Micromirror

Abstract

The invention relates to a micromirror comprising a mirror element (1) with a reflective surface, a first arm (2), a second arm (3) and a frame (4), wherein a first end (2a) of the first arm (2) is connected to the frame (4), a second end (2b) of the first arm (2) is connected to the mirror element (1), a first end (3a) of the second arm (3) is connected to the frame (4) and a second end (3b) of the second arm (3) is connected to the mirror element (1), wherein drive elements (8a-8c, 11a) are arranged on the first arm (2) and on the second arm (3) and are designed to bend the first arm (2) and the second arm (3), and wherein the mirror element (1) is arranged and connected to the second ends (2b, 3b) of the first and the second arms (2, 3) in such a way that the bending of the first and the second arms (2, 3) brings about a tilting movement of the mirror element (1) about an axis of rotation.

Description

[0001] Description

[0002] MICROMIRRORS

[0003] For projection applications, such as image and / or video projection and lidar devices, there is a need for quasi-static mirrors for raster scanning. The mirrors should cover a frequency range up to a frame rate of 120 Hz without resonant response and, accordingly, have a resonance frequency greater than 120 Hz.

[0004] The object of the present invention is to provide an improved micromirror.

[0005] A micromirror is proposed which has a mirror element with a reflective surface, a first arm, a second arm and a frame. A first end of the first arm is connected to the frame. A second end of the first arm is connected to the mirror element. A first end of the second arm is connected to the frame. A second end of the second arm is connected to the mirror element. Drive elements which are designed to bend the first arm and the second arm are arranged on the first arm and on the second arm, the mirror element being arranged and connected to the second end of the first arm and the second arm in such a way that the bending of the first and the second arm brings about a tilting movement of the mirror element about an axis of rotation.

[0006] The first arm and the second arm can have drive sections, wherein a drive element is arranged on each drive section, which is designed to bend the respective drive section. The first arm and the second arm can have a meandering structure, in which the drive sections are arranged parallel to one another and are connected to one another by connecting sections.

[0007] The drive sections can be arranged such that their deflections add up to a total deflection. The total deflection of the first arm can be the sum of the individual deflections of each drive section. By using several individual drive sections, the micromirror can be constructed more compactly, and it can be ensured that each drive section is bent in such a way that the mirror element remains free from deformation and stress. This would not be possible with a comparable total deflection of a single section.

[0008] The drive sections can run perpendicular to a rotational axis of the mirror element, wherein the first arm and the second arm further each have connecting sections, wherein two drive sections are each connected to one another by a connecting section, wherein the connecting sections run perpendicular to the drive sections and wherein no drive elements are arranged on the connecting sections.

[0009] The drive sections can have a width that indicates their extension in the direction of the rotation axis, with the width of the drive sections decreasing from the first end of the first arm to the second end of the first arm. Due to the decreasing width of the drive sections, the resonant frequency of the mirror element can be increased compared to a mirror in which all drive sections have the same width. Increasing the resonant frequency is advantageous for achieving the goal of quasi-static operation at a frequency of 120 Hz.

[0010] The drive sections can each have a constant width over their respective length. The length can specify the extent of the drive sections perpendicular to their width and perpendicular to a substrate thickness. In an alternative embodiment, the drive sections can have a width that decreases over their respective length, wherein the width at the end of the respective drive section facing the first end is greater than the width at the end facing the second end. Accordingly, the width of the first arm can decrease continuously from its first end to its second end.

[0011] The drive sections can have a length such that the mirror element is tilted with little distortion when the first and second arms are bent. In particular, the lengths of the drive sections should not be too long to ensure that the bending of the arms does not lead to distortion of the mirror element. The drive sections and the drive elements can be designed such that each of the drive sections is bent by a maximum of (7^) by an angle α, for which the following applies: — of 1 - cosa does not deviate by more than 0.2 % , preferably by not more than 0.1 % .

[0012] The mirror element, the first arm, the second arm, and the frame may be formed by a patterned silicon substrate. Accordingly, the elements may be integrally manufactured from a single substrate.

