Micromirror and projection device

Abstract

A micromirror is proposed which has 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), and 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.

Description

For projection applications, such as the projection of images and / or video, as well as lidar devices, there is a need for quasi-static mirrors for raster scanning. The mirrors should non-resonantly cover a frequency range up to a frame rate of 120 Hz and accordingly have a resonant frequency which is greater than 120 Hz.US 2015 / 0 362 724 A1 describes an optical deflection device for increasing a deflection amount of a mirror.It is now the object of the present invention to specify an improved micromirror.A micromirror is proposed, which has a mirror element having 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 member. A first end of the second arm is connected to the frame. A second end of the second arm is connected to the mirror member. On the first arm and on the second arm, drive elements are arranged which are configured to bend the first arm and the second arm, wherein the mirror element is 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 causes a tilting movement of the mirror element about a rotation axis.The first arm and the second arm have drive sections, wherein a drive element is arranged on each of the drive sections, which is configured to bend the respective drive section. The first arm and the second arm may have a meandering structure in which the driving portions are arranged parallel to each other and connected to each other by connecting portions.The drive sections can be arranged in such a way that their bendings add one another to form an overall bending. The total bending of the first arm can result as the sum of the individual bendings of each drive section. By using a plurality of individual drive sections, the micromirror can be designed more compactly and it can be ensured that the respective drive section is bent in such a way that the mirror element remains free of deformation and strain. This would not be possible with a comparable total deflection of an individual section.The drive sections can run perpendicular to a rotational axis of the mirror element, wherein the first arm and the second arm furthermore each have connecting sections, wherein two drive sections are 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.According to a first aspect, the drive sections have a width which indicates their extent in the direction of the axis of rotation, wherein the width of the drive sections decreases from the first end of the first arm to the second end of the first arm. By 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 quasistatic operation at a frequency of 120 Hz.The drive sections can each have a constant width over their respective length. The length can indicate 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 decreasing 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 may continuously decrease from its first end toward its second end.The drive sections can have such a length that the mirror element is tilted with low tension when the first and the second arm are bent. In particular, the lengths of the drive sections should not be chosen to be too long in order to ensure that the bending of the arms does not lead to a tensioning of the mirror element. According to a second aspect, the drive sections and the drive elements are configured such that each of the drive sections is maximally bent by an angle α for which it applies that the deviation from 1-cosa is not more than 0.2%, preferably not more than 0.1%.The mirror element, the first arm, the second arm and the frame can be formed by a structured silicon substrate. Accordingly, the elements may be integrally formed from a single substrate.The drive elements can comprise piezoelectric layers. The piezoelectric layers can comprise PZT, for example. The piezoelectric layers can be applied to the arms in a thin-film process.The micromirror may have a drive unit which is designed to apply a voltage to the piezoelectric layers. The drive unit may be configured to apply a voltage having a bias voltage and an AC voltage, wherein the AC voltage varies between a minimum value and a maximum value and the bias voltage remains constant. In this case, the bias voltage can be selected such that a zero crossing of the voltage, which results as the sum of bias voltage and alternating voltage, is avoided. The application of the bias voltage can have the effect that the voltage applied to the drive elements never falls into the negative range during operation and therefore polarity reversal of piezoelectric layers can be ruled out.The mirror element may have a compensation layer on a rear side opposite to the reflective surface. The compensation layer may be configured to compensate for a mechanical deformation of the mirror element caused by the application of the bias voltage and by other manufacturing steps. In its rest state, in which only the prestress is applied to the drive elements, the mirror element is then not bent, since the effects of the prestress and of the compensation layer compensate one another.The first arm and the second arm may be connected to the mirror member at a first suspension point and at a second suspension point. The first suspension point and the second suspension point may be on the rotational axis.Alternatively, the second end of the first arm may be forked and connected to the mirror element at a plurality of first suspension points. The second end of the