least one pivot joint is a single pivot joint.

[0017] In this regard, according to a preferred embodiment of the present invention, the first coil extends along a first edge of the optical element and wherein the second coil extends along an adjacent second edge of the optical element, the first and the second edge defining a corner region of the optical element, and wherein the at least one pivot joint is arranged on the carrier at a second corner region of the optical element, which second corner region is diagonally opposite the first corner region, or the first coil and the second coil extend one after the other along a first edge of the optical element and the at least one pivot joint is arranged on the carrier at an opposing second edge of the optical element, or the first coil extends along a first edge of the optical element, and the second coil extends along an opposing second edge of the optical element, and wherein the optical device comprises a third coil arranged on the carrier and a third magnet arranged on the frame facing the third coil in the direction of the optical axis, wherein the third coil extends along a third edge of the optical element which third edge is adjacent the first and the second edge, and wherein the at least one pivot joint is arranged on the carrier at a fourth edge of the optical element, which fourth edge is opposite the third edge and adjacent the first and the second edge of the optical element.

[0018] According to yet another preferred embodiment of the present invention, the first coil extends along a first edge of the optical element, and the second coil extends along an adjacent second edge of the optical element, the first and the second edge defining a corner region of the optical element, wherein the at least one pivot joint is arranged on the carrier at the corner region of the optical element.

[0019] Furthermore, according to further preferred embodiment of the present invention, the coils and the magnets are arranged on one side of the at least one pivot joint and the optical element is arranged on the other side of the at least one pivot joint.

[0020] In this regard, in a preferred embodiment of the present invention, the first coil extends along a first edge of the carrier and wherein the second coil extends along an adjacent second edge of the carrier, the first and the second edge defining a corner region of the carrier, and wherein the at least one pivot joint is arranged on the carrier at the corner region, or the first coil and the second coil extend obliquely with respect to a first edge of the carrier and the at least one pivot joint is arranged on the carrier at the first edge, or the first coil extends parallel to a first edge of the carrier, and the second coil extends perpendicular to the first edge of the carrier, and wherein the optical device comprises a third coil arranged on the carrier and a third magnet arranged on the frame facing the third coil in the direction of the optical axis, wherein the third coil extends perpendicular to the first edge of the carrier, and wherein the at least one pivot joint is arranged on the carrier at the first edge of the carrier.

[0021] According to yet another preferred embodiment of the present invention, the first and the second magnet are magnetized parallel to the optical axis.

[0022] Furthermore, in a preferred embodiment of the present invention, the carrier is a printed circuit board, wherein particularly the first and the second coil are integrated into the printed circuit board, e.g., comprise conductive tracks of the printed circuit board.

[0023] According to another preferred embodiment of the present invention, the pivot joint and the centers of the first and the second coil of the actuator define a virtual triangle that comprises an area that is at least 25% of the area of the clear aperture, preferably at least 35% of the area of the clear aperture, preferably at least 50% of the area of the clear aperture.

[0024] According to yet another preferred embodiment of the present invention, the frame comprises a first arm being connected to the pivot joint via a strut, a second arm integrally connected to a first end of the first arm, and a third arm integrally connected to a second end of the first arm, wherein the second and the third arm comprise a width along the extension plane of the optical element that is larger than a width of the first arm, and wherein the spring structure comprises a first meandering spring element and a second meandering spring element, wherein the first meandering spring element connects the end of the second arm of the frame to the carrier (particularly via the second standoff, see above), and wherein the second meandering spring element connects the end of the third arm of the frame to the carrier (particularly via the third standoff), And wherein the frame comprises a gap between the ends of the second and the third arm.

[0025] In a preferred embodiment of the invention, the optical device comprises a spring structure with a first spring element and a second spring element. The first spring element comprises a first flexible portion that connects the second arm of the frame to the carrier. The second spring element comprises a second flexible portion that connects the third arm of the frame to the carrier. The first flexible portion extends essentially parallel to a main extension direction of the second arm of the frame and the second flexible portion extends essentially parallel to a main extension direction of the third arm of the frame. According to the embodiment described above, the second and third arms of the frame are each attached to the carrier by means of a spring element. The first and / or second flexible portions can be designed with simple geometries. In particular, they can each be designed as a bending beam, which deforms as a result of a force of an actuator and thereby exerts a restoring force on the frame. As a result of the parallel orientation of the first and second flexible portions with respect to the second and third arms of the frame, a compact design of the device is possible. Preferably, the frame comprises a gap between the ends of the second and the third arm. It is within the scope of the invention that the spring elements each contain further components in addition to their respective flexible portions, for example a base by means of which the spring elements are directly or indirectly connected to the carrier and / or, for example, a connecting portion between the respective flexible portion and the base.

[0026] In a preferred embodiment, the first flexible portion is attached to the second arm of the frame in a section between the first arm of the frame and an end of the second arm of the frame. Additionally or alternatively, the second flexible portion may be attached to the third arm of the frame in a section between the first arm of the frame and an end of the third arm of the frame.

[0027] According to the embodiment described above, the first or second flexible portion of the respective spring elements may be connected to the second or third arm of the frame in an area which is arranged approximately centrally with respect to the main directions of extension of said arms. Investigations have shown that this kind of arrangement is advantageous in terms of a good ratio between the adjustment force required to tilt the frame and the restoring forces effected by the spring elements.

