MEMS mirror device comprising an aperture

Abstract

The invention relates to an MEMS mirror device for variably deflecting an incident light beam (1), said mirror device comprising a disc-shaped MEMS mirror (2) for reflecting the light beam (1), and a frame (3) surrounding the MEMS mirror (2), wherein the MEMS mirror (2) is designed to be capable of oscillating in multiple dimensions by means of at least one first connecting element (8) that connects the MEMS mirror (2) to the frame (3), and at least one aperture (7) is provided in the beam path of the light beam (1) in order to limit the light beam (1), which aperture is mounted in a defined position relative to the MEMS mirror (2) depending on the direction of incidence of the light beam (1).

Description

[0001] MEMS mirror device with aperture

[0002] The invention relates to a MEMS mirror device for the variable deflection of an incident light beam, which can be used in particular in augmented reality glasses.

[0003] Augmented reality (AR) refers to the computer-assisted enhancement of reality perception that addresses at least one of the human sensory modalities. However, AR is often understood to refer only to the visual representation of information, namely the supplementation of images or videos with computer-generated additional information and / or virtual objects by means of overlay or superimposition. In particular, the visual representation or projection of images, user interfaces, or information, such as directions, weather information, or news, represents a common application of AR and is increasingly being used in so-called AR glasses, which can display images, user interfaces, or information directly on the user's lenses or retina.

[0004] A microscanner (also known as a micro-electro-mechanical system, or MEMS for short) can be used to project images or text information. A light beam, generated by a light source located, for example, in the temple of AR glasses and then shaped, is deflected onto the MEMS scanner. The light beam can then be scanned by the MEMS scanner, generating an image in an observation field. Such an imaging system with a MEMS scanner requires comparatively few optical elements, allowing for small and cost-effective projectors. For AR applications, a projector must achieve very good optical resolution and consume very little power. Due to a lack of alternatives, edge emitters are often used as the light source. However, these emit a highly divergent, elliptically shaped light beam that must be collimated.

[0005] A MEMS scanner is described, for example, in DE 10 2021 1 16 151 B3. The MEMS scanner disclosed therein can perform simultaneous rotational oscillations around two resonant oscillation axes in order to create a nonlinear Lissajous projection into an observation field by deflecting a light beam incident on a deflection element during the oscillations.

[0006] WO 2021 / 259936 A1 discloses a MEMS mirror device for variable deflection of an electromagnetic beam. The MEMS mirror device consists of a disk-shaped first glass substrate with a MEMS mirror for reflecting the beam and a frame portion. The MEMS mirror is connected to the frame portion via at least one connecting element in a multidimensionally oscillating manner.

[0007] The oscillations scan a field of view (FOV) at high frequencies in a scan pattern resembling a Lissajous figure. Unlike conventional raster scanning methods, which periodically scan the FOV from top to bottom at maximum resolution, this allows hundreds of partial images to be processed simultaneously, enabling smoother motion representation. Furthermore, artifacts in the three-dimensional perception of fast-moving objects are greatly reduced.

[0008] The disadvantage here is that the non-moving surface elements of the MEMS mirror device ensure that additional, unwanted reflections and scattered light occur and ensure that the contrast of the MEMS mirror device decreases when creating an image.

[0009] The object of the invention is therefore to provide a MEMS mirror device that requires little installation space and has a very high contrast.

[0010] The problem is solved by a MEMS mirror device for the variable deflection of an incident light beam, comprising a disk-shaped MEMS mirror for reflecting the light beam, and a frame surrounding the MEMS mirror. The MEMS mirror is designed to be capable of oscillation in multiple dimensions by means of at least one first connecting element connecting the MEMS mirror to the frame, and at least one aperture for limiting the light beam is present in the beam path of the light beam. The aperture is mounted in a defined position relative to the MEMS mirror depending on the direction of incidence of the light beam. The MEMS mirror device can be used in particular as a microscanner and can be designed to effect a nonlinear Lissajous projection into an observation field. A MEMS microscanner is a small, integrated system used for optically scanning and imaging objects.The system consists of a tiny, movable MEMS mirror controlled by microelectromechanics (MEM). The mirror of the MEMS mirror device is typically only a few hundred micrometers or a few millimeters in size and can be moved very quickly and precisely, for example, using piezoelectric elements, to reflect the light beam coming from the light source. The movement of the MEMS mirror can be controlled by electrical signals sent to the microscanner from a computer or other control unit, which may also be part of the projection device. MEMS microscanners offer the advantages of high speed, accuracy, and reliability while being low in power and compact.

