WO2020194691A1 - Optical scanning device and method of controlling same - Google Patents

Optical scanning device and method of controlling same Download PDF

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Publication number
WO2020194691A1
WO2020194691A1 PCT/JP2019/013724 JP2019013724W WO2020194691A1 WO 2020194691 A1 WO2020194691 A1 WO 2020194691A1 JP 2019013724 W JP2019013724 W JP 2019013724W WO 2020194691 A1 WO2020194691 A1 WO 2020194691A1
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Prior art keywords
mirror
scanning mirror
signal
scanning
optical scanning
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PCT/JP2019/013724
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French (fr)
Japanese (ja)
Inventor
恭彦 伊藤
善明 平田
伸顕 紺野
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三菱電機株式会社
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Priority to PCT/JP2019/013724 priority Critical patent/WO2020194691A1/en
Publication of WO2020194691A1 publication Critical patent/WO2020194691A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
    • G02B26/10—Scanning systems

Definitions

  • the present invention relates to an optical scanning device and a control method thereof.
  • an optical scanning device that enables scanning of a light beam by changing the posture of the mirror to change the reflection direction of the light beam incident on the mirror.
  • an optical scanning device when the scanning direction of an optical beam is periodically changed in a saw-wave shape by driving an actuator that changes the posture of a mirror with a saw-wave periodic signal, the high-frequency component contained in the saw-wave periodic signal is generated.
  • the resonance characteristics of the mirror When amplified by the resonance characteristics of the mirror, ringing in the orientation of the mirror and the scanning direction of the light beam may occur.
  • Japanese Patent Application Laid-Open No. 2013-205818 discloses an optical deflector capable of suppressing the occurrence of ringing as described above.
  • This optical deflector is equipped with a circuit that detects the mechanical resonance frequency from the posture of the mirror when the posture of the mirror is changed by the piezoelectric actuator, and the resonance frequency and its harmonic component are removed by a notch filter. By driving the piezoelectric actuator with a periodic signal, the occurrence of ringing is suppressed.
  • Patent Document 1 it is necessary to provide a notch filter having steep characteristics in order to remove harmonic components for suppressing the occurrence of ringing.
  • the size of the control circuit for adjusting the characteristics of the notch filter becomes large.
  • the present disclosure has been made to solve the above-mentioned problems, and an object of the present disclosure is to provide an optical scanning device capable of suppressing the occurrence of ringing without using a notch filter.
  • the optical scanning device is configured to reflect a light source, a first scanning mirror including a reflecting portion configured to reflect the light emitted from the light source, and light reflected by the first scanning mirror.
  • a control device configured to control the light emission direction by controlling the posture of the reflecting portion of the first scanning mirror and the posture of the reflecting portion of the second scanning mirror, and the second scanning mirror including the reflecting portion.
  • the control device generates a first signal that changes periodically at the fundamental frequency, generates a second signal by adding frequency components selected from the harmonics of the fundamental frequency, and generates a second signal from the first signal to the second signal. Is subtracted to generate a difference signal.
  • the first scanning mirror is driven by the first signal.
  • the second scanning mirror is driven by the difference signal.
  • an optical scanning device capable of suppressing the occurrence of ringing without using a notch filter.
  • FIG. 2 is a sectional view taken along line III-III of the first mirror.
  • the figure which shows the waveform of a triangular wave The figure which shows the waveform (sine wave) of the 1st order harmonic component.
  • a block diagram showing the function of the control device A flowchart showing an outline of the processing executed by the control device.
  • FIG. 16 is a cross-sectional view taken along the line XVII-XVII of the second mirror.
  • FIG. 5 is a diagram schematically showing a configuration of an optical scanning device (No. 5).
  • FIG. 1 is a diagram schematically showing a configuration of an optical scanning device 1 according to the present embodiment.
  • the optical scanning device 1 includes a light source unit (hereinafter, also simply referred to as “light source”) 101, a first scanning mirror (hereinafter, also simply referred to as “first mirror”) 102, and a second scanning mirror (hereinafter, simply referred to as “first mirror”). It is provided with 103 (also referred to as "two mirrors”) and a control device 104.
  • the light source 101 emits a laser beam in the form of a beam.
  • the light source 101 includes an LD (Laser Diode) element and a collimating lens.
  • the collimating lens converts the light generated by the LD element into a parallel luminous flux.
  • Each of the first mirror 102 and the second mirror 103 is a MEMS (Micro Electro Mechanical Systems) type mirror, that is, a piezoelectric drive type mirror to which the MEMS device technology is applied.
  • the first mirror 102 has a reference plane P1 arranged on the traveling path of the light beam emitted from the light source 101.
  • the second mirror 103 has a reference plane P2 arranged on the traveling path of the light beam emitted from the light source 101 and reflected by the first mirror 102.
  • the reference surface P1 of the first mirror 102 and the reference surface P2 of the second mirror 103 face each other and are arranged in parallel.
  • the extending direction of the reference planes P1 and P2 is the "X direction”
  • the direction perpendicular to the reference planes P1 and P2 is the "Z direction”
  • the directions perpendicular to the X direction and the Z direction are defined. Also referred to as "Y direction”.
  • the first mirror 102 includes a reflecting unit 111 configured to reflect the light emitted from the light source 101.
  • the second mirror 103 includes a reflecting unit 161 configured to reflect the light reflected by the reflecting unit 111 of the first mirror 102.
  • the control device 104 is configured to generate a signal for controlling the posture of the reflection unit 111 of the first mirror 102 and the posture of the reflection unit 161 of the second mirror 103.
  • the first mirror 102 has a rotation axis Y1 extending in the Y direction, and the reflecting portion 111 is configured to be rotatable around the rotation axis Y1.
  • the second mirror 103 has a rotation axis Y2 extending in the same Y direction as the rotation axis Y1, and the reflecting portion 161 is configured to be rotatable around the rotation axis Y2. That is, the rotation axis Y1 of the first mirror 102 and the rotation axis Y2 of the first mirror 102 are arranged in parallel with each other.
  • the first mirror 102 and the second mirror 103 can rotate around the rotation axes Y1 and Y2, respectively, and are configured to change their postures according to the drive signal from the control device 104.
  • the light beam emitted from the light source 101 is reflected by the reflecting portion 111 of the first mirror 102, then further reflected by the reflecting portion 161 of the second mirror 103, and is emitted to the outside of the light scanning device 1.
  • the emission direction of the light beam from the optical scanning device 1 can be changed.
  • the clockwise direction in FIG. 1 is set as the positive direction, and the counterclockwise direction in FIG. It will be described as a negative direction.
  • FIG. 2 is a top view (viewed from the Z direction) of the first mirror 102.
  • FIG. 3 is a sectional view taken along line III-III of FIG. 2 of the first mirror 102.
  • the first mirror 102 includes a reflective portion 111, a fixed portion 112, beams 113 and 114, insulating films 121 and 131, electrodes 122 and 132, and a piezoelectric film (piezoelectric material) such as lead zirconate titanate (PZT). ) 123, 133 and electrodes 124, 134.
  • piezoelectric film piezoelectric material
  • PZT lead zirconate titanate
  • a reflective film 115 such as Au (gold) that reflects a light beam is formed on the surface of the reflective portion 111.
  • One end of each of the beams 113 and 114 is connected to the reflective portion 111, and the other end is connected to the fixed portion 112.
  • the reflective portion 111 is supported by the fixed portions 112 by the beams 113 and 114.
  • the insulating film 121, the electrode 122, the piezoelectric film 123, and the electrode 124 are formed on the beam 113 in this order.
  • the insulating film 131, the electrode 132, the piezoelectric film 133, and the electrode 134 are formed on the beam 114 in this order.
  • the electrodes 122, 124, 132, and 134 are electrically insulated from each other. Each electrode is configured to be electrically connectable to the power supply or the electrode of the control device 104 via wiring (not shown).
  • connection portion between the beam 113 and the reflecting portion 111 can be displaced in the Z direction. Further, the connection portion between the beam 114 and the reflecting portion 111 can be displaced in the Z direction by expanding and contracting the piezoelectric film 133 by applying a voltage to the electrodes 132 and 134 to deform the beam 114. As a result, the reflecting portion 111 can be rotationally displaced around the rotation axis Y1.
  • the structure of the first mirror 102 can be manufactured by applying, for example, a so-called MEMS device technique in which processes such as film formation, patterning, and etching are repeated on a silicon substrate.
  • An SOI (Silicon On Insulator) substrate 140 is used for manufacturing the first mirror 102.
  • the SOI substrate 140 has an insulating silicon oxide film 142, a conductive single crystal silicon layer 143 arranged on the front surface side of the silicon oxide film 142, and a non-silicon oxide film 142 arranged on the back surface side of the silicon oxide film 142. Includes a conductive single crystal silicon layer 141.
  • the structure of the first mirror 102 is such that the insulating film 121 is formed, the metal material Pt (platinum) is formed, the piezoelectric material (PZT) is formed, and the metal material Au (gold) is formed on the SOI substrate 140. It is manufactured by performing patterning, patterning of a piezoelectric material (PZT), patterning of a metal material Pt (platinum), etching of single crystal silicon layers 141 and 143 on the front and back surfaces, and etching of a silicon oxide film 142.
  • the operation of the first mirror 102 will be described below.
  • a voltage is applied between the electrodes 122 and 124, an electric field in the film thickness direction is applied to the piezoelectric film 123, and the piezoelectric film 123 extends in the in-plane direction (expansion of the piezoelectric film 123) according to the direction of the electric field. It expands and contracts in the current direction).
  • the piezoelectric film 123 is deformed so as to warp the beam 113. For example, when the downward electric field shown in FIG.
  • the piezoelectric film 123 is deformed so as to extend in the in-plane direction, and the beam 113 warps in an upwardly convex shape.
  • the piezoelectric film 123 is deformed so as to contract in the in-plane direction, and the beam 113 warps in a downwardly convex shape.
  • the direction of warpage of the beam 113 can be changed by changing the sign of the voltage applied to the piezoelectric film 123. Further, the curvature of the warp of the beam 113 can be changed by changing the magnitude of the voltage applied to the piezoelectric film 123. That is, it is possible to control the deformation of the beam 113 by the positive / negative and magnitude of the voltage applied to the piezoelectric film 123.
  • the deformation of the beam 114 can be controlled by applying a voltage between the electrodes 132 and 134.
  • the reflecting portion 111 of the first mirror 102 can be rotationally displaced around the rotation axis Y1 by deforming the beams 113 and 114 that support the reflecting portion 111 on the fixed portion 112.
  • the mechanical resonance frequency for the rotation of the reflecting portion 111 of the first mirror 102 around the rotation axis Y1 is referred to as “Fy1”.
  • the emission direction of the light beam reflected by the reflecting portion 111 of the first mirror 102 can be changed in the XX plane.
  • the reflecting portion 111 of the first mirror 102 rotates around the rotation axis Y1 and periodically repeats a fixed posture. As a result, the light beam reflected by the reflecting portion 111 of the first mirror 102 can be periodically scanned in a fixed direction.
  • FIG. 4 is a diagram schematically showing the relationship between the inclination angle of the first mirror 102 and the traveling direction of the light beam.
  • the inclination angle of the first mirror 102 is an inclination angle of the reflection surface (surface) of the reflection portion 111 with respect to the reference surface P1 of the first mirror 102.
  • theta 1 which positive value theta 1/2 with respect to the reference plane P1 of the reflecting surface of the reflecting portion 111 is inclined in only the forward direction (clockwise), i.e.
  • the first mirror 102 When the tilt angle of is ⁇ 1/2 , the normal of the reflecting surface of the reflecting portion 111 is tilted in the positive direction by ⁇ 1/2 , so that the traveling direction of the light beam is the reference direction (the first mirror 102 is tilted). It is tilted in the positive direction by ⁇ 1 with respect to the traveling direction of the previous light beam).
  • FIG. 5 is a diagram showing an example of the correspondence between the drive voltage of the first mirror 102 and the inclination angle of the first mirror 102.
  • the inclination angle of the first mirror 102 is shown in FIG. It can be uniquely associated with each other as in 5.
  • FIG. 6 is a diagram schematically showing the frequency response characteristics and resonance frequency of a general structure.
  • the structure resonates, and even if vibration of the same magnitude is input, vibration of a frequency other than the resonance frequency is input.
  • a resonance phenomenon occurs in which the displacement of the structure is larger than that in the case of the above.
  • the resonance frequency of the structure is generally designed to be sufficiently higher than the frequency of the drive signal of the actuator in order to suppress the influence of resonance.
  • the resonance frequency of the structure and the degree of displacement depend on the temperature and pressure around the structure. That is, the frequency response characteristics of the structure change depending on the temperature environment and pressure environment.
  • the second mirror 103 will be described below.
  • the second mirror 103 has the same configuration and the same size as the first mirror 102. Further, the second mirror 103 is manufactured by the same manufacturing method as the first mirror 102. Further, the second mirror 103 can operate in the same manner as the first mirror 102.
  • the mechanical resonance frequency for the rotation of the second mirror 103 around the rotation axis Y2 is referred to as "Fy2". Since the first mirror 102 and the second mirror 103 are manufactured by the same configuration, the same size, and the same manufacturing method, the resonance frequency Fy2 of the second mirror 103 is the same value as the resonance frequency Fy1 of the first mirror 102. ..
  • FIG. 7 is a diagram schematically showing the relationship between the inclination angle of the second mirror 103 and the traveling direction of the light beam.
  • the inclination angle of the second mirror 103 is the inclination angle of the reflection surface (surface) of the reflection portion 161 with respect to the reference surface P2 of the second mirror 103.
  • the first mirror 102 and the second mirror 103 can operate independently of each other.
  • a positive drive voltage is applied to the first mirror 102 and the second mirror 103
  • the reflective surface of the first mirror 102 rotates in the positive direction
  • the reflective surface of the second mirror 103 rotates in the negative direction. It shall be.
  • FIG. 8 is a diagram schematically showing a traveling direction ⁇ (hereinafter, also simply referred to as “light beam emitting direction”) ⁇ of a light beam emitted from the optical scanning device 1 to the outside.
  • the emission direction ⁇ of the light beam is represented with reference to the traveling direction of the light beam before tilting the first mirror 102 and the second mirror 103.
  • ⁇ (t) ⁇ 1 (t) + ⁇ 2 (t)... (1)
  • the relationship between the periodic drive signal applied to the first mirror 102 and the second mirror 103 and the posture change of the first mirror 102 and the second mirror 103 will be described.
  • the emission direction ⁇ of the light beam is periodically and repeatedly changed at the fundamental frequency Fd with respect to the time t.
  • the periodic signal is generally represented by the sum of the component of the fundamental frequency Fd and its harmonic component.
  • FIG. 9 is a diagram showing an example of the waveform of the triangular wave T (t).
  • the Fourier transform of the triangular wave T (t) as shown in FIG. 9 can be described by the following equation (2).
  • N is a natural number
  • the resonance characteristic of the structure amplifies the displacement of the structure and superimposes it on the desired displacement, that is, so-called ringing occurs. ..
  • the sum of the components of an arbitrary frequency selected from the frequency components smaller than the resonance frequency of the structure is referred to as the "low frequency component”. Is defined.
  • FIG. 10A to 10F are diagrams showing a waveform obtained by adding low frequency components of a triangular wave and harmonics of the first to fifth harmonics of the triangular wave.
  • FIG. 10A shows a triangular wave waveform
  • FIG. 10B shows a waveform of a first-order harmonic component (sine wave)
  • FIG. 10C shows a waveform obtained by adding low-frequency components from the first-order to the second-order.
  • FIG. 10D Shows a waveform obtained by adding low frequency components from 1st to 3rd order
  • FIG. 10E shows a waveform obtained by adding low frequency components from 1st to 4th order
  • FIG. 10F shows a waveform obtained by adding low frequency components from 1st to 5th order. The waveform obtained by adding the low frequency components is shown.
  • T 1 (t) the first term on the right side of the equation (3)
  • T 2 (t) the second term
  • the first term T 1 (t) is a substantially triangular wave, which is a low frequency component lower than the resonance frequency of the structure.
  • the second term T 2 (t) includes a band of the resonance frequency of the structure with other harmonic components.
  • the control device 104 generates a drive signal to the first mirror 102 and the second mirror 103 in order to incline the emission direction ⁇ of the light beam in a desired direction.
  • FIG. 11 is a block diagram showing the functions of the control device 104.
  • the control device 104 includes a periodic signal generation unit 104a, a low frequency component generation unit 104b, and a calculation unit 104c.
  • the fundamental frequency Fd of the periodic signal and its waveform are input to the periodic signal generation unit 104a and the low frequency component generation unit 104b from the outside, respectively.
  • the case where the waveform of the periodic signal is a triangular wave will be described below.
  • the periodic signal generation unit 104a generates a triangular wave signal V 1 (t) that changes at the fundamental frequency Fd.
  • the periodic signal generation unit 104a outputs the generated triangular wave signal V 1 (t) to the calculation unit 104c and the first mirror 102. As a result, the first mirror 102 is driven by the triangular wave signal V 1 (t).
  • the low frequency component generation unit 104b generates a signal V b (t) obtained by adding low frequency components from the first harmonic to the Nth (for example, fifth) harmonic to the fundamental frequency Fd.
