micromirror
By optimizing the micromirror structure and driving method, the resonant frequency was increased, solving the problem of unstable operation of micromirrors in the 120Hz frequency range in the existing technology, and achieving a highly efficient beam scanning effect.
Patent Information
- Application Number
- CN202580025494.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-04-05
- Filing Date
- 2025-03-14
- Publication Date
- 2026-11-03
AI Technical Summary
In the prior art, micromirrors used for grating scanning are difficult to achieve quasi-static operation within the 120Hz image refresh rate range, and their resonant frequency is insufficient.
A micromirror structure is designed, in which a first arm and a second arm are connected to a mirror element through a driving section. A driving element is set on the driving section, and the tilting motion of the mirror element is controlled by a piezoelectric layer and a bias voltage. The width and length of the driving section are optimized by a meandering structure to improve the resonant frequency, and a compensation layer is set on the mirror element to reduce mechanical deformation.
Quasi-static operation of the micromirror was achieved in the 120Hz frequency range, which improved the resonant frequency, reduced the mechanical stress and deformation of the mirror element, and ensured efficient beam scanning performance.
Smart Images
Figure CN123036540A_ABST
Abstract
Description
Technical Field
[0001] For projection applications, such as image and / or video projection, and for LiDAR devices, there is a need for quasi-static mirrors for raster scanning. The mirrors should non-resonantly cover a frequency range up to an image refresh rate of 120 Hz, and correspondingly have a resonant frequency greater than 120 Hz. Summary of the Invention
[0002] The present invention aims to provide an improved micromirror.
[0003] A micromirror is proposed, comprising 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. Driving elements are provided on the first and second arms, the driving elements being designed to bend the first and second arms, wherein the mirror element is positioned and connected to the second ends of the first and second arms such that bending of the first and second arms causes the mirror element to tilt about a rotation axis.
[0004] The first and second arms can have drive sections, each equipped with a drive element designed to bend the respective drive section. The first and second arms can also have a meandering structure in which the drive sections are arranged parallel to each other and connected to each other via connecting sections.
[0005] Here, the drive segments can be configured such that their bends are added together to form a total bend. The total bend of the first arm can be derived as the sum of the individual bends of each drive segment. By using multiple individual drive segments, the micromirror can be constructed more compactly, and it can be ensured that the corresponding drive segments are bent in a way that keeps the mirror element free from deformation and stress. This would not be possible with a similar total deflection of a single segment.
[0006] The drive section can extend perpendicular to the rotation axis of the mirror element, wherein the first arm and the second arm also have connecting sections, wherein every two drive sections are connected to each other through the connecting sections, wherein the connecting sections extend perpendicular to the drive sections, and wherein no drive element is provided on the connecting sections.
[0007] The drive section can have a width that indicates its extension along the rotation axis, wherein the width of the drive section decreases from the first end of the first arm to the second end of the first arm. Compared to a mirror where all drive sections have the same width, the reduced width of the drive sections allows for an increase in the resonant frequency of the mirror element. This increase in resonant frequency is advantageous for achieving the goal of quasi-static operation at a frequency of 120 Hz.
[0008] The drive segments can each have a constant width along their respective lengths. Here, the length can indicate the extension of the drive segment perpendicular to its width and perpendicular to the substrate thickness. In an alternative embodiment, the drive segments can have a decreasing width along their respective lengths, wherein the width at the end of the respective drive segment facing the first end is greater than the width at the end facing the second end. Correspondingly, the width of the first arm can continuously decrease from its first end toward its second end.
[0009] The drive segments can be of such length that the mirror element tilts in a low-stress manner when the first and second arms are bent. In particular, the length of the drive segments should not be chosen to be excessive to ensure that bending of the arms does not cause stress to the mirror element. The drive segments and drive elements can be designed such that each drive segment bends by a maximum angle α, for which: The deviation from 1−cosα should not exceed 0.2%, preferably not exceed 0.1%.