[0011] For the purposes of the invention, a system is considered capable of oscillation if it is capable of performing a periodic movement around a rest position. Thus, any system capable of performing a periodic movement around a rest position in several dimensions is capable of oscillation in multiple dimensions.

[0012] An optical aperture is a mechanical component that controls the amount of incident light in an optical system and / or spatially limits a light beam. It is a circular or polygonal opening, for example, that is embedded in an aperture material. The aperture material can be metal or plastic, for example. The aperture can be incorporated into the MEMS mirror device, particularly through wafer-level assembly. The aperture can also be created by a structured coating with an absorbing material or an absorbing surface structure on a transparent substrate.

[0013] Preferably, the aperture has a planar shape and is arranged parallel to the MEMS mirror in its rest position. Particularly preferably, at least the MEMS mirror, the frame, and the aperture are mounted using wafer-level assembly.

[0014] Wafer-level assembly refers to a technology in which parts or components are mounted directly onto a wafer. A wafer is a disc of semiconductor material, such as silicon. Wafer-level assembly offers several advantages over conventional chip assembly. By performing the assembly process at the wafer level, production time and costs can be significantly reduced.

[0015] It is advantageous for the at least one aperture to be symmetrical along at least one axis of symmetry. The aperture is particularly advantageously round. However, this is only possible if a circular light beam, preferably perpendicularly from above, is incident on the MEMS mirror device. The MEMS mirror is also preferably round.

[0016] It is advantageous if at least one aperture is located on the MEMS mirror or directly above it. However, the aperture is always positioned far enough above the scanning mirror to allow the tilting mirror to deflect without touching the aperture.

[0017] Preferably, the MEMS mirror and / or the aperture have a diameter between 0.1 mm and 5 mm. Particularly preferably, the MEMS mirror and / or the aperture have a diameter between 1 mm and 2 mm. Preferably, the distance between the MEMS mirror and the aperture is less than 1 mm, particularly preferably the distance between the MEMS mirror and the aperture is less than 0.5 mm and more than 0.1 mm. Preferably, the angle by which the MEMS mirror can be tilted relative to its rest position is between 3° and 15°, particularly preferably between 5° and 10°.

[0018] If the aperture is slightly smaller than the MEMS mirror in its planar dimension, the aperture can be mounted closer to the MEMS mirror. However, since the flexure hinges are also located in the same plane as the MEMS mirror, there must always be a gap between the aperture and the MEMS mirror.

[0019] If the distance between the MEMS mirror and the aperture is less than 1 mm, as described above as advantageous, the light beam is limited as precisely as possible to a useful diameter for the MEMS mirror. If the light beam does not pass vertically through the aperture, for example because there is an angle between the MEMS mirror and the aperture, the light beam is partially shadowed, which immediately results in a loss of intensity. The closer the aperture is to the MEMS mirror, the less this shadowing occurs. It has been shown that the shadowing of the light beam can be sufficiently reduced precisely in the aforementioned range of less than 1 mm. If the diameter of the MEMS mirror and the aperture is each 1 mm, for example, the intensity loss can be reduced to 30% with an aperture distance of 0.7 mm for a deflection of the MEMS mirror of 20°.

[0020] Particularly if the aperture is symmetrical, it can be mounted either directly on the MEMS mirror or directly above it, with an aperture diameter slightly larger than the diameter of the MEMS mirror. If the aperture is located directly above the MEMS mirror, the aperture diameter can also be slightly smaller than the diameter of the MEMS mirror.

