Scanning mirror device

Abstract

To provide a mirror device for scanning that simplifies device configuration and reduces influence of heat generated during operation.SOLUTION: A mirror device for scanning, includes: a mirror part in which a mirror surface is formed; a first mirror support part which supports the mirror part; a first axis which rotatably supports the first mirror support part in a position dividing a first region having a first mass and a second region having a second mass larger than the first mass; and a first vibration source which generates a first wave with same frequency as a first resonance frequency of the first region, resonates the first region, and vibrates the first mirror support part around the first axis.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a scanning mirror device that has been made compact by utilizing semiconductor manufacturing technology. [Background technology]

[0002] A two-dimensional scanning MEMS (Micro Electro Mechanical Systems) mirror device (planar actuator) is known for scanning laser light emitted from a laser light source and projecting it as a two-dimensional image (see, for example, Patent Document 1). The mirror device described in Patent Document 1 includes, for example, a mirror that reflects laser light, a first frame that is provided around the mirror and rotatably supports the mirror by a first rotation axis, and a second frame that is provided around the first frame and rotatably supports the first frame by a second rotation axis that is perpendicular to the first rotation axis.

[0003] The mirror device includes a first magnet that generates at least one first magnetic field along a first rotation axis and a second magnet that generates at least one second magnetic field along a second rotation axis. The mirror device also includes at least one first electrode in the mirror through which a current flows in a direction perpendicular to the second magnetic field. The mirror device also includes at least one second electrode in the first frame through which a current flows in a direction perpendicular to the first magnetic field.

[0004] This mirror device is configured to generate a Lorentz force based on an alternating current flowing through a first electrode, vibrating the mirror around a first rotation axis based on resonance, and to generate a Lorentz force based on an alternating current flowing through a second electrode, vibrating the mirror together with the first frame around a second rotation axis based on resonance, thereby scanning the laser light reflected on the mirror.

[0005] According to the mirror device described in Patent Document 1, a total of two pairs (four) of permanent magnets must be arranged around the MEMS mirror element to generate a magnetic field, which hinders miniaturization and cost reduction of the device. In order to reduce the size and cost of the device, it is desirable to reduce the number of permanent magnets, which are large and expensive compared to the MEMS element. In addition to the above configuration, Patent Document 1 also describes another mirror device in which a pair of magnets is arranged diagonally on the mirror or frame to generate magnetic field components in each of the two axial directions. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-89501 Summary of the Invention [Problem to be solved by the invention]

[0007] However, with the other mirror device described in Patent Document 1, because one magnetic field is orthogonally decomposed to obtain magnetic forces in two directions, the magnetic field in each axial direction is weakened, and as a result, the electromagnetic force proportional to the magnetic field is also weakened, which limits the rotation angle of the mirror and reduces performance.In addition, with the other mirror device described in Patent Document 1, the mirror needs to be positioned at an angle of 45 degrees with respect to the magnetic field direction, which increases the area required for the device configuration.

[0008] Furthermore, the technology described in Patent Document 1 requires the provision of a coil structure for electromagnetically generating vibrations in the moving parts of the mirror and the first frame. Therefore, according to the technology described in Patent Document 1, the moving parts of the mirror and the first frame are connected to the second frame only at the rotation axis, and are separated from the second frame. Therefore, the technology described in Patent Document 1 has the problem of complicated wiring provided in the mirror and the first frame.

[0009] Furthermore, in the technology described in Patent Document 1, the movable part including the mirror and the first frame is configured to be thermally isolated from the second frame, and when electricity is passed through the electrodes provided on the mirror or the first frame, the movable part heats up, causing changes in the resonant frequency and deflection in the mirror surface, resulting in the problem of unstable operation of the device.

[0010] In the technology described in Patent Document 1, to achieve rotation of the mirror in the first axis direction and the second axis direction based on one drive coil of the movable part, magnetic fields must be applied from outside the movable part in two directions, and two frequency signals must be electrically added together. Therefore, the technology described in Patent Document 1 not only increases the number of drive circuits for driving the drive coil, but also poses the problem of limiting the maximum current by the adder circuit.