[0013] The drive elements can comprise piezoelectric layers. The piezoelectric layers can be made of PZT, for example. The piezoelectric layers can be applied to the arms using a thin-film process.

[0014] The micromirror can have a control unit which is designed to apply a voltage to the piezoelectric layers. The control unit can be designed to apply a voltage with a bias voltage and an alternating voltage, wherein the alternating voltage varies between a minimum value and a maximum value and the bias voltage remains constant. The bias voltage can be selected such that a zero crossing of the voltage which results from the sum of the bias voltage and the alternating voltage is avoided. The application of the bias voltage can ensure that the voltage applied to the drive elements never drops into the negative range during operation and therefore a reversal of the polarity of piezoelectric layers can be ruled out.

[0015] The mirror element can have a compensation layer on a rear side opposite the reflective surface. The compensation layer can be designed to compensate for mechanical deformation of the mirror element caused by the application of the bias voltage and by other manufacturing steps. In its resting state, in which only the bias voltage is applied to the drive elements, the mirror element is then not bent, since the effects of the bias voltage and the compensation layer cancel each other out.

[0016] The first arm and the second arm can be connected to the mirror element at a first suspension point and a second suspension point, respectively. The first suspension point and the second suspension point can lie on the rotation axis.

[0017] Alternatively, the second end of the first arm can be fork-shaped and connected to the mirror element at a plurality of first suspension points. The second end of the second arm can be fork-shaped and connected to the mirror element at a plurality of second suspension points. The first and second suspension points can be connected to one another by straight lines that are perpendicular to the axis of rotation.

[0018] The axis of rotation preferably runs through a center point of the mirror element. The micromirror can be designed for quasi-static or resonant operation.

[0019] A further aspect relates to a projection device comprising the micromirror described above and a light source configured to emit a light beam onto the reflective surface, wherein the micromirror is configured to reflect the light beam, and wherein the micromirror is configured to be moved such that the reflected light beam performs a raster-like scan. The projection device may be a device for projecting images and / or videos or a lidar device.

[0020] Preferred embodiments of the present invention are described below with reference to the figures.

[0021] Figures 1 and 2 show a micromirror in perspective view.

[0022] Figure 3 shows schematically how a deflection of a mirror element by 3 a can be effected by deflecting three drive sections by the angle a each.

[0023] Figures 4 to 6 show a simulation of the deformation of the micromirror.

[0024] Figure 7 shows a diagram illustrating the maximum mechanical deflection of the mirror element and the phase between the drive signal and the mechanical deflection for different frequencies of the drive signal.

[0025] Figure 8 shows the micromirror according to a second embodiment.

[0026] Figure 9 shows the distortion of a mirror element 1 according to the first embodiment.

[0027] Figure 10 shows the distortion of the mirror element 1 according to the second embodiment.

[0028] Figures 1 and 2 show a perspective view of a micromirror. Figure 1 shows a perspective view of the top side. Figure 2 shows a perspective view of the bottom side of the micromirror.

[0029] The micromirror comprises a mirror element 1, a first arm 2, a second arm 3, and a frame 4. The mirror element 1, the first arm 2, the second arm 3, and the frame 4 are formed integrally from a single silicon substrate, with a reflective layer being applied to the mirror element 1 in addition to the structuring of the silicon substrate, and drive elements being applied to the first arm 2 and the second arm 3, respectively.

[0030] The mirror element 1 is a flat structure, for example a disc, preferably a circular disc, or a flat, rectangular structure. On its upper side, the mirror element 1 has a reflective layer, for example a reflective coating. The mirror element 1 is designed to reflect a light beam incident on the upper side of the mirror element.

[0031] The mirror element 1 is designed to perform a tilting movement about a rotation axis. In doing so, the mirror element 1 is deflected from its rest position. Depending on the respective deflection angle, a light beam incident on the mirror element 1 is reflected at different angles of reflection. In this way, the mirror element 1 can be designed to perform a scan, for example a raster scan, of the light beam.