[0010] The mirror element, first arm, second arm, and frame can be formed on a structured silicon substrate. Correspondingly, these elements can be fabricated in one piece from a single substrate.
[0011] The driving element can have a piezoelectric layer. The piezoelectric layer can be, for example, PZT. The piezoelectric layer can be coated onto the arm in a thin-layer manner.
[0012] The micromirror can have a manipulation unit designed to apply a voltage to the piezoelectric layer. The manipulation unit can be designed to apply a voltage having a bias voltage and an AC voltage, wherein the AC voltage varies between a minimum and a maximum value while the bias voltage remains constant. Here, the bias voltage can be selected such that the voltage obtained as the sum of the bias voltage and the AC voltage avoids crossing zero. Applying the bias voltage ensures that the voltage applied to the driving element never drops into the negative range during operation, thereby preventing polarity reversal of the piezoelectric layer.
[0013] The mirror element can have a compensation layer on its rear side opposite the reflective surface. This compensation layer can be designed to compensate for mechanical deformation of the mirror element caused by the applied bias voltage and other manufacturing steps. In the mirror element's stationary state, where only the bias voltage is applied to the drive element, the mirror element does not bend because the bias voltage and the effect of the compensation layer cancel each other out.
[0014] The first and second arms can be connected to the mirror element at the first and second suspension points, respectively. The first and second suspension points can be located on the axis of rotation.
[0015] Alternatively, the second end of the first arm can be forked and connected to the mirror element at a plurality of first suspension points. The second end of the second arm can be forked and connected to the mirror element at a plurality of second suspension points. Here, the first and second suspension points can be connected to each other by a straight line perpendicular to the axis of rotation.
[0016] Preferably, the axis of rotation extends through the center point of the mirror element. The micromirror can be designed to operate quasi-statically or resonantly.
[0017] On the other hand, a projection device is disclosed, having micromirrors and a light source as described above, the light source being designed to emit a light beam onto a reflective surface, wherein the micromirrors are designed to reflect the light beam, and wherein the micromirrors are designed to move such that the reflected light beam performs a raster scan. The projection device can be a device for projecting images and / or video, or a LiDAR device. Attached Figure Description
[0018] Preferred embodiments of the present invention are described below with reference to the accompanying drawings.
[0019] Figure 1 and Figure 2 A stereoscopic view of the microscope is shown.
[0020] Figure 3 The diagram illustrates how the mirror element can be deflected by 3α by deflecting the three drive sections by an angle α.
[0021] Figures 4 to 6 The simulation of micromirror deformation is shown.
[0022] Figure 7 A graph is shown that illustrates the maximum mechanical deflection of the mirror element and the phase between the control signal and the mechanical deflection at different frequencies of the control signal.
[0023] Figure 8 A micromirror according to a second embodiment is shown.
[0024] Figure 9 The distortion of mirror element 1 according to the first embodiment is shown.
[0025] Figure 10 The distortion of mirror element 1 according to the second embodiment is shown. Detailed Implementation
[0026] Figure 1 and Figure 2 The micromirror is shown in a stereoscopic view. Here, in Figure 1 The image shows a three-dimensional view of the top side. Figure 2 A stereoscopic view of the lower side of the microscope is shown.
[0027] 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 in one piece from a single silicon substrate, wherein a reflective layer is applied to the mirror element 1 in addition to the structured portion of the silicon substrate, and driving elements are respectively applied to the first arm 2 and the second arm 3.
[0028] Mirror element 1 is a flat structure, such as a disk, preferably a circular disk, or a flat, rectangular structure. On its upper side, mirror element 1 has a reflective layer, such as a reflective coating. Mirror element 1 is designed to reflect light beams incident on its upper side.
[0029] Mirror element 1 is designed to perform tilting motion about a rotation axis. Here, mirror element 1 deflects from its rest position. Depending on the corresponding deflection angle, the light beam incident on mirror element 1 is reflected at different exit angles. In this way, mirror element 1 can be designed to perform beam scanning, such as raster scanning.