[0021] The MEMS mirror also spatially limits the light beam. All arrangements that have a significant distance between the MEMS mirror and the aperture must be designed so that the two beam-limiting components (MEMS mirror and aperture) are arranged coaxially with the light beam. If this is not done sufficiently, light is lost or additional assembly work is required.

[0022] The farther the aperture is from the MEMS mirror, the more compromises must be made in the design of the aperture. Because the MEMS mirror is subject to oscillation, the light beam does not always follow the same path after being reflected from the MEMS mirror. Consequently, the aperture diameter of the aperture opening must be larger than the diameter of the light beam.

[0023] The MEMS mirror device preferably has an encapsulation that is connected to the frame and, together with the frame, forms a cavity. The encapsulation of the MEMS mirror device serves to protect the moving mechanical and optical components of the MEMS mirror device and to protect the MEMS mirror from external influences and contamination. The invention allows the encapsulation to be given additional functionality if the aperture is mounted in or on the encapsulation.

[0024] Advantageously, the cover is arranged in the cavity and connected to the encapsulation. Preferably, the cover is arranged in the cavity and connected to the frame via at least one connecting element.

[0025] The encapsulation may have a dome shape. Alternatively, the encapsulation may have a flat shape or a desk shape. When something is described as "desk-shaped," it means that it has a flat, sloping surface, similar to a desk. When something is described as "dome-shaped," it means that it has a curved or spherical, preferably hemispherical, shape, similar to a dome.

[0026] It can be advantageous if the aperture and the MEMS mirror are flat, and if the aperture and the MEMS mirror (in the rest position) are aligned parallel to each other. This is particularly the case if the light beam is incident on the MEMS mirror essentially orthogonally.

[0027] Advantageously, the cavity is sealed gas-tight by the encapsulation and the frame placed on a base plate, and the gas pressure in the cavity is lower than normal conditions.

[0028] The MEMS mirror device preferably has a drive device configured to impart a multidimensional oscillatory motion to the frame. The MEMS mirror can be driven resonantly or quasi-statically by the drive device. The scanning frequency of the MEMS mirror is between 0.1 kHz and 100 kHz.

[0029] Advantageously, the MEMS mirror is suspended from the frame by two pairs of opposing flexural joints arranged orthogonally to each other on an intermediate frame, enabling it to oscillate. When excited by the drive system, it performs multidimensional oscillatory motion in the form of a Lissajous oscillation. Flexural joints are used in precision mechanics to enable relative movement between rigid (massive) areas of a body by bending narrow (thinned) areas. The oscillatory capability of flexural joints depends on the type of joint and its mounting. Flexural joints enable suspended parts of a body to perform periodic movements around a rest position. The type of suspension influences the oscillatory capability of the joint.

[0030] Particularly advantageously, exactly two apertures are present in the beam path of the light beam, with a first aperture limiting the light beam incident on the MEMS mirror and a second aperture limiting the at least one light beam reflected by the MEMS mirror.

[0031] The object is further achieved by augmented reality glasses containing a MEMS mirror device according to one of the described embodiments.

[0032] The aforementioned aperture arrangement can also be used to achieve further positive effects for the MEMS mirror device. Alternatively to or in combination with the above solution, the aperture is arranged taking into account the light beam reflected by the MEMS mirror in order to limit it. Such a MEMS mirror device also comprises a disk-shaped MEMS mirror for reflecting the light beam and a frame surrounding the MEMS mirror. The MEMS mirror is configured to be capable of oscillation in multiple dimensions between multiple end positions by means of at least one first connecting element connecting the MEMS mirror to the frame. An aperture is provided in the beam path of the light beam to limit the light beam reflected by the MEMS mirror.The distance between the MEMS mirror and the aperture is determined as a function of the aperture diameter of an aperture opening such that the reflected light beam is partially, but not completely, obscured by the aperture in the area of ​​the end positions of the MEMS mirror.

