A galvanometer unit and a method of manufacturing the same, a scanning mirror, a radar system

Abstract

The present disclosure discloses a galvanometer unit, a preparation method thereof, a scanning mirror and a radar system. The galvanometer unit comprises a first substrate and a second substrate which are bonded, the second substrate comprises a galvanometer structure accommodated in a cavity structure, the galvanometer structure has a rotation axis, the first substrate comprises an electrostatic driving structure and a flat plate electrode which is arranged to face the second substrate and is insulated from the electrostatic driving structure, the electrostatic driving structure drives the flat plate electrode to reciprocate in a first direction, the flat plate electrode comprises a first main electrode and a second main electrode which are located on different sides of the rotation axis, and during the reciprocation of the flat plate electrode driven by the electrostatic driving structure, the overlapping area of the first main electrode and the second main electrode with the galvanometer structure changes, so that the electrostatic attraction force acting on the galvanometer structure changes, and the galvanometer structure is driven to rotate along the rotation axis.

Description

Technical Field

[0001] This disclosure relates to the field of microelectromechanical systems (MEMS) technology, and in particular to a galvanometer unit and its fabrication method, a scanning mirror, and a radar system. Background Technology

[0002] A micro-electro-mechanical system (MEMS) galvanometer is a tiny, drivable mirror fabricated using MEMS technology. Typically, the mirror diameter is only a few millimeters.

[0003] Compared to traditional optical scanning mirrors, MEMS galvanometers offer advantages such as light weight, small size, ease of mass production, and lower production costs. They also exhibit superior performance in terms of optics, mechanical properties, and power consumption. MEMS galvanometers are currently widely used in markets such as LiDAR, high-definition projection, laser confocal microscopy systems, and augmented reality (AR). MEMS galvanometers can move in two ways: translational and torsional. For torsional MEMS galvanometers, when their optical deflection angle is large (above 10°), they can achieve laser pointing deflection, patterning scanning, and image scanning.

[0004] MEMS galvanometers are driven in four ways: electrostatic, electromagnetic, piezoelectric, and electrothermal. Electrostatic driving includes two types of structures: planar electrodes and comb-tooth electrodes (referring to vertical comb teeth). Planar electrode-driven MEMS galvanometer units are simple and easy to fabricate, but the electrostatic attraction between the planar electrodes requires a large driving voltage and is prone to sticking. In contrast, a set of vertical comb teeth opposite each other is subjected to a positive voltage and ground respectively, generating an electrostatic force between the opposing vertical comb teeth. This force drives the vertical comb teeth to move, which in turn drives the micromirror connected to the vertical comb teeth. However, the vertical comb teeth present a challenge in alignment during fabrication, leading to higher production costs. Summary of the Invention

[0005] This disclosure provides a galvanometer unit and its fabrication method, a scanning mirror, and a radar system to solve the aforementioned technical problems.

[0006] In a first aspect, to solve the above-mentioned technical problems, embodiments of this disclosure provide a galvanometer unit, including a first substrate and a second substrate bonded together. The first substrate has a groove, and the second substrate has a cavity structure. The second substrate includes a galvanometer structure housed within the cavity structure. The galvanometer structure has a rotating shaft, which is fixed to the cavity structure. The first substrate includes:

[0007] First substrate;

[0008] An electrostatic drive structure is located on one side of the first substrate.

[0009] A planar electrode is located on the side of the electrostatic drive structure away from the first substrate and is insulated from the electrostatic drive structure. The electrostatic drive structure drives the planar electrode to reciprocate in a first direction. The planar electrode includes a first main electrode and a second main electrode located on different sides of the rotation axis. The first direction is perpendicular to the extension direction of the rotation axis.

[0010] During the reciprocating motion, the overlapping area of ​​the first main electrode and the second main electrode with the galvanometer structure changes, which alters the electrostatic attraction acting on the galvanometer structure and causes the galvanometer structure to rotate along the rotation axis.

[0011] In one possible implementation, the galvanometer structure, after being grounded, forms two parallel-plate capacitors with the first main electrode and the second main electrode, respectively.

[0012] One possible implementation of the electrostatic drive structure includes:

[0013] The stationary comb electrode and the moving comb electrode mesh with each other. The moving comb electrode is used to reciprocate relative to the stationary comb electrode in a plane parallel to the first substrate along the first direction under the action of electrostatic attraction with the stationary comb electrode. The first direction is the extension direction of the comb teeth.

[0014] The stationary comb electrode is fixed to one side surface of the first substrate. The movable comb electrode and the groove are fixedly installed by an elastic element. The movable comb electrode and the stationary comb electrode are located on the same plane away from the first substrate. The side of the stationary comb electrode close to the first substrate is in contact with the first substrate. The side of the movable comb electrode close to the first substrate is suspended. The flat plate electrode is fixed to the surface of the movable comb electrode away from the first substrate.

[0015] In one possible implementation, the movable comb electrode includes: a first comb substrate and a second comb substrate disposed opposite to each other, a plurality of movable comb teeth, a connecting portion connecting the first comb substrate and the second comb substrate, and a plurality of first cantilever beams.

[0016] The first comb tooth substrate and the second comb tooth substrate are arranged along the first direction and extend along the second direction. The connecting portion or the first comb tooth substrate and the second comb tooth substrate are respectively fixed to the groove by the plurality of first cantilever beams. The plurality of movable comb teeth extend along the first direction and are arranged along the second direction. The plurality of movable comb teeth are spaced apart and fixed on the first comb tooth substrate and the second comb tooth substrate. The first direction is perpendicular to the second direction.

[0017] In one possible implementation, the stationary comb electrode includes: a third comb substrate and a fourth comb substrate disposed opposite to each other, and a plurality of stationary comb teeth, wherein the third comb substrate and the fourth comb substrate are insulated from each other.

[0018] The third comb tooth substrate and the fourth comb tooth substrate are arranged along the first direction and extend along the second direction; the plurality of stationary comb teeth extend along the first direction and are arranged along the second direction, the plurality of stationary comb teeth are spaced apart and fixed on the third comb tooth substrate and the fourth comb tooth substrate, and the stationary comb teeth fixed on the third comb tooth substrate mesh with the movable comb teeth fixed on the first comb tooth substrate, and the stationary comb teeth fixed on the fourth comb tooth substrate and the movable comb teeth fixed on the second comb tooth substrate are alternately arranged.

[0019] In one possible implementation, the connecting portion is a single unit, and the connecting portion is located at the middle position between the first comb base plate and the second comb base plate.

[0020] The third comb tooth substrate and the fourth comb tooth substrate are located between the first comb tooth substrate and the second comb tooth substrate. The third comb tooth substrate and the fourth comb tooth substrate are each divided into two parts by the connecting portion, and the two parts are interconnected by the connecting line.

[0021] Alternatively, the third comb substrate and the fourth comb substrate are located on both sides of the first comb substrate and the second comb substrate.

[0022] In one possible implementation, there are two connecting portions, which are respectively connected to the ends of the first comb base plate and the second comb base plate. The first comb base plate, the second comb base plate, and the two connecting portions are sequentially connected to form a closed pattern.

[0023] The orthographic projections of the plurality of stationary comb teeth and the plurality of moving comb teeth onto the first substrate are all located inside the closed pattern; or, the orthographic projections of the plurality of stationary comb teeth and the plurality of moving comb teeth onto the first substrate are all located outside the closed pattern.

[0024] In one possible implementation, when the orthographic projections of the plurality of stationary comb teeth and the plurality of moving comb teeth on the first substrate are all located within the closed pattern, the stationary comb tooth electrode further includes:

[0025] An insulating structure is located between the third comb tooth substrate and the fourth comb tooth substrate.

[0026] In one possible implementation, the first comb substrate and the second comb substrate have a hollow structure.

[0027] In one possible implementation, the first substrate further includes:

[0028] A first isolation layer is located between the moving comb electrode and the flat plate electrode. The orthogonal projection of the first isolation layer on the first substrate covers the first comb substrate, the second comb substrate, and the plurality of first cantilever beams.

[0029] In one possible implementation, the flat plate electrode further includes: a plurality of second cantilever beams;

[0030] The orthographic projection of the first main electrode on the first substrate covers the first comb substrate, and the orthographic projection of the second main electrode on the first substrate covers the second comb substrate. The first main electrode and the second main electrode are respectively fixed to the groove by the plurality of second cantilever beams.

[0031] In one possible implementation, the first main electrode and the second main electrode further cover a portion of the movable comb teeth connected to the first comb base plate and the second comb base plate, respectively.

[0032] In one possible implementation, the planar electrode further includes: a first sub-electrode and a second sub-electrode; the orthographic projection of the first sub-electrode on the first substrate covers the third comb-tooth substrate and a portion of the stationary comb teeth connected to the third comb-tooth substrate, and the orthographic projection of the second sub-electrode on the first substrate covers the fourth comb-tooth substrate and a portion of the stationary comb teeth connected to the fourth comb-tooth substrate; during the reciprocating motion of the planar electrode driven by the moving comb-tooth electrode, the first sub-electrode contacts the first main electrode, or the second sub-electrode contacts the first main electrode.

[0033] In one possible implementation, the first isolation layer further covers the first secondary electrode and the second secondary electrode, and the side surface of the first isolation layer facing the first substrate has a plurality of recessed structures, the recessed structures covering a plurality of corresponding comb teeth.

[0034] In one possible implementation, one side surface of the first substrate has a recessed structure that coincides with the groove, and the stationary comb electrode is located within the recessed structure.

[0035] In one possible implementation, the galvanometer structure further includes:

[0036] A second substrate having an opening that coincides with the cavity structure;

[0037] A rotating plate is fixedly connected to the rotating shaft, and the rotating plate is used to rotate along the rotating shaft under the electrostatic attraction of the two parallel plate capacitors;

[0038] A reflector is located on the side of the rotating plate away from the first substrate and is fixed to the rotating plate.

[0039] Secondly, embodiments of this disclosure provide a scanning mirror, including one or a plurality of galvanometer units as described in the first aspect.