[0030] The first arm 2 and the second arm 3 are identical in their structural design and functional characteristics. Therefore, only the first arm 2 will be described in detail below.
[0031] The first arm 2 connects the mirror element 1 to the frame 4. The 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. The second end 2b of the first arm 2, opposite to 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 moves relative to the first end 2a. The bending of the first arm 2 triggers the tilting movement of the mirror element 1.
[0032] The frame 4, which is connected to the first end 2a of the first arm 2, does not move due to the bending of the first arm 2. Therefore, the frame 4 is static.
[0033] The first arm 2 has drive sections 5a, 5b, and 5c, connecting sections 6a and 6b, and an end section 7. The drive sections 5a, 5b, and 5c, and the connecting sections 6a and 6b form a meandering structure for the first arm 2. Drive elements 8a, 8b, and 8c are respectively provided on the drive sections 5a, 5b, and 5c. The drive sections 5a, 5b, and 5c are arranged parallel to each other. The connecting sections 6a and 6b connect two adjacent drive sections. No drive elements are provided on the connecting sections 6a and 6b.
[0034] exist Figure 1 and Figure 2The first arm 2 of the micromirror shown according to the first embodiment has three drive segments 5a, 5b, 5c and two connecting segments 6a, 6b. In an alternative embodiment, the first arm can have n drive segments and n-1 connecting segments, where n can be any integer greater than or equal to 2.
[0035] The driving elements 8a, 8b, and 8c each have a piezoelectric layer. This can involve a thin piezoelectric layer. The piezoelectric layer can be applied by a coating method, such as by evaporation, sputtering, or a modified sputtering process. The piezoelectric material can be lead zirconate titanate (PZT). Additionally, the driving elements 8a, 8b, and 8c have electrodes capable of applying a voltage to the piezoelectric layer.
[0036] The first arm 2 has a first set of drive elements 8a and 8c and a second set of drive elements 8b. Here, the first set of drive elements 8a is provided on a drive section 5a directly connected to the frame 4. The second set of drive elements 8b is provided on each drive section 5b, which is directly connected to the drive section 5a on which the first set of drive elements 8a is provided via a connecting section 6a. The first set of drive elements 5c is also provided on each drive section 5c, which is directly connected to the drive section 5b on which the second set of drive elements 8b is provided via a connecting section 6b. This results in a structure in which the first set of drive elements 8a and 8c and the second set of drive elements 8b alternate along the first arm 2.
[0037] An AC voltage signal and a bias voltage are applied to the drive elements 8a, 8b, and 8c. Here, the AC voltage signal applied to the first group of drive elements 8a and 8c is phase-shifted by 180° relative to the AC voltage signal applied to the second group of drive element 8b. Therefore, the drive elements 8a, 8b, and 8c of two adjacent drive sections 5a, 5b, and 5c are operated with opposite polarities.
[0038] By applying phase shifts to the AC voltage signals, two adjacent drive sections bend in opposite directions. Here, due to the meandering structure of the first arm 2, the first arm 2 bends in one direction as a whole.
[0039] End segment 7 connects to the mirror element 1 via the final drive segment 5c in the direction of the mirror element 1. End segment 7 has a second end 2b of the first arm 2. End segment 7 is forked and connects to the mirror element 1 at multiple suspension points 9a, 9b. Figure 1 and Figure 2 In the embodiment shown, the end segment 7 of the first arm 2 is connected to the mirror element 1 at two suspension points 9a and 9b.
[0040] The second arm 3 is designed similarly to the first arm 2. Here, the first end 3a of the second arm 3 is connected to the frame 4, and the second end 3b of the second arm 3 is connected to the mirror element 1.
