WO2019163754A1 - Mirror device, optical scanning device, distance-measuring device, control method for mirror device, and program - Google Patents

Mirror device, optical scanning device, distance-measuring device, control method for mirror device, and program Download PDF

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Publication number
WO2019163754A1
WO2019163754A1 PCT/JP2019/006051 JP2019006051W WO2019163754A1 WO 2019163754 A1 WO2019163754 A1 WO 2019163754A1 JP 2019006051 W JP2019006051 W JP 2019006051W WO 2019163754 A1 WO2019163754 A1 WO 2019163754A1
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WIPO (PCT)
Prior art keywords
frequency
mirror
oscillating
drive
resonance frequency
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PCT/JP2019/006051
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French (fr)
Japanese (ja)
Inventor
奥田　義行
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パイオニア株式会社
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Publication of WO2019163754A1 publication Critical patent/WO2019163754A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C3/00—Measuring distances in line of sight; Optical rangefinders
    • G01C3/02—Details
    • G01C3/06—Use of electric means to obtain final indication
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/481—Constructional features, e.g. arrangements of optical elements
    • 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
    • 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 a mirror device including a swing mirror, an optical scanning device that performs optical scanning with the mirror device, and a distance measuring device that performs optical distance measurement with the optical scanning device.
  • the distance measuring device is configured to measure the distance to the object by irradiating the object in a predetermined region and detecting the light reflected by the object.
  • a distance measuring device that has an optical scanning device that scans the area in a two-dimensional manner and obtains a two-dimensional distance measurement result in the area is known.
  • the optical scanning type distance measuring device includes, as an optical scanning device, a MEMS (Micro Electro Mechanical Systems) mirror, a light source that irradiates light to the mirror, and a light receiving unit that receives reflected light from an object.
  • the optical scanning device uses the light reflected by the mirror to scan the scanning area two-dimensionally.
  • Patent Document 1 discloses a radar apparatus having a scanner that performs two-dimensional scanning using infrared pulsed light.
  • a movable mirror such as a MEMS mirror has a light reflecting surface that oscillates around two oscillating axes (rotating axes) orthogonal to each other, for example.
  • a drive circuit for driving the mirror is connected to the mirror.
  • the drive circuit generates, for example, a drive signal that swings the light reflecting surface of the mirror, and supplies this to the mirror.
  • the movable mirror has a specific resonance frequency according to the material. Therefore, when a drive signal having a frequency about the resonance frequency is supplied to the mirror, the mirror reaches a resonance state and oscillates with a larger amplitude than that in the non-resonance state. Therefore, by resonating the mirror, the range of light reflection by the mirror is expanded, and a large range can be scanned.
  • the resonance frequency of the mirror varies depending on the temperature of the material constituting the mirror. Therefore, for example, the resonance frequency of the mirror fluctuates as the operating environment of the optical scanning device changes and the operating time advances.
  • the oscillation state of the mirror for example, each of the oscillation period and amplitude around the two oscillation axes slightly changes, and for example, the shape and size of the scanning region and the scanning trajectory (scanning pattern) of the light change. There is a case.
  • the scanning trajectory changes greatly because the ratio of the oscillation period around the two oscillation axes varies.
  • the least common multiple of the two oscillation cycles is reduced, the overlapping portions of the scanning trajectories in one scanning cycle are increased. Therefore, the number of scanning points in the scanning region is greatly reduced, and the scanning points in the scanning region are likely to be biased.
  • the present invention has been made in view of the above points, and includes a mirror device having a oscillating mirror that stably oscillates around two oscillating shafts, an optical scanning device including the mirror device, and a distance measuring device. Providing is one of the issues. Another object of the present invention is to provide a method and a program for stably driving a oscillating mirror that oscillates around two oscillation axes.
  • an oscillating mirror that oscillates around different first and second axes, and a first for the oscillating mirror to oscillate around the first and second axes, respectively.
  • a drive circuit for generating a second drive signal, and the drive circuit determines a swing frequency around the first and second axes of the swing mirror based on the swing state of the swing mirror.
  • the first drive signal and the second drive signal are generated so that the ratio between the first oscillation frequency and the second oscillation frequency of the oscillation mirror is within a predetermined range.
  • the invention according to claim 5 includes the mirror device according to claim 1 and a light source unit that emits light toward the oscillating mirror, and the oscillating mirror emits light from the light source unit. By reflecting the light, it functions as a scanning unit that scans a predetermined region with a trajectory along the Lissajous curve using the emitted light.
  • the optical scanning device according to the fifth aspect of the present invention, and a distance measuring unit that measures the distance to the object based on the reflected light from the object existing in a predetermined area. It is characterized by having.
  • the first and second drive signals are supplied to cause the oscillating mirror to oscillate around different first and second axes, and the oscillating mirror Determining the first and second oscillation frequencies around the first and second axes of the oscillating mirror based on the oscillating state, and the ratio between the first and second oscillating frequencies is within a predetermined range. Adjusting the frequency of the first and second drive signals so as to be inside.
  • the computer supplies the first and second drive signals to the oscillating mirrors that oscillate around the first and second axes different from each other.
  • the first and second oscillation frequencies around the first and second axes of the oscillating mirror are determined based on the moving state, and the ratio between the first and second oscillation frequencies is within a predetermined range. Further, it is characterized by functioning as a drive circuit for adjusting the frequency of the first and second drive signals.
  • FIG. 1 is a layout diagram of a distance measuring apparatus according to Embodiment 1.
  • FIG. 1 is a configuration diagram of a mirror device in a distance measuring device according to Embodiment 1.
  • FIG. 3 is a circuit diagram of a drive circuit of a mirror device in the distance measuring apparatus according to Embodiment 1.
  • FIG. FIG. 6 is a diagram illustrating a driving signal applied to a swing mirror and a scanning mode of an optical scanning unit in the distance measuring apparatus according to the first embodiment. It is a figure which shows the drive flow of the mirror apparatus in the ranging apparatus which concerns on Example 1.
  • FIG. FIG. 6 is a diagram illustrating an example of adjusting the frequency of a drive signal applied to the mirror device of the distance measuring apparatus according to the first embodiment.
  • FIG. 6 is a diagram illustrating an example of adjusting the frequency of a drive signal applied to the mirror device of the distance measuring apparatus according to the first embodiment.
  • FIG. 1 is a schematic layout diagram of the distance measuring apparatus 10 according to the first embodiment.
  • the distance measuring device 10 performs optical scanning of a predetermined area (hereinafter referred to as a scanning area) R0, and based on the scanning result, determines a distance to an object (ranging object) OB present in the scanning area R0. It is an optical distance measuring device to measure.
  • the overall configuration of the distance measuring device 10 will be described with reference to FIG. FIG. 1 schematically shows the scanning region R0 and the object OB.
  • the distance measuring device 10 periodically scans the scanning region R0 with pulsed laser light (hereinafter referred to as emission light) L1, and receives reflected light L3 from the object OB in the scanning region R0.
  • An optical scanning device SC that acquires optical scanning information in the scanning region R0 is included.
  • the optical scanning device SC includes a light source unit 11 that generates and emits the emitted light L1.
  • the light source unit 11 includes a laser device that generates laser light having a peak wavelength in the infrared region as the emitted light L1.
  • the optical scanning device SC includes the mirror device 12 that reflects the outgoing light L1 and emits the outgoing light L1 toward the scanning region R0 by changing the reflection direction continuously and periodically.
  • the mirror device 12 functions as a scanning unit (light sweep unit) in the optical scanning device SC.
  • the mirror device 12 has a oscillating mirror provided with a light reflecting surface 12A that reflects the emitted light L1 toward the scanning region R0.
  • the mirror device 12 continuously and periodically changes the direction in which the emitted light L1 is reflected by changing the direction of the light reflecting surface 12A.
  • the optical scanning device SC performs the optical scanning of the scanning region R0 using the outgoing light L1 reflected by the light reflecting surface 12A as the scanning light L2.
  • the scanning region R0 has a width and height corresponding to the movable range of the light reflecting surface 12A, and receives the reflected light L3 having a predetermined intensity when the scanning light L2 reaches and reflects.
  • a virtual three-dimensional space having a depth corresponding to a possible distance.
  • the outer edge of the scanning region R0 is indicated by a broken line.
  • the scanning light L2 is irradiated to the object OB. Further, when the object OB is an object having a characteristic of reflecting the scanning light L2, the scanning light L2 is reflected by the object OB.
  • the optical scanning device SC includes a light receiving unit 13 that receives and detects reflected light L3, that is, light reflected by the object OB when the object OB is irradiated with the reflected light L3.
  • the light receiving unit 13 includes, for example, a photodetector that detects light in a wavelength band including the wavelength of the emitted light L1.
  • the light receiving unit 13 performs photoelectric conversion on the received reflected light L3, and generates an electrical signal (hereinafter referred to as a received light signal) SR corresponding to the reflected light L3.
  • a beam splitter BS is provided on the optical path of the emitted light L1 between the light source unit 11 and the light reflecting surface 12A of the mirror device 12.
  • the scanning light L2 is reflected by the object OB to become reflected light L3, and returns toward the light reflecting surface 12A.
  • the reflected light L3 is reflected by the light reflecting surface 12A, separated by the beam splitter BS, and then received by the light receiving unit 13.
  • the emitted light L1 from the light source unit 11 passes through the beam splitter BS and travels toward the mirror device 12.
  • the distance measuring device 10 includes a distance measuring unit 14 that measures the distance to the object OB based on the light reception signal SR.
  • the distance measuring unit 14 detects the pulse of the reflected light L3 from the light reception signal SR, and the object OB (and a part of the surface thereof) by the time-of-flight method based on the time difference from the emission of the emission light L1. Measure the distance to the area.
  • the distance measuring unit 14 generates data (hereinafter referred to as distance measurement data) indicating the measured distance information.
  • the distance measuring unit 14 images the scanning region R0 based on the distance measurement data.
  • the distance measurement unit 14 generates distance measurement image data in which the emission direction of the scanning light L2 (that is, the direction of the light reflecting surface 12A in the mirror device 12) is associated with the distance measurement data.
  • the distance measuring unit 14 generates one distance image data for each scanning cycle of the optical scanning device SC, that is, for each oscillation cycle of the mirror device 12.
  • the ranging unit 14 may include a display unit (not shown) that displays the plurality of ranging image data as a moving image in time series.
  • the scanning cycle is, for example, when scanning is periodically performed on the scanning region R0, from the time of an arbitrary scanning state (for example, the direction of the light reflecting surface 12A that emits the scanning light L2), and then the scanning again. The period up to the point of returning to the state.
  • the optical scanning device SC scans the scanning region R0 using the scanning light L2 (emitted light L1), and outputs the scanning result (optical scanning information) as the light receiving signal SR.
  • the distance measuring device 10 optically measures the distance to the object OB based on the optical scanning information, and outputs the distance measurement result as distance measurement data (or distance measurement image data).
  • FIG. 2 is a schematic top view showing the configuration of the mirror device 12.
  • the mirror device 12 includes a oscillating mirror 20 and a drive circuit 30 that drives the oscillating mirror 20.
  • the oscillating mirror 20 is a MEMS (Micro Electro Mechanical Systems) mirror that includes a light reflecting film 24 having a light reflecting surface 12A, and the light reflecting film 24 oscillates.