[0028] In a preferred embodiment, the first flexible portion and / or the second flexible portion is a beam, which in particular is integrally connected to the second arm of the frame or the third arm of the frame respectively. This is particularly advantageous if the frame is designed as a thin-walled sheet, as the first and / or second spring element can be connected to the frame in one piece manner and according to its desired geometry, in particular the geometry of the flexible portion. Preferably, the geometries of the spring elements, especially the flexible portions, can be punched or laser-cut, making it easy to manufacture the parts concerned.

[0029] In a preferred embodiment, the length of the first flexible portion and / or the second flexible portion is chosen such that a ratio of mechanical resonance frequencies of the frame with respect to the two tilting axes is between 1 ,3 and 1 ,8, in particular between 1 ,4 and 1.7, an especially is 1.5. Preferably the resonance frequencies refer not only the frame but the assembly of the frame and the optical element. In other words, preferably there are two resonance frequencies, one of which refers to a rotating motion about one of the two tilting axes and another, which refers to another rotating motion about the other of the two tilting axes. The ratio between these frequencies is within the specified range.

[0030] Investigations by the applicant have shown that the design of the first and second spring elements with the first and second flexible portions, which extend substantially perpendicular to the second and third arms of the frame, is well suited to achieving the specified ratios of the resonance frequencies. Preferably, at least the frame has a higher resonance frequency with respect to the axis that extends in the direction of the optical element than with respect to the axis that extends laterally to the optical element, with both axes intersecting in the pivot joint.

[0031] In particular, the length of the first flexible portion is between 0,2 and 0,7 times the length of the second arm with respect to its main extension direction and / or a length of the second flexible portion is between 0,2 and 0,7 times the length of the third arm with respect to its main extension direction. The applicant's investigations have also shown that the above-mentioned length ranges are particularly advantageous for designing the first and second flexible portions, since the desired dynamic properties of the frame and the optical element held thereby can be achieved, in particular in the form of the aforementioned ratios between the resonance frequencies about the two tilting axes.

[0032] In another preferred embodiment, the spring structure comprises a first spring element and a second spring element, wherein the first spring element comprises a first flexible portion that connects the second arm of the frame to the carrier, and wherein the second spring element comprises a second flexible portion that connects the third arm of the frame to the carrier. The first flexible portion extends perpendicular to a main extension direction of the second arm of the frame and the second flexible portion extends perpendicular to a main extension direction of the third arm of the frame.

[0033] The first and second flexible portions can each be designed as bending beams, which deform as a result of a force of an actuator and thereby exert restoring forces on the frame. Preferably, the frame comprises a gap between the ends of the second and the third arm. It is within the scope of the invention that the spring elements each comprise further components in addition to their flexible portion, for example a base to which it is directly or indirectly connected to the carrier and / or, for example, a connecting portion between the respective flexible portion and the base. Preferably, the first flexible portion is attached to an end of the second arm of the frame, in particular to a protrusion of the second arm, which at least partially extends laterally and / or perpendicular to the main extension direction of the second arm. Additionally or alternatively, the second flexible portion is attached to an end of the third arm of the frame, in particular to a protrusion of the third arm, which at least partially extends laterally and / or perpendicular to the main extension direction of the third arm. The protrusions may be considered as a part or a component of the second and third arms of the frame, respectively, which project towards a gap located between the second and third arms.

[0034] Preferably, the first flexible portion and / or the second flexible portion is a beam, which in particular is integrally connected to the second arm of the frame or the third arm of the frame respectively. As already described above in connection with another embodiment, the flexible portions can be integrally connected to the frame, which can lead to advantages during manufacture.

[0035] In a preferred embodiment, a length of the first flexible portion and / or the second flexible portion is chosen such that a ratio of mechanical resonance frequencies of the frame with respect to the two tilting axes is between 0.9 and 1.1 , in particular between 0.97 and 1.03, especially is 1. In other words, preferably there are two resonance frequencies, one of which refers to a rotating motion about one of the two tilting axes and another, which refers to another rotating motion about the other of the two tilting axes. The ratio between these frequencies is within the specified range. It is a particular advantage of the embodiment that the ratio of the resonance frequencies can lie within the specified ranges and that this can be achieved by a simple geometry of the flexible portions, in particular by designing them as beams.

[0036] In a preferred embodiment, the length of the first flexible portion is between 0,05 and 0,3 times a distance between the second arm and the third arm, in particular between 0.1 and 0.2.