[0040] Thirdly, embodiments of this disclosure provide a method for fabricating a galvanometer unit, comprising:

[0041] An electrostatic drive structure is formed on one side of the first substrate.

[0042] A planar electrode is formed on the side of the electrostatic drive structure away from the first substrate to obtain a first substrate; the planar electrode includes a first main electrode and a second main electrode arranged along a first direction, and the electrostatic drive structure drives the planar electrode to reciprocate in the first direction, and is insulated from the electrostatic drive structure.

[0043] An opening is formed in a second substrate, and a rotating plate is formed in the region corresponding to the opening to obtain a second substrate with a cavity structure; wherein, the cavity structure coincides with the opening, the rotating plate is located inside the cavity structure, the rotating plate has a rotating shaft, and the rotating shaft is fixed to the cavity structure;

[0044] After the second substrate is aligned with the first substrate, a reflective layer is deposited on the surface of the rotating plate away from the first substrate, and the reflective layer is patterned to obtain a reflector; wherein, after the rotating plate is grounded, it forms two parallel plate capacitors with the first main electrode and the second main electrode; the first main electrode and the second main electrode are located on different sides of the rotating axis; during the process of the electrostatic drive structure driving the parallel plate electrodes to reciprocate, the overlapping area of ​​the first main electrode and the second main electrode with the rotating plate changes, causing the electrostatic attraction force of the two parallel plate capacitors on the rotating plate to change, thereby driving the rotating plate to rotate along the rotating axis.

[0045] One possible implementation involves forming an electrostatic drive structure on one side of a first substrate, comprising:

[0046] The first substrate is etched to obtain a first substrate with a recessed structure.

[0047] A first metal layer is deposited on the bottom surface of the recessed structure, and the first metal layer is etched to obtain a static comb electrode;

[0048] A first silicon nitride layer is deposited on the side of the stationary comb electrode away from the first substrate, and the first silicon nitride layer is patterned to obtain a first sub-isolation layer covering the connection line of the stationary comb electrode.

[0049] On the side of the first substrate near the first sub-isolation layer, a second silicon nitride layer is deposited and patterned to obtain a second sub-isolation layer covering the area outside the recessed structure; wherein the second isolation layer includes the first sub-isolation layer and the second sub-isolation layer;

[0050] A second metal layer is deposited on the side of the second sub-isolation layer away from the substrate, and the second metal layer is etched to obtain the moving comb electrode which is fixedly connected to the second sub-isolation layer and meshes with the stationary comb electrode; wherein the moving comb electrode is used to reciprocate relative to the stationary comb electrode in a plane parallel to the first substrate along the first direction under the action of electrostatic attraction, and the first direction is the extension direction of the comb teeth.

[0051] One possible implementation involves forming a planar electrode on the side of the electrostatic drive structure away from the first substrate, comprising:

[0052] A third silicon nitride layer is deposited on the side of the movable comb electrode away from the first substrate, and the third silicon nitride layer is patterned to obtain a first isolation layer covering the first comb substrate, the second comb substrate, and a plurality of first cantilever beams; wherein, the movable comb electrode includes: a first comb substrate and a second comb substrate disposed opposite to each other, a plurality of movable comb teeth, a connecting portion connecting the first comb substrate and the second comb substrate, and a plurality of first cantilever beams; the plurality of movable comb teeth are arranged along the first direction and extend along the second direction, and the plurality of movable comb teeth are spaced apart and fixed on the first comb substrate and the second comb substrate; the first direction is perpendicular to the second direction;

[0053] On the side of the first isolation layer away from the substrate, a third metal layer is deposited and patterned to obtain the planar electrode; wherein, the first main electrode covers the first comb substrate and the second main electrode covers the second comb substrate.

[0054] Fourthly, embodiments of this disclosure provide a radar system, including:

[0055] Laser emitting assembly, used to emit laser light;

[0056] Reflecting unit;

[0057] As described in the second aspect, the reflecting unit reflects the laser to the scanning mirror, which then scans the obstacle.

[0058] A focusing lens, used to focus the laser light reflected from the obstacle;

[0059] A beam receiving component is used to receive the laser light focused by the focusing lens;

[0060] A control component for forming an image of the obstacle based on signals fed back from the beam receiving component. Attached Figure Description

[0061] Figure 1 A top view of a galvanometer unit provided in an embodiment of this disclosure;

[0062] Figure 2 Provided for the embodiments of this disclosure Figure 1 A front view of the center at position AA' along the direction of rotation.

[0063] Figure 3 A top view of a galvanometer structure twisted toward the second main electrode, provided in an embodiment of this disclosure;

[0064] Figure 4 Provided for the embodiments of this disclosure Figure 3 A front view of the center at position AA' along the direction of rotation.

[0065] Figure 5 A top view of a galvanometer structure twisted toward a first main electrode, provided in an embodiment of this disclosure;

[0066] Figure 6 Provided for the embodiments of this disclosure Figure 5 A front view of the center at position AA' along the direction of rotation.

[0067] Figure 7 A top view schematic diagram of another galvanometer unit provided in an embodiment of this disclosure;

[0068] Figure 8 Provided for the embodiments of this disclosure Figure 7 A front view along the AA' direction;

[0069] Figure 9 A three-dimensional schematic diagram of a galvanometer unit provided in an embodiment of this disclosure;

[0070] Figure 10An exploded view of a galvanometer unit provided in an embodiment of this disclosure;

[0071] Figure 11 This is a top view of an electrostatic drive structure provided in an embodiment of the present disclosure;

[0072] Figure 12 This is a schematic diagram of another electrostatic drive structure provided in an embodiment of the present disclosure;

[0073] Figure 13 and Figure 14 This is a schematic diagram of another electrostatic drive structure provided in an embodiment of the present disclosure;

[0074] Figures 15-17 This is a schematic diagram of another electrostatic drive structure provided in an embodiment of the present disclosure;

[0075] Figure 18 A top view of a first isolation layer provided in an embodiment of this disclosure;

[0076] Figure 19 and Figure 20 A bottom view of a first isolation layer provided in an embodiment of this disclosure;

[0077] Figure 21 and Figure 22 A top view of a flat plate electrode provided in an embodiment of this disclosure;

[0078] Figure 23 A top view of another planar electrode provided in an embodiment of this disclosure;

[0079] Figure 24 and Figure 25 A bottom view of a flat plate electrode provided in an embodiment of this disclosure;

[0080] Figure 26 A top view of another planar electrode provided in an embodiment of this disclosure;

[0081] Figure 27 A top view of another galvanometer structure provided in an embodiment of this disclosure, twisted toward the second main electrode;

[0082] Figure 28 Provided for the embodiments of this disclosure Figure 27 A front view of the center at position AA' along the direction of rotation.

[0083] Figure 29 A top view of another galvanometer structure twisted toward the first main electrode, provided in an embodiment of this disclosure;

[0084] Figure 30 Provided for the embodiments of this disclosure Figure 29 A front view of the center at position AA' along the direction of rotation.

[0085] Figure 31 A top view of a first isolation layer provided in an embodiment of this disclosure;

[0086] Figure 32 A bottom view of a first isolation layer provided in an embodiment of this disclosure;

[0087] Figure 33 A top view of a first substrate provided in an embodiment of this disclosure;

[0088] Figure 34 Provided for the embodiments of this disclosure Figure 32 Cross-sectional view in the BB' direction;

[0089] Figure 35 A three-dimensional schematic diagram of the first substrate provided in an embodiment of this disclosure;

[0090] Figure 36 A flowchart illustrating a method for fabricating a galvanometer unit according to an embodiment of this disclosure;

[0091] Figure 37 This is a schematic diagram illustrating the fabrication of a galvanometer unit according to an embodiment of the present disclosure;

[0092] Figure 38 This is a schematic diagram illustrating the fabrication of an electrostatic drive structure according to an embodiment of the present disclosure;

[0093] Figure 39 This is a schematic diagram illustrating the fabrication of a flat plate electrode according to an embodiment of the present disclosure;

[0094] Figure 40 This is a schematic diagram of the structure of a laser system provided in an embodiment of the present disclosure.

[0095] Figure label:

[0096] First substrate 1, groove M, first substrate 11, electrostatic drive structure 12, stationary comb electrode 121, moving comb electrode 122, flat plate electrode 13, first main electrode 131, second main electrode 132, second cantilever beam 133, first auxiliary electrode 134, second auxiliary electrode 135, first comb substrate 1221, second comb substrate 1222, moving comb tooth 1223, connecting part 1224, first cantilever beam 1225, third comb substrate 1211, fourth comb substrate 1212, stationary comb tooth 1213, insulating structure 1214, connecting line 1215, recessed structure M', first isolation layer 14, second isolation layer 15, first sub-isolation layer 151, second sub-isolation layer 152, third sub-isolation layer 141, fourth sub-isolation layer 142, first direction X, second direction Y;

[0097] Second substrate 2, second substrate 20, cavity structure N, galvanometer structure 21, rotating plate 211, reflector 212, rotating shaft 22. Detailed Implementation

[0098] This disclosure provides a galvanometer unit and its fabrication method, a scanning mirror, and a radar system to solve the aforementioned technical problems.

[0099] To make the above-described objects, features, and advantages of this disclosure more apparent and understandable, the disclosure will be further described below in conjunction with the accompanying drawings and embodiments. However, the exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided to make the disclosure more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the figures denote the same or similar structures, and therefore repeated descriptions of them will be omitted. Terms describing position and direction as described in this disclosure are illustrative of the accompanying drawings, but changes may be made as needed, and all such changes are included within the scope of protection of this disclosure. The accompanying drawings of this disclosure are for illustrative purposes only and do not represent actual scale.