[0041] The second arm 3 is arranged rotationally symmetrically with respect to the first arm 2, exhibiting rotational symmetry with respect to an axis about 180° perpendicular to the surface of the mirror element 1, passing through the center point of the mirror element 1. The drive section 10a of the second arm 3, directly connected to the frame 4, has a second set of drive elements 11a. Therefore, the drive sections 10a, 10b, and 10c of the second arm 3 are operated in the opposite direction to their corresponding drive sections 5a, 5b, and 5c of the first arm 2. If the second end 2b of the first arm 2 moves in a first direction, the second end 3b of the second arm 3 moves in the opposite first negative direction.
[0042] If now, for example, the second end 2b of the first arm is moved into... Figure 1 In the plane of the diagram, and simultaneously the second end 3b of the second arm 3 from Figure 1 When the mirror element 1 moves out of the plane of the diagram, it causes the mirror element 1 to tilt about the axis of rotation. During the tilting motion, the upper half of the mirror element 1 tilts forward out of the plane of the diagram, and the lower half of the mirror element 1 tilts backward into the plane of the diagram.
[0043] exist Figure 1 and Figure 2 In the first embodiment of the micromirror shown, the first arm 2 and the second arm 3 are connected to the mirror element 1 at multiple suspension points 9a, 9b, 12a, and 12b, respectively. Here, the suspension points 9a and 9b where the second end 2b of the first arm 2 connects to the mirror element 1 are respectively opposite to the suspension points 12a and 12b where the second end 3b of the second arm 3 connects to the mirror element 1. These two suspension points 9a and 12a, 9b and 12b can be connected to each other by a straight line extending perpendicular to the axis of rotation.
[0044] The drive segments 5a-5c and 10a-10c have lengths, widths, and thicknesses that are perpendicular to each other. Here, the thickness indicates the extension of the drive segments 5a-5c and 10a-10c in the direction in which their extension is minimal. The thickness of the drive segments 5a-5c and 10a-10c corresponds to the thickness of the silicon substrate, which is structured by the drive segments 5a-5c and 10a-10c. The length of the drive segments 5a-5c and 10a-10c indicates their extension in the direction along which they bend when a voltage is applied to the drive element. The width indicates the extension of the drive segments 5a-5c and 10a-10c in the direction perpendicular to their thickness and length. The width also indicates the extension of the drive segments 5a-5c and 10a-10c in the direction pointing along the rotation axis of the mirror element 1.
[0045] The drive segments 5a-5c of the first arm 2 differ in width from each other. The drive segment 5a, which is connected to the frame 4, has the largest width. The width of the drive segments 5a-5c decreases towards the second end 2b of the first arm 2. Here, the drive segment located closer to the second end 2b of the first arm 2 has a smaller width than the drive segment located closer to the first end 2a of the first arm 2. The drive segments 10a-10c of the second arm 3 also differ in their respective widths.
[0046] Compared to an arm where all drive sections have the same width, by reducing the width of drive sections 5a-5c and 10a-10c towards the second end, the resonant frequencies of the first and second arms 2 and 3 change, and particularly increase. Therefore, the width variation of drive sections 5a-5c and 10a-10c causes a higher resonant frequency in the first and second arms 2 and 3 during bending. This increase in resonant frequency helps to excite the mirror element 1 to tilt movements with low stress and low deformation.
[0047] For example, the width of the drive section 5a, which is directly connected to the frame 4, can be between 2 mm and 4 mm, preferably between 2.5 mm 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.
[0048] In the first embodiment, the width of the drive segments 5a-5c increases from 1.0 mm to 2.78 mm from the second end 2b to the first end 2a, following a progression of 1.67 mm. The width of the connecting segments 6a and 6b increases from 0.7 mm to 1.0 mm, following a progression of 0.8 mm.
[0049] In the first embodiment, the external dimensions of the frame are 15.1 mm and 6.2 mm. The thickness of the silicon substrate can be between 250 µm and 500 µm, for example, 380 µm, and the frame 4, arms 2 and 3, and mirror element 1 are structured on the silicon substrate.