  • MEMS Micro Electro Mechanical Systems
  • the oscillating mirror 20 has a fixed portion 21 and an oscillating portion 22.
  • the swinging part 22 swings around first and second axes (hereinafter referred to as swinging axes) AX and AY that are orthogonal to each other.
  • the fixed portion 21 functions as a support portion that supports the swinging portion 22 so as to be swingable.
  • the fixed portion 21 has a frame (fixed frame) that surrounds the swing portion 22 and suspends the swing portion 22 inside thereof.
  • the rocking part 22 includes a pair of torsion bars (first torsion bars) TX each having one end fixed inside the fixing part 21.
  • Each of the pair of torsion bars TX is made of a rod-shaped elastic member having at least circumferential elasticity, and is aligned along the first swing axis AX.
  • the swinging part 22 has an annular swinging frame SX whose outer peripheral side surface is connected to the other end of each of the pair of torsion bars TX.
  • each swinging portion 22 is connected to the side surface of the inner peripheral portion of the swinging frame SX and aligned in a direction perpendicular to the pair of torsion bars TX (a direction along the second swinging axis AY). It has a pair of torsion bars (second torsion bar) TY and a swing plate SY whose outer peripheral side surface is connected to the other end of each of the pair of torsion bars TY.
  • Each of the pair of torsion bars TY is composed of a rod-like elastic member having at least circumferential elasticity.
  • the swing frame SX swings around the first swing axis AX (about the first swing axis AX), and the swing plate SY swings between the first and second swing axes. Swing around axes AX and AY.
  • a light reflecting film 24 is formed on the swing plate SY. Accordingly, the light reflecting surface 12A of the light reflecting film 24 swings around the first and second swing axes AX and AY orthogonal to each other together with the swing plate SY.
  • the oscillating mirror 20 functions as a scanning unit that scans the scanning region R0 using the emitted light L1 in the optical scanning device SC by continuously changing the reflection direction of the emitted light L1.
  • the oscillating mirror 20 includes an electrode group (hereinafter referred to as a drive electrode group) 23 to which drive signals (first and second drive signals) DX and DY from the drive circuit 30 are supplied.
  • the drive electrode group 23 includes a first drive electrode 23X to which a first drive signal DX is supplied and a second drive electrode 23Y to which a second drive signal DY is supplied.
  • the swing unit 22 swings around the first swing axis AX by the first drive signal DX, and swings around the second swing axis AY by the second drive signal DY.
  • the oscillating mirror 20 generates an oscillating force generating unit (a driving force of the oscillating unit 22) that generates an oscillating force that oscillates the oscillating unit 22 by applying the drive signals DX and DY (see FIG. Not shown).
  • the swinging force of the swinging unit 22 include piezoelectric, electromagnetic, electrostatic or thermal force.
  • the oscillating mirror 20 has a detection unit (not shown) that detects the oscillating state of the oscillating unit 22 (light reflecting surface 12A).
  • the detection unit detects the swinging state of the swinging unit 22, for example, the direction of the swinging plate SY (swing angles about the first and second swinging axes AX and AY with respect to the fixed unit 21) piezoelectrically and electrostatically. Detecting electromagnetically or thermally.
  • the oscillating mirror 20 is an electrode group (hereinafter referred to as a detection electrode group) 25 that outputs signals (hereinafter referred to as detection signals) EX and EY indicating the oscillating state of the oscillating part 22 detected by the detection unit.
  • the detection electrode group 25 includes a first detection electrode 25X that outputs the swing angle of the swing portion 22 around the first swing axis AX as a potential difference, and a second detection electrode 25X. And a second detection electrode 25Y that outputs a swing angle around the swing axis AY as a potential difference.
  • the drive circuit 30 includes a drive signal generation unit 31 that generates the drive signals DX and DY.
  • the drive circuit 30 also detects the first and second swing axes AX and AY of the swing mirror 20 based on the detection signals EX and EY from the swing mirror 20 (that is, the swing state of the swing mirror 20).
  • a resonance frequency determination unit 32 for determining the surrounding resonance frequency is included. Further, the resonance frequency determination unit 32 determines and monitors the frequency during which the oscillating mirror 20 is oscillating (hereinafter referred to as the oscillating frequency) based on the oscillation state of the oscillating mirror 20.
  • the drive circuit 30 determines the frequency of the first and second drive signals DX and DY based on the change in the ratio of the resonance frequencies around the first and second swing axes AX and AY of the swing mirror 20.
  • it has a drive frequency adjusting unit 33 that adjusts the drive frequency.
  • the drive frequency adjusting unit 33 compares the resonance frequencies around the first and second swing axes AX and AY of the swing unit 22 (light reflecting surface 12A) of the swing mirror 20.
  • the drive signal generation unit 31 generates drive signals DX and DY having the frequency adjusted (determined) by the drive frequency adjustment unit 33.
  • FIG. 3 is a schematic circuit diagram of the drive circuit 30.
  • the drive circuit 30 uses the oscillating mirror 20 as an oscillator (vibrator), and also feeds back the oscillating state of the oscillating mirror 20 to generate the drive signals DX and DY.
  • a circuit (resonance circuit) is formed.
  • the drive circuit 30 constitutes an RC resonance circuit.
  • the drive frequency adjusting unit 33 generates a signal having a predetermined frequency (for example, a target frequency) based on the detection signals EX and EY from the oscillating mirror 20, and this is used as the drive signal generating unit 31.
  • the drive signal generation unit 31 includes a phase shift circuit 31A that shifts the phase of the signal having the frequency and an amplifier 31B that amplifies the signal having the phase shifted.
  • the drive signal generator 31 supplies the amplified signal to the oscillating mirror 20 as drive signals DX and DY.
  • FIG. 4 is a diagram schematically showing the relationship between the drive signals DX and DY generated by the drive circuit 30, the change in the oscillation state of the light reflecting film 24 based on the drive signals DX, and the scanning trajectory of the scanning light L2. .
  • a scanning mode of the scanning region R0 by the optical scanning device SC will be described with reference to FIG.
  • the variable ⁇ 1 is set so that the drive signal DX is a sine wave having a frequency corresponding to the resonance frequency of the torsion bar TX, the swing frame SX, the torsion bar TY, and the swing plate SY of the swing mirror 20.
  • the variable ⁇ 2 is set so that the drive signal DY becomes a sine wave having a frequency corresponding to the resonance frequency of the torsion bar TY and the swing plate SY of the swing mirror 20.
  • the light reflecting film 24 (swing plate SY) resonates around the first swing axis AX and resonates around the second swing axis AY. Therefore, as shown in FIG. 4, when the scanning surface R1 of the scanning region R0 is viewed, the scanning light L2, which is the emitted light L1 reflected by the light reflecting film 24, has a trajectory (trajectory) TR that draws a Lissajous curve. (L2) is shown.
  • the optical scanning device SC has the oscillating mirror 20 that reflects the emitted light L1 and oscillates about the first and second oscillating axes AX and AY that are orthogonal to each other.
  • the scanning region R0 is scanned along the trajectory TR along the Lissajous curve.
  • FIG. 5 is a diagram showing a driving flow of the oscillating mirror 20 by the driving circuit 30.
  • the drive circuit 30 supplies the drive signal DX having the reference resonance frequency f0x and the drive signal DY having the reference resonance frequency f0y to the oscillating mirror 20 by the drive signal generation unit 31 (step S11).
  • the reference resonance frequencies f0x and f0y are, for example, designed resonance frequencies.
  • the resonance frequency determination unit 32 of the drive circuit 30 monitors the oscillating state by the detection signals EX and EY, and oscillates during the oscillation.
  • the oscillation frequency and resonance frequency of the mirror 20 are determined (step S12).
  • the drive frequency adjusting unit 33 detects a change in the resonance frequency of the oscillating mirror 20 (step S13).
  • the resonance frequency comparison unit 33A of the drive frequency adjustment unit 33 compares the resonance frequency every predetermined time (unit time), and changes the resonance frequency equal to or greater than a predetermined value (for example, the resonance frequency f0x changes to the resonance frequency f1x, That the resonance frequency f0y is changed to the resonance frequency f1y). Then, the resonance frequency comparison unit 33A detects a change in the ratio of the resonance frequencies (that is, f0x: f0y has changed to f1x: f1y).
  • the drive frequency adjusting unit 33 determines the target frequencies ftx and fty of the drive signals DX and DY so as to be the designed resonance frequency ratio (f0x: f0y) by the target frequency determining unit 33B (step S14). ). Then, the drive signal generation unit 31 adjusts the drive signals DX and DY so as to be the target frequencies ftx and fty determined by the drive frequency adjustment unit 33 (step S15). The drive circuit 30 operates so as to repeat steps S13 to S15.
  • FIGS. 6A and 6B are diagrams schematically showing the relationship between the change in the resonance frequency of the oscillating mirror 20 and the change in the drive frequencies fx and fy of the drive signals DX and DY based on the change.
  • the generation and adjustment operations of the drive signals DX and DY by the drive circuit 30 will be described with reference to FIGS. 6A and 6B.
  • the oscillating mirror 20 is designed so that the scanning light L2 follows a predetermined trajectory (for example, the trajectory TR in FIG. 4) when operated under predetermined conditions (environmental temperature, humidity, operating time, etc.).
  • a predetermined trajectory for example, the trajectory TR in FIG. 4
  • predetermined conditions environmental temperature, humidity, operating time, etc.
  • the oscillating mirror 20 resonates at the first reference resonance frequency f0x around the first oscillating axis AX, and the drive signal DX having the reference resonance frequency f0x is the largest when supplied. Swings with amplitude. Therefore, when the drive signal DX is the horizontal axis and the gain (level of the detection signal EX) that is the amplitude around the first swing axis AX of the swing mirror 20 is the vertical axis, the first swing of the swing mirror 20 is set.
  • the swing characteristic around the dynamic axis AX is as shown on the upper side of FIG. 6A.
  • the oscillating mirror 20 resonates at the second reference resonance frequency f0y around the second oscillating axis AY under the predetermined condition, and the drive signal DY having the reference resonance frequency f0y is supplied. Swings with the largest amplitude. Therefore, when the drive signal DY is the horizontal axis and the gain (level of the detection signal EY) that is the amplitude around the second swing axis AY of the swing mirror 20 is the vertical axis, the second swing of the swing mirror 20 is performed.
  • the swing characteristic around the dynamic axis AY is as shown in the lower side of FIG. 6A.
  • FIG. 6B is a diagram illustrating the swing characteristics around the first and second swing axes AX and AY of the swing mirror 20 when the swing characteristics are changed.
  • a curve indicating the same swing characteristic as in FIG. 6A is indicated by a broken line.
  • the resonance frequency of the oscillating mirror 20 is shifted in the direction of increasing. Accordingly, as shown in FIG. 6B, the resonance frequency around the first oscillation axis AX of the oscillation mirror 20 (hereinafter referred to as the first resonance frequency fnx) is changed from the first reference resonance frequency f0x to the frequency f1x. Then, it changes by the change amount x1.
  • the resonance frequency of the oscillating mirror 20 around the second oscillating axis AY (hereinafter referred to as the second resonance frequency fny) is changed by the amount of change y1 from the second reference resonance frequency f0y to the frequency f1y. Change.