second arm may be forked and connected to the mirror member at a plurality of second suspension points. In this case, the first and second suspension points can be connected to one another by straight lines which are perpendicular to the axis of rotation.The axis of rotation preferably extends through a center point of the mirror element. The micromirror can be designed to be operated quasistatically or to be operated resonantly.A further aspect relates to a projection apparatus which has the micromirror described above and a light source which is configured to emit a light beam onto the reflecting surface, wherein the micromirror is configured to reflect the light beam, and wherein the micromirror is configured to be moved in such a way that the reflected light beam carries out a raster-like scan. The projection device can be a device for projecting images and / or videos or a lidar device.Preferred embodiments of the present invention are described below with reference to the figures.FIGS. 1 and 2 show a micromirror in a perspective view. FIG. 3 schematically shows how a deflection of a mirror element by 3 a can be effected by the deflection of three drive sections by the angle α in each case.FIGS. 4 to 6 show a simulation of the deformation of the micromirror. FIG. 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. FIG. 8 shows the micromirror according to a second exemplary embodiment. FIG. 9 shows the distortion of a mirror element 1 according to the first exemplary embodiment. FIG. 10 shows the distortion of the mirror element 1 according to the second exemplary embodiment.FIGS. 1 and 2 show a micromirror in a perspective view. FIG. 1 shows a perspective view of the upper side. FIG. 2 shows a perspective view of the underside of the micromirror.The micromirror has 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, wherein a reflective layer is applied to the mirror element 1 in addition to the structuring of the silicon substrate and driving elements are applied respectively to the first arm 2 and the second arm 3.The mirror element 1 is a flat structure, for example a disk, preferably a circular disk, or a flat, rectangular structure. On its upper side, the mirror element 1 has the reflective layer, for example a reflective coating. The mirror element 1 is configured to reflect a light beam incident on the upper side of the mirror element.The mirror element 1 is configured to execute a tilting movement about an axis of rotation. In this case, the mirror element 1 is deflected out of its rest position. Depending on the respective deflection angle, a light beam incident on the mirror element 1 is reflected into different fall-off angles. In this way, the mirror element 1 can be configured to perform a scan, for example a raster scan, of the light beam.The first arm 2 and the second arm 3 are identical in structural construction and functional characteristics. Therefore, only the first arm 2 will be described in detail below.The first arm 2 connects the mirror member 1 to the frame 4. The first end 2 aof 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 fixed to the mirror member 1. The second end 2 bof the first arm 2 is directly connected to the mirror element 1. The first arm 2 is configured to flex, moving the second end 2 bof the first arm 2 relative to the first end 2 a. The bending of the first arm 2 triggers the tilting movement of the mirror element 1.The frame 4 to which the first end 2 aof the first arm 2 is connected is not moved by bending the first arm 2. The frame 4 is thus static.The first arm 2 has driving portions 5 a, 5 b, 5 c, connecting portions 6 a, 6 band an end portion 7. The drive sections 5 a, 5 b, 5 cand the connecting sections 6 a, 6 bresult in a meandering structure of the first arm 2. a drive element 8 a, 8 b, 8 cis arranged in each case on the drive sections 5 a, 5 b, 5 c. The driving portions 5 a, 5 b, 5 care arranged parallel to each other. The connecting sections 6 a, 6 bconnect each two drive sections arranged adjacent to one another. No drive elements are arranged on the connecting sections 6 a, 6 b.The first arm 2 of the micromirror according to a first exemplary embodiment shown in FIGS. 1 and 2 has three drive sections 5 a, 5 b, 5 cand two connecting sections 6 a, 6 b. In alternative embodiments, the first arm may have n driving portions and n-1 connecting portions, where n may be any integer greater than or equal to 2.The drive elements 8 a, 8 b, 8 ceach have a piezoelectric layer. This can be a piezoelectric thin film. The piezoelectric thin film can be applied in a coating method, for example by vapor deposition, sputtering or sputtering variants. The piezoelectric material may be lead zirconate titanate (PZT). In addition, the driving elements 8 a, 8 b, 8 ccomprise electrodes that make it possible to apply a voltage to the piezoelectric layers.The first arm 2 comprises a first group of driving elements 8a, 8c and a second group of driving elements 8b. On the drive section 5a, which is directly connected to the frame 4, a drive element 8a of the first group is arranged. On the drive sections 5 b, which are directly connected by a connecting section 6 ato a drive section 5 a, on which a drive element 8 aof the first group is arranged, a drive element 8 bof the second group is arranged in each case. On the drive sections 5 c, which are directly connected by a connecting section 6 bto a drive section 5 b, on which a drive element 8 bof the second group is arranged, a drive element 5 cof the first group is again arranged. This results in a