[0033] Such a setup has the advantage that an image generated by the MEMS mirror device, for example, using Lissajous projection, exhibits a more homogeneous brightness distribution. At the end positions, the oscillating MEMS mirror is decelerated and deflected, so that the light beam remains longer than in its rest position, where the MEMS mirror typically exhibits its maximum speed. This means that, without the aperture described above, a larger initial amount of light falls into the edge regions of the image generated in the observation field, making them brighter. This effect has so far been compensated for by shortening the deflection times of the MEMS mirror, i.e., faster deceleration and acceleration, or by appropriate control of the light source, whose intensity is reduced accordingly near the end positions.The solution just described achieves a comparable effect of reducing the first amount of light by partially covering it with the aperture described above. By specifically limiting the light beam, this amount of light becomes smaller than a second amount of light that passes through the aperture at the same time when the MEMS mirror is in its rest position and the light beam is limited or not limited at all. A further advantage of limiting the amount of light by the aperture is that the braking and acceleration of the MEMS mirror near the end positions can be smoother, thus reducing wear on the MEMS mirror device.

[0034] In this configuration, the MEMS mirror should be arranged so that it can move at a defined distance relative to the aperture. Otherwise, all applicable configurations described above can also be used here. In the advantageous configuration with exactly two apertures described above, the second aperture must be designed accordingly.

[0035] It has been shown that a distance of less than 1 mm is advantageous. In a typical application, if the diameter of the MEMS mirror and the aperture are each 1 mm, for example, the intensity loss due to an aperture distance of 0.7 mm can be 30% for a deflection of the MEMS mirror to an end position of 20° relative to a light beam passing perpendicularly through the aperture. Thanks to this arrangement, the oscillation of the MEMS mirror can be adjusted accordingly to better compensate for brightness differences in the edge regions of the projection. A sufficient travel path is maintained for the MEMS mirror between the end positions to ensure the best possible image quality and resolution with the best possible compactness of the overall system.

[0036] This effect can be enhanced, or the same effect can be achieved, by a method for controlling the MEMS mirror device. The MEMS mirror device comprises the oscillating MEMS mirror, which can be set into multidimensional oscillation around a rest position and between several end positions via a drive device, a shutter arranged above the MEMS mirror, and a control unit that controls the drive device. A light beam is incident on the MEMS mirror and directed by it onto the shutter.The control unit determines signals depending on the aperture diameter, the shape of the aperture opening, and / or the position of the aperture and sends these signals to the drive device. This causes the MEMS mirror to perform the multi-dimensional oscillation in such a way that a first amount of light from the light beam exiting through the aperture opening in the region of the end positions of the MEMS mirror is adjusted to a second amount of light from the light beam exiting through the aperture opening as the MEMS mirror passes through its rest position. Adjusting here means that any difference that would otherwise exist between the first and second amounts of light is reduced. In an advantageous adjustment, this is achieved by completely adjusting the first and second amounts of light, so that the difference in brightness in the resulting image is no longer easily perceptible to a human.

[0037] It is advantageous if the control unit determines the signals depending on the portion of the light beam obscured by the aperture. This allows the multidimensional oscillation to be even better matched to the arrangement of the MEMS mirror and aperture. The obscured portion of the light beam can be determined either mathematically by taking into account the beam cross-section of the light beam, the sizes of the MEMS mirror and aperture, as well as their relative arrangement, in particular their distance, and the current position of the MEMS mirror. Alternatively, the portion can also be determined by measurement, for example, as an intensity drop.

[0038] In a further advantageous embodiment of the method, the control unit adjusts the amplitude and / or shape of the multidimensional oscillation using the signals. By adjusting the amplitude, which corresponds to adjusting the end positions, i.e., the respective maximum deflection of the MEMS mirror, and adjusting the shape of the multidimensional oscillation, which can be used to define the frequency and speed of the deflection in the end positions, the matching of the first and second light quantities can be further improved.

[0039] Furthermore, it is advantageous if a third amount of light, which exits through the aperture opening in the range between the rest position and the end positions, is adjusted to the first and second amounts of light by means of the control unit. This makes it possible to compensate for any brightness differences in the image projected by the MEMS mirror device.