[0100] It should be noted that specific details are set forth in the following description to provide a full understanding of this disclosure. However, this disclosure can be implemented in many ways other than those described herein, and those skilled in the art can make similar extensions without departing from the spirit of this disclosure. Therefore, this disclosure is not limited to the specific embodiments disclosed below. The following descriptions are preferred embodiments for carrying out this disclosure; however, these descriptions are for the purpose of illustrating the general principles of this disclosure and are not intended to limit the scope of this disclosure. The scope of protection of this disclosure shall be determined by the appended claims.

[0101] The following description, in conjunction with the accompanying drawings, details an embodiment of the galvanometer unit, its fabrication method, a scanning mirror, and a radar system provided in this disclosure.

[0102] Please see Figure 1 and Figure 2 , Figure 1 This is a top view of a galvanometer unit provided in an embodiment of this disclosure. Figure 2 Provided for the embodiments of this disclosure Figure 1 The front view of the galvanometer unit along the rotation axis at position AA' shows that it includes a first substrate 1 and a second substrate 2 bonded together. The first substrate 1 has a groove M, and the second substrate 2 has a cavity structure N. The groove M and the cavity structure N cooperate to form a chamber. The second substrate 2 includes a galvanometer structure 21 housed within the cavity structure N. The galvanometer structure 21 has a rotation axis 22, which is fixed to the cavity structure N. The first substrate 1 includes:

[0103] First substrate 11;

[0104] An electrostatic drive structure 12 is located on one side of the first substrate 11;

[0105] The plate electrode 13 is located on the side of the electrostatic drive structure 12 away from the first substrate 11 and is insulated from the electrostatic drive structure 12. The electrostatic drive structure 12 drives the plate electrode 13 to reciprocate in the first direction X. The plate electrode 13 includes a first main electrode 131 and a second main electrode 132 located on different sides of the rotation shaft 22. The first direction X is perpendicular to the extension direction of the rotation shaft 22. The electrostatic drive structure 12 and the plate electrode 13 are both housed in the groove M and fixedly installed in the groove M by an elastic element. After grounding, the galvanometer structure 21, together with the first main electrode 131 and the second main electrode 132, forms two plate capacitors.

[0106] During the reciprocating motion of the plate electrode 13 driven by the electrostatic drive structure 12, the overlapping area of ​​the first main electrode 131 and the second main electrode 132 with the galvanometer structure 21 changes, which alters the electrostatic attraction acting on the galvanometer structure 21, causing the galvanometer structure 21 to rotate along the rotation axis 22.

[0107] The first main electrode 131 and the second main electrode 132 are connected to positive and negative voltages respectively, and the galvanometer structure 21 is grounded. At this time, the overlapping area of ​​the first main electrode 131, the second main electrode 132 and the galvanometer structure 21 forms two parallel plate capacitors.

[0108] The formula for calculating a parallel plate capacitor is:

[0109] C=εS / d (1;

[0110] Where C is the capacitance of the parallel plate capacitor, ε is the dielectric constant of the parallel plate capacitor, S is the area of ​​the parallel plate capacitor (i.e., the area of ​​the overlapping region), and d is the distance between the parallel plate electrode 13 and the galvanometer structure 21.

[0111] The formula for calculating the electrostatic attraction force generated by the parallel plate capacitor on the galvanometer structure 21 is as follows:

[0112] F=(εSV 2 ) / (2d 2 (2);

[0113] Where F is the electrostatic attraction force of the parallel plate capacitor on the galvanometer structure 21, and V is the voltage difference between the first main electrode 131 and the second main electrode 132.

[0114] As can be seen from Equation (2), the planar capacitance and the magnitude of the electrostatic attraction force it generates are determined by S, d, and V of the planar capacitance. Therefore, not only can the electrostatic attraction forces acting on both sides of the galvanometer structure 21 on both sides of the rotation axis 22 be changed by changing the voltage difference between the first main electrode 131 and the second main electrode 132, but also the electrostatic attraction forces on both sides of the galvanometer structure 21 located on both sides of the rotation axis 22 can be changed simultaneously by changing the overlapping area sizes of the planar capacitances corresponding to the first main electrode 131 and the second main electrode 132, thereby effectively increasing the electrostatic attraction forces acting on both sides of the galvanometer structure 21 on both sides of the rotation axis 22, making the change in the electrostatic attraction forces received by both sides of the galvanometer structure 21 on both sides of the rotation axis 22 more significant, and further promoting the resonant motion of the galvanometer structure 21 to achieve the effect of causing the galvanometer structure 21 to twist.

[0115] The overlapping area between the first main electrode 131 and the galvanometer structure 21 is denoted as S1, and the overlapping area between the second main electrode 132 and the galvanometer structure 21 is denoted as S2.

[0116] In Figure 1 and Figure 2 , S1 = S2. At this time, the electrostatic attraction forces received by the two parts of the galvanometer structure 21 on both sides of the rotation axis 22 are the same, and the galvanometer structure 21 remains balanced and does not rotate.

[0117] Please refer to Figures 3-6 , Figure 3 which is a top view of a galvanometer structure twisting towards the second main electrode provided by an embodiment of the present disclosure, Figure 4 which is provided by an embodiment of the present disclosure Figure 3 and is a front view along the extension direction of the rotation axis at the AA' position in Figure 5 which is a top view of a galvanometer structure twisting towards the first main electrode provided by an embodiment of the present disclosure, Figure 6 which is provided by an embodiment of the present disclosure Figure 5 and is a front view along the extension direction of the rotation axis at the AA' position in

[0118] In Figure 3 and Figure 4 , the electrostatic drive structure 12 drives the galvanometer structure 21 to move in the opposite direction of the first direction X, causing the overlapping areas between the first main electrode 131, the second main electrode 132 and the galvanometer structure 21 to change. At this time, S1 < S2. According to Equation (2), it can be seen that the electrostatic attraction force received by the side of the galvanometer structure 21 corresponding to S1 decreases, and the electrostatic attraction force received by the side of the galvanometer structure 21 corresponding to S2 increases, and the galvanometer structure 21 rotates towards the side corresponding to S2.

[0119] In Figure 5 and Figure 6The electrostatic drive structure 12 drives the galvanometer structure 21 to move along the first direction X, causing the overlapping area of ​​the first main electrode 131, the second main electrode 132 and the galvanometer structure 21 to change. At this time, S1>S2. According to formula (2), the electrostatic attraction of the galvanometer structure 21 on the side corresponding to S1 increases, and the electrostatic attraction of the galvanometer structure 21 on the side corresponding to S2 decreases. The galvanometer structure 21 rotates towards the side corresponding to S1.

[0120] As the electrostatic drive structure 12 drives the first main electrode 131 and the second main electrode 132 to reciprocate in the first direction X, the overlapping area of ​​the first main electrode 131 and the second main electrode 132 with the galvanometer structure 21 also alternates between increasing and decreasing. Consequently, the electrostatic attraction force acting on the galvanometer structure 21 on both sides of the rotation axis 22 also alternates between increasing and decreasing, causing the galvanometer structure 21 to reciprocate along the rotation axis 22.

[0121] In the embodiments provided in this disclosure, a first main electrode 131 and a second main electrode 132 arranged along a first direction X are disposed on the side of the electrostatic driving structure 12 away from the first substrate 11, and the electrostatic driving structure 12 drives the first main electrode 131 and the second main electrode 132 to reciprocate in the first direction X; after the galvanometer structure 21 is grounded, it forms two parallel plate capacitors with the first main electrode 131 and the second main electrode 132. In this way, during the reciprocating motion of the first main electrode 131 and the second main electrode 132 driven by the electrostatic driving structure 12, the overlap area between the first main electrode 131 and the second main electrode 132 and the galvanometer structure 21 changes, thereby preventing... The electrostatic attraction between the galvanometer structure 21 and the rotating shaft 22 can be changed by altering the voltage difference between the first main electrode 131 and the second main electrode 132. Simultaneously, the magnitude of the electrostatic attraction between the galvanometer structure 21 and the rotating shaft 22 can be changed by altering the overlap area of ​​the first main electrode 131, the second main electrode 132, and the galvanometer structure 21. This effectively increases the electrostatic attraction between the galvanometer structure 21 and the rotating shaft 22, making the change in the electrostatic attraction between the galvanometer structure 21 and the rotating shaft 22 more significant. This, in turn, promotes the resonant motion of the galvanometer structure 21, resulting in a more significant torsion effect on the galvanometer structure 21.

[0122] Furthermore, during the reciprocating motion of the first main electrode 131 and the second main electrode 132 along the first direction X, since the first main electrode 131 and the second main electrode 132 can be displaced relative to the galvanometer structure 21, when the first main electrode 131 or the second main electrode 132 comes into contact with the galvanometer structure 21 and forms an adhesion, the movement of the first main electrode 131 and the second main electrode 132 in the first direction X causes the first main electrode 131 or the second main electrode 132 to be misaligned with the galvanometer structure 21, thereby releasing the adhesion, reducing the failure probability of the galvanometer unit, and thus improving the reliability of the galvanometer unit.

[0123] Please continue reading Figure 2 The second substrate 2 also includes:

[0124] The second substrate 20 has an opening that coincides with the cavity structure N.

[0125] Rotating plate 211 is fixedly connected to rotating shaft 22. Rotating plate 211 is used to rotate along rotating shaft 22 under the electrostatic attraction of two parallel plate capacitors.

[0126] A reflector 212 is located on the side of the rotating plate 211 away from the first substrate 1 and is fixed to the rotating plate 211. The reflector 212 is used to reflect light, such as laser light.

[0127] The rotating plate 211 is grounded through the rotating shaft 22. Under the action of electrostatic adsorption force, the rotating plate 211 can not only rotate along the rotating shaft 22, but also support the reflector 212 fixed thereto and drive the reflector 212 to rotate synchronously.

[0128] In some embodiments, the rotating plate 211 may be made of a metal material or a semiconductor material.

[0129] Please see Figures 7-9 , Figure 7 This is a top view schematic diagram of another galvanometer unit provided in an embodiment of this disclosure. Figure 8 Provided for the embodiments of this disclosure Figure 7 The front view along the AA' direction. Figure 9 This is a three-dimensional schematic diagram of a galvanometer unit provided in an embodiment of the present disclosure.