  • the low frequency component generation unit 104b outputs the generated signal V b (t) to the calculation unit 104c.
  • the calculation unit 104c obtains a difference signal V 2 (t) obtained by subtracting the signal V b (t) generated by the low frequency component generation unit 104b from the triangular wave signal V 1 (t) generated by the periodic signal generation unit 104a. Generate.
  • the calculation unit 104c outputs the generated difference signal V 2 (t) to the second mirror 103. As a result, the second mirror 103 is driven by the difference signal V 2 (t).
  • the first mirror 102 is driven by the triangular wave signal V 1 (t) generated by the control device 104. That is, the first mirror 102 is a signal including a substantially triangular wave signal T 1 (t) obtained by adding low frequency components lower than the resonance frequency of the first mirror 102 and a frequency component near the resonance frequency of the first mirror 102. The attitude is changed according to the frequency response characteristic of the first mirror 102 by the signal V 1 (t) which is the sum of T 2 (t).
  • attitude change of the signal T 2 (t) including the frequency component near the resonance frequency of the first mirror 102 amplified by the frequency response characteristic of the first mirror 102 is defined as “R 1 (t)”
  • the first mirror The amount of change in attitude ⁇ 1 (t) of 102 can be described as the following equation (7) by normalizing with amplitude and paying attention only to the waveform.
  • ⁇ 1 (t) AT 1 (t) + R 1 (t)... (7)
  • the second mirror 103 is driven by the difference signal V 2 (t) generated by the control device 104. That is, the second mirror 103 changes its posture according to the frequency response characteristic of the second mirror 103 by the difference signal V 2 (t).
  • the difference signal V 2 (t) is the signal T 2 (t) as shown in the above equation (6). If the signal T 2 (t) amplified by the frequency response characteristic of the second mirror 103 is defined as “R 2 (t)”, the attitude change amount ⁇ 2 (t) of the second mirror 103 is normal in amplitude. If we pay attention to the waveform, we can describe it as the following equation (8).
  • ⁇ 2 (t) ⁇ R 2 (t)... (8)
  • the sign on the right side of the above equation (8) is "-" (minus) because the reflective surface of the second mirror 103 is changed when a positive drive voltage is applied to the second mirror 103 as described above. By rotating in the negative direction.
  • the emission direction ⁇ (t) of the light beam can be described by the following equation (9).
  • the relational expression of the following equation (10) is established. To establish.
  • ⁇ (t) AT 1 (t)... (11)
  • the light beam emission direction ⁇ (t) is amplified by the attitude change R 1 (t) amplified by the frequency response characteristic of the first mirror 102 and the frequency response characteristic of the second mirror 103. It can be understood that the influence of the attitude change R 2 (t) is eliminated. As a result, ringing of the light beam can be suppressed.
  • the optical scanning device 1 is placed in a temperature environment and a pressure environment. Since the resonance frequency and frequency response characteristics of the first mirror 102 and the second mirror 103 change depending on the environment, the attitude change R 1 (t) amplified by the frequency response characteristics of the first mirror 102 and the second mirror 103 The attitude change R 2 (t) amplified by the frequency response characteristic of is also changed.
  • the first mirror 102 and the second mirror 103 have the same structure and size and are manufactured by the same manufacturing method, R 1 (t) and R 2 (t) in a temperature environment and a pressure environment The change has the same characteristics. Therefore,
  • the optical scanning apparatus 1 in the optical scanning apparatus 1 according to the present embodiment, ringing can be suppressed without using a notch filter as used in the prior art. Further, a control circuit for adjusting the characteristics of the notch filter according to individual differences in the characteristics of individual mirrors due to changes in the mechanical resonance frequency of the mirrors, manufacturing variations, and the like becomes unnecessary. Therefore, the size of the optical scanning device 1 can be reduced. Further, since the notch filter generally changes its phase significantly in the vicinity of its cutoff frequency, the degree of freedom in design regarding control can be increased by not using the notch filter.
  • FIG. 12 is a flowchart showing an outline of the processing executed when the control device 104 of the optical scanning device 1 controls the first mirror 102 and the second mirror 103.
  • the control device 104 acquires the fundamental frequency Fd and the waveform of the periodic signal from the outside (step S10).
  • the waveform of the periodic signal is, for example, a triangular wave.
  • control device 104 generates a drive signal V 1 (t) that changes with the fundamental frequency Fd and the periodic signal waveform acquired in step S10 (step S11).
  • control device 104 generates a signal V b (t) obtained by adding low frequency components from the first order to the Nth order (for example, the fifth order) with respect to the fundamental frequency Fd (step S12).
  • control device 104 generates a difference signal V 2 (t) obtained by subtracting the signal V b (t) generated in step S12 from the drive signal V 1 (t) generated in step S11 (step S13). ).
  • control device 104 outputs the drive signal V 1 (t) generated in step S11 to the first mirror 102, and drives the first mirror 102 by the drive signal V 1 (t) (step S14).
  • control device 104 outputs the difference signal V 2 (t) generated in step S13 to the second mirror 103, and drives the second mirror 103 by the difference signal V 2 (t) (step S15).
  • the optical scanning apparatus 1 includes a light source 101, a first mirror 102 including a reflecting unit 111 configured to reflect the light emitted from the light source 101, and a first mirror 102.
  • a first mirror 102 including a reflecting unit 111 configured to reflect the light emitted from the light source 101
  • a first mirror 102 By controlling the posture of the second mirror 103 including the reflecting portion 161 configured to reflect the light reflected by the first mirror 102, the posture of the reflecting portion 111 of the first mirror 102, and the posture of the reflecting portion 161 of the second mirror 103.
  • a control device 104 configured to control the emission direction ⁇ of the light beam is provided.
  • the control device 104 generates a triangular wave signal that changes at the fundamental frequency Fd as a drive signal V 1 (t), and adds low frequency components of harmonics from the first to the fifth order of the fundamental frequency Fd to signal V b ( t) is generated, and the difference signal V 2 (t) obtained by subtracting the signal V b (t) from the drive signal V 1 (t) is generated. Then, the control device 104 drives the first mirror 102 by the drive signal V 1 (t), and drives the second mirror 103 by the difference signal V 2 (t). As a result, the occurrence of ringing can be suppressed without using a notch filter. Further, since the notch filter is not used, the size of the optical scanning device 1 can be reduced. Further, since the notch filter generally changes its phase significantly in the vicinity of its cutoff frequency, the degree of freedom in design regarding control can be increased by not using the notch filter.
  • the signal used for scanning may be a periodic signal, and for example, a sawtooth signal may be adopted.
  • the periodic signal When the drive target is driven by a periodic signal having a period of 1 / Fd, the periodic signal generally contains a harmonic component N times the fundamental frequency Fd (N is a natural number), and the harmonic component is driven. If it is in the vicinity of the resonance frequency of the target, there is a concern that the displacement will be amplified due to the frequency response characteristic of the drive target, and so-called ringing will occur. However, by applying the control according to the present disclosure, ringing can be suppressed as in the case of using a triangular wave signal, so that scanning with reduced distortion can be realized.
  • scanning can be performed at a constant speed, and the spatial resolution of the scanning point can be kept constant.
  • an optical component such as a beam splitter may be arranged in at least one of the optical path between the light source 101 and the first mirror 102 and the optical path between the first mirror 102 and the second mirror 103.
  • FIG. 13 is a diagram schematically showing the configuration of the optical scanning device 1A according to the modified example.
  • the optical scanning device 1A further includes beam splitters 105 and 106 in addition to the light source 101, the first mirror 102, the second mirror 103, and the control device 104.
  • the beam splitter 105 is arranged in the optical path between the light source 101 and the first mirror 102, and guides the light beam emitted from the light source 101 to the first mirror 102. Further, the beam splitters 105 and 106 are arranged in the optical path between the first mirror 102 and the second mirror 103, and guide the light beam reflected by the first mirror 102 to the second mirror 103.
  • the control according to the present disclosure can be applied to such an optical scanning device 1A.
  • the light beam reflected by the second mirror 103 is directly emitted to the outside of the optical scanning device 1, but may be emitted to the outside through an optical component such as a mirror.
  • an optical component such as a mirror
  • the first mirror 102 and the second mirror 103 are arranged so that the reference surface P1 of the first mirror 102 and the reference surface P2 of the second mirror 103 are parallel to each other.
  • the arrangement of the first mirror 102 and the second mirror 103 may be any arrangement as long as the light beam reflected by the first mirror 102 can be reflected by the second mirror 103, and the reference planes P1 and P2 are necessarily arranged in parallel with each other. Not limited to being done.
  • each of the first mirror 102 and the second mirror 103 supports the reflecting portion by two beams on the fixed portion, and reflects by utilizing the deformation of the piezoelectric film provided on the beams. Tilt the part.
  • the number, arrangement, shape, type, arrangement, and shape of the piezoelectric film can be determined in the above-described first embodiment. Not limited to what has been described.
  • first mirror 102 and the second mirror 103 may be mirrors that can be rotationally displaced and have the same mechanical frequency response characteristics around the axis, and may not be MEMS type mirrors.
  • the manufacturing method is not limited.
  • each of the first mirror 102 and the second mirror 103 changes the posture of the reflecting surface by utilizing the deformation of the piezoelectric film due to the application of an electric field to the piezoelectric film provided on the beam.
  • the method of changing the posture of the reflective surface may be one that utilizes the electrostatic attraction generated by applying a voltage to the electrodes, or by applying a magnetic field and passing a current through the wiring arranged on the element. It may utilize the generated electromagnetic force.
  • the electrostatic attraction it is not necessary to form a piezoelectric film, an insulating film, or the like on the beam, so that it is possible to reduce the generation of stress generated in the manufacturing process between the piezoelectric film and the insulating film and the silicon substrate.
  • electromagnetic force there is an advantage that the electromagnetic force can generally generate a force larger than the electrostatic attraction force and the force due to the deformation of the piezoelectric material.
  • the rotation axis of the mirror in FIG. 2 is in the X-axis direction in FIG. 2, unlike the case where the piezoelectric film is used, but when applied to the optical scanning device 1 shown in FIG. 1, the rotation axis is in the Y-axis direction. It may be arranged so as to be.
  • a square metal film is used as the reflective film of the first mirror 102 and the second mirror 103.
  • the reflective film may be any one that reflects a light beam, and its shape and material are not limited to those described above.
  • an LD element is used as a light source of the optical scanning device 1
  • the type of the light source is not particularly limited.
  • a light emitting diode element (LED) element is used instead of the LD element. May be used.
  • FIG. 14 is a diagram schematically showing the configuration of the optical scanning device 2 according to the second embodiment.
  • the optical scanning apparatus 2 according to the second embodiment is different from the optical scanning apparatus 1 according to the first embodiment in that the first mirror 102 and the second mirror 103 are arranged on the same substrate 201.
  • FIG. 15 is a top view (viewed from the Z direction) of the first mirror 102 and the second mirror 103 in the optical scanning device 2 according to the second embodiment. As shown in FIG. 15, in the optical scanning apparatus 2, the first mirror 102 and the second mirror 103 are manufactured on the same substrate 201.
  • the optical scanning apparatus 2 in order to guide the light beam reflected by the first mirror 102 to the second mirror 103, the light beam is reflected by the first mirror 102 at a position facing the substrate 201.
  • the fixed mirror 207 is arranged at a position where the light beam is incident on the second mirror 103.
  • the light reflected by the first mirror 102 is reflected by the fixed mirror 207 and guided to the second mirror 103.
  • the light reflected by the first mirror 102 is reflected by the fixed mirror 207 and guided to the second mirror 103. Therefore, the change in the optical axis of the light beam reaching the second mirror 103 with respect to the reference direction is twice as large as that in the optical scanning device 1, and the direction of change is reversed. Therefore, in the optical scanning device 2, if the second mirror 103 is driven by a signal whose magnitude is doubled and the code is inverted with respect to the difference signal V 2 (t) used in the optical scanning device 1. Good. By doing so, the attitude change amount amplified by the frequency response characteristic of the first mirror 102 and the attitude change amount amplified by the frequency response characteristic of the second mirror 103 cancel each other out. Ringing of the light emitted from the optical scanning device 2 can be suppressed.
  • the first mirror 102 and the second mirror 103 are manufactured on the same substrate 201, the deviation of the resonance frequency and the frequency response characteristic from the design values due to the manufacturing variation is the first mirror. The same occurs in both 102 and the second mirror 103. Therefore, as compared with the case where the first mirror 102 and the second mirror 103 are manufactured on different substrates, the attitude change amount amplified by the frequency response characteristic of the first mirror 102 and the frequency response characteristic of the second mirror 103 It is possible to more appropriately cancel each other's posture changes amplified by.
  • the optical scanning device 2 since the first mirror 102 and the second mirror 103 are arranged on the same substrate 201, the relative positional relationship between the first mirror 102 and the second mirror 103 is fixed. Therefore, the optical scanning device 2 can be easily assembled and aligned with other members.
  • the reference surface of the substrate 201 and the reflecting surface of the fixed mirror 207 are arranged so as to be parallel to each other. However, if the light beam reflected by the first mirror 102 is reflected by the fixed mirror and guided to the second mirror 103, the reference surface of the substrate 201 may be arranged at an angle with respect to the reflecting surface of the fixed mirror 207. ..
  • FIG. 16 is a top view (viewed from the Z direction) of the first mirror 102 and the second mirror 103 of the optical scanning apparatus 3 according to the third embodiment.
  • FIG. 17 is a cross-sectional view taken along the line XVII-XVII of FIG. 16 of the second mirror 303.
  • the optical scanning device 3 according to the third embodiment has a second mirror 303 instead of the second mirror 103 of the optical scanning device 2 according to the second embodiment described above.
  • the second mirror 303 is manufactured so as to be rotatable not only around the Y axis but also around the X axis.
  • the second mirror 303 includes a reflecting portion 161, beams 163 and 164, an intermediate fixing portion 312, and beams 173 and 174.
  • the reflecting portion 161 is supported by the intermediate fixing portion 312 by beams 163 and 164 extending in the X-axis direction.
  • the configurations of the reflecting portions 161 and the beams 163 and 164 are the same as those of the second mirror 103 according to the second embodiment described above. Therefore, the control device 104 expands and contracts the piezoelectric film on the surface of the beams 163 and 164, so that the reflecting portion 161 rotates around the Y axis.
  • the mechanical frequency response characteristic of the second mirror 303 around the Y axis is the same as the mechanical frequency response characteristic of the first mirror 102 around the Y axis.
  • the intermediate fixing portion 312 is arranged on the outer periphery of the reflecting portion 161 and the beams 163 and 164, and is supported by the fixing portion 112 by the beams 173 and 174 extending in the Y-axis direction.
  • an insulating film 321 and an electrode 322, a piezoelectric film 323, and an electrode 324 are formed on the beam 173 in this order.
  • An insulating film 331, an electrode 332, a piezoelectric film 333, and an electrode 334 are formed on the beam 174 in this order.
  • the electrodes 322, 324, 332, and 334 are electrically insulated from each other, and are configured to be electrically connectable to the electrodes of the power supply or the control device 104 via wiring (not shown).
  • the connecting portion between the beam 173 and the intermediate fixing portion 312 can be displaced in the Z direction.
  • the connection portion between the beam 174 and the intermediate fixing portion 312 can be displaced in the Z direction by expanding and contracting the piezoelectric film 333 by applying a voltage between the electrodes 332 and 334 to deform the beam 174. Therefore, the control device 104 applies a driving voltage between the electrodes 322 and 324 and between the electrodes 332 and 334 on the surface of the beams 173 and 174 to expand and contract the piezoelectric films 323 and 333 so that the reflecting portion 161 is around the Y axis.
  • the reflection portion 161 supported by the beams 163 and 164 on the intermediate fixing portion 312 and the intermediate fixing portion 312 can be rotated around the X axis.
  • the mechanical resonance frequency for the rotation of the second mirror 303 around the X axis is defined as "Fx2".
  • FIG. 18 is a diagram schematically showing biaxial scanning of the light beam by the optical scanning device 3.
  • a sine wave having a frequency of Fdx is applied between the electrodes 322 and 324 as a drive signal
  • the second mirror 303 rotates about the X axis. Since the rotation of the second mirror 103 around the X axis is independent of the rotation around the Y axis, the optical scanning device 3 can scan the light beam in the biaxial direction as shown in FIG.
  • the frequency Fdx of the drive signal around the X axis of the second mirror 303 is set to be an integral multiple of the fundamental frequency Fd, 1 / Fd can be set as one cycle and the same direction can be scanned periodically. it can.
  • Fdx Fx2
  • the drive frequency around the X axis of the second mirror 103 is set as the resonance frequency
  • the applied energy can be efficiently converted into vibration, and a large amplitude can be obtained with a small applied voltage. it can.
  • the ringing of the light emitted from the optical scanning device 3 can be suppressed, so that scanning with reduced distortion can be realized.
  • the second mirror 303 is rotatable around two axes to be a mirror capable of two-axis scanning.
  • the first mirror 102 may be a mirror capable of biaxial scanning.