  • the resonance frequencies fnx and fny of the oscillating mirror 20 and the changes thereof are based on, for example, the designed amplitude value of the oscillating mirror 20 and the change thereof, and the change of the amplitude value and the phase of the drive signals DX and DY. Can be determined by comparing.
  • the scanning region R0 is densely scanned by the Lissajous scan, even when the first and second resonance frequencies fnx and fny of the oscillating mirror 20 are changed, they are different from each other, and the ratio between the two is different. Is preferably approximately the same as the ratio of the reference resonance frequencies f0x and f0y (f0x: f0y, hereinafter referred to as the reference ratio). This is because the trajectory of the scanning light L2 overlaps and the same scanning point is suppressed from being scanned a plurality of times.
  • the amounts of change x1 and y1 of the first and second resonance frequencies fnx and fny are often not the same.
  • the oscillating part 22 of the oscillating mirror 20 is formed by processing a semiconductor substrate, its natural frequency changes at the same ratio as a whole.
  • the first and second resonance frequencies fnx and fny change from the first and second reference resonance frequencies f0x and f0y by a predetermined ratio, but the change amounts x1 and y1 are not the same. .
  • the change amount x1 of the first resonance frequency fnx is relatively small, and the change amount y1 of the second resonance frequency fny is relatively large.
  • the oscillating mirror 20 is oscillated at a ratio different from the reference ratio. Will move. Therefore, particularly when performing a Lissajous scan, the trajectory of the scanning light L2 may change greatly, and the scanning point and the distance measuring point may fluctuate.
  • the drive circuit 30 determines and monitors the first and second resonance frequencies fnx and fny around the first and second swing axes AX and AY of the swing mirror 20, respectively. Then, the drive frequencies fx and fy are adjusted so that the ratio of the first and second resonance frequencies fnx and fny becomes the reference ratio.
  • the drive frequency adjusting unit 33 adjusts the drive frequency fx of the drive signal DX, which is a drive signal having a low frequency, of the drive signals DX and DY, for example, from the resonance frequency f1x.
  • the drive frequencies fx and fy are adjusted so that the drive frequency fy of the drive signal DY, which is a drive signal having a high frequency, is increased by the amount x2, and is decreased by the adjustment amount y2 from the resonance frequency f1y.
  • the resonance frequency comparison unit 33A confirms that the first and second resonance frequencies fnx and fny of the oscillating mirror 20 are out of a predetermined range including a reference ratio (hereinafter referred to as a reference range). judge. Then, the target frequency determination unit 33B determines target frequencies ftx and fty that are targets for adjusting the drive frequencies fx and fy so that the ratio of the oscillation frequencies of the oscillation mirror 20 is within the reference range.
  • the drive signal generator 31 generates drive signals DX and DY having target frequencies ftx and fty and supplies them to the oscillating mirror 20.
  • the oscillating mirror 20 oscillates (oscillates) at a frequency slightly different from the resonance frequencies f1x and f1y.
  • the trajectory TR of the scanning light L2 reflected by the oscillating mirror 20 is stabilized. Therefore, the oscillating mirror 20 oscillates around the first and second oscillation axes AX and AY stably even under different conditions. Accordingly, it is possible to irradiate the scanning region R0 with the scanning light L2 in a stable orbit, and a stable scanning result can be obtained. Further, the distance measurement result based on the scanning result is also stabilized.
  • the drive circuit 30 determines and monitors each of the first and second resonance frequencies fnx and fny of the oscillating mirror 20, and the oscillating mirror 20 stabilizes following this. Then, the drive signals DX and DY that resonate are generated.
  • the drive circuit 30 compares the first and second resonance frequencies fnx and fny of the oscillating mirror 20, and the first and second resonance frequencies fnx and fny are changed based on a change in the ratio of the first and second resonance frequencies fnx and fny.
  • the drive frequency adjusting unit 33 performs the first and second drive when the ratio between the first and second resonance frequencies fnx and fny is within a predetermined range (reference ratio f0x: f0y).
  • the frequencies fx and fy of the first and second drive signals DX and DY are adjusted so that the frequencies fx and fy of the signals DX and DY become the first and second resonance frequencies fnx and fny, respectively.
  • the drive frequency adjusting unit 33 is configured such that when the ratio between the first and second resonance frequencies fnx and fny is out of a predetermined range (for example, when the ratio becomes f1x: f1y), The frequencies fx and fy of the first and second drive signals DX and DY are adjusted so that the frequencies fx and fy of the second drive signals DX and DY become frequencies ftx and fty different from the resonance frequencies fnx and fny. .
  • the oscillation mirror 20 has a ratio of the oscillation frequency within the reference range. Is maintained. Therefore, it is possible to provide the mirror device 12 in which the oscillating mirror 20 is stably oscillated, and the optical scanning device SC and the distance measuring device 10 including the mirror device 12.
  • the drive frequency adjusting unit 33 adjusts both the drive frequencies fx and fy has been described. However, considering that the ratio between the drive frequencies fx and fy falls within the reference range, only one of the drive frequencies fx and fy may be adjusted.
  • the drive frequency adjusting unit 33 sets the frequencies fx and fy of the first and second drive signals DX and DY to the first.
  • the frequencies fx and fy of the first and second drive signals DX and DY are adjusted so as to be the second resonance frequencies fnx and fny, and the ratio of the first and second resonance frequencies fnx and fny is within the predetermined range. If the frequency is out of the range, the frequency of the first and second drive signals DX and DY is adjusted so that one of the first and second drive signals DX and DY has a frequency different from the resonance frequency. Also good.
  • the drive frequency of a drive signal having a relatively high frequency (for example, the drive frequency fy of the drive signal DY) is lowered, and the drive frequency of a drive signal having a relatively low frequency (for example, drive)
  • the oscillating mirror 20 can be resonated without greatly deviating from the resonance frequency (resonance point) of both. That is, it is possible to stably resonate the oscillating mirror 20 while suppressing a decrease in the oscillation amplitude.
  • the drive circuit 30 adjusts the frequencies fx and fy of the drive signals DX and DY according to changes in the first and second resonance frequencies fnx and fny of the oscillating mirror 20 has been described.
  • the drive circuit 30 may generate the drive signals DX and DY so that the ratio between the first oscillation frequency and the second oscillation frequency of the oscillation mirror 20 is within the reference range.
  • the reference range that is the target range of the frequency fx of the drive signal DX and the frequency fy of the drive signal DY adjusted by the drive circuit 30 may be an absolute range or a relative range.
  • the reference range may vary based on the difference between the determined first and second resonance frequencies fnx and fny.
  • the case where the oscillating mirror 20 oscillates around the first and second oscillating axes AX and AY orthogonal to each other has been described.
  • the first and second swing axes AX and AY are not limited to being orthogonal to each other, and may be different from each other.
  • the mirror device 12 includes the oscillating mirror 20 that oscillates around the first and second oscillating shafts AX and AY that are different from each other, and the oscillating mirror 20 includes the first and second oscillating shafts, respectively.
  • a drive circuit 30 that generates first and second drive signals DX and DY for swinging around AX and AY. Further, the drive circuit 30 determines first and second oscillation frequencies around the first and second oscillation axes AX and AY of the oscillation mirror 20 based on the oscillation state of the oscillation mirror 20, respectively.
  • the first and second drive signals DX and DY are generated so that the ratio between the first oscillation frequency and the second oscillation frequency is within a predetermined range. Therefore, it is possible to provide the mirror device 12 having the oscillating mirror 20 that oscillates around the two oscillating axes AX and AY.
  • the mirror device 12 can operate as a mirror other than the optical scanning device SC.
  • the optical scanning device SC can be used for purposes other than distance measurement.
  • the present invention can be implemented as, for example, the mirror device 12, and can also be implemented as the optical scanning device SC or the distance measuring device 10.
  • the mirror device 12 is mounted on a scanning device that performs Lissajous scanning, such as the optical scanning device SC and the distance measuring device 10, or a distance measuring device including the same, so that the scanning trajectory is stabilized and has a great effect. Can be obtained.
  • the present invention can also be implemented as a method for stably oscillating the oscillating mirror 20, for example, by performing the steps shown in FIG. That is, for example, in the method according to the present invention, the first and second drive signals DX and DY are supplied, and the oscillating mirror 20 is moved around the first and second oscillating axes AX and AY which are different from each other. Based on the swinging step S11 and the swinging state of the swinging mirror 20, first and second swinging frequencies around the first and second swinging axes AX and AY of the swinging mirror 20 are determined.
  • the present invention can also be implemented, for example, by installing a program that causes a computer to function as the drive circuit 30 and connecting the computer to the oscillating mirror 20. That is, the program according to the present invention, for example, causes the computer to send the first and second drive signals DX and DY to the oscillating mirror 20 that oscillates around the first and second oscillating axes AX and AY that are different from each other.
  • the first and second oscillation frequencies around the first and second oscillation axes AX and AY of the oscillation mirror 20 are determined based on the oscillation state of the oscillation mirror 20, respectively.
  • the drive circuit 30 is configured to adjust the frequencies fx and fy of the first and second drive signals DX and DY so that the ratio between the swing frequency of the first drive signal and the second swing frequency falls within a predetermined range. Accordingly, it is possible to provide a program for stably driving the oscillating mirror 20 that oscillates around the two oscillating axes AX and AY.

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Abstract

This mirror device comprises a swing mirror that swings about mutually different first and second axes, and a drive circuit that generates first and second drive signals for swinging the swing mirror about the first and second axes. The drive circuit determines the swing frequencies about the first and second axes of the swing mirror on the basis of the swing state of the swing mirror, and generates the first and second drive signals such that the ratio between the first swing frequency and the second swing frequency of the swing mirror falls within a predetermined range.

Description

ミラー装置、光走査装置、測距装置、ミラー装置の制御方法及びプログラムMirror device, optical scanning device, distance measuring device, mirror device control method and program
　本発明は、揺動ミラーを含むミラー装置、当該ミラー装置によって光走査を行う光走査装置、及び当該光走査装置によって光学的な測距を行う測距装置に関する。 The present invention relates to a mirror device including a swing mirror, an optical scanning device that performs optical scanning with the mirror device, and a distance measuring device that performs optical distance measurement with the optical scanning device.
　例えば、測距装置は、光を所定の領域内の物体に照射し、当該物体によって反射された光を検出することで、当該物体までの距離を測定するように構成されている。また、例えば、当該領域内を２次元的に走査する光走査装置を有し、当該領域内における２次元的な測距結果を得る測距装置が知られている。 For example, the distance measuring device is configured to measure the distance to the object by irradiating the object in a predetermined region and detecting the light reflected by the object. Further, for example, a distance measuring device that has an optical scanning device that scans the area in a two-dimensional manner and obtains a two-dimensional distance measurement result in the area is known.