[0130] The electrostatic drive structure 12 includes a stationary comb electrode 121 and a moving comb electrode 122 that mesh with each other. The moving comb electrode 122 is used to reciprocate relative to the stationary comb electrode 121 in a plane parallel to the first substrate 11 along a first direction X under the action of electrostatic attraction with the stationary comb electrode 121. The first direction X is the extension direction of the comb teeth.

[0131] The stationary comb electrode 121 is fixed to one side surface of the first substrate 11, and the movable comb electrode 122 is fixedly installed with the groove M by an elastic member. The movable comb electrode 122 and the stationary comb electrode 121 are located on the same plane away from the first substrate 11, and the side of the stationary comb electrode 121 close to the first substrate 11 is in contact with the first substrate 11. The side of the movable comb electrode 122 close to the first substrate 11 is suspended. The flat plate electrode 13 is fixed to the surface of the movable comb electrode 122 away from the first substrate 11 and is insulated from the movable comb electrode 122. For example, a second isolation layer 15 is provided between the movable comb electrode 122 and the stationary comb electrode 121.

[0132] like Figure 9 As shown, the groove M is composed of a second isolation layer 15 located between the stationary comb electrode 121 and the moving comb electrode 122, a first isolation layer 14 located between the moving comb electrode 122 and the flat plate electrode 13, and a first substrate 11. The second isolation layer 15 includes a first sub-isolation layer 151 and a second sub-isolation layer 152. The first sub-isolation layer 151 surrounds the electrostatic drive structure 12 and is located between the stationary comb electrode 121 and the moving comb electrode 122, and covers a portion of the signal line led out from the stationary comb electrode 121. The second sub-isolation layer surrounds the electrostatic drive structure 12 and is disposed in the same layer as the moving comb electrode 122, and has the same thickness. The first isolation layer 14 includes a third sub-isolation layer 141 and a fourth sub-isolation layer 142. The third sub-isolation layer 141 is located between the moving comb electrode 142 and the plate electrode 13, has a frame surrounding the electrostatic drive structure 12, and completely covers the portion of the moving comb electrode 122, so that the moving comb electrode 122 is insulated from the plate electrode 13. The fourth sub-isolation layer 142 surrounds the electrostatic drive structure 12 and is disposed in the same layer as the plate electrode 13, and has the same thickness. The framework of the first sub-isolation layer 151, the second sub-isolation layer 152, the third sub-isolation layer 141, and the fourth sub-isolation layer 142 overlap in the orthographic projection of the first substrate 11, and the orthographic projection pattern is the shape of the portion of the groove M protruding from the plane of the first substrate 11. Together, they constitute the sidewall of the groove M, and the first substrate 11 constitutes the bottom of the groove M. Figure 10 The image shown is an exploded view of a galvanometer unit provided in an embodiment of this disclosure.

[0133] In the embodiments provided in this disclosure, the electrostatic drive structure 12 includes a stationary comb electrode 121 and a moving comb electrode 122 that mesh with each other. The moving comb electrode 122 is used to reciprocate relative to the stationary comb electrode 121 in a plane parallel to the first substrate 11 along a first direction X, where the first direction X is the extension direction of the comb teeth, under the action of electrostatic attraction with the stationary comb electrode 121. The moving comb electrode 122 is fixed to one side surface of the first substrate 11, and the moving comb electrode 122 is fixedly installed with the groove M by an elastic member. The sides of the moving comb electrode 122 and the stationary comb electrode 121 away from the first substrate 11 are located on the same plane, and the side of the stationary comb electrode 121 close to the first substrate 11 is in contact with the first substrate 11. The toothed electrode 122 is suspended on the side near the first substrate 11, and the flat plate electrode 13 is fixed to the surface of the movable comb electrode 122 facing away from the first substrate 11. This makes the teeth of the stationary comb electrode 121 and the movable comb electrode 122 parallel to each other, which is easy to manufacture. The movable comb electrode 122 and the flat plate electrode 13 are combined together, so that the movable comb electrode 1223, the flat plate electrode 13, the galvanometer structure 21 and the reflector 212 have sufficient space for movement. This reduces the difficulty of manufacturing process, and the movable comb electrode 122 in the electrostatic drive structure 12 can drive the flat plate electrode 13 to reciprocate in the first direction X, so that the overlapping area of ​​the first main electrode 131 and the second main electrode 132 with the galvanometer structure 21 changes.

[0134] Please see Figure 11 This is a top view of an electrostatic drive structure provided in an embodiment of this disclosure.

[0135] The movable comb electrode 122 includes: a first comb substrate 1221 and a second comb substrate 1222 disposed opposite to each other, a plurality of movable comb teeth 1223, a connecting portion 1224 connecting the first comb substrate 1221 and the second comb substrate 1222, and a plurality of first cantilever beams 1225.

[0136] The first comb tooth substrate 1221 and the second comb tooth substrate 1222 are arranged along the first direction X and extend along the second direction Y. The connecting portion 1224 or the first comb tooth substrate 1221 and the second comb tooth substrate 1222 are respectively fixed to the groove M by a plurality of first cantilever beams 1225 (i.e. elastic members). A plurality of movable comb teeth 1223 extend along the first direction X and are arranged along the second direction Y. The plurality of movable comb teeth 1223 are spaced apart and fixed on the first comb tooth substrate 1221 and the second comb tooth substrate 1222. The first direction X is perpendicular to the second direction Y. Figure 11Since the stationary comb electrode 121 and the moving comb electrode 122 need to be positioned between the first comb substrate 1221 and the second comb substrate 1222, the distance between the first comb substrate 1221 and the second comb substrate 1222 is relatively large. At this time, by fixing the first comb substrate 1221 and the second comb substrate 1222 to the groove M through multiple first cantilever beams 1225, it can be ensured that the moving comb electrode 122 has sufficient displacement space.

[0137] The stationary comb electrode 121 includes: a third comb substrate 1211 and a fourth comb substrate 1212 disposed opposite to each other, and a plurality of stationary comb teeth 1213, wherein the third comb substrate 1211 and the fourth comb substrate 1212 are insulated from each other; Figure 11 In the middle, the third comb tooth substrate 1211 and the fourth comb tooth substrate 1212 are insulated by an insulating structure 1214;

[0138] The third comb tooth substrate 1211 and the fourth comb tooth substrate 1212 are arranged along the first direction X and extend along the second direction Y; a plurality of stationary comb teeth 1213 extend along the first direction X and are arranged along the second direction Y. The plurality of stationary comb teeth 1213 are spaced apart and fixed on the third comb tooth substrate 1211 and the fourth comb tooth substrate 1212. The stationary comb teeth 1213 fixed on the third comb tooth substrate 1211 mesh with the movable comb teeth 1223 fixed on the first comb tooth substrate 1221. The stationary comb teeth 1213 fixed on the fourth comb tooth substrate 1212 and the movable comb teeth 1223 fixed on the second comb tooth substrate 1222 are alternately arranged.

[0139] In the embodiments provided in this disclosure, the moving comb electrode 122 is configured to consist of a first comb substrate 1221 and a second comb substrate 1222 disposed opposite to each other, a plurality of moving comb teeth 1223, a connecting portion 1224 connecting the first comb substrate 1221 and the second comb substrate 1222, and a plurality of first cantilever beams 1225; and the stationary comb electrode 121 is configured to consist of a third comb substrate 1211 and a fourth comb substrate 1212 disposed opposite to each other, and a plurality of stationary comb teeth 1213. The system comprises an insulating structure 1214 located between the third comb base plate 1211 and the fourth comb base plate 1212, wherein the stationary comb teeth 1213 fixed on the third comb base plate 1211 and the movable comb teeth 1223 fixed on the first comb base plate 1221 are alternately arranged, and the stationary comb teeth 1213 fixed on the fourth comb base plate 1212 and the movable comb teeth 1223 fixed on the second comb base plate 1222 are alternately arranged, such that the third comb base plate 1211 and the fourth comb base plate 1212 are alternately arranged. After positive and negative voltages are applied respectively, the positive and negative comb teeth, which are arranged in an alternating manner, will be charged with opposite charges, thereby generating an uneven electric field. Under the action of electrostatic attraction, the moving comb teeth 1223 fixed on the first comb tooth substrate 1221 or the second comb tooth substrate 1222 will move towards the third comb tooth substrate 1211 or the fourth comb tooth substrate 1212. Since the first comb tooth substrate 1221 and the second comb tooth substrate 1222 are fixedly connected by the connecting part 1224, and the first comb tooth substrate 1221 and the second comb tooth substrate 1222 are respectively fixed to the groove M by multiple first cantilever beams 1225, when the first comb tooth substrate 1221 or the second comb tooth substrate 1222 moves towards the corresponding third comb tooth substrate 1211 or the fourth comb tooth substrate 1212, the multiple first cantilever beams 1225 will undergo corresponding elastic deformation, causing the moving comb tooth electrode 122 to reciprocate in the first direction X, thereby driving the flat plate electrode 13, which is fixed in position with the moving comb tooth electrode 122, to move synchronously.

[0140] Please continue reading Figure 11 When there are two connecting parts 1224 of the moving comb electrode 122, the two connecting parts 1224 are respectively connected to the ends of the first comb substrate 1221 and the second comb substrate 1222, and the first comb substrate 1221, the second comb substrate 1222 and the two connecting parts 1224 are connected in sequence to form a closed pattern.