[0011] SUMMARY OF THE INVENTION An object of the present invention is to provide a scanning mirror device that simplifies the device configuration and can reduce the influence of heat generated during driving. [Means for solving the problem]

[0012] In order to achieve the above-mentioned object, the present invention provides a scanning mirror device comprising: a mirror section having a mirror surface formed thereon; a first mirror support section supporting the mirror section; a first axis rotatably supporting the first mirror support section at a position dividing the first mirror support section into a first region having a first mass and a second region having a second mass larger than the first mass; and a first vibration source generating a first wave having the same frequency as a first resonant frequency of the first region, thereby resonating the first region and vibrating the first mirror support section around the first axis. [Effects of the Invention]

[0013] According to the present invention, it is possible to simplify the device configuration and reduce the influence of heat generation during operation. [Brief explanation of the drawings]

[0014] [Figure 1]1 is a diagram showing a configuration of a scanning mirror device according to an embodiment of the present invention. [Figure 2] 3 is a cross-sectional view showing a schematic configuration of a scanning mirror device as viewed in a first axis direction. FIG. [Figure 3] 4 is a cross-sectional view showing a schematic configuration of a scanning mirror device as viewed in the second axis direction. FIG. [Figure 4] 10A and 10B are diagrams illustrating a state of a mirror section vibrating around a first axis based on resonance of a first frequency. [Figure 5] 10A and 10B are diagrams illustrating a state of a mirror part vibrating around a first axis based on resonance of a second frequency. [Figure 6] 10A and 10B are diagrams illustrating a state of a mirror part vibrating around a second axis based on resonance of a third frequency. [Figure 7] 10A and 10B are diagrams illustrating a state of the mirror section vibrating along the Z axis based on resonance at a fourth frequency. [Figure 8] FIG. 10 is a diagram showing measurement points in a performance test of the scanning mirror device. [Figure 9] 10A and 10B are diagrams showing the results of a performance test of the scanning mirror device. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of a scanning mirror device according to the present invention will be described with reference to the drawings. In the following description, XYZ coordinates are set. Each axial direction will be referred to as one side, the other side, etc. as appropriate. The set coordinates are relative and are not limited to these. The scanning mirror device is, for example, a two-dimensional scanning mirror element that has been miniaturized using MEMS utilizing semiconductor manufacturing technology. The scanning mirror device is configured with an electrically driven electromagnetic actuator. The scanning mirror device is used, for example, as an electromagnetic wave emission source including light in a small projector or LiDAR (Light Detection and Ranging).

[0016] 1, scanning mirror device 1 is configured to reflect electromagnetic waves emitted from wave source unit 40, to be driven by AC current input from power supply unit 20, and to two-dimensionally scan the reflected electromagnetic waves. Wave source unit 40 and power supply unit 20 are controlled by control device 10 as described below.

[0017] The scanning mirror device 1 is formed by a single substrate 2. The substrate 2 is formed with a mirror surface M1 that reflects electromagnetic waves, such as laser light or radar waves, emitted from a wave source 40. The mirror surface M1 is formed on a mirror section M. The substrate 2 is formed with a first mirror support 3 that supports the mirror section M. The first mirror support 3 is formed, for example, as a rectangular plate. A first groove H1 that separates the first mirror support 3 from the substrate 2 is formed around the first mirror support 3. The first mirror support 3 is formed, for example, with its longitudinal direction aligned with the X-axis and its lateral direction aligned with the Y-axis. The first mirror support 3 is rotatably supported relative to the substrate 2 by a first axis S1 that is aligned with the Y-axis direction in the figure.

[0018] The first shaft S1 is formed as a torsion bar that elastically deforms in the torsional direction. The first shaft S1 is formed by leaving a rod-like member of a predetermined width when forming the first groove H1 in the substrate 2. The first shaft S1 includes a first torsion bar S1A that supports a first side surface 3P on one axial side along the Y-axis direction of the first mirror support part 3, and a second torsion bar S1B that supports a second side surface 3Q on the other axial side along the Y-axis direction of the first mirror support part 3. The first torsion bar S1A connects the first side surface 3P to the substrate 2 (a first diaphragm described below). The second torsion bar S1B connects the second side surface 3Q to the substrate 2 (a second diaphragm described below).

[0019] The first axis S1 is disposed at a position that divides the first mirror support 3 into a first region 3A and a second region 3B. The first region 3A is divided so as to have a first mass. The first region 3A is formed into a first plate-like body C having a first width La on one axial side in a direction perpendicular to the first axis. The first plate-like body C is vibrating around the first axis S1. The first plate-like body C has a first resonant frequency f1. The first plate-like body C resonates with a wave having the first resonant frequency f1 that is input from the outside, and vibrates around the first axis S1.