[0040] The invention will be described in more detail below by means of exemplary embodiments based on the drawings. These show:

[0041] Fig. 1 a A view of a first embodiment of the MEMS mirror device, wherein the aperture is connected to the frame and has an opening,

[0042] Fig. 1 b is a plan view of the first embodiment of the MEMS mirror device,

[0043] Fig. 2 is a view of a second embodiment of the MEMS mirror device with a dome-shaped encapsulation on which the aperture is mounted,

[0044] Fig. 3a is a view of a third embodiment of the MEMS mirror device, wherein the aperture is mounted on the encapsulation and has two openings,

[0045] Fig. 3b is a plan view of the third embodiment of the MEMS mirror device,

[0046] Fig. 4 is a view of a fourth embodiment of the MEMS mirror device, wherein the aperture is connected to the frame via a connecting element and has an opening,

[0047] Fig. 5 is a view of a fifth embodiment of the MEMS mirror device, wherein the aperture is connected to the encapsulation and has an opening,

[0048] Fig. 6a is a view of a sixth embodiment of the MEMS mirror device, wherein the aperture is desk-shaped and has two openings,

[0049] Fig. 6b is a further view of the sixth embodiment of the MEMS mirror device, and Fig. 7 is a plan view of a seventh embodiment of the MEMS mirror device, wherein the aperture has a round opening.

[0050] Fig. 1a shows a MEMS mirror device for the variable deflection of an incident light beam 1. The MEMS mirror device comprises a disk-shaped MEMS mirror 2 for reflecting the light beam 1, and a frame 3 surrounding the MEMS mirror 2. The MEMS mirror 2 is designed to be capable of oscillation in several dimensions by means of a first connecting element 8 connecting the MEMS mirror 2 to the frame 3.

[0051] An aperture 7 is provided in the beam path of the light beam 1 to limit the light beam 1. The aperture 7 is mounted on the frame 3. The light beam 1 falls onto the MEMS mirror 2 through the opening of the aperture 7. The light beam 1 is deflected and scanned by the MEMS mirror 2. For this purpose, the MEMS mirror 2 performs periodic movements around a rest position. This is shown in Fig. 1a by dashed lines that indicate the maximum deflection of the MEMS mirror 2 in one direction. The light beam 1 leaves the MEMS mirror device through the opening of the aperture 7. The light beam 1 is scanned, for example, across an observation field. The observation field is at least one optically effective surface, for example at least one beam splitter or a holographic optical element (Holographic Optical Element, or HOE for short), which is applied in a lens of AR glasses or on a windshield of a motor vehicle.Alternatively, the observation field is a user’s retina.

[0052] A top view of the aperture 7 of the first embodiment of the MEMS mirror device is shown in Fig. 1 b. The top view clearly shows the shape of the opening of the aperture 7, which is partially circular on the incident side of the light beam 1 and becomes larger towards the exit side of the light beam 1. This is necessary because the light beam 1 always follows the same beam path upon entering the MEMS mirror device, whereas after being reflected by the MEMS mirror 2, it no longer follows the same beam path upon deflection of the MEMS mirror 2.

[0053] Fig. 2 shows a second embodiment of the MEMS mirror device. The light beam 1 passes through the aperture 7 and an encapsulation 4 onto the MEMS mirror 2. The encapsulation 4 is connected to the frame 3 and, together with the frame 3, forms a cavity 5. The cavity 5 is sealed gas-tight by the encapsulation 4 and the frame 3 mounted on a base plate 10, and the gas pressure in the cavity 5 is lower than under normal conditions.

[0054] The aperture 7 is mounted on the encapsulation 4. The opening of the aperture 7 is round and thus symmetrical along a symmetry axis (not shown). The light beam 1 incident on the MEMS mirror device is also round and has a larger diameter than the aperture diameter of the aperture 7. The light beam 1 is thus spatially limited by the aperture 7.

[0055] The MEMS mirror 2 is suspended in an oscillating manner relative to the frame 3 by two pairs of opposing solid-state joints 6 arranged orthogonally to one another on an intermediate frame 31, so that it can execute the multi-dimensional oscillating movement in the form of a Lissajous oscillating movement upon appropriate excitation by means of the drive device 9.

