JP2018005082A - Mems mirror driving circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an MEMS mirror driving circuit which can control the mirror surface to be inclined at an inclination angle if an inter-electrode potential difference of 0 V is allocated to the inclination angle.SOLUTION: The MEMS mirror driving circuit is a circuit which drives the MEMS mirror having an electrostatic actuator which inclines a mirror surface, and includes: a drive voltage generation circuit for applying a positive drive voltage for driving the electrostatic actuator to one electrode of the electrostatic actuator; and a voltage generation circuit for applying a positive constant voltage larger than an off-set in the drive voltage to the other electrode of the electrostatic actuator.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a MEMS mirror driving circuit.

  Patent Document 1 describes an optical switch control device that drives a plurality of MEMS mirrors constituting an optical switch. This apparatus includes drive means for supplying a drive voltage to a plurality of MEMS mirrors, and control means for controlling the tilt angle of each MEMS mirror by changing the supply state of the drive voltage by the drive means. The drive means outputs a drive voltage that compensates for deviation due to temperature fluctuations relative to the reference temperature.

JP 2004-219469 A

  In an optical communication network, an optical switch using a MEMS mirror is used (for example, see Patent Document 1). Some MEMS mirrors have electrostatic actuators. In such a MEMS mirror, for example, a rotation axis is provided on the mirror surface, and an electrostatic actuator that provides an inclination angle around the rotation axis is disposed. Then, by causing a potential difference between the electrodes of the electrostatic actuator, the mirror surface is inclined at an angle corresponding to the magnitude of the potential difference. In many cases, a drive voltage is applied to one electrode of the electrostatic actuator, and the other electrode is connected to a reference potential line (GND line).

  In such a MEMS mirror, for example, when an inter-electrode potential difference of 0V is assigned to an inclination angle of 0 °, a drive voltage of about 0V is supplied from the drive voltage generation circuit when controlling to an inclination angle of about 0 °. Is required to be output. However, an offset may be included in the output voltage from the drive voltage generation circuit. For example, when the drive voltage generation circuit includes a D / A converter and an amplifier circuit, the outputs of the D / A converter and the amplifier circuit include an offset. In such a case, it is difficult to control the drive voltage near 0V.

  The present invention has been made in view of such problems, and even when a potential difference between electrodes of 0 V is assigned to a certain tilt angle, the mirror surface can be controlled in the vicinity of the tilt angle. An object is to provide a possible MEMS mirror driving circuit.

  In order to solve the above-described problem, a MEMS mirror drive circuit according to an embodiment of the present invention is a circuit that drives a MEMS mirror including an electrostatic actuator that tilts a mirror surface, and is a positive drive that drives the electrostatic actuator. A driving voltage generating unit that applies the driving voltage of 1 to the one electrode of the electrostatic actuator, and a voltage generating circuit that applies a positive constant voltage larger than the offset included in the driving voltage to the other electrode of the electrostatic actuator. .

  A MEMS mirror drive circuit according to another embodiment is a circuit that drives a MEMS mirror including a plurality of electrostatic actuators that incline the mirror surface, and a plurality of positive drives that respectively drive the plurality of electrostatic actuators. A plurality of drive voltage generators for applying a voltage to one electrode of each of the plurality of electrostatic actuators, and a voltage for applying a positive constant voltage greater than the offset included in the corresponding drive voltage to the other electrode of the electrostatic actuator And a generation circuit.

  According to the MEMS mirror driving circuit of the present invention, even when a 0V inter-electrode potential difference is assigned to a certain tilt angle, the mirror surface can be controlled in the vicinity of the tilt angle.

FIG. 1 is a plan view showing a configuration of a MEMS mirror driven by a MEMS mirror driving circuit according to an embodiment of the present invention. FIG. 2 is a circuit diagram illustrating a configuration of a drive circuit according to an embodiment. FIG. 3 is a circuit diagram showing a configuration of a drive circuit according to the second modification. FIG. 4 is a circuit diagram showing a configuration of a drive circuit according to a third modification. FIG. 5 is a circuit diagram showing a drive circuit as a comparative example.