[0020] The second region 3B is divided to have a second mass that is larger than the first mass of the first plate-like body C. The second region 3B is formed into a second plate-like body D having a second width Lb that is longer than the first width La on the other axial side perpendicular to the first axis S1. The second plate-like body D is vibrating around the first axis S1. The second plate-like body D has a second resonant frequency f2. The second plate-like body D resonates with a wave having the second resonant frequency f2 that is input from the outside and vibrates around the first axis S1.

[0021] The first mirror support 3 is provided with a second mirror support 4 that supports the mirror M in a separated manner. The second mirror support 4 has a second axis S2 that is perpendicular to the first axis S1. The second mirror support 4 is rotatably supported by the first mirror support 3 by the second axis S2. The second mirror support 4 has, for example, a frame 4A formed in an annular shape. The frame 4A is formed so as to extend around the mirror M. A second groove H2 that separates the frame 4A from the first mirror support 3 is formed around the frame 4A. The second mirror support 4 is formed line-symmetrically with respect to the first axis S1 and the second axis S2.

[0022] The second axis S2 is formed as a torsion bar that elastically deforms in the torsional direction. The second axis S2 is formed by leaving a rod-like member of a predetermined width when forming the second groove H2 in the first mirror support part 3. The second axis S2 includes a third torsion bar S2A that supports one axial side of the second mirror support part 4 along the X-axis direction, and a fourth torsion bar S2B that supports the other axial side of the second mirror support part 4 along the X-axis direction. The third torsion bar S2A connects one axial side of the second mirror support part 4 along the X-axis direction to the first mirror support part 3. The fourth torsion bar S2B connects the other axial side of the second mirror support part 4 along the X-axis direction to the first mirror support part 3.

[0023] The second mirror support 4 further supports a separate mirror portion M. The mirror portion M is formed in a disk shape. A circular mirror surface M1 is formed on the surface of the mirror portion M. A third groove H3 is formed around the periphery of the mirror portion M, separating the mirror portion M from the second mirror support 4. The mirror portion M has a third axis S3 arranged coaxially with the first axis S1. The third axis S3 supports the mirror portion M rotatably relative to the second mirror support 4. The third axis is formed on a torsion bar that elastically deforms in the torsional direction.

[0024] The third axis S3 includes a fifth torsion bar S3A that supports one axial side of the mirror section M along the Y axis direction, and a sixth torsion bar S3B that supports the other axial side of the mirror section M along the Y axis direction. The fifth torsion bar S3A connects one axial side of the mirror section M along the Y axis direction to the second mirror support section 4. The sixth torsion bar S3B connects the other axial side of the mirror section M along the Y axis direction to the second mirror support section 4. The third axis S3 is disposed at a position that divides the mirror section M equally in the Y axis direction.

[0025] The second mirror support 4 (including the mirror portion M) has a third resonant frequency f3 around the second axis S2. The second mirror support 4 resonates with a wave having the third resonant frequency f3 input from the outside and vibrates around the second axis S2.

[0026] A first vibration source 5, which serves as a vibration generating source, is provided on the first side surface 3P side of the first mirror support part 3. The first vibration source 5 includes a first diaphragm 5A that elastically deforms and bends when subjected to an external force. The first diaphragm 5A is formed in a rectangular plate shape. A U-shaped fourth groove H4 is formed around the periphery of the first diaphragm 5A to separate the first diaphragm 5A from the substrate 2. The fourth groove H4 partially shares a portion with the first groove H1 on the first side surface 3P side.

[0027] With the above configuration, the first diaphragm 5A is formed as a cantilever that can vibrate with one axial side along the Y-axis direction as a base end and the other axial side as a tip end. On the other axial side along the Y-axis of the first diaphragm 5A, a first electrode 5D is formed extending in a direction perpendicular to the first axis S1 (X-axis). The first electrode 5D is formed, for example, by a wiring layer having a plurality of linear wiring structures.

[0028] A pair of wirings 5E extending along the Y-axis direction perpendicular to the first electrode 5D are electrically connected to one axial side and the other axial side of the first electrode 5D along the X-axis direction. The pair of wirings 5E are electrically connected to a pair of terminals 5F provided on one axial side of the first diaphragm 5A. The pair of terminals 5F are electrically connected to a first power supply unit 21, which will be described later. The first electrode 5D, the pair of wirings 5E, and the pair of terminals 5F are formed by a wiring layer having a linear wiring structure on the first diaphragm 5A. This simplifies the wiring paths of the first electrode 5D, the pair of wirings 5E, and the pair of terminals 5F.