[0032] The first arm 2 and the second arm 3 are identical in their structural design and functional properties. Therefore, only the first arm 2 will be described in detail below.

[0033] The first arm 2 connects the mirror element 1 to the frame 4. A first end 2a of the first arm 2 is fastened to the frame 4. The first end 2a of the first arm 2 is directly connected to the frame 4. A second end 2b of the first arm 2, opposite the first end 2a, is fastened to the mirror element 1. The second end 2b of the first arm 2 is directly connected to the mirror element 1. The first arm 2 is designed to bend, wherein the second end 2b of the first arm 2 is moved relative to the first end 2a. The bending of the first arm 2 triggers the tilting movement of the mirror element 1.

[0034] The frame 4, to which the first end 2a of the first arm 2 is connected, is not moved by bending of the first arm 2. The frame 4 is thus static.

[0035] The first arm 2 has drive sections 5a, 5b, 5c, connecting sections 6a, 6b and an end section 7. The drive sections 5a, 5b, 5c and the connecting sections 6a, 6b result in a meander-shaped structure of the first arm 2. A drive element 8a, 8b, 8c is arranged on each of the drive sections 5a, 5b, 5c. The drive sections 5a, 5b, 5c are arranged parallel to one another. The connecting sections 6a, 6b each connect two adjacent drive sections. No drive elements are arranged on the connecting sections 6a, 6b. The first arm 2 of the micromirror according to a first embodiment, shown in Figures 1 and 2, has three drive sections 5a, 5b, 5c and two connecting sections 6a, 6b. In alternative embodiments, the first arm can have n drive sections and n-1 connecting sections, where n can be any integer greater than or equal to 2.

[0036] The drive elements 8a, 8b, 8c each have a piezoelectric layer. This can be a piezoelectric thin film. The piezoelectric thin film can be applied using a coating process, for example, by vapor deposition, sputtering, or sputtering variants. The piezoelectric material can be lead zirconate titanate (PZT). In addition, the drive elements 8a, 8b, 8c have electrodes that make it possible to apply a voltage to the piezoelectric layers.

[0037] The first arm 2 has a first group of drive elements 8a, 8c and a second group of drive elements 8b. A drive element 8a of the first group is arranged on the drive section 5a, which is directly connected to the frame 4. A drive element 8b of the second group is arranged on each of the drive sections 5b, which are directly connected by a connecting section 6a to a drive section 5a on which a drive element 8a of the first group is arranged. A drive element 5c of the first group is in turn arranged on each of the drive sections 5c, which are directly connected by a connecting section 6b to a drive section 5b on which a drive element 8b of the second group is arranged. This results in a structure in which drive elements 8a, 8c of the first group and drive elements 8b of the second group alternate along the first arm 2.

[0038] An alternating voltage signal and a bias voltage are applied to the drive elements 8a, 8b, 8c. The alternating voltage signal applied to the drive elements 8a, 8c of the first group is 180° out of phase with the alternating voltage signal applied to the drive elements 8b of the second group. The drive elements 8a, 8b, 8c of two adjacent drive sections 5a, 5b, 5c are thus each driven with opposite polarity.

[0039] Due to the phase shift of the applied alternating voltage signal, two adjacent drive sections are bent in opposite directions. Due to the meandering structure of the first arm 2, the first arm 2 is bent entirely in one direction.

[0040] The end section 7 connects the last drive section 5c in the direction of the mirror element 1 to the mirror element 1. The end section 7 has the second end 2b of the first arm 2. The end section 7 is fork-shaped and connected to the mirror element 1 at several suspension points 9a, 9b. In the embodiment shown in Figures 1 and 2, the end section 7 of the first arm 2 is connected to the mirror element 1 at two suspension points 9a, 9b.

[0041] The second arm 3 is designed analogously to the first arm 2. A first end 3a of the second arm 3 is connected to the frame 4, and a second end 3b of the second arm 3 is connected to the mirror element 1.