structure in which driving elements 8 a, 8 cof the first group and driving elements 8 bof the second group alternate along the first arm 2.An AC voltage signal and a bias voltage are applied to the driving elements 8a, 8b, 8c. In this case, the AC voltage signal applied to the drive elements 8 a, 8 cof the first group is phase-shifted by 180° with respect to the AC voltage signal applied to the drive elements 8 bof the second group. The drive elements 8 a, 8 b, 8 cof two drive sections 5 a, 5 b, 5 cadjacent to one another are thus each controlled with polarity opposite to one another.By the phase shift of the respectively applied alternating voltage signal, two drive sections adjacent to one another are bent in mutually opposite directions. Due to the meandering structure of the first arm 2, the first arm 2 is bent in one direction overall.The end section 7 connects the last drive section 5 ctoward the mirror element 1 to the mirror element 1. The end section 7 is fork-shaped and connected to the mirror element 1 at a plurality of suspension points 9 a, 9 b. In the embodiment shown in FIGS. 1 and 2, the end portion 7 of the first arm 2 is connected to the mirror element 1 at two suspension points 9 a, 9 b.The second arm 3 is designed analogously to the first arm 2. Here, a first end 3 aof the second arm 3 is connected to the frame 4, and a second end 3 bof the second arm 3 is connected to the mirror member 1.The second arm 3 is arranged rotationally symmetrically to the first arm 2, wherein there is rotational symmetry with respect to a rotation through 180° about an axis through the center point of the mirror element 1, which is perpendicular to the surface of the mirror element 1. The driving portion 10 aof the second arm 3 directly connected to the frame 4 includes a second group driving member 11 a. The drive sections 10 a, 10 b, 10 cof the second arm 3 are thus respectively driven in the opposite direction to the corresponding drive sections 5 a, 5 b, 5 cof the first arm 2. If the second end 2 bof the first arm 2 is moved in the first direction, the second end 3 bof the second arm 3 is moved in the negative first direction opposite thereto.If, for example, the second end 2 bof the first arm is now moved into the representation plane of FIG. 1 and the second end 3 bof the second arm 3 is simultaneously moved out of the representation plane of FIG. 1, a tilting movement of the mirror element 1 about the axis of rotation is thereby effected, in which the upper half of the mirror element 1 is tilted forward out of the representation plane and the lower half of the mirror element 1 is tilted rearward into the representation plane.In the first exemplary embodiment of the micromirror shown in FIGS. 1 and 2, the first arm 2 and the second arm 3 are connected to the mirror element 1 at a respective plurality of suspension points 9 a, 9 b, 12 a, 12 b. In this case, a suspension point 9 a, 9 bat which the second end 2 bof the first arm 2 is connected to the mirror element 1 is situated opposite a suspension point 12 a, 12 bat which the second end 3 bof the second arm 3 is connected to the mirror element 1. In this case, the two suspension points 9 a, 12 a; 9 b, 12 bmay be connected to one another by a straight line which runs perpendicular to the axis of rotation.The driving portions 5 a- 5 c, 10 a- 10 chave a length, a width, and a thickness that are respectively perpendicular to each other. The thickness indicates the extent of the driving portions 5 a- 5 c, 10 a- 10 cin a direction in which the extent of the driving portions 5 a- 5 c, 10 a- 10 cis the smallest. The thickness of the driving portions 5a-5c, 10a-10c corresponds to the thickness of the silicon substrate from which the driving portions 5a-5c, 10a-10c are patterned. The length of the driving portions 5a-5c, 10a-10c indicates their extension in the direction in which the driving portions 5a-5c, 10a-10c are bent by applying a voltage to the driving members. The width indicates the extension of the driving portions 5a-5c, 10a-10c in a direction perpendicular to the thickness and the length. The width indicates an extension of the driving portions 5 a- 5 c, 10 a- 10 cin a direction facing along the rotation axis of the mirror member 1.The driving portions 5a-5c of the first arm 2 are different from each other in width. The width of the driving portion 5a connected to the frame 4 is the greatest. Toward the second end 2b of the first arm 2, the width of the driving portions 5a-5c decreases. A driving portion disposed closer to the second end 2 bof the first arm 2 than a driving portion disposed closer to the first end 2 ahas a smaller width. The driving portions 10a-10c of the second arm 3 are different from each other in their respective widths as well.The resonant frequency of the first and second arms 2, 3 is changed, in particular increased, by reducing the width of the drive sections 5 a- 5 c, 10 a- 10 cto the second end, in comparison with an arm in which the drive sections all have the same width. Thus, by the variation in the width of the driving portions 5a-5c, 10a-10c, a higher resonance frequency of the first and second arms 2, 3 is caused in the bendings. The increase in the resonant frequency contributes to the fact that the mirror element 1 is excited to a low-stress and low-deformation tilting movement.For example, the width of the drive section 5a directly connected to the frame 4 can be between 2 and 4 mm, preferably between 2.5 and 3 mm. The width of the driving portion 5c connected to the end portion may be between 0.5 mm and 2.5 mm, preferably between 0.5 mm and 1.5 mm.In the first embodiment, the width of the driving portions 5 a- 5 cincreases from 1.0 mm from the second end 2 bto the first end 2 a, from 1.67 mm to 2.78 mm. The width of the connecting sections 6 a, 6 bincreases from 0.7 mm, over 0.8 mm to 1.0 mm.