[0037] Further features and advantages of the present inventions as well as embodiments of the present invention shall be described in the following with reference to the Figures, wherein

[0038] Fig. 1 shows a schematic top view of an embodiment of a carrier device according to the present invention for tilting an optical element, particularly in form of a flat transparent plate, about two axes; Fig. 2 shows a schematic cross-sectional view of the optical device shown in Fig. 1;

[0039] Fig. 3 shows a perspective top view onto a further embodiment of an optical device according to the present invention;

[0040] Fig. 4 shows a top view of the optical device of Fig. 3 with the frame carrying the optical element being removed to show the positions of magnets and coils of an actuator of the device;

[0041] Figs. 5A-5D show schematic top views of different embodiments of an optical device according to the present invention wherein the actuator and optical element are arranged on one side of the pivot joint of the device;

[0042] Fig. 6 shows a schematic top view of a further embodiment of an optical device according to the present invention;

[0043] Figs. 7A-7C show schematic top views of different embodiments of an optical device according to the present invention wherein the actuator and the optical element are arranged on different sides of the pivot joint of the device;

[0044] Fig. 8 shows a schematic top view of a further embodiment of an optical device according to the present invention for tilting an optical element, wherein a virtual triangle spanned by the coil centers and pivot point comprises a defined area compared to the area of the clear aperture; and

[0045] Fig. 9 shows a top view onto a frame of an embodiment of an optical device according to the present invention;

[0046] Fig. 10 shows a schematic top view of another embodiment of a carrier device according to the present invention for tilting an optical element;

[0047] Fig. 11 shows a perspective top view onto the embodiment according to Fig. 10;

[0048] Fig. 12 shows a schematic top view of another embodiment of a carrier device according to the present invention for tilting an optical element;

[0049] Fig. 13 shows a perspective top view onto the embodiment according to Fig. 12.

[0050] Fig. 1 shows an embodiment of an optical device 1 for tilting an optical element 2, wherein the device 1 comprises a carrier 4 and a frame member 5 holding the optical element 2. The optical element 2 is preferably designed as a transparent plate 2 (e.g. glass plate) having two opposing planar and parallel surfaces 2a, 2b (cf. detail of Fig. 3). An optical axis 3 of the device extends perpendicular to the carrier 4 and in particular perpendicular to the optical element (when being in a non-tilted state. The carrier 4 can be a printed circuit board (PCB) in a preferred embodiment. The footprint of the carrier 4 can be about 35x35 mm2. Further, the optical element / glass 2 can have a footprint of 20.5x20.5 mm2. In case the clear aperture CA of the optical element is 18x16 mm2in an embodiment, the footprint of the optical element 2 can be even smaller than 20.5x20.5 mm2. The frame 5 is supported on the carrier via a single pivot joint 6 allowing the frame 5 and thus the optical element 2 connected thereto to be pivoted about two axes A, A’ that can both run through the pivot joint 6. Furthermore, by means of the pivot joint 6, the frame 5 comprises a fixed position in a direction (also denoted as z-direction) parallel to the optical axis 3 at the pivot joint 6. This enables the suppression of a parasitic third mode (piston mode) in which the frame and thus the optical element moves back and forth in the z-direction. Furthermore, the device 1 comprises a spring structure 7 connecting the frame 5 to the carrier 4, so as to allow said tilting of the frame 5 and optical element 2 with respect to the carrier about said two axes A, A’.

[0051] As shown in Fig. 1 , the carrier 4 can comprise a first leg 41 having a first end section and an opposing second end section, and a second leg 42 protruding from the first end section and a third leg 43 protruding from the second end section. The second and the third leg 42, 43 each comprise a free end, so that the three legs define a recess 44 of the carrier 4 for the passage of light L therethrough (cf. Fig. 2), wherein the optical element 2 is arranged in front of the recess 44 or at least partially in the recess. Thus, the carrier 4 essentially comprises a C-shape.

[0052] Particularly, the frame 5 is connected on one side to the first leg 41 of the frame via the pivot joint 6. On an opposing side, the spring structure 7 connects the frame to the second and the third leg 42, 43. Particularly, the spring structure 7 comprises a first spring element 73 that can be a meandering spring element 73. Similarly, a second spring element 74 comprised by the spring structure 7 connects the frame 5 to the third leg 43. Also, the second spring element 74 can be a meandering spring element 74.

[0053] Furthermore, the pivot joint 6 is connected to the first leg 41 of the carrier 4 via a first standoff 60. Preferably, the first standoff is an SMD standoff, that is soldered to a pad on the carrier 4. As shown in the schematic cross section of Fig. 2, the standoff 60 provides a defined distance D between the carrier 4 and the frame 5. In a similar fashion, the first spring element 73 is connected to the second leg 42 of the carrier via a second standoff 71 , and the second spring element 74 is connected to the third leg 43 of the carrier via a third standoff 72. Also, here, the standoffs 71 , 72 can be SMD standoffs soldered to a pad on the carrier 4, respectively.

[0054] Furthermore, the pivot joint 6 is arranged outside the clear aperture CA of the optical element 2, i.e., the pivot joint 6 is arranged further out in a lateral direction running perpendicular to the optical axis 3 than a contour 8 of the frame 5 defining the clear aperture CA of the optical element 2. Particularly, the contour 8 of the clear aperture CA comprises at least two sections 80, 82 connected by an intermediate section 81 that runs obliquely with respect to said at least two sections 80, 82. Particularly, as shown in Fig. 1 , the clear aperture CA can comprise four such oblique intermediate sections defining corner regions of the contour 8 of the clear aperture CA.