[0042] The second arm 3 is arranged rotationally symmetrically to the first arm 2, wherein a rotational symmetry exists with respect to a rotation of 180 ° about an axis through the center of the mirror element 1, which is perpendicular to the surface of the mirror element 1. The drive section 10a of the second arm 3, which is directly connected to the frame 4, has a drive element 11a of the second group. The drive sections 10a, 10b, 10c of the second arm 3 are thus each controlled in the opposite direction to the corresponding drive sections 5a, 5b, 5c of the first arm 2. If the second end 2b of the first arm 2 is moved in the first direction, the second end 3b of the second arm 3 is moved in the opposite negative first direction.

[0043] If, for example, the second end 2b of the first arm is moved into the display plane of Figure 1 and at the same time the second end 3b of the second arm 3 is moved out of the display plane of Figure 1, this causes a tilting movement of the mirror element 1 about the axis of rotation, in which the upper half of the mirror element 1 is tilted forwards out of the display plane and the lower half of the mirror element 1 is tilted backwards into the display plane.

[0044] In the first embodiment of the micromirror, which is shown in Figures 1 and 2, the first arm 2 and the second arm 3 are each connected to the mirror element 1 at a plurality of suspension points 9a, 9b, 12a, 12b. In this case, a suspension point 9a, 9b, at which the second end 2b of the first arm 2 is connected to the mirror element 1, is located opposite a suspension point 12a, 12b, at which the second end 3b of the second arm 3 is connected to the mirror element 1. The two suspension points 9a, 12a; 9b, 12b can be connected to one another by a straight line that runs perpendicular to the axis of rotation.

[0045] The drive sections 5a-5c, 10a-10c have a length, a width, and a thickness that are perpendicular to each other. The thickness indicates the extent of the drive sections 5a-5c, 10a-10c in a direction in which the extent of the drive sections 5a-5c, 10a-10c is the smallest. The thickness of the drive sections 5a-5c, 10a-10c corresponds to the thickness of the silicon substrate from which the drive sections 5a-5c, 10a-10c are structured. The length of the drive sections 5a-5c, 10a-10c indicates their extent in the direction in which the drive sections 5a-5c, 10a-10c are bent by applying a voltage to the drive elements. The width indicates the extent of the drive sections 5a-5c, 10a-10c in a direction perpendicular to the thickness and length. The width indicates an extent of the drive sections 5a-5c, 10a-10c in a direction along the rotation axis of the mirror element 1.

[0046] The drive sections 5a-5c of the first arm 2 differ from one another in their widths. The width of the drive section 5a, which is connected to the frame 4, is the largest. Toward the second end 2b of the first arm 2, the width of the drive sections 5a-5c decreases. A drive section arranged closer to the second end 2b of the first arm 2 than a drive section arranged closer to the first end 2a has a smaller width. The drive sections 10a-10c of the second arm 3 also differ from one another in their respective widths.

[0047] The resonant frequency of the first and second arms 2, 3 is changed, in particular increased, by reducing the width of the drive sections 5a-5c, 10a-10c toward the second end, compared to an arm in which the drive sections all have the same width. Varying the width of the drive sections 5a-5c, 10a-10c thus results in a higher resonant frequency of the first and second arms 2, 3 during bending. Increasing the resonant frequency contributes to stimulating the mirror element 1 to a tilting movement with low stress and deformation.

[0048] For example, the width of the drive section 5a, which is directly connected to the frame 4, can be between 2 and 4 mm, preferably between 2.5 and 3 mm. The width of the drive section 5c, which is connected to the end section, can be between 0.5 mm and 2.5 mm, preferably between 0.5 mm and 1.5 mm.

[0049] In the first embodiment, the width of the drive sections 5a-5c increases from the second end 2b to the first end 2a from 1.0 mm, through 1.67 mm, to 2.78 mm. The width of the connecting sections 6a, 6b increases from 0.7 mm, through 0.8 mm, to 1.0 mm.

[0050] In the first embodiment, the outer dimensions of the frame are 15.1 mm and 6.2 mm. The thickness of the silicon substrate on which the frame 4, the arms 2, 3, and the mirror element 1 are structured can be between 250 pm and 500 pm, for example, 380 pm.