[0141] The orthographic projections of multiple stationary comb teeth 1213 and multiple moving comb teeth 1223 onto the first substrate 11 are all located within the closed pattern; or, as... Figure 12 The diagram shown is a schematic representation of another electrostatically driven structure provided in this embodiment of the present disclosure. The orthographic projections of multiple stationary comb teeth 1213 and multiple moving comb teeth 1223 onto the first substrate 11 are all located outside the closed pattern. Figure 12In this configuration, since the stationary comb teeth 1213 and the moving comb teeth 1223 are located outside the closed pattern, the distance between the first comb tooth substrate 1221 and the second comb tooth substrate 1222 is relatively close. Therefore, fixing the two connecting portions 1224 to the groove M via multiple first cantilever beams 1225 ensures sufficient displacement space for the moving comb tooth electrode 122. Simultaneously, since the third comb tooth substrate 1211 and the fourth comb tooth substrate 1212, along with the stationary comb teeth 1213 fixed thereto, are all located outside the closed pattern, the third comb tooth substrate 1211 and the fourth comb tooth substrate 1212 are positioned on opposite sides of the closed pattern in the first direction X. At this point, the distance between the third comb tooth substrate 1211 and the fourth comb tooth substrate 1212 is sufficiently large to maintain good insulation and prevent… Figure 11 The insulation structure 1214 is short-circuited due to voltage breakdown, which can effectively improve the reliability of the electrostatic drive structure 12.

[0142] like Figure 11 As shown, when the orthographic projections of the plurality of stationary comb teeth 1213 and the plurality of moving comb teeth 1223 are all located within the closed pattern on the first substrate 11, the stationary comb tooth electrode 1213 further includes:

[0143] An insulating structure 1214 is located between the third comb tooth substrate 1211 and the fourth comb tooth substrate 1212.

[0144] When the orthographic projections of multiple stationary comb teeth 1213 and multiple moving comb teeth 1223 on the first substrate 11 are all located inside the closed pattern, by providing an insulating structure 1214 between the third comb tooth substrate 1211 and the fourth comb tooth substrate 1212, it is possible to prevent the third comb tooth substrate 1211 and the fourth comb tooth substrate 1212 from easily contacting each other due to their close proximity, thus preventing short circuits.

[0145] Please see Figure 13 and Figure 14 This is a schematic diagram of another electrostatic drive structure provided in an embodiment of the present disclosure.

[0146] The movable comb electrode 122 has one connecting part 1224, and the connecting part 1224 is connected to the middle position of the first comb substrate 1221 and the second comb substrate 1222.

[0147] like Figure 13 As shown, the third comb tooth substrate 1211 and the fourth comb tooth substrate 1212 are located between the first comb tooth substrate 1221 and the second comb tooth substrate 1222. The third comb tooth substrate 1211 and the fourth comb tooth substrate 1212 are both divided into two parts by the connecting part 1224, and the two parts are connected to each other through the connecting line 1215.

[0148] Or, such as Figure 14As shown, the third comb substrate 1211 and the fourth comb substrate 1212 are located on both sides of the first comb substrate 1221 and the second comb substrate 1222.

[0149] In the embodiments provided in this disclosure, by setting one connecting portion 1224 of the movable comb tooth 1223 and connecting the connecting portion 1224 to the middle position of the first comb tooth substrate 1221 and the second comb tooth substrate 1222, more movable comb teeth 1223 can be provided on the first comb tooth substrate 1221 and the second comb tooth substrate 1222, thereby effectively improving the electrostatic adsorption force between the stationary comb tooth electrode 121 and the movable comb tooth electrode 122, thereby improving the effect of the movable comb tooth electrode 122 reciprocating in the first direction X, and further improving the resonant frequency of the torsion of the reflector 212.

[0150] Please see Figures 15-17 This is a schematic diagram of another electrostatic drive structure provided in an embodiment of the present disclosure. The first comb substrate 1221 and the second comb substrate 1222 have a hollow structure.

[0151] like Figure 15 As shown, the hollow structure in the first comb substrate 1221 and the second comb substrate 1222 can be a large-sized through hole that penetrates through the first comb substrate 1221 and the second comb substrate 1222.

[0152] like Figure 16 , Figure 17 As shown, the hollow structure in the first comb substrate 1221 and the second comb substrate 1222 can be multiple through holes, which penetrate the first comb substrate 1221 and the second comb substrate 1222.

[0153] The aforementioned through holes can be rectangular, circular, or other shapes, which will not be elaborated here.

[0154] In the embodiments provided in this disclosure, by having the first comb tooth substrate 1221 and the second comb tooth substrate 1222 have a hollow structure, the weight of the moving comb tooth electrode 122 can be reduced, thereby reducing the inertia of the moving comb tooth electrode 122 in reciprocating motion and increasing the resonant frequency; at the same time, the capacitance structure between the first comb tooth electrode and the first main electrode 131, and between the second comb tooth electrode and the second main electrode 132 can be eliminated, thereby effectively reducing or even eliminating the participating charge between them, and preventing the electrostatic adsorption force generated by the residual charge from hindering the reverse rotation of the galvanometer structure 21.

[0155] Please see Figures 18-20 , Figure 18 This is a top view of an isolation layer provided in an embodiment of the present disclosure. Figure 19 and Figure 20 This is a bottom view of an isolation layer provided in an embodiment of the present disclosure.

[0156] The galvanometer unit also includes a first isolation layer 14 located between the moving comb electrode 122 and the flat plate electrode 13. The orthographic projection of the first isolation layer 14 on the first substrate 11 covers the first comb substrate 1221 and the second comb substrate 1222, as well as a plurality of first cantilever beams 1225.

[0157] like Figures 18-20 As shown, regardless of whether the first comb substrate 1221 and the second comb substrate 1222 have a hollow structure, the isolation layer 14 covers the first comb substrate 1221, the second comb substrate 1222, and the multiple first cantilever beams 1225 in the orthogonal projection of the first substrate 11.

[0158] The first isolation layer 14 covers the first comb substrate 1221 and the second comb substrate 1222. It can completely cover the area or cover a certain proportion (such as more than 95%) of the area.

[0159] In the embodiments provided in this disclosure, by providing a first isolation layer 14 between the moving comb electrode 122 and the flat plate electrode 13, and by having the first isolation layer 14 cover the first comb substrate 1221 and the second comb substrate 1222, as well as the plurality of first cantilever beams 1225, the moving comb electrode 1223 can be insulated from the flat plate electrode 13 to prevent short circuits. When the first comb substrate 1221 and the second comb substrate 1222 have a hollow structure, the flat plate electrode 13 can also be supported by the first isolation layer 14.

[0160] Please see Figure 21 and Figure 22 This is a top view of a planar electrode provided in an embodiment of the present disclosure.

[0161] The flat plate electrode 13 also includes: multiple second cantilever beams 133 (i.e. elastic elements).

[0162] The first main electrode 131 is projected onto the first substrate 11 and covers the first comb substrate 1221. The second main electrode 132 is projected onto the first substrate 11 and covers the second comb substrate 1222. The first main electrode 131 and the second main electrode 132 are respectively fixed to the groove M by a plurality of second cantilever beams 133.

[0163] like Figure 21 As shown, the first main electrode 131 and the second main electrode 132 can be fixed to the groove M by a second cantilever beam 133, and connected to positive and negative voltage respectively; the second cantilever beam 133 covers the corresponding first cantilever beam 1225.

[0164] like Figure 22As shown, the first main electrode 131 and the second main electrode 132 can be fixed to the groove M by two first cantilever beams 1225 respectively, and any second cantilever beam 133 connected to the first main electrode 131 and any second cantilever beam 133 connected to the second main electrode 132 can be connected to positive and negative voltage respectively, and the second cantilever beam 133 covers the corresponding first cantilever beam 1225.

[0165] If the first comb substrate 1221 and the second comb substrate 1222 have a hollow structure, the orthographic projection of the first main electrode 131 on the first substrate 11 covering the first comb substrate 1221 includes covering the hollow structure, and the orthographic projection of the second main electrode 132 on the first substrate 11 covering the second comb substrate 1222 includes covering the hollow structure. This facilitates the formation of two parallel plate capacitors by the first main electrode 131 and the second main electrode 132 with the galvanometer structure 21. The bottom view of the parallel plate electrode 13 can be referred to the bottom view of the isolation layer 14, and will not be described again here.

[0166] The projection of the first main electrode 131 onto the first substrate 11 and the first comb substrate 1221, and the projection of the second main electrode 132 onto the first substrate 11 and the second comb substrate 1222, can largely overlap, as with the first isolation layer 14, or they can completely overlap.

[0167] In the embodiments provided in this disclosure, by having the first main electrode 131 cover the first comb substrate 1221 and the second main electrode 132 cover the second comb substrate 1222, the positions of the first main electrode 131 and the second main electrode 132 with the first comb substrate 1221 and the second comb substrate 1222, respectively, are fixed, so that the first main electrode 131 and the second main electrode 132 reciprocate with the comb electrode 122 in the first direction X. By having the second cantilever beam 133 cover the first cantilever beam 1225, the limited space can be reasonably utilized to transmit positive and negative voltages through the second cantilever beam 133, which is fixed with the first main electrode 131 and the second main electrode 132, so that the first main electrode 131 and the second main electrode 132 can form two parallel plate capacitors with the galvanometer structure 21.

[0168] Please see Figures 23-25 , Figure 23 This is a top view of another planar electrode provided in an embodiment of this disclosure. Figure 24 and Figure 25 The bottom view of a planar electrode provided in an embodiment of the present disclosure shows that the first main electrode 131 and the second main electrode 132 also cover a portion of the movable comb teeth 1223 connected to the first comb tooth substrate 1221 and the second comb tooth substrate 1222, respectively.

[0169] Regardless of whether the first comb substrate 1221 and the second comb substrate 1222 have a hollow structure, the front view of the flat electrode 13 can be as shown. Figure 23As shown; when the first comb substrate 1221 and the second comb substrate 1222 do not have a hollow structure, the bottom view of the flat electrode 13 is as follows. Figure 24 As shown, when the first comb substrate 1221 and the second comb substrate 1222 have a hollow structure, the bottom view of the flat electrode 13 is as follows. Figure 25 As shown.