[0055] For tilting the frame 5 and therewith the optical element 2, the optical device 2 comprises an actuator configured to generate forces parallel to the optical axis 3 for pivoting the frame 5. By pivoting the frame 5 and optical element 2 connected thereto, light passing through the optical element 2 can be shifted by an amount Ax as shown in the detail of Fig. 3 as an example.

[0056] Preferably, in an embodiment shown in Fig. 1 , the actuator comprises a first magnet M1 and a second magnet M2, as well as a first coil C1 and a second coil C2, wherein the first magnet M1 faces the first coil C1 in the direction of the optical axis 3, and wherein the second magnet M2 faces the second coil C2 in said direction of the optical axis 3. Particularly, the first magnet M1 and the second magnet M2 are arranged on the frame 5, respectively, whereas the first coil C1 and the second coil C2 are arranged on the carrier 4. Alternatively, the position of the respective magnet M1 , M2 and its associated coil C1 , C2 can be interchanged. Particularly, in the embodiment shown in Fig. 1 , the first coil C1 is integrated into the second leg 42, and the second coil C2 is integrated into the third leg 43. Preferably, the magnets M1 , M2 are magnetized in a direction parallel to the optical axis 3. Thus, an electrical current flowing through the respective coil C1 , C2 generates a Lorenz force (depending on the direction of the electrical current tin the respective coil C1 , C2) due to the respective opposing magnet M1 , M2. By controlling the electrical current through the coils C1 , C2, the frame 5 and optical element 2 can be pivoted about axis A and / or axis A’ in a controlled fashion, thus achieving the desired pixel shift vector Ax in x and y direction (cf. , e.g., Fig. 1 or 3). Particularly, the embodiment shown in Fig. 1 has the magnets M1 , M2, coils C1 , C2, and the optical element 2 arranged on the same side of the single pivot joint 6. Such configurations are also shown in Figs. 5A to 5D, wherein particularly Fig. 5D shows a configuration of magnets M1 , M2, coils C1 , C2 and optical element 2 that corresponds to the embodiment shown in Fig. 1. Here, the first coil C1 extends along a first edge 21c of the optical element 2, and the second coil C2 extends along an opposing second edge 22c of the optical element 2, and wherein the single pivot joint 6 is arranged on the carrier 4 at a center of the third edge 23c of the optical element 2, which third edge 23c connects the first edge 21c to the second edge 22c.

[0057] Fig. 2 shows in conjunction with Fig. 3 an embodiment alternative to Fig. 1 , wherein here the coils C1 , C2 are arranged at a right angle and not parallel and opposite one another as in the embodiment of Fig. 1 (cf. also Fig. 5D). The configuration of Figs. 2 and 3 is schematically shown in Fig. 5A. According thereto, the first coil C1 extends along a first edge 21 of the optical element 2, and the second coil C2 extends along an adjacent second edge 22 of the optical element 2, wherein the first and the second edge 21 , 22 define a corner region 23 of the optical element 2, and the single pivot joint 6 is arranged on the carrier 4 at a second corner region 24 of the optical element 2, which second corner region 24 is diagonally opposite the first corner region 23.

[0058] Furthermore, in contrast to Fig. 1 , the embodiment of Figs. 2 and 3 does not comprise a C-shaped carrier, but an annular frame surrounding a through-opening 45 for the passage of light therethrough.

[0059] While in the embodiment shown in Fig. 1 , the frame 5 can have an annular shape, particularly providing a clear aperture CA with oblique corner regions 81 , and is connected at three points to the C-shaped frame (namely the two opposing standoffs 71 , 72 connected to the respective spring element 73, 74 and the standoff 60 of the pivot joint 6), the frame 5 of the embodiment shown in Figs. 2 and 3 comprises an alternative design. Here, the frame 5 is connected via the single pivot joint 6 to the carrier 4 and via a further standoff 500, which is arranged diagonally opposite the pivot joint 6. This standoff 500 is connected to a spring structure 7 comprising a connection portion 501 connected to the standoff 500, and strut 502 integrally connected to the frame 5. For forming this spring structure 7, the frame 5 is separated from the spring structure 7 by an elongated slot 503 extending along the connection portion 501 and the strut 502. An end of the strut 502 is integrally connected to the frame 5 at a corner of the frame 5. The strut 502 extends parallel to the first coil C1. Fig. 5B shows a further alternative configuration of the coils C1 , C2, magnets M1 , M2 and optical element 2 in which these components are also all arranged essentially on one side of the single pivot joint 6, wherein here the first coil C1 and the second coil C2 extend one after the other along a first edge 21a of the optical element 2, and the single pivot joint 6 is arranged on the carrier 4 at an opposing second edge 22a of the optical element 2.

[0060] Fig. 5C shows yet another alternative configuration comprising an additional third coil C3 arranged on the carrier 4 compared to the embodiment of Fig. 5D, wherein in Fig. 5C the first coil C1 extends along a first edge 21b of the optical element 2, and the second coil C2 extends along an opposing second edge 22b of the optical element 2. Besides the third coil C3 the optical device 1 comprises a third magnet M3 arranged on the frame 5 (not shown) facing the third coil C3 in the direction of the optical axis 3, wherein the third coil C3 extends along a third edge 23b of the optical element 2 which third edge 23b is adjacent the first and the second edge 21 b, 22b. Here, the single pivot joint 6 is arranged on the carrier 4 at a center of the fourth edge 24b of the optical element 2, which fourth edge 24b is opposite the third edge 23b and adjacent the first and the second edge 21b, 22b of the optical element 2.