[0029] A second vibration source 6, which serves as a vibration generating source, is provided on the second side surface 3Q side of the first mirror support part 3. The second vibration source 6 includes a second diaphragm 6A that elastically deforms and bends when subjected to an external force. The second diaphragm 6A is formed in the shape of a rectangular plate. A U-shaped fifth groove H5 is formed around the periphery of the second diaphragm 6A to separate the second diaphragm 6A from the substrate 2. The fifth groove H5 partially shares a portion with the first groove H1 on the second side surface 3Q side.

[0030] With the above configuration, the second diaphragm 6A is formed as a cantilever that can vibrate with the other axial side along the Y-axis as a base end and one axial side as a tip end. On one axial side along the Y-axis of the second diaphragm 6A, a second electrode 6D is formed extending in a direction perpendicular to the first axis S1 (X-axis). The second electrode 6D is formed, for example, by a wiring layer having a plurality of linear wiring structures.

[0031] A pair of wirings 6E extending along the Y-axis direction perpendicular to the second electrode 6D are electrically connected to one axial side and the other axial side of the second electrode 6D along the X-axis direction. The pair of wirings 6E are electrically connected to a pair of terminals 6F provided on one axial side of the second diaphragm 6A. The pair of terminals 6F are electrically connected to a second power supply unit 22 (described later). The second electrode 6D, the pair of wirings 6E, and the pair of terminals 6F are formed on the second diaphragm 6A by printed wiring. This simplifies the wiring paths of the second electrode 6D, the pair of wirings 6E, and the pair of terminals 6F. The first vibration source 5 and the second vibration source 6 are disposed between a magnetic field generating unit 30 that generates a magnetic field B1 in a direction along the first axis S1.

[0032] The magnetic field generating unit 30 includes a first permanent magnet 31 provided adjacent to one axial side of the first vibration source 5 along the Y-axis direction, and a second permanent magnet 32 ​​provided adjacent to the other axial side of the second vibration source 6 along the Y-axis direction. The magnetic field generating unit 30 generates a magnetic field B1, for example, in a direction from the first permanent magnet 31 to the second permanent magnet. The first permanent magnet 31 and the second permanent magnet 32 ​​are, for example, neodymium magnets. The first permanent magnet 31 is, for example, arranged with its north pole facing the first vibration source 5. The second permanent magnet 32 ​​is, for example, arranged with its south pole facing the second vibration source 6. The arrangement directions of the first permanent magnet 31 and the second permanent magnet 32 ​​are not limited to this, and they may be opposite each other, or they may be arranged so that their north poles or south poles face each other.

[0033] A current is input to the first electrode 5D from a first power supply unit 21 provided in the power supply unit 20. A current is input to the second electrode 6D from a second power supply unit 22 provided in the power supply unit 20. The first power supply unit 21 and the second power supply unit 22 have power supply circuits that perform AC conversion, downconversion, frequency conversion, etc. on the source power input from a power supply device 23. The first power supply unit 21 and the second power supply unit 22 generate AC currents adjusted to a predetermined frequency, voltage, and current based on the source power, and input the AC currents to the first electrode 5D and the second electrode 6D, respectively. The power supply device 23 supplies source power to the first power supply unit 21 and the second power supply unit 22 based on power input from a commercial power source or a storage battery.

[0034] For example, the first power supply unit 21 inputs an AC current of a first frequency corresponding to the first resonant frequency f1 to the first electrode 5D. As a result, as described below, a Lorentz force is generated in the first electrode 5D, causing the first diaphragm 5A to vibrate at the same frequency as the first resonant frequency f1. Similarly, the first power supply unit 21 inputs an AC current of a second frequency corresponding to the second resonant frequency f2 to the first electrode 5D, causing a Lorentz force to be generated, causing the first diaphragm 5A to vibrate at the same frequency as the second resonant frequency f2.

[0035] Similarly, second power supply unit 22 inputs an AC current of a third frequency corresponding to third resonant frequency f3 to second electrode 6D. As a result, as will be described later, a Lorentz force according to the third frequency corresponding to third resonant frequency f3 is generated in second electrode 6D, causing second diaphragm 6A to vibrate at the same frequency as third resonant frequency f3. Power supply unit 20 is controlled by control device 10.

[0036] The control device 10 includes a control unit 12 that controls the power supply unit 20 and a storage unit 14 that stores data necessary for control. The control device 10 is, for example, an information processing device such as a personal computer. The control device 10 and the power supply unit 20 are connected to each other so that they can communicate with each other via wired or wireless communication. The control device 10 may be connected to a network and control the power supply unit 20 based on remote operation. The network may be, for example, a LAN (Local Area Network), an in-vehicle LAN, a WAN (Wide Area Network), a public wireless communication network, etc.