[0170] It should be understood that, in order to facilitate viewing the positional relationship between the first main electrode 131 and the second main electrode 132 and the first comb substrate 1221, the second comb tooth, and the moving comb tooth 1223, respectively, in Figure 23 and Figure 24 The middle view is the bottom view after removing the first isolation layer 14. In practical applications, Figure 23 and Figure 24 The flat plate electrode 13 shown is also the area of ​​the insulating layer 14 shown in the bottom view. That is, the first insulating layer 14 can cover the flat plate electrode 13, which facilitates effective support of the flat plate electrode 13 and gives the side of the flat plate electrode 13 away from the first insulating layer 14 better flatness.

[0171] In the embodiments provided in this disclosure, by having the first main electrode 131 and the second main electrode 132 respectively cover a portion of the movable comb electrode 1223 connected to the first comb substrate 1221 and the second comb substrate 1222, the area of ​​the first main electrode 131 and the second main electrode 132 can be effectively increased, thereby increasing the overlap area between the first main electrode 131 and the second main electrode 132 and the galvanometer structure 21, improving the electrostatic adsorption force acting on the galvanometer structure 21, and thus improving the resonant frequency of the galvanometer structure 21.

[0172] Please see Figure 26 This is a top view of another planar electrode provided in an embodiment of this disclosure.

[0173] The flat plate electrode 13 further includes: a first sub-electrode 134 and a second sub-electrode 135; the orthographic projection of the first sub-electrode 134 on the first substrate 11 covers a portion of the third comb tooth substrate 1211 and the stationary comb tooth electrode 1213 connected to the third comb tooth substrate 1211, and the orthographic projection of the second sub-electrode 135 on the first substrate 11 covers a portion of the fourth comb tooth substrate 1212 and the stationary comb tooth 1213 connected to the fourth comb tooth substrate 1212; during the reciprocating motion of the flat plate electrode 13 driven by the moving comb tooth electrode 122, the first sub-electrode 134 contacts the first main electrode 131, or the second sub-electrode 135 contacts the first main electrode 131.

[0174] Please see Figure 27 and Figure 28 , Figure 27 This is a top view of another galvanometer structure provided in this embodiment of the present disclosure, twisted toward the second main electrode. Figure 28Provided for the embodiments of this disclosure Figure 27 The front view of the figure at position AA' along the direction of rotation. Figure 27 and Figure 28 The electrostatic drive structure 12 drives the galvanometer structure 21 to move in the opposite direction of the first direction X, so that the first main electrode 131 contacts the first secondary electrode 134. At this time, the first secondary electrode 134 and the first main electrode 131 carry the same voltage. The first main electrode 131 and the first secondary electrode 134 can be regarded as a whole. The area of ​​the parallel plate capacitors corresponding to them is the overlapping area of ​​the first main electrode 131 and the first secondary electrode 134 with the galvanometer structure 21 (S1). The area of ​​the parallel plate capacitors corresponding to the second main electrode 132 is the overlapping area of ​​the second main electrode 132 with the galvanometer structure 21 (S2). This significantly increases the electrostatic attraction force on the part of the galvanometer structure 21 corresponding to the side of the first main electrode 131, so that the galvanometer structure 21 rotates towards the first main electrode 131 faster, thereby effectively improving the rotation speed of the galvanometer structure 21.

[0175] Please see Figure 29 and Figure 30 , Figure 29 This is a top view of another galvanometer structure provided in this embodiment, twisted toward the first main electrode. Figure 30 Provided for the embodiments of this disclosure Figure 29 The front view of the figure at position AA' along the direction of rotation. Figure 29 and Figure 30 The electrostatic drive structure 12 drives the galvanometer structure 21 to move along the first direction X, causing the second main electrode 132 to contact the second secondary electrode 135. At this time, the second secondary electrode 135 and the second main electrode 132 carry the same voltage. The second main electrode 132 and the second secondary electrode 135 can be regarded as a whole. The area of ​​the parallel plate capacitors corresponding to them is the overlapping area of ​​the second main electrode 132 and the second secondary electrode 135 with the galvanometer structure 21 (S2). The area of ​​the parallel plate capacitors corresponding to the first main electrode 131 is the overlapping area of ​​the first main electrode 131 with the galvanometer structure 21 (S1). This significantly increases the electrostatic attraction force on the part of the galvanometer structure 21 corresponding to the second main electrode 132, thereby making the galvanometer structure 21 rotate towards the second main electrode 132 faster, and thus effectively improving the rotation speed of the galvanometer structure 21.

[0176] As the electrostatic drive structure 12 drives the first main electrode 131 and the second main electrode 132 to reciprocate in the first direction X, the overlapping area of ​​the first main electrode 131 and the second main electrode 132 with the galvanometer structure 21 also changes significantly between increasing and decreasing. Consequently, the electrostatic adsorption force acting on the galvanometer structure 21 on both sides of the rotation axis 22 also changes significantly between increasing and decreasing, thereby increasing the resonance efficiency of the galvanometer structure 21 as it rotates along the rotation axis 22.

[0177] In the embodiments provided in this disclosure, the flat plate electrode 13 further includes a first sub-electrode 134 and a second sub-electrode 135. The orthographic projection of the first sub-electrode 134 on the first substrate 11 covers a portion of the third comb tooth substrate 1211 and the stationary comb teeth 1213 connected to the third comb tooth substrate 1211. The orthographic projection of the second sub-electrode 135 on the first substrate 11 covers a portion of the fourth comb tooth substrate 1212 and the stationary comb teeth 1213 connected to the fourth comb tooth substrate 1212. During the reciprocating motion of the flat plate electrode 13 driven by the moving comb tooth electrode 122, the first sub-electrode 134 contacts the first main electrode 131, or the second sub-electrode 135 contacts the second main electrode 132, so that the moving comb tooth electrode 122, in the reciprocating motion... During the reciprocating motion, when the first main electrode 131 contacts the first secondary electrode 134, the electrostatic adsorption force acting on the galvanometer structure 21 corresponding to the first main electrode 131 increases significantly, while the corresponding electrostatic adsorption force acting on the galvanometer structure 21 corresponding to the second main electrode 132 decreases significantly. When the second main electrode 132 contacts the second secondary electrode 135, the electrostatic adsorption force acting on the galvanometer structure 21 corresponding to the second main electrode 132 increases significantly, while the corresponding electrostatic adsorption force acting on the galvanometer structure 21 corresponding to the first main electrode 131 decreases significantly. Consequently, the electrostatic adsorption force acting on the galvanometer structure 21 on both sides of the rotation axis 22 alternates between significantly increasing and decreasing, thereby increasing the resonance efficiency of the galvanometer structure 21 rotating along the rotation axis 22.

[0178] Please see Figure 31 and Figure 32 , Figure 31 This is a top view of a first isolation layer provided in an embodiment of the present disclosure. Figure 32 This is a bottom view of a first isolation layer provided in an embodiment of the present disclosure.

[0179] like Figure 31 As shown, the first isolation layer 14 also covers the first secondary electrode 134 and the second secondary electrode 135, thus isolating the first secondary electrode 134 and the second secondary electrode 135 from the stationary comb electrode 121 to prevent short circuits; as Figure 31 As shown, the surface of the first isolation layer 14 facing the first substrate 11 has multiple recessed structures M', each of which covers a corresponding comb tooth (i.e., each moving comb tooth 1223 and stationary comb tooth 1213 corresponds to a recessed structure M'). In this way, both the moving comb tooth 1223 and the stationary comb tooth 1213 are located within their respective recessed structures M'. This not only isolates adjacent moving comb teeth 1223 and stationary comb teeth 1213 from each other by the first isolation layer 14, but also ensures that when the moving comb teeth 1223 and stationary comb teeth 1213 intersect, they maintain a certain distance from the first isolation layer 14 above and do not come into contact, thereby ensuring that the device will not fail.

[0180] When the moving comb electrode 122 reciprocates in the first direction X, it can prevent the stationary comb tooth 1213 from contacting the moving comb tooth 1223. When the moving comb tooth 1223 moves in the first direction X, the first isolation layer 14 and the first main electrode 131 above the first comb tooth substrate 1221 first contact the first isolation layer 14 and the first auxiliary electrode 134 above the corresponding third comb tooth substrate 1211. At this time, the lower moving comb tooth 1223 cannot continue to move in the first direction X due to the contact obstruction of the upper structure, thus preventing the stationary comb tooth 1213 from short-circuiting with the moving comb tooth 1223. When the moving comb tooth 1223 moves in the opposite direction of the first direction X, the first isolation layer 14 and the second main electrode 132 above the second comb tooth substrate 1222 first contact the first isolation layer 14 and the second auxiliary electrode 135 above the corresponding fourth comb tooth substrate 1212. At this time, the lower moving comb tooth 1223 cannot continue to move in the opposite direction of the first direction X due to the contact obstruction of the upper structure, thus preventing the stationary comb tooth 1213 from short-circuiting with the moving comb tooth 1223.

[0181] Please see Figures 33-35 , Figure 33 This is a top view of a first substrate provided in an embodiment of the present disclosure. Figure 34 Provided for the embodiments of this disclosure Figure 33 Cross-sectional view in the BB' direction. Figure 35 This is a three-dimensional schematic diagram of a first substrate provided in an embodiment of this disclosure.

[0182] The first substrate 11 has a recessed structure M' on one side surface. The stationary comb electrode 121 is located in the recessed structure M. The moving comb electrode 122 and the flat plate electrode 13 are located in the recessed structure M' when projected onto the first substrate 11. The groove M is coincident with the recessed structure M' when projected onto the first substrate 11.

[0183] In the embodiments provided in this disclosure, by providing a recessed structure M' on one side surface of the first substrate 11 and placing the stationary comb electrode 121 1213 in the recessed structure M', it is convenient to arrange the stationary comb electrode 121 and the moving comb electrode 122 in different layers, so that the moving comb electrode 122 has sufficient space to move.

[0184] Based on the same inventive concept, embodiments of this disclosure provide a scanning mirror, including one or a plurality of galvanometer units as described above, arranged in an array.

[0185] In the embodiments provided in this disclosure, by including multiple galvanometer units arranged in an array, the maximum torsion angle of each galvanometer unit remains unchanged, but the scanning mirror can achieve a wider scanning range. Furthermore, the scanning mirror achieved through microfabrication processes has high integration, minimal overall volume change, and less impact on the product.