  • the second mirror 303 receives the light reflected by the first mirror 102, so that it is relative to the case where the second mirror 303 is biaxially scannable. It is necessary to increase the size of the mirror. Therefore, the optical scanning device can be downsized when the second mirror 303 is capable of biaxial scanning.
  • the second mirror 303 is a beam extending in the Y-axis direction in which a piezoelectric film is formed on the outer periphery of the structure having the same mechanical frequency response characteristic as that of the first mirror 102 around the Y-axis.
  • the structure is such that 173 and 174 are provided.
  • the structure of the second mirror 303 only needs to be able to give a rotational displacement around the X-axis independently of the Y-axis, and the number, arrangement, shape of beams, and the type, arrangement, and shape of the piezoelectric film are particularly limited. Not done.
  • the drive method for giving rotational displacement around the X-axis and the drive method for giving rotational displacement around the Y-axis are the same. However, it suffices if a rotational displacement can be applied around the X-axis independently of the Y-axis, and a structure and a drive method for imparting a rotational displacement around the X-axis, a structure for imparting a rotational displacement around the Y-axis, and The drive system may be different.
  • FIG. 19 is a diagram schematically showing the configuration of the optical scanning device 4 according to the fourth embodiment.
  • the optical scanning device 4 differs from the optical scanning device 3 according to the third embodiment in the following points.
  • the optical scanning device 4 includes an optical detector 481, a calculation unit 482, and a beam splitter 483, in addition to the configuration of the optical scanning device 3.
  • the beam splitter 483 is arranged in the optical path between the light source 101 and the first mirror 102.
  • the light detector 481 is a position where the light incident on the light scanning device 3 from the emission direction of the light scanning device 3 can be detected by the light reflected by the reflecting surface of the beam splitter 483 through the second mirror 303 and the first mirror 102. It is placed in.
  • the calculation unit 482 performs a calculation for measuring the distance to the object by comparing the light emitted from the light source 101 with the light detected by the photodetector 481. That is, the calculation unit 482 detects the light reflected by the object by the light beam emitted from the optical scanning device 4, and measures the distance to the object by comparing the detected reflected light with the emitted light. .. For example, when a light beam is emitted in a pulse shape, a pulse-shaped reflected light is also obtained from the object, so that the distance to the object can be calculated from the time difference between the emitted light and the pulse of the reflected light.
  • the optical scanning device 4 can scan the light beam in two dimensions, the distance around the optical scanning device 4 can be obtained by combining the information on the distance to the object and the information on the scanning direction of the light beam. Images can be acquired.
  • the optical scanning device 4 can also suppress the ringing of the light emitted from the optical scanning device 4, so that a distance image with reduced distortion can be obtained.
  • the reflected light from the object is guided to the photodetector 481 via the same optical path as the emitted light, that is, via the second mirror 303 and the second mirror 103. ..
  • the reflected light from the object may be guided to the photodetector 481 by an optical path different from the emitted light.
  • FIG. 20 is a diagram schematically showing the configuration of the optical scanning device 4A according to the modified example of the fourth embodiment.
  • the photodetector 4A arranges the photodetector 481 so that the reflected light from the object is guided to the photodetector 481 without passing through the second mirror 303 and the second mirror 103. This is changed to the vicinity of the exit of the emitted light of the photodetector 4A.
  • the distance to the object can be calculated by comparing the emitted light and the reflected light, and the information on the distance to the object and the information on the scanning direction of the light beam are combined to provide information on the surroundings. A distance image can be acquired.
  • optical scanning device 101 light source, 102 first mirror, 103 second mirror, 104 control device, 111, 161 reflector.

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Abstract

This optical scanning device (1) comprises: a light source (101); a first mirror (102) that includes a reflective part (111) configured to reflect light emitted from the light source; a second mirror (103) that includes a reflective part (161) configured to reflect the light reflected by the first mirror; and a control device (104). The control device generates, as a drive signal V1, a triangular wave signal changed at a fundamental frequency Fd, generates a signal Vb obtained by adding low-frequency components selected from among harmonics of the fundamental frequency Fd, and generates a differential signal V2 obtained by subtracting Vb from the drive signal V1. The control device drives the first mirror by means of the drive signal V1 and drives the second mirror by means of the differential signal V2.

Description

光走査装置およびその制御方法Optical scanning device and its control method
　本発明は、光走査装置およびその制御方法に関する。 The present invention relates to an optical scanning device and a control method thereof.
　従来、ミラーの姿勢を変化させてミラーに入射する光ビームの反射方向を変化させることで、光ビームの走査を可能とする光走査装置が知られている。光走査装置において、ミラーの姿勢を変化させるアクチュエータをのこぎり波状の周期信号で駆動することによって光ビームの走査方向をのこぎり波状に周期的に変化させる場合、のこぎり波状の周期信号に含まれる高周波成分がミラーの共振特性によって増幅されると、ミラーの姿勢および光ビームの走査方向のリンギングが発生する場合がある。 Conventionally, an optical scanning device that enables scanning of a light beam by changing the posture of the mirror to change the reflection direction of the light beam incident on the mirror is known. In an optical scanning device, when the scanning direction of an optical beam is periodically changed in a saw-wave shape by driving an actuator that changes the posture of a mirror with a saw-wave periodic signal, the high-frequency component contained in the saw-wave periodic signal is generated. When amplified by the resonance characteristics of the mirror, ringing in the orientation of the mirror and the scanning direction of the light beam may occur.
　たとえば、特開２０１３－２０５８１８号公報には、上記のようなリンギングの発生を抑制することができる光偏向器が開示されている。この光偏向器は、圧電アクチュエータによりミラーの姿勢を変化させる際に、ミラーの姿勢から機械的な共振周波数を検知する回路を備え、共振周波数とその高調波成分をノッチフィルタにより除去したのこぎり波状の周期信号で圧電アクチュエータを駆動することによって、リンギングの発生を抑制している。 For example, Japanese Patent Application Laid-Open No. 2013-205818 discloses an optical deflector capable of suppressing the occurrence of ringing as described above. This optical deflector is equipped with a circuit that detects the mechanical resonance frequency from the posture of the mirror when the posture of the mirror is changed by the piezoelectric actuator, and the resonance frequency and its harmonic component are removed by a notch filter. By driving the piezoelectric actuator with a periodic signal, the occurrence of ringing is suppressed.
特開２０１３－２０５８１８号公報Japanese Unexamined Patent Publication No. 2013-205818
　しかしながら、特許文献１では、リンギング発生の抑制に向けた高調波成分の除去のために、急峻な特性を有するノッチフィルタを設ける必要があった。また、温度および圧力等の環境変化によるミラーの機械的な応答特性の変化および製造ばらつき等による個々のミラーの特性の違い（個体差）に合わせてノッチフィルタの特性を調整する必要があるために、ノッチフィルタの特性を調整する制御回路のサイズが大きくなってしまうという問題点があった。 However, in Patent Document 1, it is necessary to provide a notch filter having steep characteristics in order to remove harmonic components for suppressing the occurrence of ringing. In addition, it is necessary to adjust the characteristics of the notch filter according to the changes in the mechanical response characteristics of the mirror due to environmental changes such as temperature and pressure, and the differences in the characteristics of individual mirrors (individual differences) due to manufacturing variations, etc. However, there is a problem that the size of the control circuit for adjusting the characteristics of the notch filter becomes large.
　本開示は、上述の課題を解決するためになされたものであって、その目的は、ノッチフィルタを用いることなくリンギングの発生を抑制可能な光走査装置を提供することである。 The present disclosure has been made to solve the above-mentioned problems, and an object of the present disclosure is to provide an optical scanning device capable of suppressing the occurrence of ringing without using a notch filter.
　本開示による光走査装置は、光源と、光源から出射された光を反射するように構成された反射部を含む第１走査ミラーと、第１走査ミラーで反射された光を反射するように構成された反射部を含む第２走査ミラーと、第１走査ミラーの反射部の姿勢および第２走査ミラーの反射部の姿勢を制御することによって光の出射方向を制御するように構成された制御装置とを備える。制御装置は、基本周波数で周期的に変化する第１信号を生成し、基本周波数の高調波のうちから選択された周波数成分を足し合わせた第２信号を生成し、第１信号から第２信号を差し引いた差分信号を生成する。第１走査ミラーは、第１信号によって駆動される。第２走査ミラーは、差分信号によって駆動される。 The optical scanning device according to the present disclosure is configured to reflect a light source, a first scanning mirror including a reflecting portion configured to reflect the light emitted from the light source, and light reflected by the first scanning mirror. A control device configured to control the light emission direction by controlling the posture of the reflecting portion of the first scanning mirror and the posture of the reflecting portion of the second scanning mirror, and the second scanning mirror including the reflecting portion. And. The control device generates a first signal that changes periodically at the fundamental frequency, generates a second signal by adding frequency components selected from the harmonics of the fundamental frequency, and generates a second signal from the first signal to the second signal. Is subtracted to generate a difference signal. The first scanning mirror is driven by the first signal. The second scanning mirror is driven by the difference signal.
　本開示によれば、ノッチフィルタを用いることなくリンギングの発生を抑制可能な光走査装置を提供することができる。 According to the present disclosure, it is possible to provide an optical scanning device capable of suppressing the occurrence of ringing without using a notch filter.
光走査装置の構成を概略的に示す図（その１）。The figure which shows the structure of the optical scanning apparatus schematic (the 1). 第１ミラーの上面図。Top view of the first mirror. 第１ミラーの図２におけるＩＩＩ－ＩＩＩ断面図。FIG. 2 is a sectional view taken along line III-III of the first mirror. 第１ミラーの傾斜角と光ビームの進行方向との関係を模式的に示す図。The figure which shows typically the relationship between the inclination angle of the 1st mirror and the traveling direction of a light beam. 第１ミラーの駆動電圧と第１ミラーの傾斜角との対応関係の一例を示す図。The figure which shows an example of the correspondence relationship between the drive voltage of the 1st mirror and the inclination angle of a 1st mirror. 一般的な構造物の周波数応答特性および共振周波数を模式的に示す図。The figure which shows the frequency response characteristic and the resonance frequency of a general structure schematically. 第２ミラーの傾斜角と光ビームの進行方向との関係を模式的に示す図。The figure which shows typically the relationship between the inclination angle of the 2nd mirror and the traveling direction of a light beam. 光ビームの出射方向φを模式的に示す図。The figure which shows typically the emission direction φ of a light beam. 三角波Ｔ（ｔ）の波形の一例を示す図。The figure which shows an example of the waveform of the triangular wave T (t). 三角波の波形を示す図。The figure which shows the waveform of a triangular wave. １次の高調波成分の波形（正弦波）を示す図。The figure which shows the waveform (sine wave) of the 1st order harmonic component. １次から２次までの低周波成分を足し合わせた波形を示す図。The figure which shows the waveform which added the low frequency components from the 1st order to the 2nd order. １次から３次までの低周波成分を足し合わせた波形を示す図。The figure which shows the waveform which added the low frequency components from the 1st order to the 3rd order. １次から４次までの低周波成分を足し合わせた波形を示す図。The figure which shows the waveform which added the low frequency components from the 1st order to the 4th order. １次から５次までの低周波成分を足し合わせた波形を示す図。The figure which shows the waveform which added the low frequency components from the 1st order to the 5th order. 制御装置の機能を示すブロック図。A block diagram showing the function of the control device. 制御装置が実行する処理の概要を示すフローチャート。A flowchart showing an outline of the processing executed by the control device. 光走査装置の構成を概略的に示す図（その２）。The figure which shows the structure of the optical scanning apparatus schematic (the 2). 光走査装置の構成を概略的に示す図（その３）。The figure which shows the structure of the optical scanning apparatus schematic (the 3). 第１ミラーおよび第２ミラーの上面図（その１）。Top view of the first mirror and the second mirror (No. 1). 第１ミラーおよび第２ミラーの上面図（その２）。Top view of the first mirror and the second mirror (No. 2). 第２ミラーの図１６におけるＸＶＩＩ－ＸＶＩＩ断面図。FIG. 16 is a cross-sectional view taken along the line XVII-XVII of the second mirror. 光走査装置による光ビームの２軸方向の走査を模式的に示す図。The figure which shows typically the scanning of the light beam in the biaxial direction by an optical scanning apparatus. 光走査装置の構成を概略的に示す図（その４）。The figure which shows the structure of the optical scanning apparatus schematic (the 4). 光走査装置の構成を概略的に示す図（その５）。FIG. 5 is a diagram schematically showing a configuration of an optical scanning device (No. 5).
　以下、本開示の実施の形態について、図面を参照しながら詳細に説明する。なお、図中同一または相当部分には同一符号を付してその説明は繰返さない。 Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals and the description is not repeated.
　実施の形態１．
　図１は、本実施の形態による光走査装置１の構成を概略的に示す図である。光走査装置１は、光源ユニット（以下、単に「光源」ともいう）１０１と、第１走査ミラー（以下、単に「第１ミラー」ともいう）１０２と、第２走査ミラー（以下、単に「第２ミラー」ともいう）１０３と、制御装置１０４とを備える。 Embodiment 1.
FIG. 1 is a diagram schematically showing a configuration of an optical scanning device 1 according to the present embodiment. The optical scanning device 1 includes a light source unit (hereinafter, also simply referred to as “light source”) 101, a first scanning mirror (hereinafter, also simply referred to as “first mirror”) 102, and a second scanning mirror (hereinafter, simply referred to as “first mirror”). It is provided with 103 (also referred to as "two mirrors") and a control device 104.
　光源１０１は、ビーム状にレーザ光を出射する。光源１０１は、ＬＤ（Laser　Diode）素子とコリメートレンズとを含む。コリメートレンズは、ＬＤ素子により発生した光を平行な光束に変換する。 The light source 101 emits a laser beam in the form of a beam. The light source 101 includes an LD (Laser Diode) element and a collimating lens. The collimating lens converts the light generated by the LD element into a parallel luminous flux.
　第１ミラー１０２および第２ミラー１０３の各々は、ＭＥＭＳ（Micro　Electro　Mechanical　Systems）方式のミラー、すなわちＭＥＭＳデバイス技術を応用した圧電駆動式のミラーである。第１ミラー１０２は、光源１０１から出射された光ビームの進行経路上に配置された基準面Ｐ１を有する。第２ミラー１０３は、光源１０１から出射され第１ミラー１０２で反射された光ビームの進行経路上に配置された基準面Ｐ２を有する。 Each of the first mirror 102 and the second mirror 103 is a MEMS (Micro Electro Mechanical Systems) type mirror, that is, a piezoelectric drive type mirror to which the MEMS device technology is applied. The first mirror 102 has a reference plane P1 arranged on the traveling path of the light beam emitted from the light source 101. The second mirror 103 has a reference plane P2 arranged on the traveling path of the light beam emitted from the light source 101 and reflected by the first mirror 102.
　第１ミラー１０２の基準面Ｐ１および第２ミラー１０３の基準面Ｐ２は、互いに対向し、平行に配置される。以下では、図１に示すように、基準面Ｐ１，Ｐ２の延在方向を「Ｘ方向」、基準面Ｐ１，Ｐ２に垂直な方向を「Ｚ方向」、Ｘ方向およびＺ方向に垂直な方向を「Ｙ方向」とも称する。 The reference surface P1 of the first mirror 102 and the reference surface P2 of the second mirror 103 face each other and are arranged in parallel. In the following, as shown in FIG. 1, the extending direction of the reference planes P1 and P2 is the "X direction", the direction perpendicular to the reference planes P1 and P2 is the "Z direction", and the directions perpendicular to the X direction and the Z direction are defined. Also referred to as "Y direction".
　第１ミラー１０２は、光源１０１から出射された光を反射するように構成された反射部１１１を含む。第２ミラー１０３は、第１ミラー１０２の反射部１１１で反射された光を反射するように構成された反射部１６１を含む。 The first mirror 102 includes a reflecting unit 111 configured to reflect the light emitted from the light source 101. The second mirror 103 includes a reflecting unit 161 configured to reflect the light reflected by the reflecting unit 111 of the first mirror 102.
　制御装置１０４は、第１ミラー１０２の反射部１１１の姿勢および第２ミラー１０３の反射部１６１の姿勢を制御する信号を生成するように構成される。第１ミラー１０２は、Ｙ方向に延在する回転軸Ｙ１を有しており、反射部１１１を回転軸Ｙ１まわりに回転可能に構成される。第２ミラー１０３は、回転軸Ｙ１と同じＹ方向に延在する回転軸Ｙ２を有しており、反射部１６１を回転軸Ｙ２まわりに回転可能に構成される。すなわち、第１ミラー１０２の回転軸Ｙ１と第１ミラー１０２の回転軸Ｙ２とは、互いに平行に配置される。 The control device 104 is configured to generate a signal for controlling the posture of the reflection unit 111 of the first mirror 102 and the posture of the reflection unit 161 of the second mirror 103. The first mirror 102 has a rotation axis Y1 extending in the Y direction, and the reflecting portion 111 is configured to be rotatable around the rotation axis Y1. The second mirror 103 has a rotation axis Y2 extending in the same Y direction as the rotation axis Y1, and the reflecting portion 161 is configured to be rotatable around the rotation axis Y2. That is, the rotation axis Y1 of the first mirror 102 and the rotation axis Y2 of the first mirror 102 are arranged in parallel with each other.
