Frameless micro-electro-mechanical galvanometer based on piston type electrostatic comb excitation

Abstract

The utility model provides a frameless micro-electro-mechanical galvanometer based on piston type electrostatic comb tooth excitation, which is provided with a bearing frame, a movable part is arranged on the bearing frame, a fixed part is arranged at a position corresponding to the movable part, the fixed part is fixed with the bearing frame, and a reflecting mirror is arranged in the middle of the bearing frame. The reflecting mirror is in coupling connection with the movable part through a beam; the movable part is provided with a first excitation area, the fixed part is provided with a second excitation area, the first excitation area and the second excitation area are respectively provided with a plurality of comb tooth rows, piston comb tooth excitation is formed when potential difference exists between the first excitation area and the second excitation area, and the beam twists to enable the reflecting mirror to turn over. Due to the fact that the piston comb tooth structure is adopted, the S-shaped bending portion is arranged, and meanwhile a frame structure is removed, the structure is simpler, impact and vibration of the MEMS scanning mirror in practical application are enhanced, the MEMS scanning mirror can carry a large mirror surface size, and the problems that the caliber is small, and the effective area is small are solved.

Description

Technical Field

[0001] The utility model relates to the field of micro-electromechanical (MEMS) driving technology, in particular to a frameless micro-electromechanical galvanometer based on piston-type electrostatic comb excitation. Background Art

[0002] MEMS scanning mirrors, due to their excellent performance, including small size, low drive power consumption, fast response speed, high scanning frequency, and long life, have enormous application value in fields such as LiDAR, projection display, optical coherence tomography, and optical communications. Traditional scanning mirrors use electromagnetic, piezoelectric, electrothermal, and electromagnetic actuation, but these suffer from high power consumption and assembly costs. Piezoelectric-driven MEMS scanning mirrors also face numerous manufacturing challenges, while electrothermal actuation suffers from slow response speed and ambient temperature interactions, significantly limiting their application. Electrostatic comb actuation, however, has become the mainstream actuation method for MEMS scanning mirrors due to its excellent process compatibility, small chip size, high reliability, and low processing costs.

[0003] However, conventional comb structures are all comb-shaped, with only the root of the comb shape fixed on one side. Furthermore, the force of conventional comb structures is proportional to the length of the extended comb teeth. To achieve greater force, the extended comb teeth must be longer, and the aspect ratio of the comb teeth must be larger, i.e., the comb teeth are thinner. Furthermore, conventional comb teeth are generally designed on the side of a mirror or beam, where space is limited. To have more teeth to generate greater force, the width of the comb teeth is generally smaller, resulting in a larger aspect ratio. In other words, the thinner the comb teeth, the weaker their impact and vibration resistance. Furthermore, existing galvanometer mirrors mostly use a frame structure, which increases unnecessary parasitic modes and reduces the effective area. Therefore, most current electrostatic comb-driven MEMS scanning mirrors cannot withstand the shock and vibration encountered in practical applications and suffer from problems such as a small aperture. Summary of the Invention

[0004] The purpose of this utility model is to provide a frameless micro-electromechanical galvanometer based on piston-type electrostatic comb excitation, so as to solve the problems of the electrostatic comb-driven MEMS scanning mirror in the existing technology that it cannot resist the impact and vibration in actual applications, and has small aperture and small effective area.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A frameless micro-electromechanical galvanometer based on piston-type electrostatic comb excitation comprises a carrier frame, a movable portion is provided on the carrier frame, a fixed portion is provided at a position corresponding to the movable portion, the fixed portion is fixed to the carrier frame, a reflector is provided in the middle of the carrier frame, and the reflector is coupled to the movable portion via a beam;

[0007] The movable part is provided with a first excitation area, and the fixed part is provided with a second excitation area. The first excitation area and the second excitation area are respectively provided with a plurality of comb tooth rows. When there is an electric potential difference between the first excitation area and the second excitation area, the piston comb teeth are acted on, and the beam is twisted to cause the reflector to flip.

[0008] Preferably, the first excitation area is a plurality of first comb tooth columns, and the second excitation area is a plurality of second comb tooth columns.

[0009] Preferably, there is a gap between the first comb teeth rows, one end of the first comb teeth is connected to the movable part, and the other end extends away from the movable part; the second comb teeth row is in a pipe shape, both ends of the second comb teeth are fixed to the fixed part, and a comb tooth groove is provided between two adjacent second comb teeth.

[0010] Preferably, the first comb teeth row is in a pipe shape, both ends of the first comb teeth are fixed to the movable part, and a comb tooth groove is provided between two adjacent first comb teeth; there is a gap between the second comb teeth rows, one end of the second comb teeth is connected to the fixed part, and the other end extends away from the fixed part.