[0186] Based on the same inventive concept, this disclosure provides a method for fabricating a galvanometer unit. Examples of galvanometer units fabricated using this method can be found in the aforementioned description of the galvanometer unit, and will not be repeated here. Figure 36 The preparation method includes:

[0187] Step S11: An electrostatic drive structure is formed on one side of the first substrate.

[0188] Step S12: A planar electrode is formed on the side of the electrostatic driving structure away from the first substrate to obtain the first substrate; the planar electrode includes a first main electrode and a second main electrode arranged along the first direction, and the electrostatic driving structure drives the planar electrode to reciprocate in the first direction and is insulated from the electrostatic driving structure.

[0189] Step S13: An opening is formed in the second substrate, and a rotating plate is formed in the region corresponding to the opening to obtain a second substrate with a cavity structure; wherein the cavity structure coincides with the opening, the rotating plate is located inside the cavity structure, the rotating plate has a rotating shaft, and the rotating shaft is fixed to the cavity structure;

[0190] Step S14: After aligning the second substrate with the first substrate, a reflective layer is deposited on the surface of the rotating plate away from the first substrate, and the reflective layer is patterned to obtain a reflector (at this time, a galvanometer structure is formed); wherein, after the rotating plate is grounded, it forms two parallel plate capacitors with the first main electrode and the second main electrode; the first main electrode and the second main electrode are located on different sides of the rotating axis; during the process of the electrostatic drive structure driving the parallel plate electrodes to reciprocate, the overlapping area of ​​the first main electrode and the second main electrode with the rotating plate changes, so that the electrostatic adsorption force of the two parallel plate capacitors on the rotating plate changes, driving the rotating plate to rotate along the rotating axis.

[0191] Please see Figure 37 This is a schematic diagram illustrating the fabrication of a galvanometer unit according to an embodiment of the present disclosure.

[0192] Step S21: An electrostatic drive structure 12 is formed on one side of the first substrate 11.

[0193] Step S22: A planar electrode 13 is formed on the side of the electrostatic drive structure 12 away from the first substrate 11 to obtain the first substrate 1.

[0194] The flat plate electrode 13 includes a first main electrode 131 and a second main electrode 132 arranged along the first direction X.

[0195] Step S23: Form an opening in the second substrate 20;

[0196] Step S24: Form a rotating plate 211 in the area corresponding to the opening, and connect the rotating plate 211 to the rotating shaft 22 to obtain a second substrate 2 with a cavity structure.

[0197] Step S25: Bond the first substrate 1 and the second substrate 2 together;

[0198] Step S26: A reflector 212 is formed on the side surface of the rotating plate 211 that is away from the first substrate 1.

[0199] The fabrication of the galvanometer unit can be completed through the above steps S21~S26.

[0200] In some embodiments, an electrostatic drive structure is formed on one side of the first substrate, which can be achieved in the following ways:

[0201] The first substrate is etched to obtain a first substrate with a recessed structure; one or multiple recessed structures can be formed by etching one side surface of the first substrate.

[0202] A first metal layer is deposited on the bottom surface of the recessed structure and then etched to obtain a static comb electrode.

[0203] A first silicon nitride layer is deposited on the side of the static comb electrode away from the first substrate, and the first silicon nitride layer is patterned to obtain a second isolation layer covering the signal lines of the static comb electrode; the second isolation layer and the recessed structure can isolate the electrostatic comb electrodes corresponding to different galvanometer units.

[0204] In some embodiments, an isolation structure may be formed between the third comb substrate and the fourth comb substrate to prevent short circuit between the third comb substrate and the fourth comb substrate.

[0205] A second silicon nitride layer is deposited on the side of the first substrate near the first sub-isolation layer, and the second silicon nitride layer is patterned to obtain a second sub-isolation layer covering the area outside the recessed structure; wherein the second isolation layer includes the first sub-isolation layer and the second sub-isolation layer.

[0206] A second metal layer is deposited on the side of the second sub-isolation layer away from the first substrate, and the second metal layer is etched to obtain a moving comb electrode that is fixedly connected to the second sub-isolation layer and meshes with the stationary comb electrode; wherein, the moving comb electrode is used to reciprocate relative to the stationary comb electrode in a plane parallel to the first substrate along a first direction under the action of electrostatic attraction, the first direction being the extension direction of the comb teeth.

[0207] Please see Figure 38 This is a schematic diagram illustrating the fabrication of an electrostatic drive structure provided in an embodiment of this disclosure.

[0208] Step S211: Etch the first substrate 11 to obtain a first substrate 11 with a recessed structure M';

[0209] Step S212: Deposit a first metal layer on the bottom surface of the recessed structure M';

[0210] Step S213: Etch the first metal layer to obtain the static comb electrode 121.

[0211] Step S214: Deposit a first silicon nitride layer (SiNx) on the side of the stationary comb electrode away from the first substrate.

[0212] Step S215: Pattern the first silicon nitride layer to obtain the first sub-isolation layer covering the signal lines of the stationary comb electrode 121;

[0213] Step 216: Deposit a second metal layer on the side of the second sub-isolation layer away from the first substrate 11;

[0214] Step S217: Etch the second metal layer to obtain the moving comb electrode 122, which is fixedly connected to the second sub-isolation layer and meshes with the stationary comb electrode 121.

[0215] In some embodiments, a planar electrode is formed on the side of the electrostatic drive structure away from the first substrate, which can be achieved in the following ways:

[0216] A third silicon nitride layer is deposited on the side of the movable comb electrode away from the first substrate, and the third silicon nitride layer is patterned to obtain a first isolation layer covering the first comb substrate, the second comb substrate, and a plurality of first cantilever beams; wherein, the movable comb electrode includes: a first comb substrate and a second comb substrate disposed opposite to each other, a plurality of movable comb teeth, a connecting portion connecting the first comb substrate and the second comb substrate, and a plurality of first cantilever beams; the plurality of movable comb teeth are arranged along a first direction and extend along a second direction, and the plurality of movable comb teeth are spaced apart and fixed on the first comb substrate and the second comb substrate; the first direction is perpendicular to the second direction;

[0217] On the side of the first isolation layer away from the first substrate, a third metal layer is deposited and patterned to obtain a planar electrode; wherein, the first main electrode covers the first comb substrate and the second main electrode covers the second comb substrate.

[0218] After forming the planar electrode, a fourth film layer can be deposited on the side of the planar electrode away from the first substrate to form a layer covering the area outside the recessed structure and the second cantilever beam, exposing the stationary comb electrode, the moving comb electrode, and the signal lines of the planar electrode, so that they can be connected to the corresponding signal terminals. Then, a planarization layer is formed on the side of the fourth film layer away from the first substrate, finally obtaining the first substrate.

[0219] Please see Figure 39 This is a schematic diagram illustrating the fabrication of a flat plate electrode according to an embodiment of the present disclosure.

[0220] Step S221: Deposit a third silicon nitride layer on the side of the moving comb electrode 121 away from the first substrate 11;

[0221] Step S222: Pattern the third silicon nitride layer to obtain a first isolation layer 14 covering the first comb substrate 1221, the second comb substrate 1222, and a plurality of first cantilever beams 1225;

[0222] Step S223: Deposit a third metal layer on the side of the first isolation layer 14 away from the first substrate 11;

[0223] Step S224: Pattern the third metal layer to obtain the planar electrode 13. The planar electrode 13 includes a first main electrode 131 and a second main electrode 132.

[0224] Based on the same inventive concept, this disclosure provides a radar system; please refer to [link to relevant documentation]. Figure 40 The radar system includes:

[0225] Laser emitting component 4001 is used to emit lasers;

[0226] Reflector unit 4002;

[0227] As described above, in the scanning mirror 4003, the reflecting unit 4002 reflects the laser to the scanning mirror 4003, and the scanning mirror 4003 scans the obstacle;

[0228] Focusing lens 4004 is used to focus the laser light reflected from the obstacle;

[0229] Beam receiving component 4005 is used to receive the laser beam focused by the focusing lens 4004;

[0230] Control component 4006 is used to form an image of the obstacle based on the signal fed back by the beam receiving component 4005.

[0231] Although preferred embodiments of this disclosure have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this disclosure.

[0232] Obviously, those skilled in the art can make various modifications and variations to this disclosure without departing from its spirit and scope. Therefore, if such modifications and variations fall within the scope of the claims of this disclosure and their equivalents, this disclosure is also intended to include such modifications and variations.

Claims

1. A galvanometer unit, comprising a first substrate and a second substrate bonded together, the first substrate having a groove, the second substrate having a cavity structure, the second substrate including a galvanometer structure housed within the cavity structure, the galvanometer structure having a rotation shaft fixed to the cavity structure, wherein... The first substrate includes: First substrate; An electrostatic drive structure is located on one side of the first substrate. A planar electrode is located on the side of the electrostatic drive structure away from the first substrate and is insulated from the electrostatic drive structure. The electrostatic drive structure drives the planar electrode to reciprocate in a first direction. The planar electrode includes a first main electrode and a second main electrode located on different sides of the rotation axis. The first direction is perpendicular to the extension direction of the rotation axis. During the reciprocating motion, the overlapping area of ​​the first main electrode and the second main electrode with the galvanometer structure changes, which alters the electrostatic attraction acting on the galvanometer structure and causes the galvanometer structure to rotate along the rotation axis.

2. The galvanometer unit as described in claim 1, wherein, After being grounded, the galvanometer structure forms two parallel plate capacitors with the first main electrode and the second main electrode, respectively.

