A high duty cycle reflector

Abstract

The invention discloses a high-duty-ratio reflector, comprising a mirror surface, a movable frame and a driving structure, wherein the mirror surface is located at the center of the reflector, and the mirror surface is connected to the inner side of the movable frame through two symmetrical rotating shafts; an anchor point is arranged in the gap between the mirror surface and the movable frame, and the anchor point is used to fix the reflector, and the anchor point and the movable frame are connected together through a connecting beam, and the position of the connecting beam is close to the rotating shaft; the driving structure is used to drive the mirror surface and the movable frame to deflect with the rotating shaft as the axis. The high-duty-ratio reflector of the invention has a fixed anchor point arranged in the gap between the movable frame and the mirror surface, and does not need to arrange a special fixing structure outside the movable frame, so that the volume of the reflector can be greatly reduced and the duty ratio of the mirror surface can be improved.

Description

Technical Field

[0001] The invention relates to the field of micro-electromechanical systems, in particular to a reflector with high duty cycle and large driving force. Background Art

[0002] In the fields of optical communication, laser projection, laser radar, three-dimensional imaging, etc., it is necessary to configure a reflector with a deflection function. Especially in the field of laser radar, in order to achieve long-distance accurate detection, a large-caliber, high-power laser is required as a light source, which puts forward the requirements of large size and large angle for the reflector used for light beam reflection. The use of MEMS technology to make reflectors has the advantages of high precision, easy batch production and mature technology. MEMS refers to micro-electromechanical system (Micro-Electro-Mechanical System), which is a revolutionary new technology developed on the basis of microelectronics technology. It is a high-tech electronic mechanical device made by integrating lithography, corrosion, thin film, silicon micromachining and precision machining technologies. MEMS devices are widely used in high-tech industries and are a key technology related to scientific and technological development, economic prosperity and national defense security. Among them, the reflector made by MEMS technology is a light reflection device developed by MEMS technology. By connecting the torsion structure of the reflector surface, under the action of micro-driving force, the mirror surface is driven to deflect, realizing the reflection scanning of the light beam in one or two dimensions. It has the advantages of low cost, high reliability, miniaturization and easy batch production, and has a huge application market in many fields.

[0003] In the existing technology, the reflectors made by MEMS process mainly include electromagnetic driven reflectors and electrostatic driven reflectors. However, in the existing technology, the driving coil of the electromagnetic driven reflector is located on the mirror surface, and the driving comb teeth of the electrostatic driven reflector are located on the mirror surface or the edge of the rotating shaft. The length of the driving coil or the number of driving comb teeth is limited, resulting in the limited driving force of the entire reflector. At the same time, in the existing reflector structure, since it is necessary to set anchor points for fixing the reflector on the periphery of the frame, the mirror duty cycle is very low, and it is difficult to make a large-sized mirror required by the laser radar. If the mirror surface is enlarged, the overall size of the reflector will be too large, increasing the manufacturing cost. Moreover, for large-sized mirrors, since the driving coils or comb teeth of the traditional structure are located at the edge of the mirror surface, when the deflection angle of the mirror surface is too large, the driving coil is easy to exceed the strong magnetic field area, or the moving teeth are completely separated from the fixed teeth, resulting in a sharp decrease in the driving force, limiting the maximum deflection angle of the reflector. Summary of the invention

[0004] In view of the shortcomings of the reflectors in the prior art, such as small driving force, low mirror duty cycle, and limited maximum deflection angle, the applicant provides a new type of high-duty-cycle reflector, which can greatly reduce the overall area of ​​the reflector while keeping the mirror area unchanged, and can provide greater driving force to increase the maximum deflection angle of the mirror.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A high-duty-cycle reflector comprises a mirror surface, a movable frame and a driving structure, wherein the mirror surface is located at the center of the reflector, and the mirror surface is connected to the inner side of the movable frame via two symmetrical rotating shafts; an anchor point is arranged in the gap between the mirror surface and the movable frame, and the anchor point is used to fix the reflector, and the anchor point and the movable frame are connected together via a connecting beam, and the connecting beam is located close to the rotating shaft; the driving structure is used to drive the mirror surface and the movable frame to deflect with the rotating shaft as the axis.