[0056] The light beam 1 is deflected by the MEMS mirror 2 in different directions depending on the position of the MEMS mirror 2. The different beam paths of the light beam 1 after it has been deflected by the MEMS mirror 2 are indicated by dashed lines in Fig. 2.

[0057] A third embodiment of the MEMS mirror device is shown in Fig. 3a and Fig. 3b. In the third embodiment, the encapsulation 4 has a planar shape, and the aperture 7 is mounted on the encapsulation 4.

[0058] In the beam path of the light beam 1, there are exactly two apertures 7, with a first aperture 71 limiting the light beam 1 incident on the MEMS mirror 2, and a second aperture 72 limiting the at least one light beam 1 reflected by the MEMS mirror 2. The opening of the first aperture 71 has a first aperture diameter that is smaller than the diameter of the light beam 1, and the opening of the second aperture 72 has a second aperture diameter that is larger than the diameter of the light beam 1 after it has been reflected by the MEMS mirror 2. The aperture diameter of the second aperture 72 does not depend on the diameter of the incident light beam 1, but rather on a maximum deflection of the MEMS mirror 2.

[0059] Fig. 4 shows a fourth embodiment of the MEMS mirror device. In the fourth embodiment, the encapsulation 4 has a dome shape. The aperture 7 is arranged directly above the MEMS mirror 2 and is connected to the frame 3 via a circumferential connecting element 8.

[0060] The frame 3 is mounted on a base plate 10. The base plate 10, together with the encapsulation 4 and the frame 3, seals the cavity 5 in a gas-tight manner.

[0061] Fig. 5 shows a fifth embodiment of the MEMS mirror device. This fifth embodiment also features a base plate 10, which, together with the encapsulation 4 and the frame 3, forms a gas-tight seal around the cavity 5.

[0062] In the fifth version, the aperture 7 is connected to the encapsulation 4.

[0063] The encapsulation 4 can also have a desk-like shape, as shown in Fig. 6a. A first aperture 71 and a second aperture 72 are applied to the encapsulation 4.

[0064] Fig. 6b also shows the sixth embodiment of the MEMS mirror device.

[0065] The openings of the first aperture 71 and the second aperture 72 are three-dimensional and do not have a constant diameter across their entire extent. The openings of the first aperture 71 and the second aperture 72 are then sealed gas-tight to the outside by a flat plate of the encapsulation 4.

[0066] The MEMS mirror device comprises a drive device 9 configured to impart a multidimensional oscillatory motion to the MEMS mirror 2 relative to the frame 3. The drive device 9 is connected to the MEMS mirror 2 and drives the MEMS mirror 2 accordingly. The MEMS mirror 2 can be driven, in particular, by electromagnetic, thermoelectric, or piezoelectric principles.

[0067] A circular opening of the aperture 7 is shown in Fig. 7. The aperture diameter of the opening of the aperture 7 is larger than the mirror diameter of the MEMS mirror 2. The circular opening of the aperture 7 is particularly advantageous when a parabolic mirror collimator or another optical system is arranged above the MEMS mirror device in order to illuminate the MEMS mirror device vertically from above with the light beam 1 or to direct the light beam 1 orthogonally onto the MEMS mirror.

[0068] The modification of the MEMS mirror device described above will now be described with reference to Figs. 1a and 6b, wherein the general structure of the modification is essentially identical to the embodiments just described. Fig. 1a corresponds to a structure with an aperture 7. The light beam 1 is reflected by the MEMS mirror 2 after it passes through the aperture 7. Here, the MEMS mirror 2 is in its rest position, with the dashed line also representing the maximum deflection, i.e., an end position, of the MEMS mirror 2. A distance between the MEMS mirror 2 and the aperture 7 is determined as a function of an aperture diameter of an opening of the aperture 7 such that the reflected light beam 1 is partially, but not completely, obscured by the aperture 7 in the region of the end positions of the MEMS mirror 2.If the distance were chosen to be larger, it would immediately follow that in the end position a significantly larger portion of the light beam 1 cannot fall through the opening of the aperture 7, until finally the entire light beam 1 is covered by the aperture 7.