　上述のように、第１ミラー１０２および第２ミラー１０３は、それぞれ回転軸Ｙ１，Ｙ２まわりに回転可能で、制御装置１０４からの駆動信号に応じて姿勢を変えるように構成される。光源１０１から出射された光ビームは、第１ミラー１０２の反射部１１１で反射し、その後、さらに第２ミラー１０３の反射部１６１で反射して光走査装置１の外部に出射される。第１ミラー１０２の反射部１１１および第２ミラー１０３の反射部１６１の姿勢を変えることで、光走査装置１からの光ビームの出射方向を変えることができる。 As described above, the first mirror 102 and the second mirror 103 can rotate around the rotation axes Y1 and Y2, respectively, and are configured to change their postures according to the drive signal from the control device 104. The light beam emitted from the light source 101 is reflected by the reflecting portion 111 of the first mirror 102, then further reflected by the reflecting portion 161 of the second mirror 103, and is emitted to the outside of the light scanning device 1. By changing the postures of the reflecting portion 111 of the first mirror 102 and the reflecting portion 161 of the second mirror 103, the emission direction of the light beam from the optical scanning device 1 can be changed.
　以下では、第１ミラー１０２の反射部１１１および第２ミラー１０３の反射部１６１の回転軸まわりの姿勢変化の向きについて、図１における時計回り方向を正方向とし、図１における反時計回り方向を負方向として説明する。 In the following, regarding the direction of the attitude change around the rotation axis of the reflecting portion 111 of the first mirror 102 and the reflecting portion 161 of the second mirror 103, the clockwise direction in FIG. 1 is set as the positive direction, and the counterclockwise direction in FIG. It will be described as a negative direction.
　図２は、第１ミラー１０２の上面図（Ｚ方向から見た図）である。図３は、第１ミラー１０２の図２におけるＩＩＩ－ＩＩＩ断面図である。第１ミラー１０２は、反射部１１１と、固定部１１２と、梁１１３，１１４と、絶縁膜１２１，１３１と、電極１２２，１３２と、チタン酸ジルコン酸鉛（ＰＺＴ）等の圧電膜（圧電材料）１２３、１３３と、電極１２４、１３４とを含む。 FIG. 2 is a top view (viewed from the Z direction) of the first mirror 102. FIG. 3 is a sectional view taken along line III-III of FIG. 2 of the first mirror 102. The first mirror 102 includes a reflective portion 111, a fixed portion 112, beams 113 and 114, insulating films 121 and 131, electrodes 122 and 132, and a piezoelectric film (piezoelectric material) such as lead zirconate titanate (PZT). ) 123, 133 and electrodes 124, 134.
　反射部１１１の表面には、光ビームを反射する、Ａｕ（金）等の反射膜１１５が形成される。梁１１３，１１４の各々は、一方の端部が反射部１１１に接続され、他方の端部が固定部１１２に接続される。これにより、反射部１１１は、梁１１３，１１４によって固定部１１２に支持される。絶縁膜１２１、電極１２２、圧電膜１２３、および電極１２４は、梁１１３上にこの順に形成される。絶縁膜１３１、電極１３２、圧電膜１３３、および電極１３４は、梁１１４上にこの順に形成される。 A reflective film 115 such as Au (gold) that reflects a light beam is formed on the surface of the reflective portion 111. One end of each of the beams 113 and 114 is connected to the reflective portion 111, and the other end is connected to the fixed portion 112. As a result, the reflective portion 111 is supported by the fixed portions 112 by the beams 113 and 114. The insulating film 121, the electrode 122, the piezoelectric film 123, and the electrode 124 are formed on the beam 113 in this order. The insulating film 131, the electrode 132, the piezoelectric film 133, and the electrode 134 are formed on the beam 114 in this order.
　電極１２２，１２４，１３２，１３４は、互いに電気的に絶縁されている。各電極は、図示しない配線を介して電源あるいは制御装置１０４の電極と電気的に接続可能に構成される。 The electrodes 122, 124, 132, and 134 are electrically insulated from each other. Each electrode is configured to be electrically connectable to the power supply or the electrode of the control device 104 via wiring (not shown).
　電極１２２，１２４への電圧印加によって圧電膜１２３を伸縮させて梁１１３を変形させることによって、梁１１３と反射部１１１との接続部分をＺ方向に変位させることができる。また、電極１３２，１３４への電圧印加によって圧電膜１３３を伸縮させて梁１１４を変形させることによって、梁１１４と反射部１１１との接続部分をＺ方向に変位させることができる。これにより、反射部１１１を回転軸Ｙ１まわりに回転変位させることができる。 By applying a voltage to the electrodes 122 and 124 to expand and contract the piezoelectric film 123 and deform the beam 113, the connection portion between the beam 113 and the reflecting portion 111 can be displaced in the Z direction. Further, the connection portion between the beam 114 and the reflecting portion 111 can be displaced in the Z direction by expanding and contracting the piezoelectric film 133 by applying a voltage to the electrodes 132 and 134 to deform the beam 114. As a result, the reflecting portion 111 can be rotationally displaced around the rotation axis Y1.
　以下、第１ミラー１０２の製造方法の一例について説明する。第１ミラー１０２の構造は、たとえばシリコン基板上に成膜、パターニング、エッチングといったプロセスを繰り返し行う、いわゆるＭＥＭＳデバイス技術を適用して製造することができる。 Hereinafter, an example of the manufacturing method of the first mirror 102 will be described. The structure of the first mirror 102 can be manufactured by applying, for example, a so-called MEMS device technique in which processes such as film formation, patterning, and etching are repeated on a silicon substrate.
　第１ミラー１０２の製造には、ＳＯＩ（Silicon　On　Insulator）基板１４０が用いられる。このＳＯＩ基板１４０は、絶縁性を有するシリコン酸化膜１４２と、シリコン酸化膜１４２の表面側に配置される導電性を有する単結晶シリコン層１４３と、シリコン酸化膜１４２の裏面側に配置される非導電性単結晶シリコン層１４１とを含む。 An SOI (Silicon On Insulator) substrate 140 is used for manufacturing the first mirror 102. The SOI substrate 140 has an insulating silicon oxide film 142, a conductive single crystal silicon layer 143 arranged on the front surface side of the silicon oxide film 142, and a non-silicon oxide film 142 arranged on the back surface side of the silicon oxide film 142. Includes a conductive single crystal silicon layer 141.
　第１ミラー１０２の構造は、ＳＯＩ基板１４０に対して、絶縁膜１２１の成膜、金属材料Ｐｔ（白金）の成膜、圧電材料（ＰＺＴ）の成膜、金属材料Ａｕ（金）の成膜およびパターニング、圧電材料（ＰＺＴ）のパターニング、金属材料Ｐｔ（白金）のパターニング、表裏面の単結晶シリコン層１４１，１４３のエッチング、シリコン酸化膜１４２のエッチングを行うことで、製造される。 The structure of the first mirror 102 is such that the insulating film 121 is formed, the metal material Pt (platinum) is formed, the piezoelectric material (PZT) is formed, and the metal material Au (gold) is formed on the SOI substrate 140. It is manufactured by performing patterning, patterning of a piezoelectric material (PZT), patterning of a metal material Pt (platinum), etching of single crystal silicon layers 141 and 143 on the front and back surfaces, and etching of a silicon oxide film 142.
　以下、第１ミラー１０２の動作について説明する。図３に示す状態において、電極１２２，１２４間に電圧を印加すると、圧電膜１２３に膜厚方向の電界が印加され、圧電膜１２３は電界の方向に応じて面内方向（圧電膜１２３の延在方向）に伸縮する。これにより、圧電膜１２３は梁１１３を反らせるように変形する。たとえば、圧電膜１２３に図３における下向きの電界が印加されたときに、圧電膜１２３が面内方向に伸びるように変形し、梁１１３は上に凸の形状に反る。一方、圧電膜１２３に図３における上向きの電界が印加されると、圧電膜１２３は面内方向に縮むように変形し、梁１１３は下に凸の形状に反る。 The operation of the first mirror 102 will be described below. In the state shown in FIG. 3, when a voltage is applied between the electrodes 122 and 124, an electric field in the film thickness direction is applied to the piezoelectric film 123, and the piezoelectric film 123 extends in the in-plane direction (expansion of the piezoelectric film 123) according to the direction of the electric field. It expands and contracts in the current direction). As a result, the piezoelectric film 123 is deformed so as to warp the beam 113. For example, when the downward electric field shown in FIG. 3 is applied to the piezoelectric film 123, the piezoelectric film 123 is deformed so as to extend in the in-plane direction, and the beam 113 warps in an upwardly convex shape. On the other hand, when the upward electric field shown in FIG. 3 is applied to the piezoelectric film 123, the piezoelectric film 123 is deformed so as to contract in the in-plane direction, and the beam 113 warps in a downwardly convex shape.
　圧電膜１２３に印加される電界の方向によって圧電膜１２３が伸びたり縮んだりするため、圧電膜１２３に印加される電圧の符号を変えるによって、梁１１３の反りの方向を変えることができる。また、圧電膜１２３に印加される電圧の大きさを変えることによって、梁１１３の反りの曲率を変えることができる。すなわち、圧電膜１２３に印加される電圧の正負および大きさによって梁１１３の変形を制御することが可能である。 Since the piezoelectric film 123 expands or contracts depending on the direction of the electric field applied to the piezoelectric film 123, the direction of warpage of the beam 113 can be changed by changing the sign of the voltage applied to the piezoelectric film 123. Further, the curvature of the warp of the beam 113 can be changed by changing the magnitude of the voltage applied to the piezoelectric film 123. That is, it is possible to control the deformation of the beam 113 by the positive / negative and magnitude of the voltage applied to the piezoelectric film 123.
　同様に、電極１３２と電極１３４との間にも電圧の印加を行って、梁１１４の変形を制御することができる。このように、反射部１１１を固定部１１２に支持する梁１１３，１１４の変形によって、第１ミラー１０２の反射部１１１を回転軸Ｙ１まわりに回転変位させることができる。以下では、第１ミラー１０２の反射部１１１の回転軸Ｙ１まわりの回転についての機械的な共振周波数を「Ｆｙ１」とする。 Similarly, the deformation of the beam 114 can be controlled by applying a voltage between the electrodes 132 and 134. In this way, the reflecting portion 111 of the first mirror 102 can be rotationally displaced around the rotation axis Y1 by deforming the beams 113 and 114 that support the reflecting portion 111 on the fixed portion 112. In the following, the mechanical resonance frequency for the rotation of the reflecting portion 111 of the first mirror 102 around the rotation axis Y1 is referred to as “Fy1”.
　第１ミラー１０２の反射部１１１を回転軸Ｙ１まわりに回転変位させるにより、第１ミラー１０２の反射部１１１で反射した光ビームの出射方向をＸ－Ｚ平面内で変えることができる。ＭＥＭＳ方式の第１ミラー１０２を周期的に変化する信号で駆動させることにより、第１ミラー１０２の反射部１１１は回転軸Ｙ１まわりに回転し、決まった姿勢を周期的に繰り返す。これにより、第１ミラー１０２の反射部１１１で反射する光ビームを決まった方向に周期的に走査させることができる。 By rotationally displacing the reflecting portion 111 of the first mirror 102 around the rotation axis Y1, the emission direction of the light beam reflected by the reflecting portion 111 of the first mirror 102 can be changed in the XX plane. By driving the MEMS-type first mirror 102 with a signal that changes periodically, the reflecting portion 111 of the first mirror 102 rotates around the rotation axis Y1 and periodically repeats a fixed posture. As a result, the light beam reflected by the reflecting portion 111 of the first mirror 102 can be periodically scanned in a fixed direction.
　図４は、第１ミラー１０２の傾斜角と光ビームの進行方向との関係を模式的に示す図である。ここで、第１ミラー１０２の傾斜角とは、第１ミラー１０２の基準面Ｐ１に対する反射部１１１の反射面（表面）の傾斜角である。図４に示すように、反射部１１１の反射面を基準面Ｐ１に対してθ１／２（θ１は正の値）だけ正方向（時計回り）に傾斜させたとき、すなわち第１ミラー１０２の傾斜角をθ１／２としたとき、反射部１１１の反射面の法線がθ１／２だけ正方向に傾くので、光ビームの進行方向は、基準方向（第１ミラー１０２を傾斜させる前の光ビームの進行方向）に対してθ１だけ正方向に傾くことになる。 FIG. 4 is a diagram schematically showing the relationship between the inclination angle of the first mirror 102 and the traveling direction of the light beam. Here, the inclination angle of the first mirror 102 is an inclination angle of the reflection surface (surface) of the reflection portion 111 with respect to the reference surface P1 of the first mirror 102. As shown in FIG. 4, when (the theta 1 which positive value) theta 1/2 with respect to the reference plane P1 of the reflecting surface of the reflecting portion 111 is inclined in only the forward direction (clockwise), i.e. the first mirror 102 When the tilt angle of is θ 1/2 , the normal of the reflecting surface of the reflecting portion 111 is tilted in the positive direction by θ 1/2 , so that the traveling direction of the light beam is the reference direction (the first mirror 102 is tilted). It is tilted in the positive direction by θ 1 with respect to the traveling direction of the previous light beam).
　図５は、第１ミラー１０２の駆動電圧と、第１ミラー１０２の傾斜角との対応関係の一例を示す図である。１つの駆動電圧の大きさに応じて、２つの梁１１３，１１４の圧電膜１２３，１３３に同じ大きさ、かつ互いに逆向きの電圧を印加することによって、第１ミラー１０２の傾斜角は、図５のように一意に対応させることができる。図５には、傾斜角が駆動電圧に対して正比例する関係にあり、その比例定数を「Ａ」とする場合が例示されている。すなわち、駆動電圧、傾斜角、比例定数Ａとの間には、傾斜角＝Ａ×駆動電圧の関係が成立する。 FIG. 5 is a diagram showing an example of the correspondence between the drive voltage of the first mirror 102 and the inclination angle of the first mirror 102. By applying voltages of the same magnitude and opposite directions to the piezoelectric films 123 and 133 of the two beams 113 and 114 according to the magnitude of one drive voltage, the inclination angle of the first mirror 102 is shown in FIG. It can be uniquely associated with each other as in 5. FIG. 5 illustrates a case where the inclination angle is directly proportional to the drive voltage and the proportionality constant is set to “A”. That is, the relationship of inclination angle = A × drive voltage is established between the drive voltage, the inclination angle, and the proportionality constant A.
　図６は、一般的な構造物の周波数応答特性および共振周波数を模式的に示す図である。一般に、構造物の共振周波数あるいはその近傍の周波数の振動が構造物に入力された場合、構造物は共振し、同じ大きさの振動が入力された場合でも、共振周波数以外の周波数の振動が入力された場合よりも、構造物の変位が大きくなるという共振現象が生じる。アクチュエータによって構造物の姿勢を変化させる場合、一般的に、共振の影響を抑えるために、構造物の共振周波数はアクチュエータの駆動信号の周波数に対して充分高くなるように設計される。構造物の共振周波数および変位の大きくなる度合いは、構造物周辺の温度および圧力に依存する。すなわち、構造物の周波数応答特性は温度環境および圧力環境によって変化する。 FIG. 6 is a diagram schematically showing the frequency response characteristics and resonance frequency of a general structure. Generally, when vibration of a frequency at or near the resonance frequency of a structure is input to the structure, the structure resonates, and even if vibration of the same magnitude is input, vibration of a frequency other than the resonance frequency is input. A resonance phenomenon occurs in which the displacement of the structure is larger than that in the case of the above. When the attitude of the structure is changed by the actuator, the resonance frequency of the structure is generally designed to be sufficiently higher than the frequency of the drive signal of the actuator in order to suppress the influence of resonance. The resonance frequency of the structure and the degree of displacement depend on the temperature and pressure around the structure. That is, the frequency response characteristics of the structure change depending on the temperature environment and pressure environment.
　以下、第２ミラー１０３について説明する。本実施の形態において、第２ミラー１０３は、第１ミラー１０２と同じ構成、同じ大きさである。また、第２ミラー１０３は、第１ミラー１０２と同じ製造方法にて製造される。また、第２ミラー１０３は、第１ミラー１０２と同様の動作が可能である。 The second mirror 103 will be described below. In the present embodiment, the second mirror 103 has the same configuration and the same size as the first mirror 102. Further, the second mirror 103 is manufactured by the same manufacturing method as the first mirror 102. Further, the second mirror 103 can operate in the same manner as the first mirror 102.
　以下では、第２ミラー１０３の回転軸Ｙ２まわりの回転についての機械的な共振周波数を「Ｆｙ２」とする。第１ミラー１０２と第２ミラー１０３とは同じ構成、同じ大きさ、同じ製造方法により製造されるため、第２ミラー１０３の共振周波数Ｆｙ２は、第１ミラー１０２の共振周波数Ｆｙ１と同じ値である。 In the following, the mechanical resonance frequency for the rotation of the second mirror 103 around the rotation axis Y2 is referred to as "Fy2". Since the first mirror 102 and the second mirror 103 are manufactured by the same configuration, the same size, and the same manufacturing method, the resonance frequency Fy2 of the second mirror 103 is the same value as the resonance frequency Fy1 of the first mirror 102. ..