[0011] Specifically, the beam includes a movable portion connecting end, which is fastened to the movable portion; a reflector connecting end, which is connected to the reflector, and the bending portion is located between the movable portion connecting end and the reflector connecting end.

[0012] Preferably, the reflector includes a mirror surface and reinforcing ribs, the mirror surface is fixed to the beam, and the back of the mirror surface is provided with reinforcing ribs.

[0013] Preferably, the bending portion is an S-shaped bending structure.

[0014] Preferably, the movable portion and the fixed portion are located at four corners of the carrying frame.

[0015] Preferably, the movable portion and the carrying frame are an integral structure.

[0016] The beneficial effects of the utility model are:

[0017] 1. Compared to existing technologies, the present invention has excellent anti-impact and anti-vibration properties. By configuring the movable portion of the piston comb structure into a comb tooth shape and the fixed portion into a pipe shape, with both sides of all capacitor surfaces in the pipe shape completely fixed, the impact and vibration resistance are greatly improved compared to the single-sided root fixation of the comb shape. Furthermore, the force of the piston comb structure is proportional to the length of the extended comb teeth (corresponding to the height of traditional comb teeth), and is unrelated to their height (corresponding to the length of traditional comb teeth). Therefore, the height of the piston comb teeth can be designed to be very low. Furthermore, the comb teeth in the piston structure are designed on the back of the structural layer, providing ample space. This allows for a wider comb tooth width and a smaller aspect ratio, making the comb teeth thicker and more resistant to impact and vibration. Furthermore, by providing an S-shaped bend, the comb teeth can be more resistant to impact and vibration without increasing their width. This structure can reduce the impact and vibration of the galvanometer in actual applications, solving the problem of a small aperture.

[0018] 2. The separate design of the excitation zone and the reflector-supporting torsion beam effectively increases the excitation zone area, thereby increasing the number of piston-shaped comb teeth and the generated torque. This increases design redundancy and the modular approach facilitates the design and optimization of the beam system's k-value and stress distribution.

[0019] 3. By setting up a gimbal-less (frameless) structure, unnecessary parasitic modes are cut off, reducing the cross-interference and mechanical coupling between the two orthogonal axes and modes, making the occupied effective area ratio larger, and also helping to increase the mirror surface and improve the operating frequency.

[0020] 4. When the potential difference between the first excitation area and the second excitation area is large, the reflector can be flipped at a large angle, and can be matched with different mirror sizes to achieve a large rotation angle and a high resonant frequency. At the same time, by setting reinforcing ribs on the back of the mirror, the dynamic deformation of the reflector can be significantly reduced without increasing the weight of the reflector.

[0021] 5. Because electrostatic drive has its own closed-loop position sensing, the structure of the electrostatically driven MEMS scanning mirror is simpler, which has obvious advantages for automotive applications with high environmental requirements, such as head-up displays and lidar. In addition, electrostatic drive is highly compatible with the semiconductor supply chain, and the cost is lower in wafer foundry, packaging and even testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the overall structure of the micro-electromechanical galvanometer of the present invention;

[0023] Figure 2 This is a top view of the structure of the micro-electromechanical galvanometer of the utility model;

[0024] Figure 3 This is a bottom view of the structure of the micro-electromechanical galvanometer of the utility model;

[0025] Figure 4 This is a schematic diagram of the structure of the micro-electromechanical galvanometer beam of the utility model;

[0026] Figure 5 This is a schematic structural diagram of the micro-electromechanical galvanometer reflector of the utility model;

[0027] Figure 6 This is a schematic structural diagram of the first excitation area of ​​the active part of the micro-electromechanical galvanometer of the present invention;

[0028] Figure 7 This is a schematic structural diagram of the second excitation area of ​​the fixed portion of the micro-electromechanical galvanometer of the present invention;

[0029] Figure 8 It is a partial schematic diagram of the second comb teeth row in the second excitation area of ​​the fixed part of the micro-electromechanical galvanometer of the present invention.

[0030] Figure 9 The figure is a schematic diagram of the piston comb structure formed by the first comb tooth row of the movable part and the second comb tooth row of the fixed part of the micro-electromechanical galvanometer of the present invention.

[0031] In the figure, 1. supporting frame, 2. movable part, 3. fixed part, 4. beam, 5. reflector, 6. connecting end of movable part, 7. bending part, 8. connecting end of reflector, 9. first excitation area, 10. first comb tooth row, 11. second excitation area, 12. second comb tooth row, 13. comb tooth groove, 14. mirror surface, 15. reinforcing rib. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. As long as the effects of the present invention can be exerted, various changes can be made to the embodiments. These embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0033] Reference Figure 1-9 A frameless micro-electromechanical galvanometer based on piston-type electrostatic comb excitation according to this embodiment is further described.

