2D scanning micromirror

Abstract

The present invention discloses a two-dimensional scanning micromirror, comprising a frame, a reflective portion, and a torsion beam with a semi-enclosed structure that is symmetrical about the center of the reflective portion, wherein the ends of the torsion beam are respectively connected to the reflective portion and the frame; the frame is processed with a metal electrode, which is connected to a conductive coil, and the conductive coil is located on the surface of the reflective portion, and the other side of the reflective portion is a mirror surface. The two-dimensional scanning micromirror of the present invention uses a novel torsion beam structure, requiring only a frame and a set of torsion beams with a semi-enclosed structure that are symmetrical about the center of the reflective portion to deflect the mirror surface in two directions, thereby achieving two-dimensional scanning of light signals. Since only a frame and a set of torsion beams are used, the mirror surface duty cycle is significantly improved, thereby improving signal transmission efficiency. Furthermore, when forming a micromirror array, the mirror surface duty cycle can also be increased, which is beneficial to the arraying of two-dimensional scanning micromirrors.

Description

Technical Field

[0001] The present invention relates to the field of micro-electromechanical systems, in particular to a two-dimensional scanning micromirror manufactured based on a MEMS processing technology. Background Art

[0002] MEMS (Micro-Electro-Mechanical System) is a revolutionary new technology developed based on microelectronics. It integrates photolithography, etching, thin film, silicon micromachining, and precision machining techniques to create high-tech electronic and mechanical devices. MEMS devices are widely used in high-tech industries and are a key technology that affects scientific and technological development, economic prosperity, and national defense security. Among them, scanning micromirrors are light-reflecting devices developed using MEMS technology. By connecting a torsional structure to a reflective mirror, electromagnetic force drives the mirror to deflect, enabling one- or two-dimensional reflection scanning of a light beam. These devices offer advantages such as low cost, high reliability, miniaturization, and ease of mass production. They have a huge market for applications in optical communications, laser projection, lidar, 3D imaging, and other fields.

[0003] In many application scenarios of MEMS micromirrors, in order to reduce the diffraction effect during the reflection process of the laser beam and obtain high-resolution images, a high-power, large-size laser light source must be used, so a MEMS micromirror with a larger reflective area is required. Figure 1 The figure shows a two-dimensional scanning micromirror with an existing structure. The micromirror has an outer torsion beam 4 and an inner torsion beam 5, which are perpendicular to each other. The inner torsion beam 5 connects the inner frame 2 and the mirror surface 3, and the outer torsion beam 4 connects the outer frame 1 and the inner frame 2. The mirror surface 3 can be deflected using the outer torsion beam 4 or the inner torsion beam 5 as the rotation axis. When an external control system simultaneously inputs two driving signals to the micromirror in two directions, the mirror surface can be controlled to twist in two directions using the two pairs of torsion beams as axes, thereby achieving two-dimensional scanning and reflection of light. However, this dual-axis micromirror structure, due to the presence of two pairs of torsion beams and two inner and outer frames, is complex and has high processing costs. In particular, the mirror surface duty cycle is very low, resulting in a low reflection ratio and high light loss when reflecting large-scale laser signals. This weakens the optical signal reaching the light receiving end after scanning, reducing the system's signal transmission efficiency. Even using a micromirror array, it is difficult to increase the mirror duty cycle, resulting in low signal transmission efficiency. Summary of the Invention

[0004] To address the problems of existing two-dimensional scanning micromirrors, which utilize two sets of inner and outer torsion beams and two inner and outer frames, resulting in complex structure, high cost, and low mirror duty cycle, the applicant has provided a novel two-dimensional scanning micromirror and array thereof. Using only a single frame and a set of torsion beams, the micromirror can be twisted in two directions, enabling two-dimensional scanning of light. This simple structure reduces process complexity and cost. Furthermore, the micromirror duty cycle can be significantly increased, achieving more efficient reflection of light signals and improving signal transmission efficiency.

[0005] The technical solutions adopted in the present invention are as follows:

[0006] A two-dimensional scanning micromirror comprises a frame, a reflective portion, and a torsion beam with a semi-enclosed structure symmetrical about the center of the reflective portion. The two ends of the torsion beam are respectively connected to the reflective portion and the frame. The frame is processed with metal electrodes, which are connected to conductive coils. The conductive coils are located on the surface of the reflective portion, and the other side of the reflective portion is a mirror surface.

[0007] As a further improvement of the above technical solution:

[0008] The mirror surface and the conductive coil are on the same surface of the reflective part; the mirror surface is plated with a reflective film, and the conductive coil is located under the film.

[0009] The reflecting part is a square structure, the torsion beam is L-shaped, one end is connected to the reflecting part, and the other end is connected to the frame; the two long right-angled sides of the torsion beam are parallel to the edge of the reflecting part.

[0010] The lengths of the two sides of the torsion beam are the same and are greater than half of the length of the side of the reflecting portion.

[0011] The torsion beam is a double L-shaped structure.