3. The galvanometer unit as described in claim 1, wherein, The electrostatic drive structure includes: The stationary comb electrode and the moving comb electrode mesh with each other. The moving comb electrode is used to reciprocate relative to the stationary comb electrode in a plane parallel to the first substrate along the first direction under the action of electrostatic attraction with the stationary comb electrode. The first direction is the extension direction of the comb teeth. The stationary comb electrode is fixed to one side surface of the first substrate. The movable comb electrode and the groove are fixedly installed by an elastic element. The movable comb electrode and the stationary comb electrode are located on the same plane away from the first substrate. The side of the stationary comb electrode close to the first substrate is in contact with the first substrate. The side of the movable comb electrode close to the first substrate is suspended. The flat plate electrode is fixed to the surface of the movable comb electrode away from the first substrate.

4. The galvanometer unit as described in claim 3, wherein, The movable comb electrode includes: a first comb base plate and a second comb base plate disposed opposite to each other, a plurality of movable comb teeth, a connecting portion connecting the first comb base plate and the second comb base plate, and a plurality of first cantilever beams; The first comb tooth substrate and the second comb tooth substrate are arranged along the first direction and extend along the second direction. The connecting portion or the first comb tooth substrate and the second comb tooth substrate are respectively fixed to the groove by the plurality of first cantilever beams. The plurality of movable comb teeth extend along the first direction and are arranged along the second direction. The plurality of movable comb teeth are spaced apart and fixed on the first comb tooth substrate and the second comb tooth substrate. The first direction is perpendicular to the second direction.

5. The galvanometer unit as described in claim 4, wherein, The stationary comb electrode includes: a third comb substrate and a fourth comb substrate disposed opposite to each other, and a plurality of stationary comb teeth, wherein the third comb substrate and the fourth comb substrate are insulated from each other; The third comb tooth substrate and the fourth comb tooth substrate are arranged along the first direction and extend along the second direction; the plurality of stationary comb teeth extend along the first direction and are arranged along the second direction, the plurality of stationary comb teeth are spaced apart and fixed on the third comb tooth substrate and the fourth comb tooth substrate, and the stationary comb teeth fixed on the third comb tooth substrate mesh with the movable comb teeth fixed on the first comb tooth substrate, and the stationary comb teeth fixed on the fourth comb tooth substrate and the movable comb teeth fixed on the second comb tooth substrate are alternately arranged.

6. The galvanometer unit as described in claim 5, wherein, The connecting part is one, and the connecting part is connected to the middle position of the first comb base plate and the second comb base plate; The third comb tooth substrate and the fourth comb tooth substrate are located between the first comb tooth substrate and the second comb tooth substrate. The third comb tooth substrate and the fourth comb tooth substrate are each divided into two parts by the connecting portion, and the two parts are interconnected by the connecting line. Alternatively, the third comb substrate and the fourth comb substrate are located on both sides of the first comb substrate and the second comb substrate.

7. The galvanometer unit as described in claim 5, wherein, There are two connecting parts, which are respectively connected to the ends of the first comb base plate and the second comb base plate. The first comb base plate, the second comb base plate and the two connecting parts are connected in sequence to form a closed pattern. The orthographic projections of the plurality of stationary comb teeth and the plurality of moving comb teeth onto the first substrate are all located inside the closed pattern; Alternatively, the orthographic projections of the plurality of stationary comb teeth and the plurality of moving comb teeth onto the first substrate are all located outside the closed pattern.

8. The galvanometer unit as described in claim 7, wherein, When the orthographic projections of the plurality of stationary comb teeth and the plurality of moving comb teeth on the first substrate are all located inside the closed pattern, the stationary comb tooth electrode further includes: An insulating structure is located between the third comb tooth substrate and the fourth comb tooth substrate.

9. The galvanometer unit as described in any one of claims 4-8, wherein, The first comb substrate and the second comb substrate have a hollow structure.

10. The galvanometer unit as described in any one of claims 4-8, wherein, The first substrate further includes a first isolation layer located between the moving comb electrode and the flat plate electrode, wherein the orthographic projection of the first isolation layer on the first substrate covers the first comb substrate, the second comb substrate, and the plurality of first cantilever beams.

11. The galvanometer unit as described in any one of claims 5-8, wherein, The flat plate electrode further includes: a plurality of second cantilever beams; The orthographic projection of the first main electrode on the first substrate covers the first comb substrate, and the orthographic projection of the second main electrode on the first substrate covers the second comb substrate. The first main electrode and the second main electrode are respectively fixed to the groove by the plurality of second cantilever beams.

12. The galvanometer unit as claimed in claim 11, wherein, The first main electrode and the second main electrode also cover a portion of the movable comb teeth connected to the first comb base plate and the second comb base plate, respectively.

13. The galvanometer unit as claimed in claim 12, wherein, The planar electrode further includes: a first sub-electrode and a second sub-electrode; the orthographic projection of the first sub-electrode on the first substrate covers the third comb-tooth substrate and a portion of the stationary comb teeth connected to the third comb-tooth substrate, and the orthographic projection of the second sub-electrode on the first substrate covers the fourth comb-tooth substrate and a portion of the stationary comb teeth connected to the fourth comb-tooth substrate; during the reciprocating motion of the planar electrode driven by the moving comb-tooth electrode, the first sub-electrode contacts the first main electrode, or the second sub-electrode contacts the first main electrode.

14. The galvanometer unit as claimed in claim 13, wherein, The first isolation layer located between the moving comb tooth electrode and the flat plate electrode also covers the first sub-electrode and the second sub-electrode. The side surface of the first isolation layer facing the first substrate has a plurality of recessed structures, and the recessed structures cover a plurality of corresponding comb teeth.

15. The galvanometer unit as described in any one of claims 3-8, wherein, One side surface of the first substrate has a recessed structure that coincides with the groove, and the stationary comb electrode is located within the recessed structure.

16. The galvanometer unit as described in any one of claims 1-8, wherein, The galvanometer structure further includes: A second substrate having an opening that coincides with the cavity structure; A rotating plate is fixedly connected to the rotating shaft. The rotating plate is used to rotate along the rotating shaft under the electrostatic attraction of the two parallel plate capacitors corresponding to the first main electrode and the second main electrode. A reflector is located on the side of the rotating plate away from the first substrate and is fixed to the rotating plate.

17. A scanning mirror comprising one or a plurality of galvanometer units as described in any one of claims 1-16, arranged in an array.

18. A method for fabricating a galvanometer unit, wherein, include: An electrostatic drive structure is formed on one side of the first substrate. A planar electrode is formed on the side of the electrostatic drive structure away from the first substrate to obtain a first substrate; the planar electrode includes a first main electrode and a second main electrode arranged along a first direction, and the electrostatic drive structure drives the planar electrode to reciprocate in the first direction, and is insulated from the electrostatic drive structure. An opening is formed in a second substrate, and a rotating plate is formed in the region corresponding to the opening to obtain a second substrate with a cavity structure; wherein, the cavity structure coincides with the opening, the rotating plate is located inside the cavity structure, the rotating plate has a rotating shaft, and the rotating shaft is fixed to the cavity structure; After the second substrate is aligned with the first substrate, a reflective layer is deposited on the surface of the rotating plate away from the first substrate, and the reflective layer is patterned to obtain a reflector; wherein, after the rotating plate is grounded, it forms two parallel plate capacitors with the first main electrode and the second main electrode; the first main electrode and the second main electrode are located on different sides of the rotating axis; during the process of the electrostatic drive structure driving the parallel plate electrodes to reciprocate, the overlapping area of ​​the first main electrode and the second main electrode with the rotating plate changes, causing the electrostatic attraction force of the two parallel plate capacitors on the rotating plate to change, thereby driving the rotating plate to rotate along the rotating axis.

19. The preparation method according to claim 18, wherein, An electrostatic drive structure is formed on one side of the first substrate, comprising: The first substrate is etched to obtain a first substrate with a recessed structure. A first metal layer is deposited on the bottom surface of the recessed structure, and the first metal layer is etched to obtain a static comb electrode; A first silicon nitride layer is deposited on the side of the stationary comb electrode away from the first substrate, and the first silicon nitride layer is patterned to obtain a first sub-isolation layer covering the connection line of the stationary comb electrode. On the side of the first substrate near the first sub-isolation layer, a second silicon nitride layer is deposited and patterned to obtain a second sub-isolation layer covering the area outside the recessed structure; wherein, the second isolation layer includes the first sub-isolation layer and the second sub-isolation layer; A second metal layer is deposited on the side of the second sub-isolation layer away from the substrate, and the second metal layer is etched to obtain a movable comb electrode that is fixedly connected to the second sub-isolation layer and meshes with the stationary comb electrode; wherein the movable comb electrode is used to reciprocate relative to the stationary comb electrode in a plane parallel to the first substrate along the first direction under the action of electrostatic attraction, and the first direction is the extension direction of the comb teeth.

20. The preparation method according to claim 19, wherein, A planar electrode is formed on the side of the electrostatic drive structure away from the first substrate, comprising: A third silicon nitride layer is deposited on the side of the movable comb electrode away from the first substrate, and the third silicon nitride layer is patterned to obtain a first isolation layer covering the first comb substrate, the second comb substrate, and a plurality of first cantilever beams; wherein, the movable comb electrode includes: a first comb substrate and a second comb substrate disposed opposite to each other, a plurality of movable comb teeth, a connecting portion connecting the first comb substrate and the second comb substrate, and a plurality of first cantilever beams; the plurality of movable comb teeth are arranged along the first direction and extend along the second direction, and the plurality of movable comb teeth are spaced apart and fixed on the first comb substrate and the second comb substrate; the first direction is perpendicular to the second direction; On the side of the first isolation layer away from the substrate, a third metal layer is deposited and patterned to obtain the planar electrode; wherein, the first main electrode covers the first comb substrate and the second main electrode covers the second comb substrate.

21. A radar system, wherein, include: Laser emitting assembly, used to emit laser light; Reflecting unit; The scanning mirror as described in claim 17, wherein the reflecting unit reflects the laser light onto the scanning mirror, and the scanning mirror scans the obstacle; A focusing lens, used to focus the laser light reflected from the obstacle; A beam receiving component is used to receive the laser light focused by the focusing lens; A control component for forming an image of the obstacle based on signals fed back from the beam receiving component.

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