　図７は、第２ミラー１０３の傾斜角と光ビームの進行方向との関係を模式的に示す図である。ここで、第２ミラー１０３の傾斜角とは、第２ミラー１０３の基準面Ｐ２に対する反射部１６１の反射面（表面）の傾斜角である。 FIG. 7 is a diagram schematically showing the relationship between the inclination angle of the second mirror 103 and the traveling direction of the light beam. Here, the inclination angle of the second mirror 103 is the inclination angle of the reflection surface (surface) of the reflection portion 161 with respect to the reference surface P2 of the second mirror 103.
　図７に示すように、反射部１６１の反射面を基準面Ｐ２に対してθ２／２（θ２は正の値）だけ負方向（反時計回り）に傾斜させたとき、すなわち第２ミラー１０３の傾斜角を－θ２／２としたとき、反射部１６１の反射面の法線がθ２／２だけ負方向に傾くので、光ビームの進行方向は、基準方向（第２ミラー１０３を傾斜させる前の光ビームの進行方向）に対してθ２だけ負方向（反時計回り）に傾くことになる。 As shown in FIG. 7, when (the theta 2 which positive values) theta 2/2 with respect to the reference plane P2 of the reflection surface of the reflection portion 161 is inclined in only the negative direction (counterclockwise), i.e. the second mirror when 103 the inclination angle was set to - [theta] 2/2, since the normal line of the reflecting surface of the reflecting portion 161 is inclined in the negative direction by theta 2/2, the traveling direction of the light beam, a reference direction (the second mirror 103 It tilts in the negative direction (counterclockwise) by θ 2 with respect to the traveling direction of the light beam before tilting.
　第１ミラー１０２と第２ミラー１０３とは、互いに独立した動作が可能である。以下では、第１ミラー１０２および第２ミラー１０３に正の駆動電圧をそれぞれ印加した場合に、第１ミラー１０２の反射面は正方向に回転し、第２ミラー１０３の反射面は負方向に回転するものとする。 The first mirror 102 and the second mirror 103 can operate independently of each other. In the following, when a positive drive voltage is applied to the first mirror 102 and the second mirror 103, the reflective surface of the first mirror 102 rotates in the positive direction, and the reflective surface of the second mirror 103 rotates in the negative direction. It shall be.
　図８は、光走査装置１から外部に出射される光ビームの進行方向（以下、単に「光ビームの出射方向」ともいう）φを模式的に示す図である。なお、光ビームの出射方向φは、第１ミラー１０２および第２ミラー１０３を傾斜させる前の光ビームの進行方向を基準として表わされる。第１ミラー１０２の光軸を正方向（時計回り）にθ１だけ傾け、第２ミラー１０３の光軸を負方向（反時計回り）にθ２だけ傾けた場合、光ビームの出射方向φは、図８に示すように、φ＝θ１＋θ２で表わすことができる。したがって、第１ミラー１０２および第２ミラー１０３の姿勢をそれぞれ時間ｔに対してθ１（ｔ）／２、θ２（ｔ）／２と変化させた場合、光ビームの出射方向φ（ｔ）は、下記の式（１）で表わすことができる。 FIG. 8 is a diagram schematically showing a traveling direction φ (hereinafter, also simply referred to as “light beam emitting direction”) φ of a light beam emitted from the optical scanning device 1 to the outside. The emission direction φ of the light beam is represented with reference to the traveling direction of the light beam before tilting the first mirror 102 and the second mirror 103. When the optical axis of the first mirror 102 is tilted by θ 1 in the positive direction (clockwise) and the optical axis of the second mirror 103 is tilted by θ 2 in the negative direction (counterclockwise), the emission direction φ of the light beam is , As shown in FIG. 8, it can be represented by φ = θ 1 + θ 2 . Therefore, when the postures of the first mirror 102 and the second mirror 103 are changed to θ 1 (t) / 2 and θ 2 (t) / 2, respectively with respect to time t, the light beam emission direction φ (t) Can be expressed by the following equation (1).
　φ（ｔ）＝θ１（ｔ）＋θ２（ｔ）　…（１）
　ここで、第１ミラー１０２および第２ミラー１０３に印加される周期的な駆動信号と、第１ミラー１０２および第２ミラー１０３の姿勢変化との関係について説明する。時間ｔに対して光ビームの出射方向φを基本周波数Ｆｄで周期的に繰り返して変化させる場合を考える。三角波およびのこぎり波等の周期信号の周期が１／Ｆｄである場合、その周期信号は、一般的に、基本周波数Ｆｄの成分と、その高調波成分との和によって表わされる。 φ (t) = θ 1 (t) + θ 2 (t)… (1)
Here, the relationship between the periodic drive signal applied to the first mirror 102 and the second mirror 103 and the posture change of the first mirror 102 and the second mirror 103 will be described. Consider a case where the emission direction φ of the light beam is periodically and repeatedly changed at the fundamental frequency Fd with respect to the time t. When the period of a periodic signal such as a triangular wave and a sawtooth wave is 1 / Fd, the periodic signal is generally represented by the sum of the component of the fundamental frequency Fd and its harmonic component.
　図９は、三角波Ｔ（ｔ）の波形の一例を示す図である。図９に示すような三角波Ｔ（ｔ）のフーリエ変換は、下記の式（２）のように記述できる。 FIG. 9 is a diagram showing an example of the waveform of the triangular wave T (t). The Fourier transform of the triangular wave T (t) as shown in FIG. 9 can be described by the following equation (2).
Figure JPOXMLDOC01-appb-M000001
Figure JPOXMLDOC01-appb-M000001
　三角波Ｔ（ｔ）の周期信号には、基本周波数Ｆｄの成分のほか、基本周波数の奇数倍（２Ｎ＋１倍、Ｎは自然数）の周波数（＝３Ｆｄ、５Ｆｄ、７Ｆｄ…）の高調波成分が含まれている。高調波成分の周波数が構造物の共振周波数近辺にある場合、構造物の共振特性によって、構造物の変位が増幅されて所望の変位に重畳される、いわゆるリンギングが生じてしまうことが懸念される。 The periodic signal of the triangular wave T (t) includes a component of the fundamental frequency Fd and a harmonic component of an odd multiple (2N + 1 times, N is a natural number) of the fundamental frequency (= 3Fd, 5Fd, 7Fd ...). ing. When the frequency of the harmonic component is near the resonance frequency of the structure, there is a concern that the resonance characteristic of the structure amplifies the displacement of the structure and superimposes it on the desired displacement, that is, so-called ringing occurs. ..
　ここで、周期信号を構成する基本周波数Ｆｄおよびその高調波の成分のうち、構造物の共振周波数よりも小さい周波数成分の中から選択された任意の周波数の成分を足し合わせものを「低周波成分」と定義する。 Here, among the components of the fundamental frequency Fd and its harmonics constituting the periodic signal, the sum of the components of an arbitrary frequency selected from the frequency components smaller than the resonance frequency of the structure is referred to as the "low frequency component". Is defined.
　図１０Ａ～図１０Ｆは、三角波と、三角波の１次から５次までの高調波の低周波成分を足し合わせた波形とを示す図である。図１０Ａは三角波の波形を示し、図１０Ｂは１次の高調波成分の波形（正弦波）を示し、図１０Ｃは１次から２次までの低周波成分を足し合わせた波形を示し、図１０Ｄは１次から３次までの低周波成分を足し合わせた波形を示し、図１０Ｅは１次から４次までの低周波成分を足し合わせた波形を示し、図１０Ｆは１次から５次までの低周波成分を足し合わせた波形を示す。 10A to 10F are diagrams showing a waveform obtained by adding low frequency components of a triangular wave and harmonics of the first to fifth harmonics of the triangular wave. FIG. 10A shows a triangular wave waveform, FIG. 10B shows a waveform of a first-order harmonic component (sine wave), and FIG. 10C shows a waveform obtained by adding low-frequency components from the first-order to the second-order. FIG. 10D. Shows a waveform obtained by adding low frequency components from 1st to 3rd order, FIG. 10E shows a waveform obtained by adding low frequency components from 1st to 4th order, and FIG. 10F shows a waveform obtained by adding low frequency components from 1st to 5th order. The waveform obtained by adding the low frequency components is shown.
　三角波の場合、１次から５次程度までの低周波成分を加えるだけで、もとの三角波に近い波形を得ることができる。すなわち、三角波Ｔ（ｔ）は次の式（３）のように分割できる。ただし、式（３）においてｍ＝５である。 In the case of a triangular wave, a waveform close to the original triangular wave can be obtained simply by adding low frequency components from the 1st to the 5th order. That is, the triangular wave T (t) can be divided as shown in the following equation (3). However, in the formula (3), m = 5.
Figure JPOXMLDOC01-appb-M000002
Figure JPOXMLDOC01-appb-M000002
　ここで、式（３）の右辺における第１項を「Ｔ１（ｔ）」、第２項を「Ｔ２（ｔ）」と定義する。第１項Ｔ１（ｔ）は、ほぼ三角波であり、構造物の共振周波数よりも低い低周波成分である。また、第２項Ｔ２（ｔ）は、それ以外の高調波成分で構造物の共振周波数の帯域を含んでいる。 Here, the first term on the right side of the equation (3) is defined as "T 1 (t)", and the second term is defined as "T 2 (t)". The first term T 1 (t) is a substantially triangular wave, which is a low frequency component lower than the resonance frequency of the structure. Further, the second term T 2 (t) includes a band of the resonance frequency of the structure with other harmonic components.
　以下、光走査装置１の制御装置１０４の機能について説明する。制御装置１０４は、光ビームの出射方向φを所望の方向に傾けるために、第１ミラー１０２および第２ミラー１０３への駆動信号を生成する。 Hereinafter, the function of the control device 104 of the optical scanning device 1 will be described. The control device 104 generates a drive signal to the first mirror 102 and the second mirror 103 in order to incline the emission direction φ of the light beam in a desired direction.
　図１１は、制御装置１０４の機能を示すブロック図である。制御装置１０４は、周期信号生成部１０４ａと、低周波成分生成部１０４ｂと、演算部１０４ｃとを含む。 FIG. 11 is a block diagram showing the functions of the control device 104. The control device 104 includes a periodic signal generation unit 104a, a low frequency component generation unit 104b, and a calculation unit 104c.
　周期信号生成部１０４ａおよび低周波成分生成部１０４ｂには、外部から、周期信号の基本周波数Ｆｄとその波形が、それぞれ入力される。以下では、周期信号の波形が三角波である場合について説明する。 The fundamental frequency Fd of the periodic signal and its waveform are input to the periodic signal generation unit 104a and the low frequency component generation unit 104b from the outside, respectively. The case where the waveform of the periodic signal is a triangular wave will be described below.
　周期信号生成部１０４ａは、基本周波数Ｆｄで変化する三角波信号Ｖ１（ｔ）を生成する。周期信号生成部１０４ａは、生成された三角波信号Ｖ１（ｔ）を演算部１０４ｃおよび第１ミラー１０２に出力する。これにより、第１ミラー１０２は、三角波信号Ｖ１（ｔ）によって駆動される。 The periodic signal generation unit 104a generates a triangular wave signal V 1 (t) that changes at the fundamental frequency Fd. The periodic signal generation unit 104a outputs the generated triangular wave signal V 1 (t) to the calculation unit 104c and the first mirror 102. As a result, the first mirror 102 is driven by the triangular wave signal V 1 (t).
　低周波成分生成部１０４ｂは、基本周波数Ｆｄに対し、１次の高調波からＮ次（たとえば５次）の高調波までの低周波成分を足し合わせた信号Ｖｂ（ｔ）を生成する。低周波成分生成部１０４ｂは、生成された信号Ｖｂ（ｔ）を演算部１０４ｃに出力する。 The low frequency component generation unit 104b generates a signal V b (t) obtained by adding low frequency components from the first harmonic to the Nth (for example, fifth) harmonic to the fundamental frequency Fd. The low frequency component generation unit 104b outputs the generated signal V b (t) to the calculation unit 104c.
　演算部１０４ｃは、周期信号生成部１０４ａで生成された三角波信号Ｖ１（ｔ）から、低周波成分生成部１０４ｂで生成された信号Ｖｂ（ｔ）を差し引いた差分信号Ｖ２（ｔ）を生成する。演算部１０４ｃは、生成された差分信号Ｖ２（ｔ）を第２ミラー１０３に出力する。これにより、第２ミラー１０３は、差分信号Ｖ２（ｔ）によって駆動される。 The calculation unit 104c obtains a difference signal V 2 (t) obtained by subtracting the signal V b (t) generated by the low frequency component generation unit 104b from the triangular wave signal V 1 (t) generated by the periodic signal generation unit 104a. Generate. The calculation unit 104c outputs the generated difference signal V 2 (t) to the second mirror 103. As a result, the second mirror 103 is driven by the difference signal V 2 (t).
　三角波信号Ｖ１（ｔ）、信号Ｖｂ（ｔ）、差分信号Ｖ２（ｔ）を波形に注目して上記の式（３）に示す三角波Ｔ（ｔ）を用いて表せば、それぞれ下記の式（４）、式（５）、式（６）となる。 If the triangular wave signal V 1 (t), the signal V b (t), and the difference signal V 2 (t) are expressed using the triangular wave T (t) shown in the above equation (3) by paying attention to the waveform, they are as follows. Equations (4), (5), and (6) are obtained.
　Ｖ１（ｔ）＝Ｔ（ｔ）＝Ｔ１（ｔ）＋Ｔ２（ｔ）　…（４）
　Ｖｂ（ｔ）＝Ｔ１（ｔ）　…（５）
　Ｖ２（ｔ）＝Ｖ１（ｔ）－Ｖｂ（ｔ）＝Ｔ（ｔ）－Ｔ１（ｔ）＝Ｔ２（ｔ）　…（６）
　第１ミラー１０２は、制御装置１０４により生成された三角波信号Ｖ１（ｔ）によって駆動される。すなわち、第１ミラー１０２は、第１ミラー１０２の共振周波数よりも低い低周波成分を足し合わせたほぼ三角波の信号Ｔ１（ｔ）と、第１ミラー１０２の共振周波数近傍の周波数成分を含む信号Ｔ２（ｔ）との和である信号Ｖ１（ｔ）によって、第１ミラー１０２の周波数応答特性に応じて姿勢を変える。 V 1 (t) = T (t) = T 1 (t) + T 2 (t) ... (4)
V b (t) = T 1 (t) ... (5)
V 2 (t) = V 1 (t) -V b (t) = T (t) -T 1 (t) = T 2 (t) ... (6)
The first mirror 102 is driven by the triangular wave signal V 1 (t) generated by the control device 104. That is, the first mirror 102 is a signal including a substantially triangular wave signal T 1 (t) obtained by adding low frequency components lower than the resonance frequency of the first mirror 102 and a frequency component near the resonance frequency of the first mirror 102. The attitude is changed according to the frequency response characteristic of the first mirror 102 by the signal V 1 (t) which is the sum of T 2 (t).
　第１ミラー１０２の共振周波数近傍の周波数成分を含む信号Ｔ２（ｔ）が第１ミラー１０２の周波数応答特性によって増幅された姿勢変化分を「Ｒ１（ｔ）」と定義すると、第１ミラー１０２の姿勢変化量θ１（ｔ）は、振幅で正規化しその波形にのみに注目すれば、次の式（７）のように記述できる。 If the attitude change of the signal T 2 (t) including the frequency component near the resonance frequency of the first mirror 102 amplified by the frequency response characteristic of the first mirror 102 is defined as “R 1 (t)”, the first mirror The amount of change in attitude θ 1 (t) of 102 can be described as the following equation (7) by normalizing with amplitude and paying attention only to the waveform.
　θ１（ｔ）＝Ａ・Ｔ１（ｔ）＋Ｒ１（ｔ）　…（７）
　第２ミラー１０３は、制御装置１０４により生成された差分信号Ｖ２（ｔ）によって駆動される。すなわち、第２ミラー１０３は、差分信号Ｖ２（ｔ）によって、第２ミラー１０３の周波数応答特性に応じて姿勢を変える。ここで、差分信号Ｖ２（ｔ）は、上記の式（６）に示すように信号Ｔ２（ｔ）である。信号Ｔ２（ｔ）が第２ミラー１０３の周波数応答特性によって増幅された信号を「Ｒ２（ｔ）」と定義すると、第２ミラー１０３の姿勢変化量θ２（ｔ）は、振幅で正規化しその波形に注目すれば、下記の式（８）のように記述できる。 θ 1 (t) = AT 1 (t) + R 1 (t)… (7)
The second mirror 103 is driven by the difference signal V 2 (t) generated by the control device 104. That is, the second mirror 103 changes its posture according to the frequency response characteristic of the second mirror 103 by the difference signal V 2 (t). Here, the difference signal V 2 (t) is the signal T 2 (t) as shown in the above equation (6). If the signal T 2 (t) amplified by the frequency response characteristic of the second mirror 103 is defined as “R 2 (t)”, the attitude change amount θ 2 (t) of the second mirror 103 is normal in amplitude. If we pay attention to the waveform, we can describe it as the following equation (8).