[Description of Embodiment of Present Invention]
First, the contents of the embodiment of the present invention will be listed and described. A MEMS mirror driving circuit according to an embodiment of the present invention is a circuit for driving a MEMS mirror including an electrostatic actuator that tilts a mirror surface, and applies a positive driving voltage for driving the electrostatic actuator to one of the electrostatic actuators. And a voltage generation circuit for applying a positive constant voltage larger than the offset included in the drive voltage to the other electrode of the electrostatic actuator.

  In this MEMS mirror drive circuit, the voltage generation circuit applies a positive constant voltage to the other electrode of the electrostatic actuator. The electrostatic actuator is driven by an electrostatic force generated by a potential difference between one electrode and the other electrode. Therefore, even when the positive drive voltage applied to one electrode does not become 0 V due to the offset of the drive voltage generation unit, a positive constant voltage larger than the offset is applied from the voltage generation circuit to the other electrode. If applied, the potential difference between one electrode and the other electrode can be controlled to be around 0V. Therefore, according to the MEMS mirror driving circuit described above, the mirror surface can be controlled in the vicinity of the tilt angle even when an interelectrode potential difference of 0 V is assigned to a certain tilt angle.

  In the MEMS mirror driving circuit described above, the positive constant voltage of the voltage generation circuit may be variable. Since the magnitude of the offset differs for each individual MEMS mirror driving circuit, when the positive constant voltage is fixed, the positive constant voltage is set to a voltage value larger than the maximum value of the assumed offset. There is a need. However, the larger the positive constant voltage, the narrower the variable range of the potential difference between one electrode and the other electrode (that is, the tilt angle range of the mirror surface). On the other hand, if the positive constant voltage of the voltage generation circuit is variable, an appropriate positive constant voltage value can be set according to the magnitude of the offset, so the variable range of the potential difference between one electrode and the other electrode Can be widened.

  The MEMS mirror drive circuit further includes a voltage measurement unit that measures the voltage of the other electrode or the potential difference between the one electrode and the other electrode, and the drive voltage generation unit displays the measurement result of the voltage measurement unit. Based on this, the magnitude of the drive voltage may be corrected. Thereby, the potential difference between one electrode and the other electrode can be controlled with higher accuracy.

  A MEMS mirror drive circuit according to another embodiment is a circuit that drives a MEMS mirror including a plurality of electrostatic actuators that incline the mirror surface, and a plurality of positive drives that respectively drive the plurality of electrostatic actuators. A drive voltage generator that applies a voltage to one electrode of each of the plurality of electrostatic actuators, and a positive constant voltage that is greater than the offset included in the corresponding drive voltage for each of the other electrodes of the plurality of electrostatic actuators. And a plurality of voltage generation circuits applied to the.

  According to this MEMS mirror driving circuit, similarly to the MEMS mirror driving circuit described above, even when a potential difference between electrodes of 0 V is assigned to a certain tilt angle, the mirror surface is controlled in the vicinity of the tilt angle. Can do. Also, depending on the circuit configuration of the drive voltage generator, the offset value differs for each drive voltage. Therefore, if the voltage generator circuit is common, the positive voltage value is set to a voltage value that is larger than the assumed maximum offset value. It is necessary to set the voltage. However, the larger the positive constant voltage, the narrower the variable range of the potential difference between one electrode and the other electrode. On the other hand, if a plurality of voltage generation circuits individually apply a positive constant voltage to the other electrode of each electrostatic actuator, an appropriate positive constant voltage value according to the magnitude of the offset included in each drive voltage Therefore, the variable range of the potential difference between one electrode and the other electrode can be widened.

[Details of the embodiment of the present invention]
A specific example of the MEMS mirror driving circuit according to the embodiment of the present invention will be described below with reference to the drawings. In addition, this invention is not limited to these illustrations, is shown by the claim, and intends that all the changes within the meaning and range equivalent to the claim are included. In the following description, the same reference numerals are given to the same elements in the description of the drawings, and redundant descriptions are omitted.