　当該光走査型の測距装置は、例えば、光走査装置として、ＭＥＭＳ（Micro Electro Mechanical Systems）ミラーと、当該ミラーに光を照射する光源と、対象物からの反射光を受光する受光部とを有する。当該光走査装置は、当該ミラーによって反射された光を使用し、当該走査用の領域を２次元的に走査する。例えば、特許文献１には、赤外線パルス光を用いて２次元走査を行うスキャナを有するレーダ装置が開示されている。 For example, the optical scanning type distance measuring device includes, as an optical scanning device, a MEMS (Micro Electro Mechanical Systems) mirror, a light source that irradiates light to the mirror, and a light receiving unit that receives reflected light from an object. Have. The optical scanning device uses the light reflected by the mirror to scan the scanning area two-dimensionally. For example, Patent Document 1 discloses a radar apparatus having a scanner that performs two-dimensional scanning using infrared pulsed light.
特開2003-4851号公報Japanese Patent Laid-Open No. 2003-4851
　ＭＥＭＳミラーなどの可動ミラーは、例えば互いに直交する２つの揺動軸（回転軸）を中心として揺動する光反射面を有する。また、当該ミラーには、当該ミラーを駆動する駆動回路が接続される。当該駆動回路は、例えば、ミラーの光反射面を揺動させる駆動信号を生成し、これをミラーに供給する。 A movable mirror such as a MEMS mirror has a light reflecting surface that oscillates around two oscillating axes (rotating axes) orthogonal to each other, for example. In addition, a drive circuit for driving the mirror is connected to the mirror. The drive circuit generates, for example, a drive signal that swings the light reflecting surface of the mirror, and supplies this to the mirror.
　また、当該可動ミラーは、その材料などに応じた固有の共振周波数を持っている。従って、当該ミラーに当該共振周波数程度の周波数の駆動信号を供給すると、当該ミラーは、共振状態に至って、非共振状態の時よりも大きな振幅で揺動する。従って、当該ミラーを共振させることで、当該ミラーによる光の反射方向範囲が広がり、大きな範囲を走査することができる。 Also, the movable mirror has a specific resonance frequency according to the material. Therefore, when a drive signal having a frequency about the resonance frequency is supplied to the mirror, the mirror reaches a resonance state and oscillates with a larger amplitude than that in the non-resonance state. Therefore, by resonating the mirror, the range of light reflection by the mirror is expanded, and a large range can be scanned.
　しかし、ミラーの共振周波数は、ミラーを構成する材料の温度などによって異なる。従って、例えば、光走査装置の動作環境の変化や、動作時間の進行に伴って、ミラーの共振周波数が変動する。この場合、ミラーの揺動状態、例えば２つの揺動軸周りの揺動周期及び振幅の各々がわずかに変化し、例えば走査領域の形状及びサイズ、並びに光の走査軌道（走査パターン）が変化する場合がある。これらは、光走査装置における走査結果の精度の低下、同様に測距装置における測距結果の精度の低下につながる。 However, the resonance frequency of the mirror varies depending on the temperature of the material constituting the mirror. Therefore, for example, the resonance frequency of the mirror fluctuates as the operating environment of the optical scanning device changes and the operating time advances. In this case, the oscillation state of the mirror, for example, each of the oscillation period and amplitude around the two oscillation axes slightly changes, and for example, the shape and size of the scanning region and the scanning trajectory (scanning pattern) of the light change. There is a case. These lead to a decrease in the accuracy of the scanning result in the optical scanning device, as well as a decrease in the accuracy of the distance measurement result in the distance measuring device.
　特に、当該ミラーを用いてリサージュスキャンを行う場合、２つの揺動軸周りの揺動周期の比が変動することで、走査軌道が大きく変化する。例えば、２つの揺動周期の最小公倍数が小さくなると、１つの走査周期中における走査軌道の重複部分が多くなる。従って、走査領域内における走査ポイントの数が大きく減少し、また、走査領域内における当該走査ポイントの偏りが生じやすくなる。 In particular, when a Lissajous scan is performed using the mirror, the scanning trajectory changes greatly because the ratio of the oscillation period around the two oscillation axes varies. For example, when the least common multiple of the two oscillation cycles is reduced, the overlapping portions of the scanning trajectories in one scanning cycle are increased. Therefore, the number of scanning points in the scanning region is greatly reduced, and the scanning points in the scanning region are likely to be biased.
　本発明は上記した点に鑑みてなされたものであり、安定して２つの揺動軸の周りを揺動する揺動ミラーを有するミラー装置、当該ミラー装置を含む光走査装置及び測距装置を提供することを課題の１つとしている。また、本発明は、２つの揺動軸周りを揺動する揺動ミラーを安定して駆動する方法及びプログラムを提供することを課題の１つとしている。 The present invention has been made in view of the above points, and includes a mirror device having a oscillating mirror that stably oscillates around two oscillating shafts, an optical scanning device including the mirror device, and a distance measuring device. Providing is one of the issues. Another object of the present invention is to provide a method and a program for stably driving a oscillating mirror that oscillates around two oscillation axes.
　請求項１に記載の発明は、互いに異なる第１及び第２の軸の周りを揺動する揺動ミラーと、揺動ミラーがそれぞれ第１及び第２の軸周りを揺動するための第１及び第２の駆動信号を生成する駆動回路と、を有し、駆動回路は、揺動ミラーの揺動状態に基づいて揺動ミラーの第１及び第２の軸周りの揺動周波数を判定し、揺動ミラーの第１の揺動周波数と第２の揺動周波数との比率が所定範囲内となるように第１及び第２の駆動信号を生成することを特徴とする。 According to a first aspect of the present invention, there is provided an oscillating mirror that oscillates around different first and second axes, and a first for the oscillating mirror to oscillate around the first and second axes, respectively. And a drive circuit for generating a second drive signal, and the drive circuit determines a swing frequency around the first and second axes of the swing mirror based on the swing state of the swing mirror. The first drive signal and the second drive signal are generated so that the ratio between the first oscillation frequency and the second oscillation frequency of the oscillation mirror is within a predetermined range.
　また、請求項５に記載の発明は、請求項１に記載のミラー装置と、揺動ミラーに向けて光を出射する光源部と、を有し、揺動ミラーは、光源部からの出射光を反射させることで出射光を用いて所定の領域をリサージュ曲線に沿った軌道で走査する走査部として機能することを特徴とする。 The invention according to claim 5 includes the mirror device according to claim 1 and a light source unit that emits light toward the oscillating mirror, and the oscillating mirror emits light from the light source unit. By reflecting the light, it functions as a scanning unit that scans a predetermined region with a trajectory along the Lissajous curve using the emitted light.
　また、請求項６に記載の発明は、請求項５に記載の光走査装置と、所定の領域内に存在する対象物からの反射光に基づいて対象物までの距離を測定する測距部と、を有することを特徴とする。 According to a sixth aspect of the present invention, there is provided the optical scanning device according to the fifth aspect of the present invention, and a distance measuring unit that measures the distance to the object based on the reflected light from the object existing in a predetermined area. It is characterized by having.
　また、請求項７に記載の発明は、第１及び第２の駆動信号を供給して、揺動ミラーを、互いに異なる第１及び第２の軸の周りを揺動させるステップと、揺動ミラーの揺動状態に基づいて揺動ミラーのそれぞれ第１及び第２の軸周りの第１及び第２の揺動周波数を判定するステップと、第１及び第２の揺動周波数の比率が所定範囲内となるように、第１及び第２の駆動信号の周波数を調節するステップと、を有することを特徴とする。 According to a seventh aspect of the present invention, the first and second drive signals are supplied to cause the oscillating mirror to oscillate around different first and second axes, and the oscillating mirror Determining the first and second oscillation frequencies around the first and second axes of the oscillating mirror based on the oscillating state, and the ratio between the first and second oscillating frequencies is within a predetermined range. Adjusting the frequency of the first and second drive signals so as to be inside.
　また、請求項８に記載の発明は、コンピュータを、互いに異なる第１及び第２の軸の周りを揺動する揺動ミラーに第１及び第２の駆動信号を供給し、揺動ミラーの揺動状態に基づいて揺動ミラーのそれぞれ第１及び第２の軸周りの第１及び第２の揺動周波数を判定し、第１及び第２の揺動周波数の比率が所定範囲内となるように、第１及び第２の駆動信号の周波数を調節する駆動回路として機能させることを特徴とする。 According to an eighth aspect of the present invention, the computer supplies the first and second drive signals to the oscillating mirrors that oscillate around the first and second axes different from each other. The first and second oscillation frequencies around the first and second axes of the oscillating mirror are determined based on the moving state, and the ratio between the first and second oscillation frequencies is within a predetermined range. Further, it is characterized by functioning as a drive circuit for adjusting the frequency of the first and second drive signals.
実施例１に係る測距装置の配置図である。1 is a layout diagram of a distance measuring apparatus according to Embodiment 1. FIG. 実施例１に係る測距装置におけるミラー装置の構成図である。1 is a configuration diagram of a mirror device in a distance measuring device according to Embodiment 1. FIG. 実施例１に係る測距装置におけるミラー装置の駆動回路の回路図である。3 is a circuit diagram of a drive circuit of a mirror device in the distance measuring apparatus according to Embodiment 1. FIG. 実施例１に係る測距装置における揺動ミラーに印加される駆動信号及び光走査部の走査態様を示す図である。FIG. 6 is a diagram illustrating a driving signal applied to a swing mirror and a scanning mode of an optical scanning unit in the distance measuring apparatus according to the first embodiment. 実施例１に係る測距装置におけるミラー装置の駆動フローを示す図である。It is a figure which shows the drive flow of the mirror apparatus in the ranging apparatus which concerns on Example 1. FIG. 実施例１に係る測距装置のミラー装置に印加する駆動信号の周波数の調整例を示す図である。FIG. 6 is a diagram illustrating an example of adjusting the frequency of a drive signal applied to the mirror device of the distance measuring apparatus according to the first embodiment. 実施例１に係る測距装置のミラー装置に印加する駆動信号の周波数の調整例を示す図である。FIG. 6 is a diagram illustrating an example of adjusting the frequency of a drive signal applied to the mirror device of the distance measuring apparatus according to the first embodiment.
　以下に本発明の実施例について詳細に説明する。 Hereinafter, embodiments of the present invention will be described in detail.
　図１は、実施例１に係る測距装置１０の模式的な配置図である。測距装置１０は、所定の領域（以下、走査領域と称する）Ｒ０の光走査を行い、その走査結果に基づいて走査領域Ｒ０内に存在する対象物（測距対象物）ＯＢまでの距離を測定する光測距装置である。図１を用いて、測距装置１０の全体構成について説明する。なお、図１には、走査領域Ｒ０及び対象物ＯＢを模式的に示している。 FIG. 1 is a schematic layout diagram of the distance measuring apparatus 10 according to the first embodiment. The distance measuring device 10 performs optical scanning of a predetermined area (hereinafter referred to as a scanning area) R0, and based on the scanning result, determines a distance to an object (ranging object) OB present in the scanning area R0. It is an optical distance measuring device to measure. The overall configuration of the distance measuring device 10 will be described with reference to FIG. FIG. 1 schematically shows the scanning region R0 and the object OB.
　測距装置１０は、パルス化されたレーザ光（以下、出射光と称する）Ｌ１によって走査領域Ｒ０を周期的に走査し、走査領域Ｒ０内の対象物ＯＢからの反射光Ｌ３を受光することで走査領域Ｒ０内の光走査情報を取得する光走査装置ＳＣを有する。 The distance measuring device 10 periodically scans the scanning region R0 with pulsed laser light (hereinafter referred to as emission light) L1, and receives reflected light L3 from the object OB in the scanning region R0. An optical scanning device SC that acquires optical scanning information in the scanning region R0 is included.