　θ２（ｔ）＝－Ｒ２（ｔ）　…（８）
　なお、上記の式（８）の右辺の符号を「－」（マイナス）としているのは、上述したように第２ミラー１０３に正の駆動電圧を印加した場合に第２ミラー１０３の反射面が負方向に回転することによる。 θ 2 (t) = −R 2 (t)… (8)
The sign on the right side of the above equation (8) is "-" (minus) because the reflective surface of the second mirror 103 is changed when a positive drive voltage is applied to the second mirror 103 as described above. By rotating in the negative direction.
　したがって、光ビームの出射方向φ（ｔ）は下記の式（９）のように記述できる。
　φ（ｔ）＝θ１（ｔ）＋θ２（ｔ）＝Ａ・Ｔ１（ｔ）＋Ｒ１（ｔ）－Ｒ２（ｔ）…（９）
　ここで、第１ミラー１０２と第２ミラー１０３とは同様の構成、同様の製造方法により製造され、同じ大きさであるため同じ周波数応答特性を持つから、下記の式（１０）の関係式が成立する。 Therefore, the emission direction φ (t) of the light beam can be described by the following equation (9).
φ (t) = θ 1 (t) + θ 2 (t) = AT 1 (t) + R 1 (t) -R 2 (t) ... (9)
Here, since the first mirror 102 and the second mirror 103 are manufactured by the same configuration and the same manufacturing method and have the same frequency response characteristics because they have the same size, the relational expression of the following equation (10) is established. To establish.
　｜Ｒ１（ｔ）｜＝｜Ｒ２（ｔ）｜　…（１０）
　したがって、上記の式（９）において、第１ミラー１０２の周波数応答特性によって増幅された姿勢変化分「Ｒ１（ｔ）」と、第２ミラー１０３の周波数応答特性によって増幅された姿勢変化分「－Ｒ２（ｔ）」とが互いに相殺し合うことになり、下記の式（１１）が得られる。 | R 1 (t) | = | R 2 (t) | ... (10)
Therefore, in the above equation (9), the attitude change “R 1 (t)” amplified by the frequency response characteristic of the first mirror 102 and the attitude change “R 1 (t)” amplified by the frequency response characteristic of the second mirror 103. -R 2 (t) "will cancel each other out, and the following equation (11) will be obtained.
　φ（ｔ）＝Ａ・Ｔ１（ｔ）　…（１１）
　式（１１)から、光ビームの出射方向φ（ｔ）には、第１ミラー１０２の周波数応答特性によって増幅された姿勢変化分Ｒ１（ｔ）、および第２ミラー１０３の周波数応答特性によって増幅された姿勢変化分Ｒ２（ｔ）の影響が排除されていることが理解できる。これにより、光ビームのリンギングを抑制することができる。 φ (t) = AT 1 (t)… (11)
From the equation (11), the light beam emission direction φ (t) is amplified by the attitude change R 1 (t) amplified by the frequency response characteristic of the first mirror 102 and the frequency response characteristic of the second mirror 103. It can be understood that the influence of the attitude change R 2 (t) is eliminated. As a result, ringing of the light beam can be suppressed.
　さらに、光走査装置１が温度環境および圧力環境のもとに置かれた場合を考える。第１ミラー１０２および第２ミラー１０３の共振周波数および周波数応答特性はその環境によって変化するため、第１ミラー１０２の周波数応答特性によって増幅された姿勢変化分Ｒ１（ｔ）、および第２ミラー１０３の周波数応答特性によって増幅された姿勢変化分Ｒ２（ｔ）も変化する。しかしながら、第１ミラー１０２および第２ミラー１０３は同じ構造および大きさであり、同じ製造方法にて製造されているため、温度環境および圧力環境でのＲ１（ｔ）、Ｒ２（ｔ）の変化も同じ特性となる。そのため、温度環境および圧力環境に依らず｜Ｒ１（ｔ）｜＝｜Ｒ２（ｔ）｜が成立するため、温度環境および圧力環境が変化したとしても光ビームのリンギングを抑制することが可能である。 Further, consider the case where the optical scanning device 1 is placed in a temperature environment and a pressure environment. Since the resonance frequency and frequency response characteristics of the first mirror 102 and the second mirror 103 change depending on the environment, the attitude change R 1 (t) amplified by the frequency response characteristics of the first mirror 102 and the second mirror 103 The attitude change R 2 (t) amplified by the frequency response characteristic of is also changed. However, since the first mirror 102 and the second mirror 103 have the same structure and size and are manufactured by the same manufacturing method, R 1 (t) and R 2 (t) in a temperature environment and a pressure environment The change has the same characteristics. Therefore, | R 1 (t) | = | R 2 (t) | is established regardless of the temperature environment and pressure environment, so that ringing of the light beam can be suppressed even if the temperature environment and pressure environment change. Is.
　また、本実施の形態による光走査装置１においては、先行技術で用いられていたようなノッチフィルタを用いることなく、リンギングを抑制することができる。また、ミラーの機械的な共振周波数の変化および製造ばらつき等による個々のミラーの特性の個体差に合わせてノッチフィルタの特性を調整するための制御回路も不要となる。そのため、光走査装置１のサイズを小型化することができる。さらに、ノッチフィルタは一般的にその遮断周波数近辺で大きく位相を変化させるため、ノッチフィルタを用いないことにより、制御に関する設計の自由度を高めることができる。 Further, in the optical scanning apparatus 1 according to the present embodiment, ringing can be suppressed without using a notch filter as used in the prior art. Further, a control circuit for adjusting the characteristics of the notch filter according to individual differences in the characteristics of individual mirrors due to changes in the mechanical resonance frequency of the mirrors, manufacturing variations, and the like becomes unnecessary. Therefore, the size of the optical scanning device 1 can be reduced. Further, since the notch filter generally changes its phase significantly in the vicinity of its cutoff frequency, the degree of freedom in design regarding control can be increased by not using the notch filter.
　図１２は、光走査装置１の制御装置１０４が第１ミラー１０２および第２ミラー１０３を制御する際に実行する処理の概要を示すフローチャートである。 FIG. 12 is a flowchart showing an outline of the processing executed when the control device 104 of the optical scanning device 1 controls the first mirror 102 and the second mirror 103.
　制御装置１０４は、外部から、周期信号の基本周波数Ｆｄおよび波形を取得する（ステップＳ１０）。なお、周期信号の波形は、上述のように、たとえば三角波である。 The control device 104 acquires the fundamental frequency Fd and the waveform of the periodic signal from the outside (step S10). As described above, the waveform of the periodic signal is, for example, a triangular wave.
　次いで、制御装置１０４は、ステップＳ１０において取得した基本周波数Ｆｄおよび周期信号波形で変化する駆動信号Ｖ１（ｔ）を生成する（ステップＳ１１）。 Next, the control device 104 generates a drive signal V 1 (t) that changes with the fundamental frequency Fd and the periodic signal waveform acquired in step S10 (step S11).
　次いで、制御装置１０４は、基本周波数Ｆｄに対し、１次からＮ次（たとえば５次）までの低周波成分を足し合わせた信号Ｖｂ（ｔ）を生成する（ステップＳ１２）。 Next, the control device 104 generates a signal V b (t) obtained by adding low frequency components from the first order to the Nth order (for example, the fifth order) with respect to the fundamental frequency Fd (step S12).
　次いで、制御装置１０４は、ステップＳ１１において生成された駆動信号Ｖ１（ｔ）から、ステップＳ１２において生成された信号Ｖｂ（ｔ）を差し引いた差分信号Ｖ２（ｔ）を生成する（ステップＳ１３）。 Next, the control device 104 generates a difference signal V 2 (t) obtained by subtracting the signal V b (t) generated in step S12 from the drive signal V 1 (t) generated in step S11 (step S13). ).
　次いで、制御装置１０４は、ステップＳ１１において生成された駆動信号Ｖ１（ｔ）を第１ミラー１０２に出力して、駆動信号Ｖ１（ｔ）によって第１ミラー１０２を駆動する（ステップＳ１４）。 Next, the control device 104 outputs the drive signal V 1 (t) generated in step S11 to the first mirror 102, and drives the first mirror 102 by the drive signal V 1 (t) (step S14).
　次いで、制御装置１０４は、ステップＳ１３において生成された差分信号Ｖ２（ｔ）を第２ミラー１０３に出力して、差分信号Ｖ２（ｔ）によって第２ミラー１０３を駆動する（ステップＳ１５）。 Next, the control device 104 outputs the difference signal V 2 (t) generated in step S13 to the second mirror 103, and drives the second mirror 103 by the difference signal V 2 (t) (step S15).
　以上のように、本実施の形態による光走査装置１は、光源１０１と、光源１０１から出射された光を反射するように構成された反射部１１１を含む第１ミラー１０２と、第１ミラー１０２で反射された光を反射するように構成された反射部１６１を含む第２ミラー１０３と、第１ミラー１０２の反射部１１１の姿勢および第２ミラー１０３の反射部１６１の姿勢を制御することによって光ビームの出射方向φを制御するように構成された制御装置１０４とを備える。制御装置１０４は、基本周波数Ｆｄで変化する三角波信号を駆動信号Ｖ１（ｔ）として生成し、基本周波数Ｆｄの１次から５次までの高調波の低周波成分を足し合わせた信号Ｖｂ（ｔ）を生成し、駆動信号Ｖ１（ｔ）から信号Ｖｂ（ｔ）を差し引いた差分信号Ｖ２（ｔ）を生成する。そして、制御装置１０４は、駆動信号Ｖ１（ｔ）によって第１ミラー１０２を駆動し、差分信号Ｖ２（ｔ）によって第２ミラー１０３を駆動する。これにより、ノッチフィルタを用いることなく、リンギングの発生を抑制することができる。また、ノッチフィルタを用いないため、光走査装置１のサイズを小型化することができる。さらに、ノッチフィルタは一般的にその遮断周波数近辺で大きく位相を変化させるため、ノッチフィルタを用いないことにより、制御に関する設計の自由度を高めることができる。 As described above, the optical scanning apparatus 1 according to the present embodiment includes a light source 101, a first mirror 102 including a reflecting unit 111 configured to reflect the light emitted from the light source 101, and a first mirror 102. By controlling the posture of the second mirror 103 including the reflecting portion 161 configured to reflect the light reflected by the first mirror 102, the posture of the reflecting portion 111 of the first mirror 102, and the posture of the reflecting portion 161 of the second mirror 103. A control device 104 configured to control the emission direction φ of the light beam is provided. The control device 104 generates a triangular wave signal that changes at the fundamental frequency Fd as a drive signal V 1 (t), and adds low frequency components of harmonics from the first to the fifth order of the fundamental frequency Fd to signal V b ( t) is generated, and the difference signal V 2 (t) obtained by subtracting the signal V b (t) from the drive signal V 1 (t) is generated. Then, the control device 104 drives the first mirror 102 by the drive signal V 1 (t), and drives the second mirror 103 by the difference signal V 2 (t). As a result, the occurrence of ringing can be suppressed without using a notch filter. Further, since the notch filter is not used, the size of the optical scanning device 1 can be reduced. Further, since the notch filter generally changes its phase significantly in the vicinity of its cutoff frequency, the degree of freedom in design regarding control can be increased by not using the notch filter.
　上述の実施の形態１においては三角波信号を用いて走査する例を示したが、走査に用いられる信号は、周期信号であればよく、たとえば、のこぎり波信号を採用してもよい。 In the first embodiment described above, an example of scanning using a triangular wave signal is shown, but the signal used for scanning may be a periodic signal, and for example, a sawtooth signal may be adopted.
　周期が１／Ｆｄである周期信号によって駆動対象を駆動する場合、一般的に、周期信号には基本周波数ＦｄのＮ倍（Ｎは自然数）の高調波成分が含まれ、その高調波成分が駆動対象の共振周波数近傍にあれば、駆動対象の周波数応答特性により、その変位が増幅され、いわゆるリンギングが生じてしまうことが懸念される。しかしながら、本開示による制御を適用することによって、三角波信号を用いる場合と同様にリンギングを抑制することができるので、ひずみを低減した走査を実現することができる。 When the drive target is driven by a periodic signal having a period of 1 / Fd, the periodic signal generally contains a harmonic component N times the fundamental frequency Fd (N is a natural number), and the harmonic component is driven. If it is in the vicinity of the resonance frequency of the target, there is a concern that the displacement will be amplified due to the frequency response characteristic of the drive target, and so-called ringing will occur. However, by applying the control according to the present disclosure, ringing can be suppressed as in the case of using a triangular wave signal, so that scanning with reduced distortion can be realized.
　また、走査に用いる信号として三角波信号あるいはのこぎり波信号を採用する場合、走査を一定の速度で行うことができ、走査点の空間分解能を一定に保つことができる。 Further, when a triangular wave signal or a sawtooth wave signal is adopted as the signal used for scanning, scanning can be performed at a constant speed, and the spatial resolution of the scanning point can be kept constant.
　上述の実施の形態１においては、光源１０１から出射された光ビームが第１ミラー１０２に直接導かれ、また、第１ミラー１０２で反射した光ビームが第２ミラー１０３に直接導かれる例について説明した。 In the first embodiment described above, an example will be described in which the light beam emitted from the light source 101 is directly guided to the first mirror 102, and the light beam reflected by the first mirror 102 is directly guided to the second mirror 103. did.
　しかしながら、光源１０１と第１ミラー１０２との間の光路、および第１ミラー１０２と第２ミラー１０３との間の光路の少なくとも一方に、ビームスプリッタ等の光学部品を配置するようにしてもよい。 However, an optical component such as a beam splitter may be arranged in at least one of the optical path between the light source 101 and the first mirror 102 and the optical path between the first mirror 102 and the second mirror 103.
　図１３は、変形例による光走査装置１Ａの構成を概略的に示す図である。光走査装置１Ａは、光源１０１、第１ミラー１０２、第２ミラー１０３、および制御装置１０４に加えて、ビームスプリッタ１０５，１０６をさらに備える。 FIG. 13 is a diagram schematically showing the configuration of the optical scanning device 1A according to the modified example. The optical scanning device 1A further includes beam splitters 105 and 106 in addition to the light source 101, the first mirror 102, the second mirror 103, and the control device 104.
　ビームスプリッタ１０５は、光源１０１と第１ミラー１０２との間の光路に配置され、光源１０１から出射された光ビームを第１ミラー１０２に導く。また、ビームスプリッタ１０５，１０６は、第１ミラー１０２と第２ミラー１０３との間の光路に配置され、第１ミラー１０２で反射した光ビームを第２ミラー１０３に導く。このような光走査装置１Ａにも本開示による制御を適用可能である。 The beam splitter 105 is arranged in the optical path between the light source 101 and the first mirror 102, and guides the light beam emitted from the light source 101 to the first mirror 102. Further, the beam splitters 105 and 106 are arranged in the optical path between the first mirror 102 and the second mirror 103, and guide the light beam reflected by the first mirror 102 to the second mirror 103. The control according to the present disclosure can be applied to such an optical scanning device 1A.
　上述の実施の形態１においては第２ミラー１０３で反射した光ビームが光走査装置１の外部に直接出射されるが、ミラー等の光学部品を介して外部に出射されてもよい。これにより、光走査装置１を構成する部品の配置の自由度を上げることができる。 In the first embodiment described above, the light beam reflected by the second mirror 103 is directly emitted to the outside of the optical scanning device 1, but may be emitted to the outside through an optical component such as a mirror. As a result, the degree of freedom in arranging the components constituting the optical scanning device 1 can be increased.
　上述の実施の形態１においては第１ミラー１０２の基準面Ｐ１と第２ミラー１０３の基準面Ｐ２とが互いに平行になるように第１ミラー１０２および第２ミラー１０３が配置される。しかしながら、第１ミラー１０２および第２ミラー１０３の配置は、第１ミラー１０２で反射した光ビームが第２ミラー１０３で反射可能な配置であればよく、必ずしも基準面Ｐ１，Ｐ２が互いに平行に配置されることに限定されない。 In the first embodiment described above, the first mirror 102 and the second mirror 103 are arranged so that the reference surface P1 of the first mirror 102 and the reference surface P2 of the second mirror 103 are parallel to each other. However, the arrangement of the first mirror 102 and the second mirror 103 may be any arrangement as long as the light beam reflected by the first mirror 102 can be reflected by the second mirror 103, and the reference planes P1 and P2 are necessarily arranged in parallel with each other. Not limited to being done.
　上述の実施の形態１においては、第１ミラー１０２および第２ミラー１０３の各々は、反射部を２本の梁で固定部に支持し、梁上に設けた圧電膜の変形を利用して反射部を傾斜させる。しかしながら、反射部の姿勢を変えることにより光軸の方向を変化させることができるものであれば、梁の本数、配置、形状、圧電膜の種類、配置、形状は、上述の実施の形態１で説明したものに限定されない。 In the first embodiment described above, each of the first mirror 102 and the second mirror 103 supports the reflecting portion by two beams on the fixed portion, and reflects by utilizing the deformation of the piezoelectric film provided on the beams. Tilt the part. However, as long as the direction of the optical axis can be changed by changing the posture of the reflecting portion, the number, arrangement, shape, type, arrangement, and shape of the piezoelectric film can be determined in the above-described first embodiment. Not limited to what has been described.