[0050] The thicknesses of the driving elements 5a-5c and 10a-10c are derived from the sum of the thicknesses of the two electrode layers and the thickness of the piezoelectric layer. The thickness of the piezoelectric layer is between 1µm and 3µm, and preferably 1.7µm.
[0051] The diameter of mirror element 1 is between 1 mm and 10 mm, preferably between 2 mm and 5 mm, and for example, 3 mm. The lengths of the drive sections 5a-5c and 10a-10c correspond to the diameter of mirror element 1.
[0052] The meandering structure of the first and second arms 2 and 3 can also be referred to as arm folding. The meandering structure of arms 2 and 3 can prevent the segments from having large lengths. The resonant frequency will decrease due to the excessively long segments of the arms (on which the mirror element 1 is suspended).
[0053] The length along which the drive section bends is chosen such that the following approximation applies: Here, α represents the maximum deflection experienced by the drive segments 5a-5c and 10a-10c during the operation of the microscope. If these two values deviate from each other by no more than 0.2%, preferably if they deviate from each other by no more than 0.1%, then this approximation is considered satisfied.
[0054] If arms 2 and 3 are formed by n meandering drive segments, each capable of deflecting by a maximum angle α_max, then the mirror element 1 will deflect by n×α_max as a whole. If the approximation mentioned above is satisfied, the mirror element 1 will deflect with almost no stress and almost no deformation.
[0055] Figure 3 The diagram illustrates how the mirror element can be deflected by 3α by deflecting the three drive sections 5a, 5b, and 5c by an angle α.
[0056] The driving elements 8a-8c and 10a-10c have a piezoelectric thin layer. This piezoelectric thin layer operates beyond its coercive field strength. Correspondingly, a negative voltage should not be applied to the piezoelectric element, as this would otherwise cause the piezoelectric layer to reverse its polarity. Therefore, a bias voltage is applied to the piezoelectric layer. The height of the bias voltage is chosen such that a positive potential is always applied to the driving element. The height of the bias voltage can be between 5V and 25V, and for example, 10V.
[0057] Applying a bias voltage can cause mechanical distortion of the mirror element 1. One or more compensation layers 13 can be applied to the back side of the mirror element 1, opposite the upper side where reflection occurs, to compensate for the mechanical distortion. The piezoelectric layer is under tensile stress, which is increased by the applied bias voltage. In the delivered state without a bias voltage, the mirror element is distorted due to the compensation layers 13. In the stationary state where only a bias voltage is applied to the drive element, the distortion caused by the bias voltage and the compensation layers 13 cancel each other out, resulting in no distortion of the mirror element.
[0058] Figure 4 The simulation results are shown, in which the bias voltage is not considered and the AC voltage applied to the drive element is between 4V and -4V. Here, a mirror element deflection of 9.1° is obtained, resulting in a full optical angle of 36.4°. Here, e31f is assumed to be 16.25C / m. 2 .
[0059] Figure 5 This simulation is also shown, where... Figure 5 The diagram shows the deflection of the micromirror's components. Here, the end segments 7 of the first and second arms 2 and 3 experience the largest deflection.
[0060] exist Figure 6 The figure shows a simulation of the static deformation of mirror element 1 in nm when it is deflected by 15°.
[0061] Micromirrors can operate quasi-statically or resonantly. In quasi-static operation, the frequency of the applied AC voltage is lower than the resonant frequency of the micromirror.
[0062] exist Figure 7 In the diagram, the frequencies of the signals applied to the drive elements 8a-8c and 10a-10c are plotted on the horizontal axis. On the vertical axis, the mechanical deflection is plotted for curve K1, and the phase between the control signal and the mechanical deflection is plotted for curve K2. Resonance characteristics appear at a frequency of approximately 320Hz.
[0063] Figure 8 A micromirror according to a second embodiment is shown. The second embodiment differs from the first embodiment in the design of the end portion 7.