　光走査装置ＳＣは、出射光Ｌ１を生成及び出射する光源部１１を有する。本実施例においては、光源部１１は、出射光Ｌ１として、赤外領域にピーク波長を有するレーザ光を生成するレーザ装置を有する。 The optical scanning device SC includes a light source unit 11 that generates and emits the emitted light L1. In the present embodiment, the light source unit 11 includes a laser device that generates laser light having a peak wavelength in the infrared region as the emitted light L1.
　また、光走査装置ＳＣは、出射光Ｌ１を反射させ、またその反射方向を連続的かつ周期的に変化させることで、出射光Ｌ１を走査領域Ｒ０に向けて出射するミラー装置１２を有する。ミラー装置１２は、光走査装置ＳＣにおける走査部（光掃引部）として機能する。 Further, the optical scanning device SC includes the mirror device 12 that reflects the outgoing light L1 and emits the outgoing light L1 toward the scanning region R0 by changing the reflection direction continuously and periodically. The mirror device 12 functions as a scanning unit (light sweep unit) in the optical scanning device SC.
　ミラー装置１２は、出射光Ｌ１を走査領域Ｒ０に向けて反射させる光反射面１２Ａが設けられた揺動ミラーを有する。本実施例においては、ミラー装置１２は、光反射面１２Ａの向きを変化させることで、出射光Ｌ１が反射する方向を連続的かつ周期的に変化させる。光走査装置ＳＣは、この光反射面１２Ａによって反射された出射光Ｌ１を走査光Ｌ２として用い、走査領域Ｒ０の光走査を行う。 The mirror device 12 has a oscillating mirror provided with a light reflecting surface 12A that reflects the emitted light L1 toward the scanning region R0. In the present embodiment, the mirror device 12 continuously and periodically changes the direction in which the emitted light L1 is reflected by changing the direction of the light reflecting surface 12A. The optical scanning device SC performs the optical scanning of the scanning region R0 using the outgoing light L1 reflected by the light reflecting surface 12A as the scanning light L2.
　なお、図１に示すように、走査領域Ｒ０は、光反射面１２Ａの可動範囲に対応する幅及び高さを有し、走査光Ｌ２が到達及び反射したときに所定強度の反射光Ｌ３を受光可能な距離に対応する奥行を有する仮想の３次元空間である。図１においては、走査領域Ｒ０の外縁を破線で示した。 As shown in FIG. 1, the scanning region R0 has a width and height corresponding to the movable range of the light reflecting surface 12A, and receives the reflected light L3 having a predetermined intensity when the scanning light L2 reaches and reflects. A virtual three-dimensional space having a depth corresponding to a possible distance. In FIG. 1, the outer edge of the scanning region R0 is indicated by a broken line.
　図１に示すように、走査領域Ｒ０内における走査光Ｌ２の光路上に対象物ＯＢが存在する場合、走査光Ｌ２が対象物ＯＢに照射される。また、対象物ＯＢが走査光Ｌ２を反射する特性を持った物体である場合、走査光Ｌ２は対象物ＯＢによって反射される。 As shown in FIG. 1, when the object OB exists on the optical path of the scanning light L2 in the scanning region R0, the scanning light L2 is irradiated to the object OB. Further, when the object OB is an object having a characteristic of reflecting the scanning light L2, the scanning light L2 is reflected by the object OB.
　また、光走査装置ＳＣは、反射光Ｌ３、すなわち走査光Ｌ２が対象物ＯＢに照射されることで対象物ＯＢによって反射された光を受光して検出する受光部１３を有する。受光部１３は、例えば、出射光Ｌ１の波長を含む波長帯域の光を検出する光検出器を含む。受光部１３は、受光した反射光Ｌ３に対して光電変換を行い、反射光Ｌ３に応じた電気信号（以下、受光信号と称する）ＳＲを生成する。 Also, the optical scanning device SC includes a light receiving unit 13 that receives and detects reflected light L3, that is, light reflected by the object OB when the object OB is irradiated with the reflected light L3. The light receiving unit 13 includes, for example, a photodetector that detects light in a wavelength band including the wavelength of the emitted light L1. The light receiving unit 13 performs photoelectric conversion on the received reflected light L3, and generates an electrical signal (hereinafter referred to as a received light signal) SR corresponding to the reflected light L3.
　なお、本実施例の光走査装置ＳＣにおいては、光源部１１とミラー装置１２の光反射面１２Ａとの間の出射光Ｌ１の光路上には、ビームスプリッタＢＳが設けられている。走査光Ｌ２は、対象物ＯＢによって反射されて反射光Ｌ３となり、光反射面１２Ａに向かって戻る。そして、反射光Ｌ３は、光反射面１２Ａによって反射され、ビームスプリッタＢＳによって分離された後、受光部１３によって受光される。なお、光源部１１からの出射光Ｌ１は、ビームスプリッタＢＳを透過してミラー装置１２に向かって進む。 In the optical scanning device SC of the present embodiment, a beam splitter BS is provided on the optical path of the emitted light L1 between the light source unit 11 and the light reflecting surface 12A of the mirror device 12. The scanning light L2 is reflected by the object OB to become reflected light L3, and returns toward the light reflecting surface 12A. The reflected light L3 is reflected by the light reflecting surface 12A, separated by the beam splitter BS, and then received by the light receiving unit 13. The emitted light L1 from the light source unit 11 passes through the beam splitter BS and travels toward the mirror device 12.
　測距装置１０は、受光信号ＳＲに基づいて、対象物ＯＢまでの距離を測定する測距部１４を有する。本実施例においては、測距部１４は、受光信号ＳＲから反射光Ｌ３のパルスを検出し、出射光Ｌ１の出射からの時間差に基づくタイムオブフライト法によって対象物ＯＢ（及びその一部の表面領域）までの距離を測定する。測距部１４は、測定した距離情報を示すデータ（以下、測距データと称する）を生成する。 The distance measuring device 10 includes a distance measuring unit 14 that measures the distance to the object OB based on the light reception signal SR. In the present embodiment, the distance measuring unit 14 detects the pulse of the reflected light L3 from the light reception signal SR, and the object OB (and a part of the surface thereof) by the time-of-flight method based on the time difference from the emission of the emission light L1. Measure the distance to the area. The distance measuring unit 14 generates data (hereinafter referred to as distance measurement data) indicating the measured distance information.
　本実施例においては、測距部１４は、当該測距データに基づいて走査領域Ｒ０の画像化を行う。測距部１４は、走査光Ｌ２の出射方向（すなわちミラー装置１２における光反射面１２Ａの向き）と当該測距データとを対応付けた測距画像データを生成する。 In the present embodiment, the distance measuring unit 14 images the scanning region R0 based on the distance measurement data. The distance measurement unit 14 generates distance measurement image data in which the emission direction of the scanning light L2 (that is, the direction of the light reflecting surface 12A in the mirror device 12) is associated with the distance measurement data.
　また、本実施例においては、測距部１４は、光走査装置ＳＣの走査周期毎、すなわちミラー装置１２の揺動周期毎に１つの測距画像データを生成する。測距部１４は、当該複数の測距画像データを時系列に沿って動画として表示する表示部（図示せず）を有していてもよい。なお、走査周期とは、例えば、走査領域Ｒ０に対する走査を周期的に行う場合において、任意の走査状態（例えば走査光Ｌ２を出射する光反射面１２Ａの向き）の時点から、その後に再度当該走査状態に戻る時点までの期間をいう。 In the present embodiment, the distance measuring unit 14 generates one distance image data for each scanning cycle of the optical scanning device SC, that is, for each oscillation cycle of the mirror device 12. The ranging unit 14 may include a display unit (not shown) that displays the plurality of ranging image data as a moving image in time series. Note that the scanning cycle is, for example, when scanning is periodically performed on the scanning region R0, from the time of an arbitrary scanning state (for example, the direction of the light reflecting surface 12A that emits the scanning light L2), and then the scanning again. The period up to the point of returning to the state.
　このように、光走査装置ＳＣは、走査光Ｌ２（出射光Ｌ１）を用いて走査領域Ｒ０を走査し、その走査結果（光走査情報）を受光信号ＳＲとして出力する。測距装置１０は、当該光走査情報に基づいて対象物ＯＢまでの距離を光学的に測定し、その測距結果を測距データ（又は測距画像データ）として出力する。 Thus, the optical scanning device SC scans the scanning region R0 using the scanning light L2 (emitted light L1), and outputs the scanning result (optical scanning information) as the light receiving signal SR. The distance measuring device 10 optically measures the distance to the object OB based on the optical scanning information, and outputs the distance measurement result as distance measurement data (or distance measurement image data).
　図２は、ミラー装置１２の構成を示す模式的な上面図である。ミラー装置１２は、揺動ミラー２０及び揺動ミラー２０を駆動する駆動回路３０を含む。本実施例においては、揺動ミラー２０は、光反射面１２Ａを有する光反射膜２４を含み、この光反射膜２４が揺動するＭＥＭＳ（Micro Electro Mechanical Systems）ミラーである。 FIG. 2 is a schematic top view showing the configuration of the mirror device 12. The mirror device 12 includes a oscillating mirror 20 and a drive circuit 30 that drives the oscillating mirror 20. In this embodiment, the oscillating mirror 20 is a MEMS (Micro Electro Mechanical Systems) mirror that includes a light reflecting film 24 having a light reflecting surface 12A, and the light reflecting film 24 oscillates.
　より具体的には、揺動ミラー２０は、固定部２１及び揺動部２２を有する。本実施例においては、揺動部２２は、互いに直交する第１及び第２の軸（以下、揺動軸と称する）ＡＸ及びＡＹの周りを揺動する。 More specifically, the oscillating mirror 20 has a fixed portion 21 and an oscillating portion 22. In this embodiment, the swinging part 22 swings around first and second axes (hereinafter referred to as swinging axes) AX and AY that are orthogonal to each other.
　固定部２１は、揺動部２２を揺動可能に支持する支持部として機能する。本実施例においては、固定部２１は、揺動部２２を取り囲み、その内側において揺動部２２を懸架するフレーム（固定枠）を有する。 The fixed portion 21 functions as a support portion that supports the swinging portion 22 so as to be swingable. In the present embodiment, the fixed portion 21 has a frame (fixed frame) that surrounds the swing portion 22 and suspends the swing portion 22 inside thereof.
　揺動部２２は、各々の一端が固定部２１の内側に固定された一対のトーションバー（第１のトーションバー）ＴＸを含む。一対のトーションバーＴＸの各々は、少なくとも周方向の弾性を有する棒状の弾性部材からなり、第１の揺動軸ＡＸに沿って整列している。また、揺動部２２は、外周部側面が一対のトーションバーＴＸの各々の他端に接続された環状の揺動枠ＳＸを有する。 The rocking part 22 includes a pair of torsion bars (first torsion bars) TX each having one end fixed inside the fixing part 21. Each of the pair of torsion bars TX is made of a rod-shaped elastic member having at least circumferential elasticity, and is aligned along the first swing axis AX. Further, the swinging part 22 has an annular swinging frame SX whose outer peripheral side surface is connected to the other end of each of the pair of torsion bars TX.