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

[0008] The connecting beam is in an L-shape, one side of the L-shape is parallel to the rotating shaft, an end point is connected to the inner side of the movable frame, and the end point of the other side is connected to the anchor point.

[0009] The driving structure includes a driving coil on a movable frame, and two ends of the driving coil are respectively connected to driving electrodes; two permanent magnets with NS poles facing each other are placed outside the movable frame to form a strong magnetic field in the area where the reflector is located.

[0010] The driving electrode is located on the anchor point.

[0011] The driving structure includes a comb tooth group, wherein the movable teeth of the comb tooth group are located on the two sides of the movable frame that are not connected to the rotating shaft, and the stationary teeth of the comb tooth group are processed at the position of the anchor point edge opposite to the movable teeth; an isolation groove is processed on the anchor point to separate the anchor point into a comb tooth part and a connecting part; a first electrode is processed on the comb tooth part, and a second electrode is processed on the connecting part, and a driving signal is provided or the capacitance of the comb tooth group is measured through the first electrode and the second electrode.

[0012] The movable frame has edges close to the mirror surface on both sides that are not connected to the rotating shaft.

[0013] The shape of the mirror surface is circular, elliptical or square; the shape of the movable frame is square, circular or elliptical.

[0014] The beneficial effects of the present invention are as follows:

[0015] The high duty cycle reflector of the present invention sets a fixed anchor point in the gap between the movable frame and the mirror surface, and does not need to set a special fixed structure outside the movable frame, which can greatly reduce the volume of the reflector and improve the duty cycle of the mirror surface. At the same time, when the reflector of the present invention is working, since the driving coil or the comb tooth group is located on the movable frame, the deflection angle of the movable frame is small, the coil will not exceed the strong magnetic field area, or the movable teeth and the static teeth of the comb tooth group will not be completely separated, thereby avoiding the phenomenon of a sudden reduction in driving force, and greatly improving the maximum deflection angle of the mirror surface.

[0016] The driving coil or driving comb teeth of the present invention are both located on the movable frame. Compared with the prior art where the coil or moving teeth are processed on the mirror surface or the rotating shaft, the driving coil is longer or the number of driving comb teeth is greater, which can provide a greater driving force. Moreover, since the driving force acts directly on the movable frame, compared with the prior art where the force acts directly on the mirror surface, the mirror surface is subjected to less force and has less dynamic deformation, which can avoid the influence of the deformation of the mirror surface on the reflected laser, and more accurately reflect the laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic structural diagram of the reflector of the present invention.

[0018] Figure 2 It is a structural diagram of embodiment 1 of the present invention.

[0019] Figure 3 It is a structural diagram of embodiment 2 of the present invention.

[0020] Figure 4 It is a schematic diagram of the deflection of the reflector of the present invention when it is working.

[0021] In the figure: 1. mirror; 2. movable frame; 2-1. comb teeth; 2-2. connecting part; 3. rotating shaft; 4. anchor point; 5. connecting beam; 6. driving coil; 7. driving electrode; 8. permanent magnet; 9. isolation slot; 10. first electrode; 11. second electrode; 12. comb teeth group. DETAILED DESCRIPTION

[0022] The specific implementation of the present invention is described below in conjunction with the accompanying drawings.

[0023] like Figure 1 As shown, the reflector of the present invention includes a mirror surface 1 and a movable frame 2, the mirror surface 1 is located at the center of the overall structure of the reflector, the movable frame 2 is located at the outer circle of the mirror surface 1, the mirror surface 1 is connected to the two sides of the movable frame 2 through two symmetrical rotating shafts 3, and the other two sides of the movable frame 2 are close to the edges of the mirror surface 1.