[0061] Fig. 6 shows yet another configuration, wherein here the first coil C1 extends along a first edge 21 d of the optical element 2, and the second coil C2 extends along an adjacent second edge 22d of the optical element 2, the first and the second edge 21 d, 22d defining a corner region 23d of the optical element 2, and wherein the single pivot joint 6 is arranged on the carrier 4 at the corner region 23d of the optical element 2.

[0062] Furthermore, Figs. 7A-7C show further configurations, wherein here the coils C1 , C2 (and particularly C3) and the corresponding magnets M1 , M2, M3 are arranged on one side of the single pivot joint 6 whereas the optical element 2 is arranged on the other side of the single pivot joint 6.

[0063] Particularly, in Fig. 7A, the first coil C1 extends along a first edge 401 of the carrier 4 and the second coil C2 extends along an adjacent second edge 402 of the carrier 4, wherein the first and the second edge 401 , 402 define a corner region 403 of the carrier 4, and wherein the single pivot joint 6 is arranged on the carrier 4 at the corner region 403.

[0064] Particularly, in Fig. 7B, the first coil C1 and the second coil C2 extend obliquely with respect to a first edge 401a of the carrier 4 and the single pivot joint 6 is arranged on the carrier 4 at the first edge 401a. Particularly, in Fig. 7C, the first coil C1 extends parallel to a first edge 401 b of the carrier 4, and the second coil C2 extends perpendicular to the first edge 401b of the carrier 4, wherein the optical device 1 comprises a third coil C3 arranged on the carrier 4 and a third magnet M3 arranged on the frame 5 facing the third coil C3 in the direction of the optical axis 3, wherein the third coil C3 extends perpendicular to the first edge 401 b of the carrier 4, and wherein the at least one pivot joint 6 is arranged on the carrier 4 at the first edge 401b of the carrier 4. Please note that for the sake of simplicity, the magnets are not depicted in Figs. 6, 5A-5D, 7A-7C. But their positions can be inferred from the positions of the coils C1 , C2, C3 as the coils C1 , C2, C3 are arranged opposite the respective magnet M1 , M2, M3 in the direction of the optical axis 3 which runs perpendicular to the optical element 2, i.e., perpendicular to the drawing plane of Figs. 6, 5A-5D, 7A-7C.

[0065] Also, in the actuator configurations shown in Fig. 7A-7C, the position of the respective magnet M1 , M2 (and particularly M3) and the associated coil C1 , C2, C3 can be interchanged. Particularly, each configuration has its own, specific transfer function that converts currents in the coils C1 , C2, C3 into motions around the two tilting axes A and A’.

[0066] Furthermore, a control circuit for controlling the application of an electrical current to the respective coil C1 , C2 (and particularly C3) can be provided on the carrier 4 or can be connected thereto, e.g., via a connector 9 (cf. Fig. 1 for example). A corresponding energy source can also be connected to the device in a suitable manner.

[0067] Furthermore, according to the embodiment of the optical device indicated in Fig. 8, the single pivot joint 6, and the centers A1 , A2 of the first and the second coil C1 , C2 define a virtual triangle T that comprises an area that is at least 25% of the area of the clear aperture CA, preferably at least 35% of the area of the clear aperture CA, preferably at least 50% of the area of the clear aperture CA of the optical element 2.

[0068] Furthermore, Fig. 9 shows a top view onto a frame 5 of a preferred embodiment of the optical device 1 of the present invention. According thereto, the frame 5 comprises a first arm 50 being connected to the single pivot joint 6 via a strut 51 , a second arm 52 integrally connected to a first end of the first arm 50, and a third arm 53 integrally connected to a second end of the first arm 50. Preferably, the second 52 and the third arm 53 each comprise a width along the extension plane of the optical element that is larger than a width of the first arm 50. Furthermore, particularly, the spring structure 7 comprises a first meandering spring element 73 and a second meandering spring element 74, wherein the first meandering spring element 73 connects the end of the second arm 52 of the frame 5 to the carrier 4, and wherein the second meandering spring element 74 connects the end of the third arm 53 of the frame 5 to the carrier 4. Further, preferably, the frame 5 comprises a gap 54 between the ends of the second and the third arm 52, 53.

[0069] Summarizing, the present invention offers the advantage that at least along one side of the optical element 2 no actuator needs to be present thus improving usability of the device in tight installation spaces. Furthermore, a piston mode of the frame 5, optical element 2 can be suppressed since the pivot joint 6 fixes the frame in z-direction.

[0070] Fig. 10 shows a device 1 which is used for pixel shifting and, similarly to the embodiment shown in Fig. 1 , comprises a carrier 4 on which a frame 5 is arranged by means of a pivot joint 6. The pivot joint 6 is arranged outside the clear aperture of an optical element 2, which is held by the frame 5. An actuator (not discussed here in detail) is configured to generate forces parallel to an optical axis 3 in order to pivot the frame 5. The pivot joint 6 allows to pivot / tilt the frame 5 together with the optical element 2 about two axes A and A’. It is relevant, that the tilting axes A and A’ intersect outside the clear aperture of the optical element 2.