　また、揺動部２２は、各々の一端が揺動枠ＳＸの内周部側面に接続され、一対のトーションバーＴＸに直交する方向（第２の揺動軸ＡＹに沿った方向）に整列した一対のトーションバー（第２のトーションバー）ＴＹと、外周部側面が一対のトーションバーＴＹの各々の他端に接続された揺動板ＳＹと、を有する。一対のトーションバーＴＹの各々は、少なくとも周方向の弾性を有する棒状の弾性部材からなる。 Further, each swinging portion 22 is connected to the side surface of the inner peripheral portion of the swinging frame SX and aligned in a direction perpendicular to the pair of torsion bars TX (a direction along the second swinging axis AY). It has a pair of torsion bars (second torsion bar) TY and a swing plate SY whose outer peripheral side surface is connected to the other end of each of the pair of torsion bars TY. Each of the pair of torsion bars TY is composed of a rod-like elastic member having at least circumferential elasticity.
　本実施例においては、揺動枠ＳＸは第１の揺動軸ＡＸの周りを（第１の揺動軸ＡＸを中心として）揺動し、揺動板ＳＹは第１及び第２の揺動軸ＡＸ及びＡＹの周りを揺動する。また、揺動板ＳＹ上には光反射膜２４が形成されている。従って、光反射膜２４の光反射面１２Ａは、揺動板ＳＹと共に、互いに直交する第１及び第２の揺動軸ＡＸ及びＡＹの周りを揺動する。 In this embodiment, the swing frame SX swings around the first swing axis AX (about the first swing axis AX), and the swing plate SY swings between the first and second swing axes. Swing around axes AX and AY. A light reflecting film 24 is formed on the swing plate SY. Accordingly, the light reflecting surface 12A of the light reflecting film 24 swings around the first and second swing axes AX and AY orthogonal to each other together with the swing plate SY.
　光反射面１２Ａが揺動することで、出射光Ｌ１の反射方向、すなわち走査光Ｌ２の出射方向が周期的かつ連続的に変化する。揺動ミラー２０は、出射光Ｌ１の反射方向を連続的に変化させることで、光走査装置ＳＣ内において、出射光Ｌ１を用いて走査領域Ｒ０を走査する走査部として機能する。 When the light reflecting surface 12A swings, the reflection direction of the outgoing light L1, that is, the outgoing direction of the scanning light L2, changes periodically and continuously. The oscillating mirror 20 functions as a scanning unit that scans the scanning region R0 using the emitted light L1 in the optical scanning device SC by continuously changing the reflection direction of the emitted light L1.
　また、揺動ミラー２０は、駆動回路３０からの駆動用の信号（第１及び第２の駆動信号）ＤＸ及びＤＹが供給される電極群（以下、駆動電極群と称する）２３を有する。駆動電極群２３は、第１の駆動信号ＤＸが供給される第１の駆動電極２３Ｘと、第２の駆動信号ＤＹが供給される第２の駆動電極２３Ｙとを含む。揺動部２２は、第１の駆動信号ＤＸによって第１の揺動軸ＡＸの周りを揺動し、第２の駆動信号ＤＹによって第２の揺動軸ＡＹの周りを揺動する。 Further, the oscillating mirror 20 includes an electrode group (hereinafter referred to as a drive electrode group) 23 to which drive signals (first and second drive signals) DX and DY from the drive circuit 30 are supplied. The drive electrode group 23 includes a first drive electrode 23X to which a first drive signal DX is supplied and a second drive electrode 23Y to which a second drive signal DY is supplied. The swing unit 22 swings around the first swing axis AX by the first drive signal DX, and swings around the second swing axis AY by the second drive signal DY.
　なお、本実施例においては、揺動ミラー２０は、駆動信号ＤＸ及びＤＹの印加によって揺動部２２が揺動する揺動力（揺動部２２の駆動力）を生成する揺動力生成部（図示せず）を有する。揺動部２２の揺動力としては、例えば、圧電的、電磁気的、静電気的又は熱的な力が挙げられる。 In the present embodiment, the oscillating mirror 20 generates an oscillating force generating unit (a driving force of the oscillating unit 22) that generates an oscillating force that oscillates the oscillating unit 22 by applying the drive signals DX and DY (see FIG. Not shown). Examples of the swinging force of the swinging unit 22 include piezoelectric, electromagnetic, electrostatic or thermal force.
　また、本実施例においては、揺動ミラー２０は、揺動部２２（光反射面１２Ａ）の揺動状態を検出する検出部（図示せず）を有する。当該検出部は、揺動部２２の揺動状態、例えば揺動板ＳＹの向き（固定部２１に対する第１及び第２の揺動軸ＡＸ及びＡＹ周りの揺動角度）を圧電的、静電気的、電磁気的又は熱的に検出する。 In the present embodiment, the oscillating mirror 20 has a detection unit (not shown) that detects the oscillating state of the oscillating unit 22 (light reflecting surface 12A). The detection unit detects the swinging state of the swinging unit 22, for example, the direction of the swinging plate SY (swing angles about the first and second swinging axes AX and AY with respect to the fixed unit 21) piezoelectrically and electrostatically. Detecting electromagnetically or thermally.
　揺動ミラー２０は、当該検出部によって検出された揺動部２２の揺動状態を示す信号（以下、検出信号と称する）ＥＸ及びＥＹを出力する電極群（以下、検出電極群と称する）２５を有する。本実施例においては、検出電極群２５は、揺動部２２の第１の揺動軸ＡＸ周りの揺動角度を電位差として出力する第１の検出電極２５Ｘと、揺動部２２の第２の揺動軸ＡＹ周りの揺動角度を電位差として出力する第２の検出電極２５Ｙとを含む。 The oscillating mirror 20 is an electrode group (hereinafter referred to as a detection electrode group) 25 that outputs signals (hereinafter referred to as detection signals) EX and EY indicating the oscillating state of the oscillating part 22 detected by the detection unit. Have In the present embodiment, the detection electrode group 25 includes a first detection electrode 25X that outputs the swing angle of the swing portion 22 around the first swing axis AX as a potential difference, and a second detection electrode 25X. And a second detection electrode 25Y that outputs a swing angle around the swing axis AY as a potential difference.
　次に、駆動回路３０の構成について説明する。駆動回路３０は、駆動信号ＤＸ及びＤＹを生成する駆動信号生成部３１を有する。また、駆動回路３０は、揺動ミラー２０からの検出信号ＥＸ及びＥＹ（すなわち揺動ミラー２０の揺動状態）に基づいて、揺動ミラー２０の第１及び第２の揺動軸ＡＸ及びＡＹ周りの共振周波数を判定する共振周波数判定部３２を有する。また、共振周波数判定部３２は、揺動ミラー２０の揺動状態に基づいて、揺動ミラー２０の揺動中の周波数（以下、揺動周波数と称する）を判定及び監視する。 Next, the configuration of the drive circuit 30 will be described. The drive circuit 30 includes a drive signal generation unit 31 that generates the drive signals DX and DY. The drive circuit 30 also detects the first and second swing axes AX and AY of the swing mirror 20 based on the detection signals EX and EY from the swing mirror 20 (that is, the swing state of the swing mirror 20). A resonance frequency determination unit 32 for determining the surrounding resonance frequency is included. Further, the resonance frequency determination unit 32 determines and monitors the frequency during which the oscillating mirror 20 is oscillating (hereinafter referred to as the oscillating frequency) based on the oscillation state of the oscillating mirror 20.
　また、駆動回路３０は、揺動ミラー２０の第１及び第２の揺動軸ＡＸ及びＡＹ周りの共振周波数の比率の変化に基づいて、第１及び第２の駆動信号ＤＸ及びＤＹの周波数（以下、駆動周波数と称する場合がある）を調節する駆動周波数調節部３３を有する。 Further, the drive circuit 30 determines the frequency of the first and second drive signals DX and DY based on the change in the ratio of the resonance frequencies around the first and second swing axes AX and AY of the swing mirror 20. Hereinafter, it has a drive frequency adjusting unit 33 that adjusts the drive frequency.
　本実施例においては、駆動周波数調節部３３は、揺動ミラー２０における揺動部２２（光反射面１２Ａ）の第１及び第２の揺動軸ＡＸ及びＡＹ周りの共振周波数の各々を比較する共振周波数比較部３３Ａと、駆動信号ＤＸ及びＤＹの周波数を調節するための目標値（以下、目標周波数と称する）を決定する目標周波数決定部３３Ｂとを有する。駆動信号生成部３１は、駆動周波数調節部３３によって調節された（決定された）周波数を有する駆動信号ＤＸ及びＤＹを生成する。 In the present embodiment, the drive frequency adjusting unit 33 compares the resonance frequencies around the first and second swing axes AX and AY of the swing unit 22 (light reflecting surface 12A) of the swing mirror 20. The resonance frequency comparison unit 33A and a target frequency determination unit 33B that determines a target value (hereinafter referred to as a target frequency) for adjusting the frequencies of the drive signals DX and DY. The drive signal generation unit 31 generates drive signals DX and DY having the frequency adjusted (determined) by the drive frequency adjustment unit 33.
　図３は、駆動回路３０の模式的な回路図である。本実施例においては、駆動回路３０は、揺動ミラー２０を発振子（振動子）として用い、また揺動ミラー２０の揺動状態をフィードバックして駆動信号ＤＸ及びＤＹを生成するフィードバック型の発振回路（共振回路）を構成する。 FIG. 3 is a schematic circuit diagram of the drive circuit 30. In this embodiment, the drive circuit 30 uses the oscillating mirror 20 as an oscillator (vibrator), and also feeds back the oscillating state of the oscillating mirror 20 to generate the drive signals DX and DY. A circuit (resonance circuit) is formed.
　本実施例においては、駆動回路３０は、ＲＣ共振回路を構成する。例えば図３に示すように、駆動周波数調節部３３は、揺動ミラー２０からの検出信号ＥＸ及びＥＹに基づいて所定の周波数（例えば目標周波数）の信号を生成し、これを駆動信号生成部３１に供給する。駆動信号生成部３１は、当該周波数の信号の位相をシフトする位相シフト回路３１Ａと、当該位相がシフトした信号を増幅する増幅器３１Ｂとを有する。駆動信号生成部３１は、当該増幅された信号を駆動信号ＤＸ及びＤＹとして揺動ミラー２０に供給する。 In this embodiment, the drive circuit 30 constitutes an RC resonance circuit. For example, as shown in FIG. 3, the drive frequency adjusting unit 33 generates a signal having a predetermined frequency (for example, a target frequency) based on the detection signals EX and EY from the oscillating mirror 20, and this is used as the drive signal generating unit 31. To supply. The drive signal generation unit 31 includes a phase shift circuit 31A that shifts the phase of the signal having the frequency and an amplifier 31B that amplifies the signal having the phase shifted. The drive signal generator 31 supplies the amplified signal to the oscillating mirror 20 as drive signals DX and DY.