[0034] Figure 1 The structure of the first embodiment of the frameless micro-electromechanical galvanometer based on piston-type electrostatic comb excitation of the present invention is shown in FIG. Figure 1 、 Figure 2 and Figure 3As shown, the micro-electromechanical galvanometer comprises a carrying frame 1, a movable portion 2, a fixed portion 3, a beam 4 and a reflector 5, wherein the four corners of the carrying frame 1 are provided with four movable portions 2 which are integral with the carrying frame 1 and fixed portions 3 corresponding to the movable portions 2, the fixed portions 3 being fixed to the carrying frame 1, one side of the movable portion 2 being connected to the carrying frame 1 as an integral structure, and the other side corresponding to the movable portion 2 being connected to the beam 4 near the carrying frame 1; Figure 4 As shown, the beam 4 has a movable part connecting end 6, a reflector connecting end 8 and a bending part 7. The beam 4 is connected to the movable part 2 and the reflector 5 through the movable part connecting end 6 and the reflector connecting end 9 respectively. Specifically, the movable part connecting end 6 is fixedly connected to the movable part 2, the reflector connecting end 8 is coupled to the reflector 5, and the bending part 7 is arranged between the movable part connecting end 6 and the reflector connecting end 8, and is an S-shaped bending structure; the beam 4 provides support and reset force for the reflector 5, and the reflector 5 is suspended in the middle of the supporting frame 1 through the beam 4, and the supporting frame 1 carries and fixes other structures.

[0035] like Figure 2 、 Figure 6 and Figure 9 As shown, the movable part 2 is located at the four corners of the carrier frame 1. A first excitation area 9 is provided on the side of the movable part 2 close to the fixed part 3. The first excitation area 9 is a plurality of first comb tooth rows 10. The first comb tooth rows 10 are composed of a plurality of first comb teeth. There is a certain gap between each first comb tooth row 10. It is appropriate for the first comb tooth rows 10 to cover the entire movable part 2. One end of the first comb tooth is connected to the movable part 2, and the other end extends away from the movable part 2.

[0036] like Figure 3 、 Figure 7 、 Figure 8 and Figure 9 As shown, the fixed portion 3 is located at the four corners of the carrier frame 1 and corresponds to the movable portion 2. The fixed portion 3 is provided with a second excitation area 11. The second excitation area 11 is composed of a plurality of second comb tooth rows 12. The second comb tooth rows 12 are composed of a plurality of second comb teeth. The second comb tooth rows 12 are the same number as the first comb tooth rows 10 and are positioned correspondingly. The second comb tooth rows 12 are pipe-shaped. The first comb tooth rows 10 can be inserted into the second comb tooth rows 12. Both ends of the second comb teeth are fixed to the fixed portion 3. A comb tooth groove 13 is provided between two adjacent second comb teeth. Compared with the single-sided root fixing of the comb tooth shape, the pipe-shaped comb tooth row has greatly improved impact and vibration resistance.

[0037] like Figure 4 、 Figure 5 As shown, the reflector 5 includes a mirror surface 14 and reinforcement ribs 15. The outer periphery of the mirror surface is fixedly connected to the beam 4 via the reflector connection end 8, and the back of the mirror surface is provided with reinforcement ribs 15. The back reinforcement ribs 15 significantly reduce the dynamic deformation of the reflector 5 while hardly increasing the weight of the reflector 5, thereby increasing the strength of the reflector 5.

[0038] like Figure 2 As shown, preferably, the movable part 2 and the fixed part 3 are rectangular, a gap is left between the movable part 2 and the inner edge of the carrier frame 1, and the four movable parts 2 are arranged clockwise or counterclockwise as a whole according to the position of the movable part connection end 6.

[0039] like Figure 5 As shown, preferably, the reflector connection ends 8 are arranged opposite to each other in pairs and away from the movable part connection end 6, so that the S-shaped bending portion 7 is distributed over the largest area in the space formed by the reflector 5, the movable part 2 and the supporting frame 1, thereby producing better resistance and anti-vibration effects.

[0040] The force of this piston comb structure is proportional to the length of the extended comb teeth, but has nothing to do with their height. The height of the piston comb teeth can be designed to be very low. Because the comb teeth are designed on the back of the structural layer, there is a large space, so the width of the comb teeth can be made larger and the aspect ratio can be smaller, that is, the comb teeth are thicker, making them more resistant to impact and vibration.