  FIG. 1 is a plan view showing a configuration of a MEMS mirror 10 driven by a MEMS mirror driving circuit (hereinafter simply referred to as a driving circuit) according to an embodiment of the present invention. The MEMS mirror 10 has a configuration of a so-called gimbal type tilt mirror, and is used, for example, in an optical switch constituting an optical network. As shown in FIG. 1, the MEMS mirror 10 has a mirror surface 11 and rotates around a first rotation shaft 12 a and a first rotation unit 13 and a first rotation unit 13. And a second rotating section 14 that supports the second rotating shaft 12b and rotates around the second rotating shaft 12b.

  The planar shape of the mirror surface 11 is various such as a circular shape and a quadrangular shape, and the first rotation shaft 12a extends through the center of the mirror surface 11 along the Y-axis direction. The first rotating portion 13 has a pair of cylindrical shaft portions 13 a and 13 b with the first rotating shaft 12 a as a central axis, and the pair of shaft portions 13 a and 13 b are the second rotating portion 14. It is supported so that it can rotate freely. The first rotating unit 13 includes one comb-like electrode 15 a constituting the electrostatic actuator 15 and one comb-like electrode 16 a constituting the electrostatic actuator 16.

  The second rotation shaft 12b passes through the center of the mirror surface 11 and extends along the X-axis direction. The second rotating portion 14 has a pair of cylindrical shaft portions 14 a and 14 b with the second rotating shaft 12 b as a central axis, and the pair of shaft portions 14 a and 14 b is a frame body of the MEMS mirror 10. 19 is rotatably supported. The second rotating unit 14 includes the other comb-like electrode 15 b constituting the electrostatic actuator 15 and the other comb-like electrode 16 b constituting the electrostatic actuator 16.

  The electrostatic actuators 15 and 16 are disposed on both sides of the first rotation shaft 12a with the first rotation shaft 12a interposed therebetween. The electrostatic actuator 15 operates the mirror surface 11 in the forward rotation direction around the first rotation shaft 12a. The comb-like electrode 15a and the comb-like electrode 15b are alternately arranged so that the electrostatic force corresponding to the potential difference is generated between the comb-like electrode 15a and the comb-like electrode 15b. A positive tilt angle corresponding to the force (exactly proportional to the square of the potential difference) is given to the mirror surface 11. Further, the electrostatic actuator 16 moves the mirror surface 11 in the reverse rotation direction around the first rotation shaft 12a. The comb-like electrode 16a and the comb-like electrode 16b are alternately arranged so that the electrostatic force corresponding to the potential difference is generated between the comb-like electrode 16a and the comb-like electrode 16b. A negative tilt angle corresponding to the force (exactly proportional to the square of the potential difference) is given to the mirror surface 11. The tilt angle range of the mirror surface 11 is, for example, ± several degrees.

  The second rotating unit 14 further includes one comb-like electrode 17 a constituting the electrostatic actuator 17 and one comb-like electrode 18 a constituting the electrostatic actuator 18. The frame body 19 includes the other comb-like electrode 17 b constituting the electrostatic actuator 17 and the other comb-like electrode 18 b constituting the electrostatic actuator 18.

  The electrostatic actuators 17 and 18 are disposed on both sides of the second rotation shaft 12b with the second rotation shaft 12b interposed therebetween. The electrostatic actuator 17 operates the mirror surface 11 in the forward rotation direction around the second rotation shaft 12b. The comb-like electrode 17a and the comb-like electrode 17b are arranged so as to alternately mesh with each other, and an electrostatic force corresponding to a potential difference is generated between the comb-like electrode 17a and the comb-like electrode 17b. A positive tilt angle corresponding to the force (exactly proportional to the square of the potential difference) is given to the mirror surface 11. The electrostatic actuator 18 moves the mirror surface 11 in the reverse rotation direction around the second rotation shaft 12b. The comb-shaped electrodes 18a and the comb-shaped electrodes 18b are arranged so as to alternately mesh with each other, and an electrostatic force corresponding to a potential difference is generated between the comb-shaped electrodes 18a and the comb-shaped electrodes 18b. A negative tilt angle corresponding to the force (exactly proportional to the square of the potential difference) is given to the mirror surface 11.