[0024] The shape of the mirror surface 1 of the present invention is preferably circular, oval or square, and the shape of the movable frame 2 is preferably square, circular or oval. Figure 1As shown, the mirror surface 1 is circular, and there is a large gap between the circular mirror surface 1 and the square movable frame 2. Four anchor points 4 are arranged in the gap, and the anchor points 4 are used to fix the entire reflector. The anchor points 4 and the movable frame 2 are connected together by connecting beams 5, and the connection beams 5 are located close to the rotating shaft 3. In this embodiment, the shape of the connecting beam 5 is L-shaped, one side of the L-shape is parallel to the rotating shaft 3, the end point is connected to the inner side of the movable frame 2, and the end point of the other side is connected to the anchor point 4. The present invention can provide support for the mirror surface 1 and the movable frame 2 at the same time through the combination of the rotating shaft 3 and the connecting beam 5, and connect all the components together. At the same time, the reflector of the present invention also includes a driving structure for driving the mirror surface 1 and the movable frame 2 to deflect. When the reflector is working, the movable frame 2 and the mirror surface 1 are simultaneously deflected with different frequencies and amplitudes with the rotating shaft 3 as the axis.

[0025] The present invention effectively utilizes the gap between the movable frame 2 and the mirror 1 to set a fixed anchor point 4, without setting a special fixed structure outside the movable frame 2, thereby greatly reducing the volume of the reflector and improving the duty cycle of the mirror.

[0026] Embodiment 1:

[0027] like Figure 2 As shown, the driving mode of the reflector in this embodiment is electromagnetic driving, and a plurality of turns of driving coils 6 are arranged on the movable frame 2, and the two ends of the driving coils 6 are respectively connected to a driving electrode 7, and the driving electrode 7 is located on the anchor point 4. Two permanent magnets 8 are placed on the outer sides of the movable frame 2 that are not connected to the rotating shaft 3, with the N and S poles facing each other, forming a strong magnetic field in the area where the reflector is located.

[0028] When the reflector of this embodiment is working, a driving signal is provided to the driving coil 6 through the driving electrode 7. Under the action of the magnetic field, the driving coil 6 generates a Lorentz force, driving the movable frame 2 to vibrate at a certain frequency and amplitude. Due to the special structure of the connection between the movable frame 2 and the anchor point 4, the deflection angle of the movable frame 2 is small. During the vibration of the movable frame 2, the torsional force of the shaft 3 drives the mirror surface 1 to deflect. Due to the different shapes of the movable frame 2 and the mirror surface 1, and the different shapes and sizes of the shaft 3 and the connecting beam 5, the resonant frequencies of the movable frame 2 and the mirror surface 1 are inconsistent. Figure 4 As shown, by providing a special driving signal, when the mirror 1 vibrates at a certain resonant frequency, the movable frame 2 only deflects a very small angle θ1, while the mirror 1 can obtain a large deflection angle θ2. Since the driving coil 6 is located on the movable frame 2, the small angle deflection of the movable frame 2 will not cause the coil to exceed the strong magnetic field area, so the driving force will not suddenly decrease. It can be ensured that the movable frame 2 always vibrates within the magnetic field range, while the mirror 1 can obtain a large angle of deflection. Compared with the prior art, the structure of this embodiment can greatly increase the maximum deflection angle of the mirror 1.

[0029] Embodiment 2:

[0030] like Figure 3 As shown, the driving mode of the reflector in this embodiment is electrostatic driving. The movable teeth of the comb tooth group 12 are processed on the inner sides of the two sides of the movable frame 2 that are not connected to the rotating shaft 3, and the static teeth of the comb tooth group 12 are processed at the position opposite to the movable teeth on the edge of the anchor point 4. An isolation groove 9 is processed on the anchor point 4 to separate the anchor point 4 into a comb tooth part 2-1 and a connecting part 2-2, and the two parts are electrically isolated. A first electrode 10 is processed on the comb tooth part 2-1, and a second electrode 11 is processed on the connecting part 2-2. The driving signal is provided or the capacitance of the comb tooth group 12 is measured through the first electrode 10 and the second electrode 11.