[0037] The control unit 12 is realized by, for example, a hardware processor such as a CPU (Central Processing Unit) executing a program (software). Some or all of these components may be realized by hardware (including circuitry) such as an LSI (Large Scale Integration), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a GPU (Graphics Processing Unit), or may be realized by a combination of software and hardware. The program may be stored in advance in a storage device (a storage device having a non-transitory storage medium) such as an HDD or flash memory provided in the storage unit 14, or may be stored in a removable storage medium (a non-transitory storage medium) such as a DVD or CD-ROM, and installed in the storage device by inserting the storage medium into a drive device.

[0038] The control unit 12 controls the wave source unit 40 to output electromagnetic waves 41. For example, the wave source unit 40 outputs laser light in the case of a light source such as a projector or LiDAR, and outputs electromagnetic waves in the case of a radar or the like. The electromagnetic waves 41 are input to the mirror surface M1. The control unit 12 controls the AC currents output from the first power supply unit 21 and the second power supply unit 22.

[0039] The control unit 12 controls the first power supply unit 21 to input a predetermined AC current to the first electrode 5D, causing the first vibration source 5 to vibrate. The first mirror support unit 3 resonates with the vibration generated in the first vibration source 5, causing it to vibrate around the first axis S1. That is, the control unit 12 controls the vibration of the first mirror support unit 3 based on the control of the first vibration source 5.

[0040] The control unit 12 controls the second power supply unit 22 to input a predetermined AC current to the second electrode 6D, causing the second vibration source 6 to vibrate. The second mirror support unit 4 resonates with the vibration generated in the second vibration source 6, causing it to vibrate around the second axis S2. That is, the control unit 12 controls the vibration of the second mirror support unit 4 based on the control of the second vibration source 6.

[0041] The operating principle of the scanning mirror device 1 will now be described.

[0042] As shown in FIG. 2, the first mirror support 3 is supported by the substrate 2 so as to be rotatable about a first axis S1. Because the first axis S1 is formed as a torsion bar that elastically deforms in the torsional direction, the first mirror support 3 vibrates based on torsional vibrations generated about the first axis S1. The first region 3A side of the first mirror support 3 has a first resonant frequency f1, and when a wave having the same frequency as the first resonant frequency f1 is input from the outside, the first region 3A vibrates by resonance about the first axis S1 based on a force T1 generated at the center of gravity G1. The second region 3B side of the first mirror support 3 has a second resonant frequency f2, and when a wave having the same frequency as the second resonant frequency f2 is input from the outside, the first region 3B vibrates by resonance about the first axis S1 based on a force T2 generated at the center of gravity G2.

[0043] The first mirror support 3 vibrates, for example, in resonance with vibrations generated by the adjacent first vibration source 5. The first vibration source 5 generates, for example, a first wave having the same frequency as the first resonance frequency f1 of the first region 3A, causing the first region 3A to resonate and vibrate the first mirror support 3 about the first axis S1. The first vibration source 5 vibrates the first diaphragm 5A based on an AC current input to the first electrode 5D. A magnetic field B1 is generated in the Y-axis direction by the magnetic field generator 30. When an AC current of a first frequency is input to the first electrode 5D, a Lorentz force acts periodically on the first electrode 5D in the +Z-axis direction and the -Z-axis direction in accordance with the first resonance frequency f1.

[0044] The first diaphragm 5A vibrates in response to the periodic Lorentz force corresponding to the first resonant frequency f1 acting on the first electrode 5D. This causes the first vibration source 5 to vibrate at the same frequency as the first resonant frequency f1. When the first vibration source 5 vibrates at the same frequency as the first resonant frequency f1, the first region 3A of the first mirror support 3 resonates and vibrates at the first resonant frequency f1. At this time, because the center of gravity G1 of the first region 3A is located at the mirror portion M, the force generated by the resonance is applied to the mirror portion M. Therefore, the mirror portion M vibrates around the third axis S3. That is, when an AC current of a first frequency corresponding to the first resonant frequency f1 is input to the first electrode 5D by the first power supply unit 21, the first diaphragm 5A vibrates based on the Lorentz force generated in the first electrode 5D, and the mirror portion M resonates at the first resonant frequency and vibrates around the third axis S3.