  FIG. 2 is a circuit diagram showing a configuration of the drive circuit 1A of the present embodiment. FIG. 2 also shows a circuit portion that simulates the electrostatic actuators 15 to 18 of the MEMS mirror 10. The electrostatic actuators 15 to 18 are simulated by a resistor Ra and a capacitor Ca connected in parallel to each other. The resistance value of the resistor Ra is an extremely large value such as several GΩ. The capacitance value of the capacitor Ca is a small value such as several tens of pF. The MEMS mirror 10 shown in this example includes four input terminals 10a to 10d and one common terminal 10e. The four input terminals 10a to 10d are connected to one comb-like electrodes of the corresponding electrostatic actuators 15 to 18, respectively. One common terminal 10e is connected to the other comb-like electrodes of the four electrostatic actuators 15-18.

  The drive circuit 1A applies positive drive voltages VD1 to VD4 for driving the electrostatic actuators 15 to 18 to one comb-like electrode of the electrostatic actuators 15 to 18 and the common terminal 10e. And a voltage generation circuit 29 that is electrically connected. The drive voltage generation unit 20 includes a micro control unit (MCU) 21 as a control unit, D / A converters 22a to 22d, amplification circuits 25a to 25d, filter circuits 26a to 26d, and current limiting resistors 27a to 27d. Have.

  The MCU 21 has a central processing circuit and a memory, and operates according to a program stored in advance. The MCU 21 is electrically connected to the input ends of the D / A converters 22a to 22d. The MCU 21 outputs a digital drive signal D1 for driving the electrostatic actuator 15 to the D / A converter 22a, and outputs a digital drive signal D2 for driving the electrostatic actuator 16 to the D / A converter 22b. The digital drive signal D3 for driving the electrostatic actuator 17 is output to the D / A converter 22c, and the digital drive signal D4 for driving the electrostatic actuator 18 is output to the D / A converter 22d. Output. The wiring between the MCU 21 and the D / A converters 22a to 22d is, for example, a data bus. The D / A converters 22a to 22d may be built in the MCU 21. Data relating to the relationship between the tilt angle of the mirror surface 11 and the digital drive signals D1 to D4 is stored in advance in a storage device. When the MCU 21 receives a request for the optical path of the connection destination from the host controller, the MCU 21 changes the digital drive signals D1 to D4 according to the data in the storage device.

  Output terminals of the D / A converters 22a to 22d are electrically connected to the amplifier circuits 25a to 25d, respectively. The D / A converters 22a to 22d convert the digital drive signals D1 to D4 output from the MCU 21 into voltage signals V1 to V4, respectively. The output voltages from the D / A converters 22a to 22d are, for example, within a range where the lower limit value is an output offset voltage and the upper limit value is several volts. The offset voltage is a unique offset voltage that each of the D / A converters 22a to 22d has.

  The amplifier circuits 25a to 25d are electrically connected between the D / A converters 22a to 22d and the electrostatic actuators 15 to 18. These amplifier circuits 25a to 25d amplify the voltage signals V1 to V4 obtained from the D / A converters 22a to 22d, for example, within a voltage range in which the upper limit value is several tens to several hundreds V (for example, 200V). , Drive voltages VD1 to VD4 are generated. These drive voltages VD1 to VD4 include output offset voltages of the amplifier circuits 25a to 25d.