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 patterned may be between 250 μm and 500 μm, for example 380 μm.The thickness of the drive elements 5 a- 5 c, 10 a- 10 cresults 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 μm and 3 μm, and is preferably 1.7 μm.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 driving portions 5a-5c, 10a-10c corresponds to the diameter of the mirror member 1.The meandering structure of the first and second arms 2, 3 can also be referred to as folding of the arms. The meandering structure of the arms 2, 3 makes it possible to avoid sections with a long length. By too long portions of the arms from which the mirror element 1 is suspended, the resonance frequency would be reduced.The length of the drive sections in which they are bent is selected such that the following approximation applies: in this case, α indicates the maximum deflection of the drive sections 5 a- 5 c, 10 a- 10 cwhich they experience during operation of the micromirror. The approximation is considered to be fulfilled if the two values deviate from one another by not more than 0.2%, preferably if they deviate from one another by not more than 0.1%.If the arms 2, 3 are formed with n drive sections arranged in meandering fashion, which can be maximally deflected by the angle α_max, a deflection of the mirror element 1 by n×α_max is effected overall. If the above-mentioned approximation is fulfilled, the mirror element 1 is deflected almost without stress and almost without deformation.FIG. 3 schematically shows how a deflection of the mirror element by 3 acan be effected by the deflection of three drive sections 5 a, 5 b, 5 cby the angle α in each case.The driving 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, because 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 present at the drive elements. The bias voltage may be between 5 V and 25 V, for example 10 V.The application of the bias voltage may cause mechanical distortion of the mirror element 1. On the rear side of the mirror element 1, which is opposite the reflective upper side, one or more compensation layers 13 can be applied, which compensate for the mechanical distortion. The piezoelectric layer is under a tensile stress that is amplified by the application of 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 balance each other, so that the mirror element is not distorted.FIG. 4 shows the result of a simulation in which the bias voltage is not taken into account and the AC voltage applied to the driving elements is between 4 V and -4 V. This results in a deflection of the mirror element by 9.1°, so that an optical full angle of 36.4° results. In this case, e31f of 16.25 C / m 2 was assumed.FIG. 5 likewise shows this simulation, wherein FIG. 5 shows the deflection of the elements of the micromirror. The strongest deflection is thereby experienced by the end sections 7 of the first and second arms 2, 3.FIG. 6 shows a simulation of the static deformation of the mirror element 1 in nm at a deflection of 15°.The micromirror can be operated either quasistatically or in resonance. In a quasistatic operation, the frequency of the applied alternating voltage is below the resonant frequency of the micromirror.In FIG. 7, the frequency of the signals applied to the drive elements 8 a- 8 c, 10 a- 10 cis plotted on the horizontal axis. The vertical axis plots the mechanical deflection for the curve K 1 and the phase between the drive signal and the mechanical deflection for the curve K 2. At a frequency of about 320 Hz, resonance behavior occurs.FIG. 8 shows the micromirror according to a second exemplary embodiment. The second exemplary embodiment differs in the configuration of the end sections 7 from the first exemplary embodiment.In the second exemplary embodiment, the first arm 2 and the second arm 3 are each connected to the mirror element at a suspension point 14, 15, wherein the two suspension points are located on the axis of rotation. The end portion 7 of the first arm 2 and the end portion of the second arm 3 are connected to each other.The second exemplary embodiment is distinguished by a high degree of robustness with respect to inadequate flatness of the mirror element 1 in the initial state. It ensures that mechanical distortions occur substantially outside the mirror element.FIG. 9 shows the distortion of a mirror element 1 according to the first exemplary embodiment. FIG. 10 shows the distortion of the mirror element 1 according to the second exemplary embodiment. In this case, a deflection of 15° and an applied voltage of 4 V are assumed. A comparison of FIGS. 9 and 10 shows that the mirror element 1 in the second exemplary embodiment experiences less mechanical distortion. However, the resonant frequency of the second embodiment is somewhat lower than that of the first embodiment. The resonant frequency may be 288 Hz. The second exemplary embodiment has somewhat larger external dimensions than the first exemplary embodiment if the mirror element, the drive sections and the connecting sections are identical. For example, the external dimensions may be 15.74 mm and 6.2 mm.The mirror member 1 and the driving portions 5a-5c, 10a-10c are arranged such that a center line of the mirror member 1 perpendicular to the length of