[0051] The thickness of the drive elements 5a-5c, 10a-10c results from the sum of the thicknesses of two electrode layers and the thickness of a piezoelectric layer. The thickness of the piezoelectric layer is between 1 pm and 3 pm, and is preferably 1.7 pm.

[0052] The diameter of the mirror element 1 is between 1 mm and 10 mm, preferably between 2 mm and 5 mm, and is, for example, 3 mm. The length of the drive sections 5a-5c, 10a-10c corresponds to the diameter of the mirror element 1.

[0053] The meandering structure of the first and second arms 2, 3 can also be referred to as folding the arms. The meandering structure of the arms 2, 3 makes it possible to avoid excessively long sections. Excessively long sections of the arms, from which the mirror element 1 is suspended, would reduce the resonant frequency.

[0054] The length of the drive sections in which they are bent is chosen so that the following approximation applies: — — « 1 — cos (o: ) . Here, a indicates the maximum deflection of the drive sections 5a-5c, 10a-10c that they experience during operation of the micromirror. The approximation is considered satisfied if the two values ​​do not differ by more than 0.2%, preferably if they do not differ by more than 0.1%.

[0055] If the arms 2, 3 are arranged with n meandering

[0056] If the drive sections are formed, each of which can be deflected by the maximum angle a_max, the overall deflection of the mirror element 1 is nxajnax. If the above approximation is met, the mirror element 1 is deflected with virtually no stress and virtually no deformation.

[0057] Figure 3 shows schematically how a deflection of the mirror element by 3 a can be effected by the deflection of three drive sections 5a, 5b, 5c by the angle a in each case.

[0058] The drive elements 8a-8c, 10a-10c comprise piezoelectric thin films. These are operated beyond their coercive field strength. Accordingly, no negative voltages should be applied to the piezoelectric elements, as otherwise the polarity of the piezoelectric layer would be reversed. A bias voltage is therefore applied to the piezoelectric layers. The magnitude of the bias voltage is selected such that a positive potential is always applied to the drive elements. The magnitude of the bias voltage can be between 5 V and 25 V and can be, for example, 10 V.

[0059] Applying the bias voltage can cause a mechanical distortion of the mirror element 1. One or more compensation layers 13 can be applied to the back of the mirror element 1, which is opposite the reflective top side, to compensate for the mechanical distortion. The piezoelectric layer is subject to tensile stress which is amplified by applying the bias voltage. In a delivery state in which the bias voltage is not applied, the mirror element is then distorted by the compensation layers 13. In a rest state in which only the bias voltage is applied to the drive elements, the distortion due to the bias voltage and the compensation layers 13 cancel each other out, so that the mirror element is not distorted.

[0060] Figure 4 shows the result of a simulation in which the bias voltage is not taken into account and the AC voltage applied to the drive elements is between 4 V and -4 V. This results in a deflection of the mirror element of 9.1 °, resulting in an optical full angle of 36.4 °. The e31 f was 16.25 C / m. 2 assumed .

[0061] Figure 5 also shows this simulation, showing the deflection of the elements of the micromirror. The end sections 7 of the first and second arms 2, 3 experience the greatest deflection.

[0062] Figure 6 shows a simulation of the static deformation of the mirror element 1 in nm at a deflection of 15 ° .

[0063] The micromirror can be operated either quasi-statically or at resonance. In quasi-static operation, the frequency of the applied alternating voltage is below the resonance frequency of the micromirror.

[0064] In Figure 7, the frequency of the signals applied to the drive elements 8a-8c, 10a-10c is plotted on the horizontal axis. The vertical axis shows the mechanical deflection for curve K1 and the phase between the drive signal and the mechanical deflection for curve K2. Resonance behavior occurs at a frequency of approximately 320 Hz. Figure 8 shows the micromirror according to a second

[0065] Embodiment. The second embodiment differs from the first embodiment in the design of the end sections 7.