[0041] The structure of the second embodiment of the frameless micro-electromechanical galvanometer based on piston-type electrostatic comb tooth excitation of the present invention is different from the first embodiment in that a first excitation area 9 is provided on the movable part 2, and the first excitation area 9 is a plurality of first comb tooth rows 10. The first comb tooth rows 10 are in the shape of a pipe, and both ends of the first comb teeth are fixed to the movable part 2, and a comb tooth groove 13 is provided between two adjacent first comb teeth; a second excitation area 11 is provided on the side of the fixed part 3 close to the movable part 2, and the second excitation area 11 is a plurality of second comb tooth rows 12, and there is a certain gap between each second comb tooth row 12, one end of the second comb tooth is connected to the fixed part 3, and the other end extends away from the fixed part 3; it is preferable that the first comb tooth rows 10 cover the entire movable part 2, the second comb tooth rows 12 are the same in number and corresponding in position to the first comb tooth rows 10, and the second comb tooth rows 12 can be inserted into the first comb tooth row 10.

[0042] When an external electrical signal transmits electrical signals to the first excitation zone 9 and the second excitation zone 11, a potential difference will be generated between the first excitation zone 9 and the second excitation zone 11. The first excitation zone 9 will approach the second excitation zone 11 due to the attraction, thereby driving the movable part 2 to approach the fixed part 3, causing the beam bending part 7 to twist, and then driving the reflector 5 to move and flip. When the external electrical signal disappears, the first excitation zone 9 gradually moves away from the second excitation zone 11 due to the elimination of the attraction, thereby causing the movable part 2 to move away from the fixed part 3, the beam bending part 7 to return to its original state, and the reflector 5 to reset.

[0043] The preferred specific implementation methods and embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above implementation methods and embodiments. Various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the concept of the present invention. The scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A frameless micro-electromechanical galvanometer based on piston-type electrostatic comb excitation, characterized in that: A carrying frame (1) is provided with a movable portion (2) on the carrying frame (1), a fixed portion (3) is provided at a position corresponding to the movable portion (2), the fixed portion (3) is fixed to the carrying frame (1), a reflector (5) is provided in the middle of the carrying frame (1), and the reflector (5) is coupled to the movable portion (2) via a beam (4); The movable part (2) is provided with a first excitation area (9), and the fixed part (3) is provided with a second excitation area (11). The first excitation area (9) and the second excitation area (11) are respectively provided with a plurality of comb tooth rows. When there is a potential difference between the first excitation area (9) and the second excitation area (11), the fixed part (3) will attract the movable part (2) toward the fixed part (3), thereby causing the beam (4) to deform and thereby causing the reflector (5) to flip.

2. The piston-type electrostatic comb-excited frameless micro-electromechanical galvanometer according to claim 1, characterized in that: The first excitation area (9) is a plurality of first comb tooth rows (10), and the second excitation area (11) is a plurality of second comb tooth rows (12).

3. The piston-type electrostatic comb-excited frameless micro-electromechanical galvanometer according to claim 2, characterized in that: There are gaps between the first comb tooth rows (10), one end of the first comb teeth is connected to the movable portion (2), and the other end extends in a direction away from the movable portion (2); the second comb tooth row (12) is in the shape of a pipe, both ends of the second comb teeth are fixed to the fixed portion (3), and a comb tooth groove (13) is provided between two adjacent second comb teeth.

4. The piston-type electrostatic comb-excited frameless micro-electromechanical galvanometer according to claim 2, characterized in that: The first comb tooth row (10) is in the shape of a pipe, with both ends of the first comb teeth fixed to the movable portion (2), and a comb tooth groove (13) provided between two adjacent first comb teeth; there is a gap between the second comb tooth rows (12), with one end of the second comb teeth connected to the fixed portion (3) and the other end extending in a direction away from the fixed portion (3).

5. The piston-type electrostatic comb-excited frameless micro-electromechanical galvanometer according to claim 1, characterized in that: The beam (4) comprises a movable portion connecting end (6) which is tightly connected to the movable portion (2); a reflector connecting end (8) which is connected to the reflector (5); and a bent portion (7) which is located between the movable portion connecting end (6) and the reflector connecting end (8).

6. The piston-type electrostatic comb-excited frameless micro-electromechanical galvanometer according to claim 1, characterized in that: The reflector (5) comprises a mirror surface (14) and a reinforcing rib (15); the mirror surface (14) is fixed to the beam (4); and the back of the mirror surface (14) is provided with a reinforcing rib (15).

7. The piston-type electrostatic comb-excited frameless micro-electromechanical galvanometer according to claim 5, characterized in that: The bending portion (7) is an S-shaped bending structure.

8. The piston-type electrostatic comb-excited frameless micro-electromechanical galvanometer according to claim 1, characterized in that: The movable portion (2) and the fixed portion (3) are located at the four corners of the carrying frame (1).

9. The piston-type electrostatic comb-excited frameless micro-electromechanical galvanometer according to claim 1, characterized in that: The movable portion (2) and the carrying frame (1) are an integrated structure.

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