  The filter circuits 26a to 26d are electrically connected between the D / A converters 22a to 22d and the electrostatic actuators 15 to 18 (between the amplification circuits 25a to 25d and the electrostatic actuators 15 to 18 in this embodiment). It is connected. These filter circuits 26a to 26d are circuits for reducing (preferably removing) noise included in the drive voltages VD1 to VD4 and the resonance frequency component of the MEMS mirror 10. In one example, the filter circuits 26a to 26d include a resistor R1 connected between the D / A converters 22a to 22d and the electrostatic actuators 15 to 18, and one end of the resistor R1 on the electrostatic actuator 15 to 18 side and a reference. The capacitor C <b> 1 connected between the potential line 5 is included.

  The current limiting resistors 27a to 27d are electrically connected between the D / A converters 22a to 22d and the electrostatic actuators 15 to 18, respectively. The current limiting resistors 27a to 27d are resistors for protecting the MEMS mirror 10, and limit the current flowing through the electrostatic actuators 15 to 18. Note that the current limiting resistor may be connected between the common terminal 10 e and the voltage generation circuit 29.

  The voltage generation circuit 29 is a circuit that applies a positive constant voltage VC larger than the offset of the drive voltage generation unit 20 to the other comb-like electrodes of the electrostatic actuators 15 to 18. Here, the offset of the drive voltage generation unit 20 is an offset voltage included in the final drive voltages VD1 to VD4. For example, the output offset voltages of the D / A converters 22a to 22d are the amplification circuits 25a to 25d. And the output offset voltage of the amplifier circuits 25a to 25d. In an example, the offset of the drive voltage generation unit 20 is 0 to 2V.

  The voltage generation circuit 29 of the present embodiment is electrically connected to the common terminal 10e, and applies a common constant voltage VC to the other comb-like electrodes of the electrostatic actuators 15 to 18 via the common terminal 10e. To do. The voltage generation circuit 29 is realized by a constant voltage output circuit such as a voltage reference IC, for example.

  The effect by the drive circuit 1A of this embodiment demonstrated above is demonstrated. FIG. 5 is a circuit diagram showing a drive circuit 100 as a comparative example. The drive circuit 100 includes the drive voltage generation unit 20 having the same configuration as that of the present embodiment, but does not include the voltage generation circuit 29, and the common terminal 10e is connected to the reference potential line 5. This is different from the present embodiment.

  In this drive circuit 100, for example, when an interelectrode potential difference of 0V is assigned to a tilt angle of 0 ° in the MEMS mirror 10, in order to control the tilt angle near 0 °, the drive voltage generator 20 supplies 0V. It is required to output nearby driving voltages VD1 to VD4. However, as described above, the drive voltages VD1 to VD4 include offsets due to the output offset voltages of the D / A converters 22a to 22d and the amplifier circuits 25a to 25d. Therefore, in this drive circuit 100, it becomes difficult to control the potential difference between the electrodes of the electrostatic actuators 15 to 18 to around 0V.

  On the other hand, in the drive circuit 1A of the present embodiment, the voltage generation circuit 29 applies a positive constant voltage VC to the other comb-like electrodes of the electrostatic actuators 15-18. Therefore, even when the positive drive voltages VD1 to VD4 applied to one of the comb-shaped electrodes do not become 0V due to the offset included in the drive voltages VD1 to VD4, the positive constant voltage VC that is larger than the offset. Is applied from the voltage generating circuit 29 to the other comb-like electrode, the potential difference between the one comb-like electrode and the other comb-like electrode can be changed from a negative value and controlled to be close to 0V. Is possible. Therefore, according to the drive circuit 1A of the present embodiment, the mirror surface 11 can be controlled in the vicinity of the tilt angle even when an interelectrode potential difference of 0 V is assigned to a certain tilt angle.

  Note that the potential difference between one comb-shaped electrode and the other comb-shaped electrode can also be controlled to around 0 V by outputting a positive voltage and a negative voltage from the D / A converter. However, in this case, it is necessary to provide a negative power source and a positive power source, and to configure the D / A converter and the amplifier circuit to input positive and negative power source voltages, which causes a problem that the circuit scale increases. On the other hand, according to the drive circuit 1A of the present embodiment, it is sufficient to output only a positive voltage from the D / A converters 22a to 22d, so that the circuit scale of the power source and the like can be suppressed.