[0045] Similarly, the first vibration source 5 generates, for example, a second wave having the same frequency as the second resonant frequency f2 of the second region 3B, causing the second region 3B to resonate and vibrate the first mirror support 3 about the first axis S1. The first vibration source 5 vibrates the first diaphragm 5A based on an AC current input to the first electrode 5D. When an AC current of the second frequency is input to the first electrode 5D, a Lorentz force acts periodically on the first electrode 5D in the +Z-axis direction and the −Z-axis direction in accordance with the second resonant frequency f2.

[0046] The first diaphragm 5A vibrates in response to the periodic Lorentz force acting on the first electrode 5D at the second resonant frequency f2. This causes the first vibration source 5 to vibrate at the same frequency as the second resonant frequency f2. When the first vibration source 5 vibrates at the same frequency as the second resonant frequency f2, the second region 3B of the first mirror support 3 resonates and vibrates at the second resonant frequency f2.

[0047] At this time, the center of gravity G2 of the second region 3B is not located on the mirror portion M, so the force generated by the resonance is not applied to the mirror portion M. Therefore, the mirror portion M vibrates around the first axis S1 together with the second region 3B. That is, when an AC current of a second frequency corresponding to the second resonance frequency f2 is input to the first electrode 5D by the first power supply unit 21, the first electrode 5D vibrates based on the Lorentz force, and the mirror portion M resonates at the second resonance frequency f2 together with the second region 3B and vibrates around the first axis S1.

[0048] 3, the second mirror support 4 is supported by the substrate 2 so as to be rotatable about a second axis S2. The second axis S2 is formed on a torsion bar that elastically deforms in the torsional direction, and therefore the second mirror support 4 vibrates based on torsional vibrations that occur about the second axis S2. The second mirror support 4 has a third resonant frequency f3, and when a wave having the same frequency as the third resonant frequency f3 is input from the outside, the second mirror support 4 vibrates by resonance about the second axis S2 based on a force T3 generated at the center of gravity G3.

[0049] The second mirror support 4 vibrates, for example, in resonance with vibrations generated by the adjacent second vibration source 6. The second vibration source 6 generates, for example, a third wave having the same frequency as the third resonance frequency f3 of the second mirror support 4, causing the second mirror support 4 to resonate and vibrate around the second axis S2. The second vibration source 6 vibrates the second diaphragm 6A based on an AC current input to the second electrode 6D. A magnetic field B1 is generated in the Y-axis direction by the magnetic field generator 30. When an AC current of a third frequency corresponding to the third resonance frequency f3 is input to the second electrode 6D, a Lorentz force acts periodically on the second electrode 6D in the +Z-axis direction and the -Z-axis direction in accordance with the third resonance frequency f3.

[0050] The second diaphragm 6A vibrates in response to the periodic Lorentz force corresponding to the third resonant frequency f3 acting on the second electrode 6D. This causes the second vibration source 6 to vibrate at the same frequency as the third resonant frequency f3. When the second vibration source 6 vibrates at the same frequency as the third resonant frequency f3, the second mirror support 4 resonates and vibrates at the third resonant frequency f3. That is, when an AC current of a third frequency corresponding to the third resonant frequency f3 is input to the second electrode 6D by the second power supply unit 22, the second diaphragm 6A vibrates based on the Lorentz force generated in the second electrode 6D, and the second mirror support 4 resonates and vibrates at the third resonant frequency f3 around the second axis S2.

[0051] As described above, in the scanning mirror device 1, the first mirror support 3 and the second mirror support 4 are configured to be separated from the first vibration source 5 and the second vibration source 6. Therefore, in the scanning mirror device 1, even if the first vibration source 5 and the second vibration source 6 are heated during operation, the heat is not transferred to the first mirror support 3 and the second mirror support 4, preventing distortion of the first mirror support 3 and the second mirror support 4 and changes in the resonant frequency, allowing the device to operate stably.

[0052] 4 shows the state of the mirror section M vibrating at the first frequency. The mirror section M vibrates around the third axis S3 (first axis S1) along the Y-axis direction in resonation with the same vibration as the first resonance frequency f1 generated in the first vibration source 5. In the scanning mirror device 1 according to the embodiment, the first resonance frequency f1 is, for example, 2.582 kHz.

[0053] 5 shows the state of the second region 3B vibrating at the second frequency. The second region 3B, together with the mirror portion M, vibrates around the first axis S1 along the Y-axis direction in resonation with the same vibration as the second resonant frequency f2 generated in the first vibration source 5. In the scanning mirror device 1 according to this embodiment, the second resonant frequency f2 is, for example, 234 Hz. The mirror portion M can be vibrated at high speed at the first frequency and at low speed at a second frequency lower than the first frequency.