　上述の実施の形態１においては、第１ミラー１０２および第２ミラー１０３として、半導体微細加工技術により製造した、いわゆるＭＥＭＳ方式のミラーが用いられる例を説明した。しかしながら、第１ミラー１０２および第２ミラー１０３は、回転変位可能で、軸まわりの機械的な周波数応答特性が同じであるミラーであればよく、ＭＥＭＳ方式のミラーでなくてもよく、また、その製造方法は限定されない。 In the above-described first embodiment, an example in which a so-called MEMS type mirror manufactured by semiconductor microfabrication technology is used as the first mirror 102 and the second mirror 103 has been described. However, the first mirror 102 and the second mirror 103 may be mirrors that can be rotationally displaced and have the same mechanical frequency response characteristics around the axis, and may not be MEMS type mirrors. The manufacturing method is not limited.
　上述の実施の形態１においては、第１ミラー１０２および第２ミラー１０３の各々は、梁上に設けた圧電膜への電界印加による圧電膜の変形を利用して反射面の姿勢を変化させる。 In the first embodiment described above, each of the first mirror 102 and the second mirror 103 changes the posture of the reflecting surface by utilizing the deformation of the piezoelectric film due to the application of an electric field to the piezoelectric film provided on the beam.
　しかしながら、反射面の姿勢を変化させる手法に依らない。たとえば、反射面の姿勢を変化させる手法は、電極への電圧印加により発生する静電引力を利用するものであってもよいし、磁界を印加し素子上に配置した配線に電流を流すことにより発生する電磁力を利用するものであってもよい。静電引力を利用する場合には、梁に圧電膜および絶縁膜等を製膜する必要がないため、圧電膜および絶縁膜とシリコン基板との間に製造プロセス上で生じる応力発生を低減できる。また、電磁力を利用する場合には、電磁力は一般的に静電引力および圧電材料の変形による力よりも大きな力を発生することができるという利点がある。 However, it does not depend on the method of changing the posture of the reflective surface. For example, the method of changing the posture of the reflecting surface may be one that utilizes the electrostatic attraction generated by applying a voltage to the electrodes, or by applying a magnetic field and passing a current through the wiring arranged on the element. It may utilize the generated electromagnetic force. When the electrostatic attraction is used, it is not necessary to form a piezoelectric film, an insulating film, or the like on the beam, so that it is possible to reduce the generation of stress generated in the manufacturing process between the piezoelectric film and the insulating film and the silicon substrate. Further, when electromagnetic force is used, there is an advantage that the electromagnetic force can generally generate a force larger than the electrostatic attraction force and the force due to the deformation of the piezoelectric material.
　静電引力および電磁力を用いる場合、一般にミラーを支持する梁をねじる方向に力を加え、ミラーの姿勢を変化させる。その場合、図２におけるミラーの回転軸は、圧電膜を用いる場合とは異なり、図２のＸ軸方向となるが、図１に示す光走査装置１に適用する際に回転軸をＹ軸方向となるように配置すればよい。 When electrostatic attraction and electromagnetic force are used, generally, a force is applied in the direction of twisting the beam that supports the mirror to change the posture of the mirror. In that case, the rotation axis of the mirror in FIG. 2 is in the X-axis direction in FIG. 2, unlike the case where the piezoelectric film is used, but when applied to the optical scanning device 1 shown in FIG. 1, the rotation axis is in the Y-axis direction. It may be arranged so as to be.
　上述の実施の形態１においては、第１ミラー１０２および第２ミラー１０３の反射膜として、四角形状の金属膜が用いられている。しかしながら、反射膜は、光ビームを反射するものであればよく、その形状、材質は上記のものに限定されない。 In the above-described first embodiment, a square metal film is used as the reflective film of the first mirror 102 and the second mirror 103. However, the reflective film may be any one that reflects a light beam, and its shape and material are not limited to those described above.
　本実施の形態１においては光走査装置１の光源としてＬＤ素子を用いる例を示したが、光源の種類は特に限定されるものではなく、たとえば、ＬＤ素子に変えて発光ダイオード素子（ＬＥＤ）素子を用いるようにしてもよい。 In the first embodiment, an example in which an LD element is used as a light source of the optical scanning device 1 is shown, but the type of the light source is not particularly limited. For example, a light emitting diode element (LED) element is used instead of the LD element. May be used.
　実施の形態２．
　図１４は、本実施の形態２による光走査装置２の構成を概略的に示す図である。本実施の形態２による光走査装置２は、上述の実施の形態１による光走査装置１に対して、第１ミラー１０２と第２ミラー１０３とが同じ基板２０１上に配置される点が異なる。 Embodiment 2.
FIG. 14 is a diagram schematically showing the configuration of the optical scanning device 2 according to the second embodiment. The optical scanning apparatus 2 according to the second embodiment is different from the optical scanning apparatus 1 according to the first embodiment in that the first mirror 102 and the second mirror 103 are arranged on the same substrate 201.
　図１５は、本実施の形態２による光走査装置２における第１ミラー１０２および第２ミラー１０３の上面図（Ｚ方向から見た図）である。図１５に示すように、光走査装置２においては、第１ミラー１０２と第２ミラー１０３とが同じ基板２０１上に製造されている。 FIG. 15 is a top view (viewed from the Z direction) of the first mirror 102 and the second mirror 103 in the optical scanning device 2 according to the second embodiment. As shown in FIG. 15, in the optical scanning apparatus 2, the first mirror 102 and the second mirror 103 are manufactured on the same substrate 201.
　さらに、本実施の形態２による光走査装置２においては、第１ミラー１０２で反射した光ビームを第２ミラー１０３に導くために、基板２０１と対向する位置であって、第１ミラー１０２で反射した光ビームが第２ミラー１０３に入射する位置に、固定ミラー２０７が配置されている。光走査装置２においては、第１ミラー１０２によって反射した光が、固定ミラー２０７により反射して第２ミラー１０３に導かれる。 Further, in the optical scanning apparatus 2 according to the second embodiment, in order to guide the light beam reflected by the first mirror 102 to the second mirror 103, the light beam is reflected by the first mirror 102 at a position facing the substrate 201. The fixed mirror 207 is arranged at a position where the light beam is incident on the second mirror 103. In the optical scanning device 2, the light reflected by the first mirror 102 is reflected by the fixed mirror 207 and guided to the second mirror 103.
　光走査装置２においては、第１ミラー１０２で反射した光が、固定ミラー２０７で反射して第２ミラー１０３に導かれている。そのため、第２ミラー１０３に達した光ビームの基準方向に対する光軸変化は、光走査装置１に対して、光軸変化の大きさは２倍になり、変化方向は反転する。したがって、光走査装置２においては、光走査装置１で用いた差分信号Ｖ２（ｔ）に対して、大きさを２倍に、符号を反転させた信号で、第２ミラー１０３を駆動すればよい。このようにすることで、第１ミラー１０２の周波数応答特性によって増幅された姿勢変化分と、第２ミラー１０３の周波数応答特性によって増幅された姿勢変化分とが互いに相殺し合うことになるため、光走査装置２からの出射光のリンギングを抑制することができる。 In the optical scanning device 2, the light reflected by the first mirror 102 is reflected by the fixed mirror 207 and guided to the second mirror 103. Therefore, the change in the optical axis of the light beam reaching the second mirror 103 with respect to the reference direction is twice as large as that in the optical scanning device 1, and the direction of change is reversed. Therefore, in the optical scanning device 2, if the second mirror 103 is driven by a signal whose magnitude is doubled and the code is inverted with respect to the difference signal V 2 (t) used in the optical scanning device 1. Good. By doing so, the attitude change amount amplified by the frequency response characteristic of the first mirror 102 and the attitude change amount amplified by the frequency response characteristic of the second mirror 103 cancel each other out. Ringing of the light emitted from the optical scanning device 2 can be suppressed.
　光走査装置２では、第１ミラー１０２と第２ミラー１０３とが同じ基板２０１上に製造されているため、製造ばらつきに起因する共振周波数および周波数応答特性の設計値からのずれは、第１ミラー１０２と第２ミラー１０３とのどちらにも同じように生ずる。そのため、第１ミラー１０２と第２ミラー１０３とを別の基板上に製造する場合に比べて、第１ミラー１０２の周波数応答特性によって増幅された姿勢変化分と、第２ミラー１０３の周波数応答特性によって増幅された姿勢変化分とを、より適切に互いに相殺させることができる。 In the optical scanning device 2, since the first mirror 102 and the second mirror 103 are manufactured on the same substrate 201, the deviation of the resonance frequency and the frequency response characteristic from the design values due to the manufacturing variation is the first mirror. The same occurs in both 102 and the second mirror 103. Therefore, as compared with the case where the first mirror 102 and the second mirror 103 are manufactured on different substrates, the attitude change amount amplified by the frequency response characteristic of the first mirror 102 and the frequency response characteristic of the second mirror 103 It is possible to more appropriately cancel each other's posture changes amplified by.
　また、光走査装置２においては、第１ミラー１０２および第２ミラー１０３を同じ基板２０１に配置しているため、第１ミラー１０２と第２ミラー１０３との相対的な位置関係が固定される。そのため、光走査装置２の組み立ておよび他の部材とのアライメントを容易に行うことができる。 Further, in the optical scanning device 2, since the first mirror 102 and the second mirror 103 are arranged on the same substrate 201, the relative positional relationship between the first mirror 102 and the second mirror 103 is fixed. Therefore, the optical scanning device 2 can be easily assembled and aligned with other members.
　なお、光走査装置２においては、基板２０１の基準面と固定ミラー２０７の反射面とが平行となるように配置されている。しかしながら、第１ミラー１０２で反射した光ビームが固定ミラーで反射し第２ミラー１０３に導かれるのであれば、基板２０１の基準面を固定ミラー２０７の反射面に対して傾けて配置してもよい。 In the optical scanning device 2, the reference surface of the substrate 201 and the reflecting surface of the fixed mirror 207 are arranged so as to be parallel to each other. However, if the light beam reflected by the first mirror 102 is reflected by the fixed mirror and guided to the second mirror 103, the reference surface of the substrate 201 may be arranged at an angle with respect to the reflecting surface of the fixed mirror 207. ..
　実施の形態３．
　図１６は、本実施の形態３による光走査装置３の第１ミラー１０２および第２ミラー１０３の上面図（Ｚ方向から見た図）である。図１７は、第２ミラー３０３の図１６におけるＸＶＩＩ－ＸＶＩＩ断面図である。 Embodiment 3.
FIG. 16 is a top view (viewed from the Z direction) of the first mirror 102 and the second mirror 103 of the optical scanning apparatus 3 according to the third embodiment. FIG. 17 is a cross-sectional view taken along the line XVII-XVII of FIG. 16 of the second mirror 303.
　本実施の形態３による光走査装置３は、上述の実施の形態２による光走査装置２の第２ミラー１０３に代えて、第２ミラー３０３を有する。第２ミラー３０３は、Ｙ軸まわりだけでなくＸ軸まわりにも回転可能に製造されている。 The optical scanning device 3 according to the third embodiment has a second mirror 303 instead of the second mirror 103 of the optical scanning device 2 according to the second embodiment described above. The second mirror 303 is manufactured so as to be rotatable not only around the Y axis but also around the X axis.
　すなわち、第２ミラー３０３は、反射部１６１と、梁１６３，１６４と、中間固定部３１２と、梁１７３，１７４とを備える。反射部１６１は、Ｘ軸方向に延在する梁１６３，１６４によって中間固定部３１２に支持される。反射部１６１および梁１６３，１６４の構成は、上述の実施の形態２による第２ミラー１０３と同じである。したがって、制御装置１０４が梁１６３，１６４の表面の圧電膜を伸縮させることによって、反射部１６１がＹ軸まわりに回転する。なお、第２ミラー３０３のＹ軸まわりの機械的な周波数応答特性は、第１ミラー１０２のＹ軸まわりの機械的な周波数応答特性と同一である。 That is, the second mirror 303 includes a reflecting portion 161, beams 163 and 164, an intermediate fixing portion 312, and beams 173 and 174. The reflecting portion 161 is supported by the intermediate fixing portion 312 by beams 163 and 164 extending in the X-axis direction. The configurations of the reflecting portions 161 and the beams 163 and 164 are the same as those of the second mirror 103 according to the second embodiment described above. Therefore, the control device 104 expands and contracts the piezoelectric film on the surface of the beams 163 and 164, so that the reflecting portion 161 rotates around the Y axis. The mechanical frequency response characteristic of the second mirror 303 around the Y axis is the same as the mechanical frequency response characteristic of the first mirror 102 around the Y axis.
　図１６に示すように、中間固定部３１２は、反射部１６１および梁１６３，１６４の外周に配置され、Ｙ軸方向に延在する梁１７３，１７４によって、固定部１１２に支持される。図１７に示すように、梁１７３上には、絶縁膜３２１、電極３２２、圧電膜３２３、および電極３２４が、この順に形成される。梁１７４上には、絶縁膜３３１、電極３３２、圧電膜３３３、および電極３３４が、この順に形成される。電極３２２，３２４，３３２，３３４は、互いに電気的に絶縁されており、図示しない配線を介して電源あるいは制御装置１０４の電極と電気的に接続可能に構成される。 As shown in FIG. 16, the intermediate fixing portion 312 is arranged on the outer periphery of the reflecting portion 161 and the beams 163 and 164, and is supported by the fixing portion 112 by the beams 173 and 174 extending in the Y-axis direction. As shown in FIG. 17, an insulating film 321 and an electrode 322, a piezoelectric film 323, and an electrode 324 are formed on the beam 173 in this order. An insulating film 331, an electrode 332, a piezoelectric film 333, and an electrode 334 are formed on the beam 174 in this order. The electrodes 322, 324, 332, and 334 are electrically insulated from each other, and are configured to be electrically connectable to the electrodes of the power supply or the control device 104 via wiring (not shown).
　電極３２２，３２４間への電圧印加によって圧電膜３２３を伸縮させて梁１７３を変形させることによって、梁１７３と中間固定部３１２との接続部分をＺ方向に変位させることができる。また、電極３３２，３３４間への電圧印加によって圧電膜３３３を伸縮させて梁１７４を変形させることによって、梁１７４と中間固定部３１２との接続部分をＺ方向に変位させることができる。したがって、制御装置１０４が梁１７３，１７４の表面の電極３２２，３２４間および電極３３２，３３４間へ駆動電圧を印加して圧電膜３２３，３３３を伸縮させることによって、反射部１６１のＹ軸まわりの回転とは独立に、中間固定部３１２および中間固定部３１２に梁１６３，１６４によって支持される反射部１６１をＸ軸まわりに回転させることができる。ここで、第２ミラー３０３のＸ軸まわりの回転についての機械的な共振周波数を「Ｆｘ２」とする。 By applying a voltage between the electrodes 322 and 324 to expand and contract the piezoelectric film 323 and deform the beam 173, the connecting portion between the beam 173 and the intermediate fixing portion 312 can be displaced in the Z direction. Further, the connection portion between the beam 174 and the intermediate fixing portion 312 can be displaced in the Z direction by expanding and contracting the piezoelectric film 333 by applying a voltage between the electrodes 332 and 334 to deform the beam 174. Therefore, the control device 104 applies a driving voltage between the electrodes 322 and 324 and between the electrodes 332 and 334 on the surface of the beams 173 and 174 to expand and contract the piezoelectric films 323 and 333 so that the reflecting portion 161 is around the Y axis. Independent of the rotation, the reflection portion 161 supported by the beams 163 and 164 on the intermediate fixing portion 312 and the intermediate fixing portion 312 can be rotated around the X axis. Here, the mechanical resonance frequency for the rotation of the second mirror 303 around the X axis is defined as "Fx2".
　図１８は、光走査装置３による光ビームの２軸方向の走査を模式的に示す図である。電極３２２、３２４間に周波数Ｆｄｘの正弦波が駆動信号として印加されると、第２ミラー３０３がＸ軸まわりに回転する。第２ミラー１０３のＸ軸まわりの回転はＹ軸まわりの回転とは独立なので、図１８に示すように、光走査装置３は光ビームを２軸方向に走査可能である。 FIG. 18 is a diagram schematically showing biaxial scanning of the light beam by the optical scanning device 3. When a sine wave having a frequency of Fdx is applied between the electrodes 322 and 324 as a drive signal, the second mirror 303 rotates about the X axis. Since the rotation of the second mirror 103 around the X axis is independent of the rotation around the Y axis, the optical scanning device 3 can scan the light beam in the biaxial direction as shown in FIG.
　また、第２ミラー３０３のＸ軸まわりの駆動信号の周波数Ｆｄｘが、基本周波数Ｆｄの整数倍となるように設定すれば、１／Ｆｄを１周期として、周期的に同じ方向を走査することができる。 Further, if the frequency Fdx of the drive signal around the X axis of the second mirror 303 is set to be an integral multiple of the fundamental frequency Fd, 1 / Fd can be set as one cycle and the same direction can be scanned periodically. it can.