[0071] A spring structure 7 connects the frame 5 to the carrier 4 and comprises a first spring element 75 and a second spring element 76. The first spring element 75 connects the second arm 52 of the frame 5 to the carrier 4. The second spring element 76 connects the third arm 53 of the frame 5 to the carrier 4. The second arm 52 of the frame 5 extends along a main extension direction 55 and the third arm 53 of the frame 5 extends along a main extension direction 56. Both, the second and third arm 52 and 53 each have a length L0, which refers to the outer edges of the second and third arm with respect to their main extension axes 55, 56.

[0072] The first spring element 75 comprises a first flexible portion 77 and the second spring element 76 comprises a second flexible portion 78, each having a length L1 , which is between 0,2 and 0,7 times the length L0 of the second and third arm with respect to their main extension directions. The first flexible portion 77 and the second flexible portion 78 extend essentially parallel to the second arm 52 and the third arm 53 respectively.

[0073] The lengths of the first flexible portion 77 and the second flexible portion 78 within the specified range allow to set a ratio of mechanical resonance frequencies of the frame with respect to the two tilting axes A and A’ between 1 ,3 and 1 ,8 and in particular to 1 ,5. The resonance frequency with respect to a rotation about axis A’ is higher than the resonance frequency with respect to a rotation about axis A.

[0074] Fig.11 shows the device 1 according to Fig. 10 in a perspective view. The explanations for Fig. 10 therefore apply accordingly.

[0075] Fig. 12 shows another device 1 , which is also used for pixel shifting and, similarly to the embodiments shown in Fig. 10 and 11 , comprises a carrier 4 on which a frame 5 is arranged by means of a pivot joint 6. The pivot joint 6 is arranged outside the clear aperture of an optical element 2, which is held by the frame. An actuator (not shown in detail) is configured to generate forces parallel to an optical axis 3 in order to pivot the frame 5. The pivot joint 6 allows to pivot / tilt the frame 5 together with the optical element 2 about two axes A and A’. It is relevant, that the tilting axes A and A’ intersect outside the clear aperture of the optical element 2.

[0076] A spring structure 7 connects the frame 5 to the carrier 4 and comprises a first spring element 75 and a second spring element 76. The first spring element 75 connects the second arm 52 of the frame 5 to the carrier 4. The second spring element 76 connects the third arm 53 of the frame 5 to the carrier 4. The second arm 52 of the frame 5 extends along a main extension direction 55 and the third arm 53 of the frame 5 extends along a main extension direction 56. The second arm 52 and the third arm 53 are spaced apart from each other by a distance L2, referring to the outer edges of the second arm 52 and third arm 53.

[0077] Similarly to the device 1 as shown in Fig. 10 and 11 , the spring structure 7 comprises a first spring element 75 and a second spring element 76, wherein the first spring element 75 comprises a first flexible portion 77 that connects the second arm 52 of the frame 5 to the carrier 4, and wherein the second spring element 76 comprises a second flexible portion 78 that connects the third arm 53 of the frame 5 to the carrier 4. The first flexible portion 77 extends perpendicular to a main extension direction 55 of the second arm 52 of the frame 5 and the second flexible portion 78 extends perpendicular to a main extension direction 56 of the third arm 53 of the frame 5.

[0078] The lengths of the first and second flexible portions 77, 78 are essentially identical and correspond to L3, which is between 0,05 and 0,3 times a distance L2 that is measurable between the second arm 52 and the third arm 53. These lengths L3 in particular are chosen such that a ratio of mechanical resonance frequencies of the frame with respect to the two tilting axes A and A’ is between 0.9 and 1.1 and may especially be 1. The first flexible portion 77 is attached at an end of the second arm 52 of the frame 5 to a protrusion 57, which extends perpendicular and / or laterally to the main extension direction 55. Furthermore, the second flexible portion 78 is attached at an end of the third arm 53 of the frame 5 to a protrusion 58, which extends perpendicular and / or laterally to the main extension direction 56 of the third arm 53.

Claims

Claims1. An optical device (1) for carrying an optical element (2), particularly for pixel shifting, the optical device (1) comprising: an optical axis (3), a carrier (4), a frame (5) supported on the carrier (4) via at least one pivot joint (6) allowing the frame (5) to be pivoted about two axes (A, A’), an optical element (2) connected to the frame (5), the optical element comprising a clear aperture (CA), a spring structure (7) connecting the frame (5) to the carrier (4), and an actuator (M1 , M2, C1 , C2) configured to generate forces parallel to the optical axis (3) for pivoting the frame (5), wherein the pivot joint (6) is arranged outside the clear aperture (CA) of the optical element (2).

2. The optical device according to claim 1 , wherein the actuator comprises a first magnet (M1) and a second magnet (M2), as well as a first coil (C1) and a second coil (C2), wherein the first magnet (M1) faces the first coil (C1) in the direction of the optical axis (3), and wherein the second magnet (M2) faces the second coil (C2) in said direction of the optical axis (3), wherein the first magnet (M1) and the second magnet (M2) are arranged on the frame (5), respectively, and the first coil (C1) and the second coil (C2) are arranged on the carrier (4), or the first magnet (M1) and the second magnet (M2) are arranged on the carrier (4), respectively, and the first coil (C1) and the second coil (C2) are arranged on the frame (5).