(First modification)
In the above embodiment, the constant voltage VC output from the voltage generation circuit 29 is fixed, but the constant voltage VC may be variable. Since the magnitude of the offset included in the drive voltages VD1 to VD4 differs for each individual drive circuit 1A, when the constant voltage VC is fixed, it is larger than the maximum offset value among the offsets assumed for each individual. It is necessary to set the constant voltage VC to the voltage value. However, as the value of the constant voltage VC increases, the variable range of the potential difference between one comb-shaped electrode and the other comb-shaped electrode (that is, the tilt angle range of the mirror surface 11) becomes narrower. By making the constant voltage VC of the voltage generation circuit 29 variable, an appropriate constant voltage value VC can be set for each individual according to the magnitude of the offset included in the drive voltages VD1 to VD4. The variable range of the potential difference between the electrode and the other comb-shaped electrode can be widened, and the tilt angle range of the mirror surface 11 can be widened.

(Second modification)
FIG. 3 is a circuit diagram showing a configuration of a drive circuit 1B according to the second modification. The difference between the present modification and the above embodiment is the configuration of the voltage generation circuit. That is, the drive circuit 1A of the above embodiment includes the voltage generation circuit 29 common to the plurality of electrostatic actuators 15 to 18, while the drive circuit 1B of the present modification includes a plurality of voltage generation circuits 29a to 29d. The voltage generation circuit 29a applies a positive constant voltage VC1 larger than the offset included in the drive voltage VD1 to the other comb-like electrode of the electrostatic actuator 15. Similarly, the voltage generation circuits 29b to 29d individually apply positive constant voltages VC2 to VC4 larger than the offset included in the corresponding drive voltages VD2 to VD4 with respect to the other comb-shaped electrodes of the electrostatic actuators 16 to 18. Apply to. The specific configuration of the voltage generation circuits 29a to 29d is the same as that of the voltage generation circuit 29 of the above embodiment.

  According to this drive circuit 1B, similarly to the drive circuit 1A of the above-described embodiment, even when an inter-electrode potential difference of 0V is assigned to a certain tilt angle, the mirror surface 11 is controlled near the tilt angle. be able to. Further, since the drive voltage generator 20 is provided with the D / A converter and the amplifier circuit for each of the drive voltages VD1 to VD4, the offset value is different for each of the drive voltages VD1 to VD4. Therefore, when the voltage generation circuit 29 is common as in the above embodiment, it is necessary to set the constant voltage VC to a voltage value larger than the maximum offset value among the offsets assumed for the drive voltages VD1 to VD4. There is. However, as described above, the greater the constant voltage VC, the narrower the variable range of the potential difference between one comb-shaped electrode and the other comb-shaped electrode (that is, the tilt angle range of the mirror surface 11). As in this modification, the plurality of voltage generation circuits 29a to 29d individually apply the constant voltages VC1 to VC4 to the other comb-like electrodes of the electrostatic actuators 15 to 18, thereby driving the drive voltages VD1 to VD4. Appropriate constant voltages VC1 to VC4 can be individually set in accordance with the magnitude of the offset included in the mirror, so that the variable range of the potential difference between one comb-shaped electrode and the other comb-shaped electrode can be widened, and the mirror The inclination angle range of the surface 11 can be widened.

(Third Modification)
FIG. 4 is a circuit diagram showing a configuration of a drive circuit 1C according to the third modification. The drive circuit 1 </ b> C of the present modification further includes a voltage measurement unit 30 in addition to the configuration of the above embodiment. The voltage measuring unit 30 measures the magnitude of the voltage of the other comb-like electrode of each of the electrostatic actuators 15 to 18 (that is, the constant voltage VC). The voltage measuring unit 30 is connected between, for example, a wiring 31 that connects the common terminal 10 e and the voltage generation circuit 29 and the reference potential line 5. Then, the measurement result of the voltage measurement unit 30 is fed back to the MCU 21, and the MCU 21 corrects the signal values of the digital drive signals D1 to D4 based on the measurement result. That is, the drive voltage generation unit 20 corrects the magnitudes of the drive voltages VD1 to VD4 based on the measurement result of the voltage measurement unit 30. Thereby, the potential difference between one comb-shaped electrode and the other comb-shaped electrode of each of the electrostatic actuators 15 to 18 can be controlled with higher accuracy.