[0054] 6 shows the state of the mirror section M vibrating at the third frequency. The mirror section M vibrates around the second axis S2 along the X-axis direction in resonation with the same vibration as the third resonant frequency f3 generated in the first vibration source 5. In the scanning mirror device 1 according to this embodiment, the third resonant frequency f3 is, for example, 1.461 kHz. The third frequency is a different value from the first frequency and the second frequency.

[0055] Therefore, according to the scanning mirror device 1, by generating a wave of a first frequency or a second frequency from the first vibration source 5 and generating a wave of a third frequency different from the first frequency and the second frequency from the second vibration source 6, it is possible to individually control the vibration of the mirror part M around the first axis S1 and the vibration of the mirror part M around the second axis S2.

[0056] 7 shows a state in which the mirror portion M vibrates along the Z-axis direction based on the fourth frequency. In addition to modes of vibration around the first axis S1 and the second axis S2, the mirror portion M may also have a mode of vibration along the Z-axis based on a force T4 generated at the center of the mirror portion M. The fourth frequency in this case is, for example, 945 Hz.

[0057] Figure 8 shows the locations where displacement was measured in a performance test of the created scanning mirror device 1. At each measurement point, displacement was measured using a laser Doppler measurement device. The displacement when the mirror part M vibrated around the first axis S1 (Y-axis) was measured at the Y-axis measurement point. The displacement when the mirror part M vibrated around the second axis S2 (X-axis) was measured at the X-axis measurement point.

[0058] 9 shows the measurement results of a performance test of the scanning mirror device 1. As shown in the figure, a vibration mode around the first axis S1 (Y-axis) and a vibration mode around the second axis S2 (X-axis) were measured. In addition, a vibration mode around the X-axis, which is not used in the scanning mirror device 1, was measured around 1.75 kHz. Furthermore, a vibration mode along the Z-axis, which is not used in the scanning mirror device 1, was measured at 945 Hz.

[0059] 10 shows the scanning light generated by irradiating the laser light onto the driven scanning mirror device 1. As shown in the figure, the scanning mirror device 1 oscillates the mirror portion M about the first axis S1 and also about the second axis S2, thereby scanning the laser light on a two-dimensional plane and realizing projection of a two-dimensional image.

[0060] As described above, according to the scanning mirror device 1, the vibration of the mirror portion M about the first axis S1 and the vibration about the second axis S2 can be individually controlled based on the first vibration source 5 and the second vibration source 6. According to the scanning mirror device 1, the first mirror support 3 and the second mirror support 4 on which the mirror portion M is provided are separated from the first vibration source 5 and the second vibration source 6, and therefore heat generated in the first vibration source 5 and the second vibration source 6 is prevented from being transmitted to the first mirror support 3 and the second mirror support 4. According to the scanning mirror device 1, since heat generated in the first vibration source 5 and the second vibration source 6 is not transmitted to the first mirror support 3 and the second mirror support 4, distortion of the mirror portion M and changes in the resonant frequency are prevented, and the device can be operated stably.

[0061] The following describes modified examples of the scanning mirror device 1. In the following description, the same components as those in the above embodiment are designated by the same names and reference numerals, and overlapping descriptions will be omitted as appropriate. [Variations] The magnetic field generating unit 30 may generate the magnetic field B1 using a pair of first permanent magnets 31 and second permanent magnets 32, or may generate the magnetic field using an electromagnetic coil. The first vibration source 5 and the second vibration source 6 may be the electromagnetic actuators exemplified above, or may be mechanically configured actuators. For example, the first vibration source 5 and the second vibration source 6 may be configured with a vibrating membrane using a piezoelectric element. The first vibration source 5 and the second vibration source 6 may be configured with a vibrator using a motor and a weight, or a linear actuator using a solenoid coil. The first vibration source 5 and the second vibration source 6 may be any device that can generate vibrations of a predetermined frequency.

[0062] The first vibration source 5 and the second vibration source 6 do not necessarily have to be provided adjacent to the first mirror support 3, and may be provided in any position as long as they can drive the mirror M based on resonance. Also, in the example shown, the first mirror support 3 is divided into a first region 3A and a second region 3B, and the first region 3A is adjusted to a first mass and the second region 3B is adjusted to a second mass. The first mirror support 3 and the mirror M may be formed in any shape, and the resonant frequency of the vibration about the first axis S1 and the resonant frequency of the vibration about the second axis S2 may be adjusted based on the weight and the position of the weight.