[0066] In the second embodiment, the first arm 2 and the second arm 3 are each connected to the mirror element at a suspension point 14, 15, with the two suspension points lying on the rotation axis. The end section 7 of the first arm 2 and the end section of the second arm 3 are connected to each other.

[0067] The second embodiment is characterized by its high robustness against insufficient flatness of the mirror element 1 in the initial state. It ensures that mechanical distortions occur essentially outside the mirror element.

[0068] Figure 9 shows the distortion of a mirror element 1 according to the first embodiment. Figure 10 shows the distortion of the mirror element 1 according to the second embodiment. In each case, a deflection of 15° and an applied voltage of 4 V are assumed. A comparison of Figures 9 and 10 shows that the mirror element 1 in the second embodiment experiences less mechanical distortion. However, the resonant frequency of the second embodiment is somewhat lower than in the first embodiment. The resonant frequency can be 288 Hz. The second embodiment has somewhat larger external dimensions than the first embodiment if the mirror element, the drive sections, and the connecting sections are identical. For example, the external dimensions can be 15.74 mm and 6.2 mm.The mirror element 1 and the drive sections 5a-5c, 10a-10c are arranged such that a center line of the mirror element 1, which is perpendicular to the length of the drive sections 5a-5c, 10a-10c, and the center lines of the drive sections 5a-5c, 10a-10c, which are perpendicular to the length of the respective drive sections, are not offset from each other in the direction of the length. The mirror element 1 is thus located in the center of the direction in which the drive sections 5a-5c, 10a-10c can be bent. This prevents jamming of the micromirror.

[0069] Reference symbol list

[0070] Mirror element

[0071] 2 first arm

[0072] 2a first end of the first arm

[0073] 2b second end of the first arm

[0074] 3 second arm

[0075] 3a first end of the second arm

[0076] 3b second end of the second arm

[0077] 4 frames

[0078] 5a, 5b, 5c Drive section of the first arm

[0079] 6a, 6b Connecting section of the first arm

[0080] 7 End section of the first arm

[0081] 8a, 8b, 8c Drive element of the first arm

[0082] 9a, 9b Suspension point of the first arm

[0083] 10a, 10b, 10c Drive section of the second arm

[0084] 11a Drive element of the second arm

[0085] 12a, 12b Suspension point of the second arm

[0086] Kempens at ions layer

[0087] 14 , 15 Suspension point (second embodiment)

Claims

Patent claims 1. Micromirror, comprising: - a mirror element (1) with a reflective surface, - a first arm (2) , - a second arm (3) , and - a frame (4), wherein a first end (2a) of the first arm (2) is connected to the frame (4), wherein a second end (2b) of the first arm (2) is connected to the mirror element (1), wherein a first end (3a) of the second arm (3) is connected to the frame (4), wherein a second end (3b) of the second arm (3) is connected to the mirror element (1), wherein drive elements (8a-8c, 11a) are arranged on the first arm (2) and on the second arm (3), which drive elements are designed to bend the first arm (2) and the second arm (3), wherein the mirror element (1) is arranged and connected to the second ends (2b, 3b) of the first and second arms (2, 3) in such a way that the bending of the first and second arms (2, 3) causes a tilting movement of the mirror element (1) about a rotation axis.

2. Micromirror according to claim 1, wherein the first arm (2) and the second arm (3) have drive sections (5a-5c, 10a-10c), wherein on each drive section (5a-5c, 10a-10c) a drive element (8a-8c, 11a) is arranged, which is designed to bend the respective drive section (10a-10c), wherein the drive sections (5a-5c, 10a-10c) are arranged parallel to one another.

3. Micromirror according to claim 2, wherein the drive sections (5a-5c, 10a-10c) run perpendicular to the axis of rotation of the mirror element (1), wherein the first arm (2) and the second arm (3) each have connecting sections (6a, 6b), wherein each drive section (5a-5c, 10a-10c) is connected to one another by one of the connecting sections (6a, 6b), wherein the connecting sections (6a, 6b) run perpendicular to the drive sections (5a-5c, 10a-10c), and wherein no drive elements are arranged on the connecting sections (6a, 6b).