  The voltage measuring unit may measure a potential difference between one comb-shaped electrode and the other comb-shaped electrode of each of the electrostatic actuators 15 to 18. Even in such a case, the measurement result of the voltage measurement unit is fed back to the MCU 21, and the MCU 21 can correct the signal values of the digital drive signals D1 to D4 based on the measurement result.

  The measurement by the voltage measuring unit 30 is performed at the time of adjustment when manufacturing the drive circuit, for example, and the measurement result is stored in a storage device such as a memory included in the MCU 21 or temporarily when the drive voltage value is changed. This can be done when the drive voltage is set to 0V.

  The drive circuit according to the present invention is not limited to the above-described embodiment, and various other modifications are possible. For example, the above-described embodiments and modifications may be combined with each other according to the necessary purpose and effect. For example, a plurality of voltage measuring units may be connected to the plurality of electrostatic actuators of the second modified example, respectively.

  Moreover, although the circuit which drives a MEMS mirror provided with two rotation axes was illustrated in the said embodiment, the number of the rotation axes of a MEMS mirror may be one or more various numbers. Alternatively, the present invention can also be applied to a MEMS mirror that is not provided with a rotating shaft and is driven by one electrostatic actuator.

  DESCRIPTION OF SYMBOLS 1A, 1B, 1C ... Drive circuit, 5 ... Reference potential line, 10 ... MEMS mirror, 10a-10d ... Input terminal, 10e ... Common terminal, 11 ... Mirror surface, 12a ... 1st rotation axis, 12b ... 2nd time Moving shaft, 13... First rotating portion, 13a, 13b... Shaft portion, 14... Second rotating portion, 14a, 14b .. Shaft portion, 15-18 .. Electrostatic actuator, 15a, 15b, 16a, 16b, 17a , 17b, 18a, 18b ... comb-like electrodes, 19 ... frame, 20 ... drive voltage generator, 22a-22d ... D / A converter, 25a-25d ... amplifier circuit, 26a-26d ... filter circuit, 27a-27d ... Current limiting resistor, 29, 29a to 29d ... Voltage generating circuit, 30 ... Voltage measuring unit, 31 ... Wiring, D1-D4 ... Digital drive signal, V1-V4 ... Voltage signal, VC, VC1-VC4 ... Constant voltage, VD1 ~ V 4 ... the driving voltage.

Claims (4)

A circuit for driving a MEMS mirror including an electrostatic actuator for tilting a mirror surface,
A drive voltage generator for applying a positive drive voltage for driving the electrostatic actuator to one electrode of the electrostatic actuator;
A voltage generating circuit for applying a positive constant voltage larger than the offset included in the drive voltage to the other electrode of the electrostatic actuator;
A MEMS mirror driving circuit comprising:   The MEMS mirror driving circuit according to claim 1, wherein the positive constant voltage of the voltage generating circuit is variable. A voltage measuring unit for measuring a voltage of the other electrode or a potential difference between the one electrode and the other electrode;
The MEMS mirror drive circuit according to claim 1, wherein the drive voltage generation unit corrects the magnitude of the drive voltage based on a measurement result of the voltage measurement unit. A circuit for driving a MEMS mirror comprising a plurality of electrostatic actuators for tilting the mirror surface,
A drive voltage generator for applying a plurality of positive drive voltages for driving the plurality of electrostatic actuators to one electrode of the plurality of electrostatic actuators, respectively;
A plurality of voltage generation circuits for individually applying a positive constant voltage larger than the offset included in the corresponding driving voltage to the other electrode of the plurality of electrostatic actuators;
A MEMS mirror driving circuit comprising:

Images