　図４は、駆動回路３０が生成する駆動信号ＤＸ及びＤＹと、これに基づいた光反射膜２４の揺動状態の変化及び走査光Ｌ２の走査軌道と、の関係を模式的に示す図である。図４を用いて、光走査装置ＳＣによる走査領域Ｒ０の走査態様について説明する。 FIG. 4 is a diagram schematically showing the relationship between the drive signals DX and DY generated by the drive circuit 30, the change in the oscillation state of the light reflecting film 24 based on the drive signals DX, and the scanning trajectory of the scanning light L2. . A scanning mode of the scanning region R0 by the optical scanning device SC will be described with reference to FIG.
　まず、駆動信号ＤＸは、Ａ1及びＢ1を定数とし、θ1を変数としたとき、ＤＸ（θ1）＝Ａ1ｓｉｎ（θ1＋Ｂ1）の式で示される正弦波の信号である。また、駆動信号ＤＹは、Ａ2及びＢ2を定数とし、θ2を変数としたとき、ＤＹ（θ2）＝Ａ2ｓｉｎ（θ2＋Ｂ2）の式で示される正弦波の信号である。 First, the drive signal DX is a sine wave signal represented by the formula DX (θ 1 ) = A 1 sin (θ 1 + B 1 ), where A 1 and B 1 are constants and θ 1 is a variable. . The drive signal DY is a sine wave signal represented by the equation DY (θ 2 ) = A 2 sin (θ 2 + B 2 ), where A 2 and B 2 are constants and θ 2 is a variable. .
　また、変数θ1は、駆動信号ＤＸが、揺動ミラー２０のトーションバーＴＸ、揺動枠ＳＸ、トーションバーＴＹ及び揺動板ＳＹの共振周波数に対応する周波数の正弦波となるように設定される。また、変数θ2は、駆動信号ＤＹが、揺動ミラー２０のトーションバーＴＹ及び揺動板ＳＹの共振周波数に対応する周波数の正弦波となるように設定される。 The variable θ 1 is set so that the drive signal DX is a sine wave having a frequency corresponding to the resonance frequency of the torsion bar TX, the swing frame SX, the torsion bar TY, and the swing plate SY of the swing mirror 20. The The variable θ 2 is set so that the drive signal DY becomes a sine wave having a frequency corresponding to the resonance frequency of the torsion bar TY and the swing plate SY of the swing mirror 20.
　従って、光反射膜２４（揺動板ＳＹ）は、第１の揺動軸ＡＸを中心に共振し、かつ第２の揺動軸ＡＹを中心に共振する。従って、図４に示すように、走査領域Ｒ０の走査面Ｒ１を見たとき、光反射膜２４に反射された出射光Ｌ１である走査光Ｌ２は、リサージュ曲線を描くような軌道（軌跡）ＴＲ（Ｌ２）を示す。 Therefore, the light reflecting film 24 (swing plate SY) resonates around the first swing axis AX and resonates around the second swing axis AY. Therefore, as shown in FIG. 4, when the scanning surface R1 of the scanning region R0 is viewed, the scanning light L2, which is the emitted light L1 reflected by the light reflecting film 24, has a trajectory (trajectory) TR that draws a Lissajous curve. (L2) is shown.
　換言すれば、本実施例においては、光走査装置ＳＣは、出射光Ｌ１を反射させかつ互いに直交する第１及び第２の揺動軸ＡＸ及びＡＹを中心に揺動する揺動ミラー２０を有し、リサージュ曲線に沿った軌道ＴＲで走査領域Ｒ０を走査する走査態様を有する。 In other words, in this embodiment, the optical scanning device SC has the oscillating mirror 20 that reflects the emitted light L1 and oscillates about the first and second oscillating axes AX and AY that are orthogonal to each other. In addition, the scanning region R0 is scanned along the trajectory TR along the Lissajous curve.
　図５は、駆動回路３０による揺動ミラー２０の駆動フローを示す図である。まず、駆動回路３０は、駆動信号生成部３１によって、基準共振周波数ｆ０ｘの駆動信号ＤＸ及び基準共振周波数ｆ０ｙの駆動信号ＤＹを揺動ミラー２０に供給する（ステップＳ１１）。基準共振周波数ｆ０ｘ及びｆ０ｙは、例えば設計上の共振周波数である。 FIG. 5 is a diagram showing a driving flow of the oscillating mirror 20 by the driving circuit 30. FIG. First, the drive circuit 30 supplies the drive signal DX having the reference resonance frequency f0x and the drive signal DY having the reference resonance frequency f0y to the oscillating mirror 20 by the drive signal generation unit 31 (step S11). The reference resonance frequencies f0x and f0y are, for example, designed resonance frequencies.
　次に、駆動回路３０の共振周波数判定部３２は、揺動ミラー２０が共振状態（定常状態）に至った後、その揺動状態を検出信号ＥＸ及びＥＹによって監視し、揺動中の揺動ミラー２０の揺動周波数及び共振周波数を判定する（ステップＳ１２）。 Next, after the oscillating mirror 20 reaches the resonance state (steady state), the resonance frequency determination unit 32 of the drive circuit 30 monitors the oscillating state by the detection signals EX and EY, and oscillates during the oscillation. The oscillation frequency and resonance frequency of the mirror 20 are determined (step S12).
　また、駆動周波数調節部３３は、揺動ミラー２０の共振周波数の変化を検出する（ステップＳ１３）。例えば、駆動周波数調節部３３の共振周波数比較部３３Ａは、共振周波数を所定時間（単位時間）毎に比較し、所定値以上の共振周波数の変化（例えば共振周波数ｆ０ｘが共振周波数ｆ１ｘに変化し、共振周波数ｆ０ｙが共振周波数ｆ１ｙに変化したこと）を検出する。そして、共振周波数比較部３３Ａは、共振周波数の比率の変化（ｆ０ｘ：ｆ０ｙがｆ１ｘ：ｆ１ｙに変化したこと）を検出する。 Further, the drive frequency adjusting unit 33 detects a change in the resonance frequency of the oscillating mirror 20 (step S13). For example, the resonance frequency comparison unit 33A of the drive frequency adjustment unit 33 compares the resonance frequency every predetermined time (unit time), and changes the resonance frequency equal to or greater than a predetermined value (for example, the resonance frequency f0x changes to the resonance frequency f1x, That the resonance frequency f0y is changed to the resonance frequency f1y). Then, the resonance frequency comparison unit 33A detects a change in the ratio of the resonance frequencies (that is, f0x: f0y has changed to f1x: f1y).
　続いて、駆動周波数調節部３３は、目標周波数決定部３３Ｂによって、設計上の共振周波数の比率（ｆ０ｘ：ｆ０ｙ）となるような駆動信号ＤＸ及びＤＹの目標周波数ｆｔｘ及びｆｔｙを決定する（ステップＳ１４）。そして、駆動信号生成部３１は、駆動周波数調節部３３が決定した目標周波数ｆｔｘ及びｆｔｙとなるように駆動信号ＤＸ及びＤＹを調節する（ステップＳ１５）。駆動回路３０は、ステップＳ１３～Ｓ１５を繰り返すように動作する。 Subsequently, the drive frequency adjusting unit 33 determines the target frequencies ftx and fty of the drive signals DX and DY so as to be the designed resonance frequency ratio (f0x: f0y) by the target frequency determining unit 33B (step S14). ). Then, the drive signal generation unit 31 adjusts the drive signals DX and DY so as to be the target frequencies ftx and fty determined by the drive frequency adjustment unit 33 (step S15). The drive circuit 30 operates so as to repeat steps S13 to S15.
　図６Ａ及び図６Ｂは、揺動ミラー２０の共振周波数の変化と、これに基づいた駆動信号ＤＸ及びＤＹの駆動周波数ｆｘ及びｆｙの変化との関係を模式的に示す図である。図６Ａ及び図６Ｂを用いて、駆動回路３０による駆動信号ＤＸ及びＤＹの生成及び調節動作について説明する。 6A and 6B are diagrams schematically showing the relationship between the change in the resonance frequency of the oscillating mirror 20 and the change in the drive frequencies fx and fy of the drive signals DX and DY based on the change. The generation and adjustment operations of the drive signals DX and DY by the drive circuit 30 will be described with reference to FIGS. 6A and 6B.
　まず、揺動ミラー２０には、所定の条件下（環境温度、湿度及び動作時間など）で動作した場合に走査光Ｌ２が所定の軌道（例えば図４の軌道ＴＲ）をたどるように設計されている。図６Ａは、当該所定の条件下での揺動ミラー２０の第１及び第２の揺動軸ＡＸ及びＡＹ周りの揺動特性を示す図である。 First, the oscillating mirror 20 is designed so that the scanning light L2 follows a predetermined trajectory (for example, the trajectory TR in FIG. 4) when operated under predetermined conditions (environmental temperature, humidity, operating time, etc.). Yes. FIG. 6A is a diagram illustrating the swing characteristics of the swing mirror 20 around the first and second swing axes AX and AY under the predetermined condition.
　揺動ミラー２０は、当該所定の条件下では、第１の揺動軸ＡＸ周りにおいて第１の基準共振周波数ｆ０ｘで共振し、この基準共振周波数ｆ０ｘの駆動信号ＤＸが供給されることで最も大きな振幅で揺動する。従って、駆動信号ＤＸを横軸、揺動ミラー２０の第１の揺動軸ＡＸ周りの振幅であるゲイン（検出信号ＥＸのレベル）を縦軸とした場合、揺動ミラー２０の第１の揺動軸ＡＸ周りの揺動特性は、図６Ａの上側に示すような特性を示す。 Under the predetermined condition, the oscillating mirror 20 resonates at the first reference resonance frequency f0x around the first oscillating axis AX, and the drive signal DX having the reference resonance frequency f0x is the largest when supplied. Swings with amplitude. Therefore, when the drive signal DX is the horizontal axis and the gain (level of the detection signal EX) that is the amplitude around the first swing axis AX of the swing mirror 20 is the vertical axis, the first swing of the swing mirror 20 is set. The swing characteristic around the dynamic axis AX is as shown on the upper side of FIG. 6A.
　同様に、揺動ミラー２０は、当該所定の条件下では、第２の揺動軸ＡＹ周りにおいて第２の基準共振周波数ｆ０ｙで共振し、この基準共振周波数ｆ０ｙの駆動信号ＤＹが供給されることで最も大きな振幅で揺動する。従って、駆動信号ＤＹを横軸、揺動ミラー２０の第２の揺動軸ＡＹ周りの振幅であるゲイン（検出信号ＥＹのレベル）を縦軸とした場合、揺動ミラー２０の第２の揺動軸ＡＹ周りの揺動特性は、図６Ａの下側に示すような特性を示す。 Similarly, the oscillating mirror 20 resonates at the second reference resonance frequency f0y around the second oscillating axis AY under the predetermined condition, and the drive signal DY having the reference resonance frequency f0y is supplied. Swings with the largest amplitude. Therefore, when the drive signal DY is the horizontal axis and the gain (level of the detection signal EY) that is the amplitude around the second swing axis AY of the swing mirror 20 is the vertical axis, the second swing of the swing mirror 20 is performed. The swing characteristic around the dynamic axis AY is as shown in the lower side of FIG. 6A.