4. Micromirror according to one of claims 2 or 3, wherein the drive sections (5a-5c, 10a-10c) have a width which indicates their extension in the direction of the axis of rotation, wherein the width of the drive sections (5a-5c) of the first arm (2) decreases from the first end (2a) of the first arm (2) to the second end (2b) of the first arm (2).

5. A micromirror according to claim 4, wherein the drive sections (5a-5c, 10a-10c) have a constant width over their respective length, the length being perpendicular to the width of the drive section (5a-5c, 10a-10c).

6. Micromirror according to claim 4, wherein the drive sections (5a-5c, 10a-10c) have a width decreasing over their respective length, wherein the length is perpendicular to the width of the drive section (5a-5c, 10a-10c), wherein the width of the drive sections (5a-5c, 10a-10c) at the end of the respective drive section (5a-5c, 10a-10c) connected to the first end (2a, 3a) is greater than the width of the drive sections (5a-5c, 10a-10c) at the end of the drive section (5a-5c, 10a-10c) connected to the second end (2b, 3b).

7. Micromirror according to one of claims 2 to 6, wherein the drive sections (5a-5c, 10a-10c) have a length such that the mirror element (1) is tilted with little stress and little deformation when the first and second arms (3) are bent.

8. Micromirror according to one of claims 2 to 7, wherein the drive sections (5a-5c, 10a-10c) and the drive elements (8a-8c, 11a) are designed such that each of the meander-shaped sections is bent by a maximum angle a, for which a 2 / 2 of l-cos(a) does not deviate by more than 0.2%.

9. Micromirror according to one of the preceding claims, wherein the mirror element (1), the first arm (2), the second arm (3) and the frame (4) are formed by a structured silicon substrate.

10. Micromirror according to one of the preceding claims, wherein the drive elements (8a-8c, 11a) have piezoelectric layers.

11. Micromirror according to claim 10, comprising a drive unit configured to apply a voltage to the piezoelectric layers, wherein the voltage is composed of a bias voltage and an alternating voltage, and wherein the bias voltage is selected such that a zero crossing of the voltage is avoided.

12. Micromirror according to one of the preceding claims, wherein the mirror element (1) has a compensation layer (13) on a rear side opposite the reflective surface.

13. Micromirror according to claim 11 and claim 12, wherein the compensation layer (13) is designed to compensate for a mechanical deformation of the mirror element (1) caused by the bias voltage.

14. Micromirror according to one of the preceding claims, wherein the first arm (2) and the second arm (3) are connected to the mirror element (1) at a first suspension point (14) and at a second suspension point (15), and wherein the first suspension point (14) and the second suspension point (15) lie on the axis of rotation.

15. Micromirror according to one of claims 1 to 13, wherein the second end (2b) of the first arm (2) is connected to the mirror element (1) at several suspension points (9a, 9b), wherein the second end of the second arm (3) is connected to the mirror element (1) at a plurality of suspension points (12a, 12b).

16. Micromirror according to claim 15, wherein the suspension points (9a, 9b) at which the second end (2b) of the first arm (2) is connected to the mirror element (1) and the suspension points (12a, 12b) at which the second end (3b) of the second arm (3) is connected to the mirror element (1) can be connected to one another by straight lines which are perpendicular to the axis of rotation.

17. Micromirror according to one of the preceding claims, wherein the axis of rotation passes through a center of the mirror element (1).

18. Micromirror according to one of the preceding claims, wherein the micromirror is designed to be operated quasi-statically, or wherein the micromirror is designed to be operated resonantly.

19. A projection device comprising a micromirror according to any one of the preceding claims and a light source configured to emit a light beam onto the reflecting surface, wherein the micromirror is configured to reflect the light beam, wherein the micromirror is configured to be moved such that the reflected light beam performs a raster-like scan.

20. Projection device according to the preceding claim, which is a device for projecting images and / or videos or a lidar device.

Images