[0012] The reflecting portion is circular, and the torsion beams are two semi-enclosed arc beams that are symmetrical about the center of the reflecting portion.

[0013] The torsion beams are two pairs of L-shaped structures, which are symmetrical about the center of the reflection part.

[0014] The metal electrode is connected to the conductive coil through a metal lead, and the end of the inner circle of the conductive coil is connected to a metal lead through a jumper; the metal lead is arranged on the surface of the torsion beam.

[0015] Feedback comb teeth are provided on the torsion beam.

[0016] The mirror surface is plated with a reflective film; the reflective film is made of gold, silver or aluminum; the conductive coil is wound in a square or circular shape.

[0017] The beneficial effects of the present invention are as follows:

[0018] The two-dimensional scanning micromirror of the present invention utilizes a novel torsion beam structure. Requiring only a single frame and a set of centrosymmetrical, semi-enclosed torsion beams, the mirror surface can be deflected in two directions, achieving two-dimensional scanning of light signals. By utilizing only a single frame and a set of torsion beams, the mirror surface duty cycle is significantly increased, improving signal transmission efficiency. Furthermore, when assembled into a micromirror array, the mirror surface duty cycle can also be increased, facilitating the arraying of two-dimensional scanning micromirrors.

[0019] The two-dimensional scanning micromirror of the present invention has a simple overall structure, low process difficulty, is easy to manufacture, and improves the yield rate during the manufacturing process. Moreover, if the mirror surface uses the same area as the existing structure, the total area of ​​the micromirror can be greatly reduced compared to the existing structure, thereby reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the structure of an existing two-dimensional scanning micromirror.

[0021] Figure 2 This is a structural diagram of embodiment 1 of the present invention.

[0022] Figure 3 for Figure 2 Schematic diagram of the deflection axis.

[0023] Figure 4 This is a structural diagram of embodiment 2 of the present invention.

[0024] Figure 5 This is a structural diagram of embodiment 4 of the present invention.

[0025] Figure 6 This is a structural diagram of embodiment 5 of the present invention.

[0026] Figure 7 This is a structural diagram of embodiment 6 of the present invention.

[0027] In the figure: 1. Outer frame; 2. Inner frame; 3. Mirror; 4. Outer torsion beam; 5. Inner torsion beam; 11. Frame; 12. Torsion beam; 13. Reflecting part; 14. Metal electrode; 15. Conductive coil; 16. Metal lead; 17. Feedback comb teeth; 18. Magnet. DETAILED DESCRIPTION

[0028] The specific embodiments of the present invention will be described below with reference to the accompanying drawings.

[0029] Example 1:

[0030] like Figure 2As shown, the two-dimensional scanning micromirror of the present invention is an electromagnetically driven micromirror with a silicon material as its basic structure. It includes a frame 11 and a reflective portion 13. The reflective portion 13 and the frame 11 are connected together by two semi-enclosed torsion beams 12. The two torsion beams 12 are symmetrical about the center of the reflective portion 13. In this embodiment, the reflective portion 13 has a square structure, and the torsion beam 12 is L-shaped, with two long right-angled sides parallel to the adjacent edges of the reflective portion 13. One end of the torsion beam 12 is connected to the edge of the reflective portion 13, and the other end is connected to the frame 11.

[0031] Preferably, the two sides of the torsion beam 12 have the same length.

[0032] Preferably, the lengths of the two sides of the torsion beam 12 are greater than half the length of the side of the reflecting portion 13 .

[0033] There are two metal electrodes 14 on the frame 11. The metal electrodes 14 are connected to an external signal source and are connected to the two ends of the conductive coil 15 through metal leads 16. The metal leads 16 are arranged on the surface of the torsion beam 12. The conductive coil 15 is wound in a circular shape and is distributed on the surface of the reflective part 13. The end of the inner circle of the conductive coil 15 is connected to a metal lead 16 through a jumper. The other side of the reflective part 13 is a mirror surface that reflects light. The surface is coated with an optical reflective film to improve the light reflection efficiency. The material of the optical reflective film is gold, silver or aluminum. Of course, the mirror surface can also be on the same side of the reflective part 13 as the conductive coil 15, and the conductive coil 15 is located in the lower layer of the mirror reflective film.

[0034] like Figure 2 and Figure 3 As shown, two magnets 18 are placed externally on the body of the two-dimensional scanning micromirror of the present invention, with their north and south poles facing each other. A conductive coil 15 is located within the stable magnetic field generated by the magnets. During operation, an external signal source energizes the conductive coil 15 via the metal electrode 14. This energization generates a Lorentz force, which deflects the reflector 13. To achieve two-dimensional scanning of optical signals by the micromirror, two superimposed signals of different frequencies are input into the control signal. This causes the reflector 13 to rotate two-dimensionally, with the deflection axes in the mutually perpendicular diagonal directions A and B, respectively, to perform two-dimensional scanning of the optical signal.