[0064] In the second embodiment, the first arm 2 and the second arm 3 are connected to the mirror element at a suspension point 14, 15, respectively, where these two suspension points are located on the rotation axis. The end segment 7 of the first arm 2 and the end segment of the second arm 3 are connected to each other.
[0065] The second embodiment is characterized by high robustness to insufficient flatness of the mirror element 1 in its initial state. This ensures that mechanical distortion occurs substantially outside the mirror element.
[0066] Figure 9 The distortion of mirror element 1 according to the first embodiment is shown. Figure 10 The distortion of mirror element 1 according to the second embodiment is shown. Here it is based on a deflection of 15° and an applied voltage of 4V, respectively. Figure 9 and Figure 10 The comparison shows that mirror element 1 experiences less mechanical distortion in the second embodiment. However, the resonant frequency of the second embodiment is slightly lower than that of the first embodiment. The resonant frequency can be 288Hz. When the mirror element, driving section, and connecting section are the same, the second embodiment has slightly larger external dimensions than the first embodiment. For example, the external dimensions can be 15.74mm and 6.2mm.
[0067] The mirror element 1 and the drive sections 5a-5c and 10a-10c are arranged such that the center line of the mirror element 1 perpendicular to the length of the drive sections 5a-5c and 10a-10c, and the center lines of the drive sections 5a-5c and 10a-10c perpendicular to the length of their respective drive sections, are not offset from each other in the length direction. Therefore, the mirror element 1 is located at the midpoint of the direction along which the drive sections 5a-5c and 10a-10c can be bent. This prevents the micromirror from getting stuck.
[0068] List of reference numerals
[0069] 1 mirror element
[0070] 2 First Arm
[0071] 2a First end of the first arm
[0072] 2b Second end of the first arm
[0073] 3 Second Arm
[0074] 3a The first end of the second arm
[0075] 3b Second end of the second arm
[0076] 4-frame
[0077] Drive sections of the first arm (5a, 5b, 5c)
[0078] 6a, 6b Connecting sections of the first arm
[0079] 7. End section of the first arm
[0080] Drive elements of the first arm of 8a, 8b, 8c
[0081] 9a, 9b Suspension points of the first arm
[0082] Drive sections of the second arm, 10a, 10b, and 10c
[0083] 11a Drive element of the second arm
[0084] 12a, 12b Suspension points of the second arm
[0085] 13 compensation layers
[0086] Suspension points 14 and 15 (Second embodiment)
Claims
1. A micromirror, said micromirror having: - Mirror element with reflective surface (1). - First arm (2) - Second arm (3), and - Frame (4), The first end (2a) of the first arm (2) is connected to the frame (4). The second end (2b) of the first arm (2) is connected to the mirror element (1). The first end (3a) of the second arm (3) is connected to the frame (4). The second end (3b) of the second arm (3) is connected to the mirror element (1). A drive element (8a-8c, 11a) is provided on the first arm (2) and the second arm (3), the drive element being designed to bend the first arm (2) and the second arm (3). The mirror element (1) is configured and connected to the second ends (2b, 3b) of the first and second arms (2, 3) such that bending of the first and second arms (2, 3) causes the mirror element (1) to tilt about the axis of rotation.
2. The micromirror according to claim 1, The first arm (2) and the second arm (3) have drive sections (5a-5c, 10a-10c). Each drive segment (5a-5c, 10a-10c) is provided with a drive element (8a-8c, 11a), which is designed to bend the corresponding drive segment (5a-5c, 10a-10c). The drive sections (5a-5c, 10a-10c) are arranged parallel to each other.
3. The micromirror according to claim 2, The drive sections (5a-5c, 10a-10c) extend perpendicular to the rotation axis of the mirror element (1). The first arm (2) and the second arm (3) each have connecting segments (6a, 6b). The drive sections (5a-5c, 10a-10c) are connected to each other via one of the connecting sections (6a, 6b). The connecting segments (6a, 6b) extend perpendicularly to the driving segments (5a-5c, 10a-10c), and No driving element is provided on the connecting sections (6a, 6b).