[0069] The MEMS mirror device shown in Fig. 6a operates in a very similar manner and can also be adapted to the modification. Here, the light beam 1 passes through the first aperture 71, and the reflected light beam 1 is correspondingly obscured by the second aperture 72. The multidimensional oscillation of the MEMS mirror 2 around its rest position and between its end positions is excited by the drive device 9, which contains or is connected to a control unit.Depending on an aperture diameter, a shape of an opening of the second aperture 72, and / or a position of the second aperture 72, the control unit determines signals and sends them to the drive device 9, so that the MEMS mirror 2 executes the multi-dimensional oscillation in such a way that a first amount of light of the light beam 1 exiting through the aperture 72 in the region of the end positions of the MEMS mirror 2 is adjusted to a second amount of light of the light beam 1 as it passes through the rest position of the MEMS mirror 2. When determining the signals, the control unit also takes into account the portion of the light beam 1 that is obscured by the aperture 72 and thus does not pass through its opening.This proportion can be determined geometrically by the control unit from the properties of the light beam 1, the current position of the MEMS mirror 2, the size of both the MEMS mirror 2 and the second aperture 72, as well as the distance between the second aperture 72 and the MEMS mirror 2. Other known methods, such as measuring a drop in intensity using a sensor not shown here, are also possible. The control unit adjusts an amplitude and / or a shape of the multi-dimensional oscillation using the signals in order to adjust the first and second amounts of light. It is also possible to adjust a third amount of light, which passes through the opening of the second aperture 72 in the area between the rest position and the end positions, to the first and second amounts of light using the control unit. For this purpose, the above-mentioned parameters are also adjusted.

[0070] List of reference symbols

[0071] 1 light beam

[0072] 2 MEMS mirrors

[0073] 3 Frame 4 Encapsulation

[0074] 5 Cavity

[0075] 6 Solid joint

[0076] 7 aperture

[0077] 71 first aperture 72 second aperture

[0078] 8 Connecting element

[0079] 9 Drive device

[0080] 10 Base plate

Claims

Patent claims 1. MEMS mirror device for variable deflection of an incident light beam (1), comprising: - a disc-shaped MEMS mirror (2) for reflecting the light beam (1 ), and - a frame (3) surrounding the MEMS mirror (2), wherein - the MEMS mirror (2) is designed to be capable of oscillation in several dimensions by means of at least one first connecting element (8) connecting the MEMS mirror (2) to the frame (3), and - in the beam path of the light beam (1) there is at least one aperture (7) for limiting the light beam (1), which aperture is mounted in a defined relative position to the MEMS mirror (2) as a function of a direction of incidence of the light beam (1).

2. MEMS mirror device according to claim 1, wherein the aperture (7) has a planar shape and is arranged parallel to the MEMS mirror (2) in its rest position.

3. MEMS mirror device according to claim 2, wherein at least the MEMS mirror (2), the frame (3) and the aperture (7) are mounted by wafer-level mounting.

4. MEMS mirror device according to one of claims 1 to 3, wherein an opening of the at least one aperture (7) is symmetrical along at least one axis of symmetry.

5. MEMS mirror device according to one of claims 1 to 4, wherein the at least one aperture (7) is arranged on the MEMS mirror (2) or immediately above it.

6. MEMS mirror device according to claim 5, wherein a distance between the MEMS mirror (2) and the aperture (7) is less than 1 mm.

7. MEMS mirror device according to one of claims 1 to 6, wherein the MEMS mirror device has an encapsulation (4) which is connected to the frame (3) and together with the frame (3) forms a cavity (5).

8. MEMS mirror device according to claim 7, wherein the aperture (7) is arranged in the cavity (5) and is connected to the encapsulation (4).

9. MEMS mirror device according to claim 7, wherein the aperture (7) is arranged in the cavity (5) and is connected to the frame (3) via at least one connecting element (8).

10. MEMS mirror device according to one of claims 1 to 9, wherein the aperture (7) is mounted in or on the encapsulation (4).