[0031] In one working mode, multiple first electrodes 10 are used to simultaneously provide driving signals to the comb tooth groups 12 on both sides, and all the comb tooth groups 12 are driving comb teeth, providing electrostatic driving force for the reflector. In another working mode, the first electrode 10 on one side provides a driving signal, and the first electrode 10 on the other side is used to measure the capacitance of the comb tooth group 12, and then calculate the real-time deflection angle of the mirror 1.

[0032] When the reflector of this embodiment is working, the movable frame 2 and the mirror surface 1 vibrate at different frequencies and angles as in the first embodiment. The vibration amplitude of the movable frame 2 is small, and the movable teeth and the static teeth will not be completely separated, thereby avoiding the situation where the driving force suddenly decreases and increasing the maximum deflection angle of the mirror surface 1.

[0033] Of course, regardless of the structure of the first or second embodiment, the driving coil or driving comb teeth are located on the movable frame 2. Compared with the prior art in which the coil or moving teeth are processed on the mirror surface or the rotating shaft, the driving coil is longer or the number of driving comb teeth is greater, which can provide a greater driving force. Moreover, since the driving force acts directly on the movable frame 2, compared with the prior art in which the force acts directly on the mirror surface, the mirror surface is subjected to less force and has less dynamic deformation, which can avoid the influence of the deformation of the mirror surface on the reflected laser, and more accurately reflect the laser.

[0034] 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 high duty cycle reflector, characterized in that: The invention comprises a mirror surface (1), a movable frame (2) and a driving structure, wherein the mirror surface (1) is located at the center of a reflector, and the mirror surface (1) is connected to the inner side of the movable frame (2) via two symmetrical rotating shafts (3); an anchor point (4) is arranged in the gap between the mirror surface (1) and the movable frame (2), and the anchor point (4) is used to fix the reflector; the anchor point (4) and the movable frame (2) are connected together via a connecting beam (5), and the connecting beam (5) is located close to the rotating shaft (3); and the driving structure is used to drive the mirror surface (1) and the movable frame (2) to deflect with the rotating shaft (3) as the axis.

2. The high duty cycle reflector according to claim 1, characterized in that: The connecting beam (5) is in an L-shape, one side of the L-shape is parallel to the rotating shaft (3), an end point is connected to the inner side of the movable frame (2), and the end point of the other side is connected to the anchor point (4).

3. The high duty cycle reflector according to claim 1, characterized in that: The driving structure comprises a driving coil (6) on a movable frame (2), with two ends of the driving coil (6) respectively connected to driving electrodes (7); two permanent magnets (8) with NS poles facing each other are placed outside the movable frame (2), forming a strong magnetic field in the area where the reflector is located.

4. The high duty cycle reflector according to claim 3, characterized in that: The driving electrode (7) is located on the anchor point (4).

5. The high duty cycle reflector according to claim 1, characterized in that: The driving structure comprises a comb tooth group (12), wherein the movable teeth of the comb tooth group (12) are located on two sides of the movable frame (2) not connected to the rotating shaft (3), and the stationary teeth of the comb tooth group (12) are processed at the position of the edge of the anchor point (4) opposite to the movable teeth; an isolation groove (9) is processed on the anchor point (4) to separate the anchor point (4) into a comb tooth part (2-1) and a connecting part (2-2); a first electrode (10) is processed on the comb tooth part (2-1), and a second electrode (11) is processed on the connecting part (2-2); a driving signal is provided or the capacitance of the comb tooth group (12) is measured via the first electrode (10) and the second electrode (11).

6. The high duty cycle reflector according to claim 1, characterized in that: The two sides of the movable frame (2) that are not connected to the rotating shaft (3) are close to the edges of the mirror surface (1).

7. The high duty cycle reflector according to claim 1, characterized in that: The mirror surface (1) is in the shape of a circle, an ellipse or a square; the movable frame (2) is in the shape of a square, a circle or an ellipse.

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