　さらに、Ｆｄｘ＝Ｆｘ２、すなわち第２ミラー１０３のＸ軸まわり駆動周波数を、その共振周波数とすれば、印加したエネルギーを効率よく振動に変換することができ、小さな印加電圧で大きな振幅を得ることができる。 Further, if Fdx = Fx2, that is, the drive frequency around the X axis of the second mirror 103 is set as the resonance frequency, the applied energy can be efficiently converted into vibration, and a large amplitude can be obtained with a small applied voltage. it can.
　本実施の形態３による光走査装置３においても、光走査装置３からの出射光のリンギングを抑制することができるので、ひずみを低減した走査を実現することができる。 Also in the optical scanning device 3 according to the third embodiment, the ringing of the light emitted from the optical scanning device 3 can be suppressed, so that scanning with reduced distortion can be realized.
　なお、光走査装置３では、第２ミラー３０３を２軸まわりに回転可能として、２軸走査が可能なミラーとしている。しかしながら、第２ミラー３０３に変えて第１ミラー１０２を２軸走査が可能なミラーとしてもよい。第１ミラー１０２を２軸走査可能とした場合には、第２ミラー３０３は第１ミラー１０２で反射した光を受けるために、第２ミラー３０３を２軸走査可能とした場合に較べ、相対的にミラーのサイズを大きくする必要がある。そのため、第２ミラー３０３を２軸走査可能とした場合の方が、光走査装置を小型化することができる。 In the optical scanning device 3, the second mirror 303 is rotatable around two axes to be a mirror capable of two-axis scanning. However, instead of the second mirror 303, the first mirror 102 may be a mirror capable of biaxial scanning. When the first mirror 102 is biaxially scantable, the second mirror 303 receives the light reflected by the first mirror 102, so that it is relative to the case where the second mirror 303 is biaxially scannable. It is necessary to increase the size of the mirror. Therefore, the optical scanning device can be downsized when the second mirror 303 is capable of biaxial scanning.
　また、光走査装置３では、第２ミラー３０３を、Ｙ軸まわりの機械的な周波数応答特性が第１ミラー１０２と同一の構造の外周に、圧電膜を形成したＹ軸方向に延在する梁１７３，１７４を設ける構造としている。しかしながら、第２ミラー３０３の構造は、Ｘ軸まわりにＹ軸まわりとは独立に回転変位を与えることができればよく、梁の本数、配置、形状、および圧電膜の種類、配置、形状は特に限定されない。 Further, in the optical scanning device 3, the second mirror 303 is a beam extending in the Y-axis direction in which a piezoelectric film is formed on the outer periphery of the structure having the same mechanical frequency response characteristic as that of the first mirror 102 around the Y-axis. The structure is such that 173 and 174 are provided. However, the structure of the second mirror 303 only needs to be able to give a rotational displacement around the X-axis independently of the Y-axis, and the number, arrangement, shape of beams, and the type, arrangement, and shape of the piezoelectric film are particularly limited. Not done.
　また、光走査装置３では、Ｘ軸まわりに回転変位を与えるための駆動方式と、Ｙ軸まわりの回転変位を与えるための駆動方式とが同じである。しかしながら、Ｘ軸まわりにＹ軸まわりとは独立に回転変位を与えることができればよく、Ｘ軸まわりに回転変位を与えるための構造および駆動方式と、Ｙ軸まわりの回転変位を与えるための構造および駆動方式とが異なってもよい。 Further, in the optical scanning device 3, the drive method for giving rotational displacement around the X-axis and the drive method for giving rotational displacement around the Y-axis are the same. However, it suffices if a rotational displacement can be applied around the X-axis independently of the Y-axis, and a structure and a drive method for imparting a rotational displacement around the X-axis, a structure for imparting a rotational displacement around the Y-axis, and The drive system may be different.
　実施の形態４．
　図１９は、本実施の形態４による光走査装置４の構成を概略的に示す図である。光走査装置４は、実施の形態３による光走査装置３と以下の点が異なる。 Embodiment 4.
FIG. 19 is a diagram schematically showing the configuration of the optical scanning device 4 according to the fourth embodiment. The optical scanning device 4 differs from the optical scanning device 3 according to the third embodiment in the following points.
　光走査装置４は、光走査装置３の構成に加えて、光検出器４８１と、演算部４８２と、ビームスプリッタ４８３とを備える。 The optical scanning device 4 includes an optical detector 481, a calculation unit 482, and a beam splitter 483, in addition to the configuration of the optical scanning device 3.
　ビームスプリッタ４８３は、光源１０１と第１ミラー１０２との間の光路に配置される。光検出器４８１は、光走査装置３の出射方向から反対に光走査装置３に入射した光が第２ミラー３０３、第１ミラー１０２を経てビームスプリッタ４８３の反射面で反射した光が検出できる位置に配置している。 The beam splitter 483 is arranged in the optical path between the light source 101 and the first mirror 102. The light detector 481 is a position where the light incident on the light scanning device 3 from the emission direction of the light scanning device 3 can be detected by the light reflected by the reflecting surface of the beam splitter 483 through the second mirror 303 and the first mirror 102. It is placed in.
　演算部４８２は、光源１０１から出射された光と光検出器４８１にて検出された光とを比較することによって、物体までの距離を測定するための演算を行なう。すなわち、演算部４８２は、光走査装置４から出射された光ビームが物体で反射した光を検出し、検出された反射光と出射光とを比較することで、その物体までの距離を測定する。たとえば、光ビームをパルス状に出射すると、物体からもパルス状の反射光を得るので、出射光と反射光のパルスの時間差により物体までの距離を算出できる。 The calculation unit 482 performs a calculation for measuring the distance to the object by comparing the light emitted from the light source 101 with the light detected by the photodetector 481. That is, the calculation unit 482 detects the light reflected by the object by the light beam emitted from the optical scanning device 4, and measures the distance to the object by comparing the detected reflected light with the emitted light. .. For example, when a light beam is emitted in a pulse shape, a pulse-shaped reflected light is also obtained from the object, so that the distance to the object can be calculated from the time difference between the emitted light and the pulse of the reflected light.
　さらに、光走査装置４は、２次元的に光ビームを走査することができるので、物体までの距離の情報と光ビームの走査方向の情報とを合わせることで、光走査装置４の周辺の距離画像を取得することができる。 Further, since the optical scanning device 4 can scan the light beam in two dimensions, the distance around the optical scanning device 4 can be obtained by combining the information on the distance to the object and the information on the scanning direction of the light beam. Images can be acquired.
　光走査装置４においても、光走査装置４からの出射光のリンギングを抑制することができるので、ひずみを低減した距離画像を得ることができる。 The optical scanning device 4 can also suppress the ringing of the light emitted from the optical scanning device 4, so that a distance image with reduced distortion can be obtained.
　なお、光走査装置４においては、物体からの反射光が、出射光と同じ光路を経由して、すなわち第２ミラー３０３および第２ミラー１０３を経由して、光検出器４８１に導かれている。しかしながら、出射光とは別の光路によって物体からの反射光を光検出器４８１に導いてもよい。 In the optical scanning device 4, the reflected light from the object is guided to the photodetector 481 via the same optical path as the emitted light, that is, via the second mirror 303 and the second mirror 103. .. However, the reflected light from the object may be guided to the photodetector 481 by an optical path different from the emitted light.
　図２０は、実施の形態４の変形例による光走査装置４Ａの構成を概略的に示す図である。光走査装置４Ａは、光走査装置４に対し、物体からの反射光が第２ミラー３０３および第２ミラー１０３を経由することなく光検出器４８１に導かれるように、光検出器４８１の配置を光走査装置４Ａの出射光の出口付近に変更したものである。このような光走査装置４Ａにおいても、出射光と反射光とを比較することで物体までの距離を算出でき、物体までの距離の情報と光ビームの走査方向の情報とを合わせることで周辺の距離画像を取得することができる。 FIG. 20 is a diagram schematically showing the configuration of the optical scanning device 4A according to the modified example of the fourth embodiment. The photodetector 4A arranges the photodetector 481 so that the reflected light from the object is guided to the photodetector 481 without passing through the second mirror 303 and the second mirror 103. This is changed to the vicinity of the exit of the emitted light of the photodetector 4A. Even in such an optical scanning device 4A, the distance to the object can be calculated by comparing the emitted light and the reflected light, and the information on the distance to the object and the information on the scanning direction of the light beam are combined to provide information on the surroundings. A distance image can be acquired.
　今回開示された実施の形態はすべての点で例示であって制限的なものではないと考えられるべきである。本開示の範囲は上記した説明ではなくて請求の範囲によって示され、請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。 It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present disclosure is indicated by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope of the claims.
　１　光走査装置、１０１　光源、１０２　第１ミラー、１０３　第２ミラー、１０４　制御装置、１１１，１６１　反射部。 1 optical scanning device, 101 light source, 102 first mirror, 103 second mirror, 104 control device, 111, 161 reflector.

Claims (14)

  1. 　光源と、
    　前記光源から出射された光を反射するように構成された反射部を含む第１走査ミラーと、
    　前記第１走査ミラーで反射された光を反射するように構成された反射部を含む第２走査ミラーと、
    　前記第１走査ミラーの前記反射部の姿勢および前記第２走査ミラーの前記反射部の姿勢を制御することによって光の出射方向を制御するように構成された制御装置とを備え、
    　前記制御装置は、
    　　基本周波数で周期的に変化する第１信号を生成し、
    　　前記基本周波数の高調波のうちから選択された周波数成分を足し合わせた第２信号を生成し、
    　　前記第１信号から前記第２信号を差し引いた差分信号を生成し、
    　前記第１走査ミラーは、前記第１信号によって駆動され、
    　前記第２走査ミラーは、前記差分信号によって駆動される、光走査装置。     Light source and
    A first scanning mirror including a reflecting unit configured to reflect the light emitted from the light source, and
    A second scanning mirror including a reflecting portion configured to reflect the light reflected by the first scanning mirror, and a second scanning mirror.
    A control device configured to control the light emission direction by controlling the posture of the reflecting portion of the first scanning mirror and the posture of the reflecting portion of the second scanning mirror is provided.
    The control device is
    Generates a first signal that changes periodically at the fundamental frequency,
    A second signal is generated by adding the frequency components selected from the harmonics of the fundamental frequency.
    A difference signal obtained by subtracting the second signal from the first signal is generated.
    The first scanning mirror is driven by the first signal.
    The second scanning mirror is an optical scanning device driven by the difference signal.
  2. 　前記選択された周波数成分は、前記第１走査ミラーの共振周波数および前記第２走査ミラーの共振周波数よりも低い周波数成分である、請求項１に記載の光走査装置。 The optical scanning apparatus according to claim 1, wherein the selected frequency component is a frequency component lower than the resonance frequency of the first scanning mirror and the resonance frequency of the second scanning mirror.
  3. 　前記第１信号は、三角波またはのこぎり波である、請求項１または２に記載の光走査装置。 The optical scanning device according to claim 1 or 2, wherein the first signal is a triangular wave or a sawtooth wave.
  4. 　前記第１走査ミラーの少なくとも１軸まわりの機械的な周波数応答特性と、前記第２走査ミラーの少なくとも１軸まわりの機械的な周波数応答特性とが同じである、請求項１～３のいずれか１項に記載の光走査装置。 Any one of claims 1 to 3, wherein the mechanical frequency response characteristic around at least one axis of the first scanning mirror is the same as the mechanical frequency response characteristic around at least one axis of the second scanning mirror. The optical scanning apparatus according to item 1.
  5. 　前記第１走査ミラーの構造と前記第２走査ミラーの構造とが同じである、請求項１～４のいずれか１項に記載の光走査装置。 The optical scanning apparatus according to any one of claims 1 to 4, wherein the structure of the first scanning mirror and the structure of the second scanning mirror are the same.
  6. 　前記第１走査ミラーと前記第２走査ミラーとの間の光路に配置され、前記第１走査ミラーで反射された光を反射するように構成された固定ミラーをさらに備え、
    　前記第２走査ミラーは、前記第１走査ミラーで反射され、かつ前記固定ミラーで反射された光を反射するように構成される、請求項１～５のいずれか１項に記載の光走査装置。     Further comprising a fixed mirror arranged in an optical path between the first scanning mirror and the second scanning mirror and configured to reflect the light reflected by the first scanning mirror.
    The optical scanning apparatus according to any one of claims 1 to 5, wherein the second scanning mirror is configured to reflect light reflected by the first scanning mirror and reflected by the fixed mirror. ..
  7. 　前記第１走査ミラーおよび前記第２走査ミラーは、同一の基板上に配置される、請求項６に記載の光走査装置。 The optical scanning apparatus according to claim 6, wherein the first scanning mirror and the second scanning mirror are arranged on the same substrate.
  8. 　前記第１走査ミラーおよび前記第２走査ミラーは、ＭＥＭＳ方式のミラーである、請求項１～７のいずれか１項に記載の光走査装置。 The optical scanning device according to any one of claims 1 to 7, wherein the first scanning mirror and the second scanning mirror are MEMS type mirrors.
  9. 　前記第１走査ミラーの回転軸方向と前記第２走査ミラーの回転軸方向とが同じである、請求項１～８のいずれか１項に記載の光走査装置。 The optical scanning apparatus according to any one of claims 1 to 8, wherein the rotation axis direction of the first scanning mirror and the rotation axis direction of the second scanning mirror are the same.
  10. 　前記第１走査ミラーおよび前記第２走査ミラーの各々は、圧電材料の変形、静電力あるいは電磁力による変位、変形のいずれかにより前記反射部の姿勢を変化させる、請求項１～９のいずれか１項に記載の光走査装置。 Any of claims 1 to 9, wherein each of the first scanning mirror and the second scanning mirror changes the posture of the reflecting portion by any of deformation of the piezoelectric material, displacement due to electrostatic force or electromagnetic force, and deformation. The optical scanning apparatus according to item 1.
  11. 　前記第１走査ミラーおよび前記第２走査ミラーの少なくとも一方は、２軸方向に走査可能に構成される、請求項１～１０のいずれか１項に記載の光走査装置。 The optical scanning apparatus according to any one of claims 1 to 10, wherein at least one of the first scanning mirror and the second scanning mirror is configured to be capable of scanning in two axial directions.
  12. 　前記第２走査ミラーは、２軸方向に走査可能に構成される、請求項１～１０のいずれか１項に記載の光走査装置。 The optical scanning device according to any one of claims 1 to 10, wherein the second scanning mirror is configured to be capable of scanning in two axial directions.
  13. 　前記光走査装置は、
    　前記光走査装置からの出射光が照射された物体からの反射光を受ける光検出器と、
    　前記出射光と前記反射光との関係から前記物体までの距離を算出するように構成された演算装置とをさらに備える、請求項１～１２のいずれかに記載の光走査装置。     The optical scanning device is
    A photodetector that receives reflected light from an object irradiated with light emitted from the optical scanning device, and a photodetector.
    The optical scanning apparatus according to any one of claims 1 to 12, further comprising an arithmetic unit configured to calculate a distance to the object from the relationship between the emitted light and the reflected light.
  14. 　光走査装置の制御方法であって、
    　前記光走査装置は、
    　　光源と、
    　　前記光源から出射された光を反射するように構成された反射部を含む第１走査ミラーと、
    　　前記第１走査ミラーで反射された光を反射するように構成された反射部を含む第２走査ミラーとを備え、
    　前記制御方法は、
    　　基本周波数で周期的に変化する第１信号を生成するステップと、
    　　前記基本周波数の高調波のうちから選択された周波数成分を足し合わせた第２信号を生成するステップと、
    　　前記第１信号から前記第２信号を差し引いた差分信号を生成するステップと、
    　前記第１信号によって前記第１走査ミラーを駆動するステップと、
    　前記差分信号によって前記第２走査ミラーを駆動するステップとを含む、光走査装置の制御方法。     It is a control method of an optical scanning device.
    The optical scanning device is
    Light source and
    A first scanning mirror including a reflecting unit configured to reflect the light emitted from the light source, and
    A second scanning mirror including a reflecting portion configured to reflect the light reflected by the first scanning mirror is provided.
    The control method is
    The step of generating the first signal that changes periodically at the fundamental frequency,
    A step of generating a second signal by adding frequency components selected from the harmonics of the fundamental frequency, and
    A step of generating a difference signal obtained by subtracting the second signal from the first signal, and
    The step of driving the first scanning mirror by the first signal and
    A method for controlling an optical scanning apparatus, which comprises a step of driving the second scanning mirror by the difference signal.
PCT/JP2019/013724 2019-03-28 2019-03-28 Optical scanning device and method of controlling same WO2020194691A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1078559A (en) * 1996-09-05 1998-03-24 Hamamatsu Photonics Kk Optical beam scanner
JP2011090030A (en) * 2009-10-20 2011-05-06 Brother Industries Ltd Image display device
JP2013205818A (en) * 2012-03-29 2013-10-07 Stanley Electric Co Ltd Light deflector

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1078559A (en) * 1996-09-05 1998-03-24 Hamamatsu Photonics Kk Optical beam scanner
JP2011090030A (en) * 2009-10-20 2011-05-06 Brother Industries Ltd Image display device
JP2013205818A (en) * 2012-03-29 2013-10-07 Stanley Electric Co Ltd Light deflector

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