3. The optical device according to claim 1 or 2, wherein the clear aperture (CA) comprises a contour (8) comprising at least two sections (80, 82) connected by an intermediate section (81) that runs obliquely with respect to said at least two sections (80, 82).

4. The optical device according to one of the preceding claims, wherein the at least one pivot joint (6) is a single pivot joint (6).

5. The optical device according to one of the preceding claims, wherein the carrier (4) comprises a first leg (41) having a first end section and an opposing second end section, and wherein the carrier (4) comprises a second leg (42) protruding from the first end section and a third leg (43) protruding from the second end section, wherein the second and the third leg (42, 43) each comprise a free end.

6. The optical device according to claim 5, wherein the first coil (C1) is arranged on the second leg (42), and wherein the second coil (C2) is arranged on the third leg (43), and wherein the pivot joint (6) is arranged on the first leg (41).

7. The optical device according to claim 6, wherein the pivot joint (6) is connected to the first leg (41) of the carrier (4) via a first standoff (60).

8. The optical device according to claim 7, wherein the standoff (60) is an SMD standoff soldered to the carrier (4), or wherein the standoff is integrally formed with the frame (5) and / or the carrier (4).

9. The optical device according to claim 2 or according to one of the claims 3 to 8 insofar referring to claim 2, wherein the magnets (M1 , M2), coils (C1 , C2), and the optical element (2) are arranged on the same side of the at least one pivot joint (6).

10. The optical device according to claim 9, wherein the first coil (C1) extends along a first edge (21) of the optical element (2) and wherein the second coil (C2) extends along an adjacent second edge (22) of the optical element (2), the first and the second edge (21 , 22) defining a corner region (23) of the optical element (2), and wherein the at least one pivot joint (6) is arranged on the carrier (4) at a second corner region (24) of the optical element (2), which second corner region (24) is diagonally opposite the first corner region (23), or the first coil (C1) and the second coil (C2) extend one after the other along a first edge (21a) of the optical element (2) and the at least one pivot joint (6) is arranged on the carrier (4) at an opposing second edge (22a) of the optical element (2), or the first coil (C1) extends along a first edge (21b) of the optical element (2), and the second coil (C2) extends along an opposing second edge (22b) of the optical element (2), and wherein the optical device (1) comprises a third coil (C3) arranged on the carrier (4) and a thirdmagnet (M3) arranged on the frame (5) facing the third coil (C3) in the direction of the optical axis (3), wherein the third coil (C3) extends along a third edge (23b) of the optical element (2) which third edge (23b) is adjacent the first and the second edge (21 b, 22b), and wherein the at least one pivot joint (6) is arranged on the carrier (4) at a fourth edge (24b) of the optical element (2), which fourth edge (24b) is opposite the third edge (23b) and adjacent the first and the second edge (21b, 22b) of the optical element (2).

11. The optical device according to one of the claims 1 to 3, 6 to 9, wherein the first coil (C1) extends along a first edge (21 d) of the optical element (2), and wherein the second coil (C2) extends along an adjacent second edge (22d) of the optical element (2), the first and the second edge (21 d, 22d) defining a corner region (23d) of the optical element (2), and wherein the at least one pivot joint (6) is arranged on the carrier (4) at the corner region (23d) of the optical element (2).

12. The optical device according to one of the claims 1 to 4, wherein the coils (C1 , C2) and the magnets (M1 , M2) are arranged on one side of the at least one pivot joint (6) and the optical element (2) is arranged on the other side of the at least one pivot joint (6).

13. The optical device according to claim 12, wherein the first coil (C1) extends along a first edge (401) of the carrier (4) and wherein the second coil (C2) extends along an adjacent second edge (402) of the carrier (4), the first and the second edge (401 , 402) defining a corner region (403) of the carrier (4), and wherein the at least one pivot joint (6) is arranged on the carrier (4) at the corner region (403), or the first coil (C1) and the second coil (C2) extend obliquely with respect to a first edge (401a) of the carrier (4) and the at least one pivot joint (6) is arranged on the carrier (4) at the first edge (401a), or the first coil (C1) extends parallel to a first edge (401b) of the carrier (4), and the second coil (C2) extends perpendicular to the first edge (401 b) of the carrier (4), and wherein the optical device (1) comprises a third coil (C3) arranged on the carrier (4) and a third magnet (M3) arranged on the frame (5) facing the third coil (C3) in the direction of the optical axis (3), wherein the third coil (C3) extends perpendicular to the firstedge (401b) of the carrier (4), and wherein the at least one pivot joint (6) is arranged on the carrier (4) at the first edge (401b) of the carrier (4).

14. The optical device according to one of the preceding claims, wherein the first and the second magnet (M1 , M2) are magnetized parallel to the optical axis(3).

15. The optical device according to one of the preceding claims, wherein the carrier(4) is a printed circuit board, wherein particularly the first and the second coil (C1 , C2) are integrated into the printed circuit board.