the driving portions 5a-5c, 10a-10c and the center lines of the driving portions 5a-5c, 10a-10c perpendicular to the length of the respective driving portions are not offset from each other in the direction of the length. The mirror member 1 is thus located at the center of the direction in which the driving portions 5a-5c, 10a-10c can be bent. As a result, jamming of the micromirror can be prevented.List of reference characters1 Mirror element 2 First arm 2 aFirst end of first arm 2 bSecond end of first arm 3 Second arm 3 aFirst end of second arm 3 bSecond end of second arm 4 Frame 5 a, 5 b, 5 cDrive portion of first arm 6 a, 6 bConnect portion of first arm 7 End portion of first arm 8 a, 8 b, 8 cDrive element of first arm 9 a, 9 b Aufhängungs point of first arm 10 a, 10 b, 10 cDrive portion of second arm 11 aDrive element of second arm 12 a, 12 b Aufhängungs point of second arm 13 Compensation layer 14, 15 Aufhängungs point (second embodiment)

Claims

Micromirror, comprising: - a mirror element (1) having 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), said drive elements being configured 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 an axis of rotation, wherein the first arm (2) and the second arm (3) have drive sections (5a-5c, 10a-10c), wherein a drive element (8a-8c, 11a) is arranged on each drive section (5a-5c, 10a-10c) and is configured to bend the respective drive section (5a-5c, 10a-10c), wherein the drive sections (5a-5c, 10a-10c) are arranged parallel to one another, and wherein the drive sections (5a-5c, 10a-10c) have a width indicating their extension in the direction of the axis of rotation, wherein from the first end (2a) of the first arm (2) to the second end (2b) of the first arm (2) the width of the drive sections (5a-5c) of the first arm (2) decreases.Micromirror according to the preceding claim, wherein the drive sections (5a-5c, 10a-10c) and the drive elements (8a-8c, 11a) are designed such that each of the meandering sections is maximally bent by an angle α for which it applies that α 2 / 2 deviates from 1-cos(α) by not more than 0.2%.A micromirror according to any preceding claim, wherein the drive sections (5a-5c, 10a-10c) have a constant width along their respective length, the length being perpendicular to the width of the drive section (5a-5c, 10a-10c).Micromirror according to one of the preceding claims, 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) which is 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) which is connected to the second end (2b, 3b).Micromirror, comprising: - a mirror element (1) having 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), said drive elements being configured 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 an axis of rotation, wherein the first arm (2) and the second arm (3) have drive sections (5a-5c, 10a-10c), wherein a drive element (8a-8c, 11a) is arranged on each drive section (5a-5c, 10a-10c) and is configured to bend the respective drive section (5a-5c, 10a-10c), wherein the drive sections (5a-5c, 10a-10c) are arranged parallel to one another, and wherein the drive sections (5a-5c, 10a-10c) and the drive elements (8a-8c, 11a) are configured such that each of the meandering sections is maximally bent by an angle α for which it applies that α 2 / 2 deviates from 1-cos(α) by not more than 0.2%.Micromirror according to one of the preceding claims, 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).Micromirror according to one of the preceding claims, wherein the drive sections (5a-5c, 10a-10c) have a length such that the mirror element (1) is tilted with low stress and low deformation when the first and second arms (3) are bent.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.Micromirror according to one of the preceding claims, wherein the drive elements (8a-8c, 11a) have piezoelectric layers.Micromirror according to Claim 9, having a drive unit which is designed to apply a voltage to the piezoelectric layers, the voltage being composed of a bias voltage and an AC voltage, and the bias voltage being selected such that a zero crossing of the voltage is avoided.Micromirror according to one of the preceding claims, wherein the mirror element (1) has a compensation layer (13) on a rear side which is opposite the reflective surface.Micromirror according to Claim 10 and Claim 11, wherein the compensation layer (13) is designed to compensate for a mechanical deformation of the mirror element (1) caused by the prestress.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.Micromirror according to one of Claims 1 to 12, wherein the second end (2b) of the first arm (2) is connected to the mirror element (1) at a plurality of 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).Micromirror according to Claim 14, 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.Micromirror according to one of the preceding claims, wherein the axis of rotation runs through a center point of the mirror element (1).The micromirror of any preceding claim, wherein the micromirror is configured to be operated quasistatically, or wherein the micromirror is configured to be operated resonantly.Projection device comprising a micromirror according to one of the preceding claims and a light source which is 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 in such a way that the reflected light beam performs a raster-like scan.Projection device according to the preceding claim, wherein it is a device for projecting images and / or videos or a lidar device.

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