[0063] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and can be modified as appropriate without departing from the spirit of the present invention. For example, the scanning mirror device may be used not only in light sources and LiDAR, but also in three-dimensional measurement devices that use ultrasound or electromagnetic waves. [Explanation of symbols]

[0064] 1. Scanning mirror device 3 First mirror support 3A 1st area 3B 2nd area 4 Second mirror support 5 First vibration source 5A 1st diaphragm 5D 1st electrode 6 Second vibration source 6A Second diaphragm 6D 2nd electrode 20 Power supply section 21 1st power supply section 22 2nd power supply section 30 Magnetic field generating unit B1 magnetic field C. First plate-shaped body D Second plate-shaped body M mirror part M1 mirror surface S1 1st axis S2 2nd axis S3 3rd axis

Claims

1. a mirror portion having a mirror surface formed thereon; a first mirror support portion that supports the mirror portion; a second mirror support portion that supports the mirror portion separately in the first mirror support portion; a first shaft that rotatably supports the first mirror support portion at a position that divides the first mirror support portion into a first region having a first mass and a second region having a second mass that is larger than the first mass; a second axis that is perpendicular to the first axis and that rotatably supports the second mirror support portion on the first mirror support portion; a third axis that supports the mirror portion rotatably relative to the second mirror support portion and is disposed coaxially with the first axis; Equipped with The third shaft is formed as a torsion bar that elastically deforms in a torsional direction, the first mirror support portion is formed in a plate shape, The first shaft is formed as a torsion bar that elastically deforms in a torsional direction, the first region is formed in a first plate-like body having a first width on one side of the first mirror support portion in a direction perpendicular to the first axis, the second region is formed on a second plate-like body having a second width longer than the first width on the other side of the first mirror support portion in a direction perpendicular to the first axis, a center of gravity of the first region is disposed at a position overlapping with the mirror portion in a direction perpendicular to the first axis, a center of gravity of the second region is disposed at a position away from the mirror portion of the second region in a direction perpendicular to the first axis, a first vibration source that generates a first wave having the same frequency as a first resonance frequency of the first region, causing the first region to resonate and vibrate the first mirror support portion around the first axis and vibrates the mirror portion around the third axis, and generates a second wave having the same frequency as a second resonance frequency of the second region, causing the second region to resonate and vibrate the first mirror support portion around the first axis and vibrates the mirror portion and the second region around the first axis, Scanning mirror device.

2. a magnetic field generating unit that generates a magnetic field in a direction along the first axis, the first vibration source includes a first diaphragm that elastically deforms and bends when subjected to an external force, and a first electrode formed on the first diaphragm along a direction perpendicular to the first axis; a first power supply unit that inputs an AC current having the same frequency as the first resonance frequency to the first electrode, vibrates the first diaphragm based on a Lorentz force generated in the first electrode by the magnetic field, and resonates and vibrates the first region at the first resonance frequency, 2. The scanning mirror device according to claim 1.

3. the first power supply unit inputs an AC current having the same frequency as the second resonance frequency of the second region to the first electrode, vibrates the first diaphragm based on Lorentz force, and vibrates the second region by resonating with the second resonance frequency.

3. The scanning mirror device according to claim 2.

4. A second vibration source that generates a second wave having the same vibration frequency as the third resonant frequency of the second mirror support portion, causing the second mirror support portion to resonate and vibrate around the second axis.

4. The scanning mirror device according to claim 3.

5. the second mirror support portion is formed in a plate shape, The second shaft is formed as a torsion bar that elastically deforms in a torsional direction, the second vibration source includes a second diaphragm that elastically deforms and bends when subjected to an external force, and a second electrode formed on the second diaphragm along a direction perpendicular to the first axis, a second power supply unit that inputs an AC current with the same frequency as the third resonance frequency to the second electrode, vibrating the second diaphragm based on a Lorentz force generated in the second electrode by the magnetic field, and resonating the second mirror support unit at the third resonance frequency to vibrate it around the second axis, 5. The scanning mirror device according to claim 4.

6. The first power supply unit inputs an alternating current having the same frequency as the first resonant frequency to the first electrode, vibrates the first diaphragm based on the Lorentz force generated in the first electrode by the magnetic field, and causes the mirror unit to resonate at the first resonant frequency and vibrate around the third axis.

6. The scanning mirror device according to claim 5.

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