4. The micromirror according to any one of claims 2 or 3, The drive sections (5a-5c, 10a-10c) have widths that indicate the extension of the drive section in the direction of the rotation axis. The width of the drive section (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. The micromirror according to claim 4, The drive segments (5a-5c, 10a-10c) have a constant width along their respective lengths, wherein the lengths are perpendicular to the widths of the drive segments (5a-5c, 10a-10c).
6. The micromirror according to claim 4, The drive segments (5a-5c, 10a-10c) have a width that decreases over their respective lengths, wherein the length is perpendicular to the width of the drive segments (5a-5c, 10a-10c). The width of the drive segment (5a-5c, 10a-10c) at the end of the respective drive segment (5a-5c, 10a-10c) connected to the first end (2a, 3a) is greater than the width of the drive segment (5a-5c, 10a-10c) at the end of the drive segment (5a-5c, 10a-10c) connected to the second end (2b, 3b).
7. The micromirror according to any one of claims 2 to 6, The drive sections (5a-5c, 10a-10c) have such length that when the first and second arms (3) are bent, the mirror element (1) tilts in a manner with low stress and low deformation.
8. The micromirror according to any one of claims 2 to 7, The drive sections (5a-5c, 10a-10c) and the drive elements (8a-8c, 11a) are designed such that each of the meandering sections bends at a maximum angle α, where α is the angle of bending. 2 The deviation between / 2 and 1−cos(α) does not exceed 0.2%.
9. The micromirror according to any one of the preceding claims, The mirror element (1), the first arm (2), the second arm (3) and the frame (4) are formed on a structured silicon substrate.
10. The micromirror according to any one of the preceding claims, The driving elements (8a-8c, 11a) have a piezoelectric layer.
11. The micromirror according to claim 10, It has a control unit designed to apply voltage to the piezoelectric layer. The voltage described therein consists of a bias voltage and an AC voltage, and The bias voltage is selected such that the voltage is prevented from crossing zero.
12. The micromirror according to any one of the preceding claims, The mirror element (1) has a compensation layer (13) on its rear side opposite to the reflective surface.
13. The micromirror according to claims 11 and 12, The compensation layer (13) is designed to compensate for mechanical deformation of the mirror element (1) caused by the bias voltage.
14. The micromirror according to any one of the preceding claims, The first arm (2) and the second arm (3) are connected to the mirror element (1) at the first suspension point (14) and the second suspension point (15), respectively. The first suspension point (14) and the second suspension point (15) are located on the rotation axis.
15. The micromirror according to any one of claims 1 to 13, The second end (2b) of the first arm (2) is connected to the mirror element (1) at multiple suspension points (9a, 9b). The second end of the second arm (3) is connected to the mirror element (1) at a plurality of suspension points (12a, 12b).
16. The micromirror according to claim 15, The suspension points (9a, 9b) at the connection between the second end (2b) of the first arm (2) and the mirror element (1) and the suspension points (12a, 12b) at the connection between the second end (3b) of the second arm (3) and the mirror element (1) can be connected to each other by a straight line perpendicular to the axis of rotation.
17. The micromirror according to any one of the preceding claims, The axis of rotation extends through the center point of the mirror element (1).
18. The micromirror according to any one of the preceding claims, The micromirrors described therein are designed for quasi-static operation, or The micromirrors described therein are designed to operate resonantly.
19. A projection device comprising a micromirror and a light source according to any one of the preceding claims, the light source being designed to emit a light beam onto the reflective surface. The micromirrors are designed to reflect the light beam. The micromirror is designed to move in such a way that the reflected light beam performs a raster scan.
20. The projection device according to the preceding claim, This includes devices for projecting images and / or videos, or LiDAR devices.