[0035] When the micromirror performs two-dimensional scanning, in order to provide real-time feedback on the deflection angle, such as Figure 2As shown, feedback comb teeth 17 are provided at each end of one torsion beam 12. Deflection of the reflector 13 changes the overlapping area of ​​the feedback comb teeth 17, causing a change in capacitance. By extracting the capacitance signal via output leads, real-time feedback of the deflection angle of the reflector 13 can be achieved through the output capacitor. Alternatively, a feedback comb tooth 17 could be provided on each of the two torsion beams 12 to facilitate better differential processing of the capacitance signal and obtain more accurate deflection angle feedback information.

[0036] Example 2:

[0037] In the first embodiment, a set of L-shaped torsion beams 12 is used to limit the deflection angle of the reflector 13. In order to achieve a larger deflection angle, Figure 4 As shown, the torsion beam 12 is a double L-shaped structure. Due to the adoption of the folded double L-shaped structure, the stress of the rotating shaft can be reduced and a larger angle of deflection can be achieved.

[0038] Example 3:

[0039] In this embodiment, the reflector 13 can also be processed into a circular shape, and the torsion beams 12 are two semi-enclosed arc beams arranged on the outer circle of the reflector 13 . The arc-shaped torsion beams 12 are symmetrical about the center of the reflector 13 .

[0040] Example 4:

[0041] like Figure 5 As shown, the torsion beams 12 are two pairs of L-shaped structures and are symmetrical about the center of the reflector 13. The use of two pairs of L-shaped torsion beams 12 can provide four connection points between the reflector 13 and the frame 11, thereby improving symmetry and structural stability.

[0042] Embodiment 5:

[0043] like Figure 6 As shown, there are two pairs of magnets 18 disposed outside the micromirror, as long as a stable magnetic field can be formed at the location of the micromirror. The conductive coil 15 can also be wound into different shapes such as a square.

[0044] Example 6:

[0045] like Figure 7 As shown, the micromirrors of the present invention can be formed into an M×N two-dimensional scanning micromirror array, where M and N are arbitrary positive integers. When using a micromirror array, the absolute mirror surface area can be increased. When applied to a surface light source, it can effectively reflect light signals over a large area, improving signal transmission efficiency.

[0046] The above description is an explanation of the present invention, not a limitation of the present invention. The present invention may be modified in any form without violating the spirit of the present invention.

Claims

1. A two-dimensional scanning micromirror, characterized in that: The invention comprises a frame (11), a reflecting portion (13), and a torsion beam (12) of a semi-enclosed structure symmetrical about the center of the reflecting portion (13), wherein both ends of the torsion beam (12) are respectively connected to the reflecting portion (13) and the frame (11); a metal electrode (14) is processed on the frame (11), and the metal electrode (14) is connected to a conductive coil (15); the conductive coil (15) is located on the surface of the reflecting portion (13), and the other surface of the reflecting portion (13) is a mirror surface; The reflecting portion (13) and the frame (11) are connected together via two torsion beams (12) of a semi-enclosed structure; The metal electrode (14) is connected to the conductive coil (15) via a metal lead (16), and the end of the inner circle of the conductive coil (15) is connected to a metal lead (16) via a jumper wire; the metal lead (16) is arranged on the surface of the torsion beam (12); The two-dimensional scanning mirror is an electromagnetically driven micromirror with a basic structure made of silicon-based materials; A magnet (18) is placed outside the body of the two-dimensional scanning micromirror, the N pole and the S pole of the magnet (18) are opposite to each other, and the conductive coil (15) is located in the stable magnetic field generated by the magnet.

2. The two-dimensional scanning micromirror according to claim 1, wherein: The mirror surface and the conductive coil (15) are on the same surface of the reflective portion (13); the mirror surface is plated with a reflective film, and the conductive coil (15) is located under the film.

3. The two-dimensional scanning micromirror according to claim 1, wherein: The reflecting portion (13) is a square structure, the torsion beam (12) is L-shaped, one end of which is connected to the reflecting portion (13) and the other end of which is connected to the frame (11); the two long right-angled sides of the torsion beam (12) are parallel to the edge of the reflecting portion (13).

4. The two-dimensional scanning micromirror according to claim 3, wherein: The lengths of the two sides of the torsion beam (12) are the same and are greater than half the length of the side of the reflection portion (13).

5. The two-dimensional scanning micromirror according to claim 1, wherein: The torsion beam (12) is a double L-shaped structure.

6. The two-dimensional scanning micromirror according to claim 1, wherein: The reflecting portion (13) is circular, and the torsion beam (12) is two semi-enclosed arc beams that are symmetrical about the center of the reflecting portion (13).

7. The two-dimensional scanning micromirror according to claim 1, wherein: The torsion beams (12) are two pairs of L-shaped structures, which are symmetrical about the center of the reflection part (13).

8. The two-dimensional scanning micromirror according to claim 1, wherein: Feedback comb teeth (17) are provided on the torsion beam (12).

9. The two-dimensional scanning micromirror according to claim 1, wherein: The mirror surface is plated with a reflective film; the reflective film is made of gold, silver or aluminum; and the conductive coil (15) is wound in a square or circular shape.

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