16. The optical device according to claim 2 or according to one of the claims 3 to 15 insofar referring to claim 2, wherein the pivot joint (6), and the centers (A1 , A2) of the first and the second coil (C1 , C2) define a virtual triangle (T) that comprises an area that is at least 25% of the area of the clear aperture (CA), preferably at least 35% of the area of the clear aperture (CA), preferably at least 50% of the area of the clear aperture (CA).

17. The optical device according to one of the preceding claims, wherein the frame(5) comprises a first arm (50) being connected to the pivot joint (6) via a strut (51), a second arm (52) integrally connected to a first end of the first arm (50), and a third arm (53) integrally connected to a second end of the first arm (50), wherein the second and the third arm (52, 53) comprise a width that is larger than a width of the first arm (50), and wherein the spring structure (7) comprises a first meandering spring element (73) and a second meandering spring element (74), wherein the first meandering spring element (73) connects the end of the second arm (52) of the frame (5) to the carrier (4), and wherein the second meandering spring element (74) connects the end of the third arm (53) of the frame (5) to the carrier (4), and wherein the frame (5) comprises a gap (54) between the ends of the second and the third arm (52, 53).

18. The optical device according to at least one of the claims 1 to 16, wherein the spring structure (7) comprises a first spring element (75) and a second spring element (76), wherein the first spring element (75) comprises a first flexible portion (77) that connects the second arm (52) of the frame (5) to the carrier (4), and wherein the second spring element (76) comprises a second flexible portion (78) that connects the third arm (53) of the frame (5) to the carrier (4), wherein the first flexible portion (77) extends essentially parallel to a mainextension direction (55) of the second arm (52) of the frame (5) and / or wherein the second flexible portion (78) extends essentially parallel to a main extension direction (56) of the third arm (53) of the frame (5).

19. The optical device according to claim 18, wherein the first flexible portion (77) is attached to the second arm (52) of the frame (5) in a section between the first arm (50) of the frame (5) and an end of the second arm (52) of the frame (5) and / or wherein the second flexible portion (78) is attached to the third arm (53) of the frame (5) in a section between the first arm (50) of the frame (5) and an end of the third arm (53) of the frame (5).

20. The optical device according to at least one of the claims 18 or 19, wherein the first flexible portion (77) and / or the second flexible portion (78) is a beam, which in particular is integrally connected to the second arm (52) of the frame (5) or the third arm (53) of the frame (5) respectively.

21. The optical device according to at least one of the claims 18 to 20, wherein a length (L1) of the first flexible portion (77) and / or the second flexible portion (78) is chosen such that a ratio of mechanical resonance frequencies of the frame, and in particular the optical element (2), with respect to the two tilting axes (A, A’) is between 1 ,3 and 1 ,8, in particular between 1 ,4 and 1.7, especially is 1.5.

22. The optical device according to at least one of the claims 18 to 21 , wherein a length (L1) of the first flexible portion (77) is between 0,2 and 0,7 times the length (L0) of the second arm (52) with respect to its main extension direction (55) and / or a length (L1) of the second flexible portion (78) is between 0,2 and 0,7 times the length (L0) of the third arm (53) with respect to its main extension direction (56).

23. The optical device according to at least one of the claims 1 to 16, wherein the spring structure (7) comprises a first spring element (75) and a second spring element (75), wherein the first spring element (77) comprises a first flexible portion that connects the second arm (52) of the frame (5) to the carrier (4), and wherein the second spring element (76) comprises a second flexible portion (78) that connects the third arm (53) of the frame (5) to the carrier (4), wherein the first flexible portion (77) extends perpendicular to a main extension direction (55) of the second arm (52) of the frame (5) and wherein the secondflexible portion (78) extends laterally to a main extension direction (56) of the third arm (53) of the frame (5).

24. The optical device according to claim 23, wherein the first flexible portion (77) is attached to an end of the second arm (52) of the frame (5), in particular to a protrusion (57) of the second arm (52), which at least partially extends perpendicular to the main extension direction (55) of the second arm (52) and / or wherein the second flexible portion is (78) attached to an end of the third arm (53) of the frame (5), in particular to a protrusion (58) of the third arm (53), which at least partially extends perpendicular to the main extension direction (56) of the third arm (53).

25. The optical device according to at least one of the claims 23 or 24, wherein the first flexible portion (77) and / or the second flexible portion (78) is a beam, which in particular is integrally connected to the second arm (52) of the frame (5) or the third arm (53) of the frame (5) respectively.

26. The optical device according to at least one of the claims 23 to 25, wherein a length (L3) of the first flexible portion (77) and / or the second flexible portion (78) is chosen such that a ratio of mechanical resonance frequencies of the frame (5), and in particular the optical element (2), with respect to the two tilting axes (A, A’) is between 0.9 and 1.1 , in particular between 0.97 and 1.03, especially is 1.

27. The optical device according to at least one of the claims 23 to 26, wherein a length (L3) of the first flexible portion (77) and / or second flexible portion (78) each is between 0,05 and 0,3 times a distance (L2) between the second arm (52) and the third arm (52), in particular between 0.1 and 0.2.*****

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