11. MEMS mirror device according to one of claims 1 to 10, wherein the encapsulation (4) has a dome shape.

12. MEMS mirror device according to one of claims 1 to 11, wherein the encapsulation (4) has a planar shape.

13. MEMS mirror device according to claim 12, wherein the encapsulation (4) has a desk shape.

14. MEMS mirror device according to one of claims 1 to 13, wherein the aperture (7) and the MEMS mirror (2) are flat and the aperture (7) and the MEMS mirror (2) are aligned parallel to each other.

15. MEMS mirror device according to one of claims 1 to 14, wherein the cavity (5) is sealed gas-tight by the encapsulation (4) and the frame (3) placed on a base plate (10), and a lower gas pressure prevails in the cavity (5) compared to normal conditions.

16. MEMS mirror device according to one of claims 1 to 15, wherein the MEMS mirror device comprises a drive device (9) which is designed to to set the MEMS mirror (2) into a multi-dimensional oscillating movement relative to the frame (3).

17. MEMS mirror device according to claim 16, wherein the MEMS mirror (2) is suspended in an oscillatory manner relative to the frame (3) by means of two pairs of opposing solid-state joints (6) arranged orthogonally to one another on an intermediate frame (31), so that it executes the multi-dimensional oscillatory movement in the form of a Lissajous oscillatory movement upon appropriate excitation by means of the drive device (9).

18. MEMS mirror device according to one of claims 1 to 17, wherein exactly two apertures are present in the beam path of the light beam (1), wherein a first aperture (71) limits the light beam (1) incident on the MEMS mirror (2) and a second aperture (72) limits the at least one light beam (1) reflected by the MEMS mirror (2).

19. Augmented reality glasses comprising a MEMS mirror device according to one of claims 1 to 18.

20. MEMS mirror device for variable deflection of an incident light beam (1), comprising: - a disc-shaped MEMS mirror (2) for reflecting the light beam (1 ), and - a frame (3) surrounding the MEMS mirror (2), wherein - the MEMS mirror (2) is designed to be capable of oscillation in several dimensions between several end positions by means of at least one first connecting element (8) connecting the MEMS mirror (2) to the frame (3), and - in the beam path of the light beam (1) there is a diaphragm (7) for limiting the light beam (1) reflected by the MEMS mirror (2), wherein a distance between the MEMS mirror (2) and the diaphragm (7) is determined as a function of a diaphragm diameter of the diaphragm (7) such that the reflected light beam (1) is partially but not completely covered by the aperture (7) in the area of ​​the end positions of the MEMS mirror (2).

21. The MEMS mirror device of claim 20, wherein the distance is less than 1 mm.

22. Method for controlling a MEMS mirror device, which - an oscillating MEMS mirror (2) which can be set into a multi-dimensional oscillation about a rest position and between several end positions via a drive device (9), a diaphragm (7) arranged above the MEMS mirror (2), and a control unit which controls the drive device (9), wherein - a light beam (1 ) falls on the MEMS mirror (2) and is directed by it onto the aperture (7), - the control unit determines signals as a function of an aperture diameter, a shape of an opening of the aperture (7) and / or a position of the aperture (7) and sends them to the drive device (9), so that the MEMS mirror (2) carries out the multi-dimensional oscillation in such a way that a first quantity of light of the light beam (1) emerging through the opening of the aperture (7) in the region of the end positions of the MEMS mirror (2) is adjusted to a second quantity of light of the light beam (1) emerging through the opening of the aperture (7) as the MEMS mirror (2) passes through the rest position.

23. Method according to claim 22, wherein the control unit additionally determines the signals as a function of a portion of the light beam (1) concealed by the aperture (7).

24. The method according to claim 22 or 23, wherein the control unit adjusts an amplitude and / or a shape of the multi-dimensional oscillation by means of the signals.

25. Method according to one of claims 22 to 24, wherein a third quantity of light which exits through the opening of the diaphragm (7) in the region between the rest position and the end positions is adjusted to the first and second quantities of light by means of the control unit.

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