　次に、揺動ミラー２０は、例えば上記した条件から外れた条件で動作する場合、揺動部２２の材料などの固有振動数が変化し、これによって異なる揺動特性を示す。図６Ｂは、揺動特性が変化した際の揺動ミラー２０の第１及び第２の揺動軸ＡＸ及びＡＹ周りの揺動特性を示す図である。なお、図６Ｂには、図６Ａと同様の揺動特性を示す曲線を破線で示した。 Next, when the oscillating mirror 20 operates under conditions other than the above-described conditions, for example, the natural frequency of the material of the oscillating portion 22 changes, and thus exhibits different oscillation characteristics. FIG. 6B is a diagram illustrating the swing characteristics around the first and second swing axes AX and AY of the swing mirror 20 when the swing characteristics are changed. In FIG. 6B, a curve indicating the same swing characteristic as in FIG. 6A is indicated by a broken line.
　例えば、揺動ミラー２０が比較的高温となる環境下又は動作時間で動作する場合、揺動ミラー２０の共振周波数は高くなる方向にズレる。従って、図６Ｂに示すように、揺動ミラー２０の第１の揺動軸ＡＸ周りの共振周波数（以下、第１の共振周波数ｆｎｘと称する）は、第１の基準共振周波数ｆ０ｘから、周波数ｆ１ｘに、変化量ｘ１だけ変化する。同様に、揺動ミラー２０の第２の揺動軸ＡＹ周りの共振周波数（以下、第２の共振周波数ｆｎｙと称する）は、第２の基準共振周波数ｆ０ｙから、周波数ｆ１ｙに、変化量ｙ１だけ変化する。 For example, when the oscillating mirror 20 operates in an environment where the temperature of the oscillating mirror 20 is relatively high or during an operation time, the resonance frequency of the oscillating mirror 20 is shifted in the direction of increasing. Accordingly, as shown in FIG. 6B, the resonance frequency around the first oscillation axis AX of the oscillation mirror 20 (hereinafter referred to as the first resonance frequency fnx) is changed from the first reference resonance frequency f0x to the frequency f1x. Then, it changes by the change amount x1. Similarly, the resonance frequency of the oscillating mirror 20 around the second oscillating axis AY (hereinafter referred to as the second resonance frequency fny) is changed by the amount of change y1 from the second reference resonance frequency f0y to the frequency f1y. Change.
　なお、揺動ミラー２０の共振周波数ｆｎｘ及びｆｎｙ並びにその変化は、例えば、設計上の揺動ミラー２０の振幅値及びその変化に基づいて、また当該振幅値の変化と駆動信号ＤＸ及びＤＹの位相とを比較することで、判定することができる。 Note that the resonance frequencies fnx and fny of the oscillating mirror 20 and the changes thereof are based on, for example, the designed amplitude value of the oscillating mirror 20 and the change thereof, and the change of the amplitude value and the phase of the drive signals DX and DY. Can be determined by comparing.
　ここで、走査領域Ｒ０をリサージュスキャンによって密に走査することを考慮すると、揺動ミラー２０の第１及び第２の共振周波数ｆｎｘ及びｆｎｙが変化した場合でも、両者は互いに異なり、また両者の比率が基準共振周波数ｆ０ｘ及びｆ０ｙの比率（ｆ０ｘ：ｆ０ｙ、以下、基準比率と称する）と同程度であることが好ましい。これによって、走査光Ｌ２の軌道が重複し、同一の走査ポイントを複数回に亘って走査することが抑制されるからである。 Here, considering that the scanning region R0 is densely scanned by the Lissajous scan, even when the first and second resonance frequencies fnx and fny of the oscillating mirror 20 are changed, they are different from each other, and the ratio between the two is different. Is preferably approximately the same as the ratio of the reference resonance frequencies f0x and f0y (f0x: f0y, hereinafter referred to as the reference ratio). This is because the trajectory of the scanning light L2 overlaps and the same scanning point is suppressed from being scanned a plurality of times.
　しかし、第１及び第２の共振周波数ｆｎｘ及びｆｎｙの各々の変化量ｘ１及びｙ１は、同一ではない場合が多い。例えば、揺動ミラー２０の揺動部２２が半導体基板を加工することで形成されている場合、その固有振動数は全体的に同一比率で変化する。これによって、第１及び第２の共振周波数ｆｎｘ及びｆｎｙは、それぞれ、第１及び第２の基準共振周波数ｆ０ｘ及びｆ０ｙから、所定の割合だけ変化するものの、その変化量ｘ１及びｙ１は同一ではない。 However, the amounts of change x1 and y1 of the first and second resonance frequencies fnx and fny are often not the same. For example, when the oscillating part 22 of the oscillating mirror 20 is formed by processing a semiconductor substrate, its natural frequency changes at the same ratio as a whole. As a result, the first and second resonance frequencies fnx and fny change from the first and second reference resonance frequencies f0x and f0y by a predetermined ratio, but the change amounts x1 and y1 are not the same. .
　例えば、第２の基準共振周波数ｆ０ｙが第２の基準共振周波数ｆ０ｘよりも高い場合、第１の共振周波数ｆｎｘの変化量ｘ１は比較的小さく、第２の共振周波数ｆｎｙの変化量ｙ１は比較的大きい。 For example, when the second reference resonance frequency f0y is higher than the second reference resonance frequency f0x, the change amount x1 of the first resonance frequency fnx is relatively small, and the change amount y1 of the second resonance frequency fny is relatively large.
　従って、第１及び第２の共振周波数ｆｎｘ及びｆｎｙが変化した場合に、その変化後の共振周波数で駆動信号ＤＸ及びＤＹを供給しても、基準比率とは異なる比率で揺動ミラー２０が揺動することとなる。従って、特にリサージュスキャンを行う場合、走査光Ｌ２の軌道が大きく変化し、走査ポイント及び測距ポイントが変動する場合がある。 Therefore, when the first and second resonance frequencies fnx and fny change, even if the drive signals DX and DY are supplied at the changed resonance frequency, the oscillating mirror 20 is oscillated at a ratio different from the reference ratio. Will move. Therefore, particularly when performing a Lissajous scan, the trajectory of the scanning light L2 may change greatly, and the scanning point and the distance measuring point may fluctuate.
　これに対し、本実施例においては、駆動回路３０は、揺動ミラー２０のそれぞれ第１及び第２の揺動軸ＡＸ及びＡＹ周りの第１及び第２の共振周波数ｆｎｘ及びｆｎｙを判定及び監視し、これら第１及び第２の共振周波数ｆｎｘ及びｆｎｙの比率が基準比率となるように、駆動周波数ｆｘ及びｆｙを調節する。 In contrast, in this embodiment, the drive circuit 30 determines and monitors the first and second resonance frequencies fnx and fny around the first and second swing axes AX and AY of the swing mirror 20, respectively. Then, the drive frequencies fx and fy are adjusted so that the ratio of the first and second resonance frequencies fnx and fny becomes the reference ratio.
　本実施例においては、図６Ｂに示すように、駆動周波数調節部３３は、例えば、駆動信号ＤＸ及びＤＹのうち、周波数が低い駆動信号である駆動信号ＤＸの駆動周波数ｆｘを共振周波数ｆ１ｘから調節量ｘ２だけ上げ、周波数が高い駆動信号である駆動信号ＤＹの駆動周波数ｆｙを共振周波数ｆ１ｙから調節量ｙ２だけ下げるように、駆動周波数ｆｘ及びｆｙを調節する。 In this embodiment, as shown in FIG. 6B, the drive frequency adjusting unit 33 adjusts the drive frequency fx of the drive signal DX, which is a drive signal having a low frequency, of the drive signals DX and DY, for example, from the resonance frequency f1x. The drive frequencies fx and fy are adjusted so that the drive frequency fy of the drive signal DY, which is a drive signal having a high frequency, is increased by the amount x2, and is decreased by the adjustment amount y2 from the resonance frequency f1y.
　具体的には、まず、共振周波数比較部３３Ａは、揺動ミラー２０の第１及び第２の共振周波数ｆｎｘ及びｆｎｙが基準比率を含む所定範囲（以下、基準範囲と称する）から外れたことを判定する。そして、目標周波数決定部３３Ｂは、揺動ミラー２０の揺動周波数の比率が当該基準範囲内となるように、駆動周波数ｆｘ及びｆｙを調節する目標となる目標周波数ｆｔｘ及びｆｔｙを決定する。また、駆動信号生成部３１は、目標周波数ｆｔｘ及びｆｔｙの駆動信号ＤＸ及びＤＹを生成し、これを揺動ミラー２０に供給する。 Specifically, first, the resonance frequency comparison unit 33A confirms that the first and second resonance frequencies fnx and fny of the oscillating mirror 20 are out of a predetermined range including a reference ratio (hereinafter referred to as a reference range). judge. Then, the target frequency determination unit 33B determines target frequencies ftx and fty that are targets for adjusting the drive frequencies fx and fy so that the ratio of the oscillation frequencies of the oscillation mirror 20 is within the reference range. The drive signal generator 31 generates drive signals DX and DY having target frequencies ftx and fty and supplies them to the oscillating mirror 20.
　従って、揺動ミラー２０は、共振周波数ｆ１ｘ及びｆ１ｙとはわずかに異なる周波数で揺動（発振）する。しかし、揺動ミラー２０によって反射される走査光Ｌ２の軌道ＴＲは安定する。従って、揺動ミラー２０は、異なる条件下であっても安定して第１及び第２の揺動軸ＡＸ及びＡＹ周りを揺動することとなる。従って、安定した軌道で走査光Ｌ２を走査領域Ｒ０に照射することができ、安定した走査結果を得ることができる。また、当該走査結果に基づく測距結果も安定することとなる。 Therefore, the oscillating mirror 20 oscillates (oscillates) at a frequency slightly different from the resonance frequencies f1x and f1y. However, the trajectory TR of the scanning light L2 reflected by the oscillating mirror 20 is stabilized. Therefore, the oscillating mirror 20 oscillates around the first and second oscillation axes AX and AY stably even under different conditions. Accordingly, it is possible to irradiate the scanning region R0 with the scanning light L2 in a stable orbit, and a stable scanning result can be obtained. Further, the distance measurement result based on the scanning result is also stabilized.
　このように、本実施例においては、駆動回路３０は、揺動ミラー２０の第１及び第２の共振周波数ｆｎｘ及びｆｎｙの各々を判定及び監視し、これに追従して揺動ミラー２０が安定して共振する駆動信号ＤＸ及びＤＹを生成する。 Thus, in this embodiment, the drive circuit 30 determines and monitors each of the first and second resonance frequencies fnx and fny of the oscillating mirror 20, and the oscillating mirror 20 stabilizes following this. Then, the drive signals DX and DY that resonate are generated.
　また、駆動回路３０は、揺動ミラー２０の第１及び第２の共振周波数ｆｎｘ及びｆｎｙを比較し、第１及び第２の共振周波数ｆｎｘ及びｆｎｙの比率の変化に基づいて第１及び第２の駆動信号ＤＸ及びＤＹの周波数ｆｘ及びｆｙを調節する駆動周波数調節部３３を有する。 Further, the drive circuit 30 compares the first and second resonance frequencies fnx and fny of the oscillating mirror 20, and the first and second resonance frequencies fnx and fny are changed based on a change in the ratio of the first and second resonance frequencies fnx and fny. A drive frequency adjusting unit 33 for adjusting the frequencies fx and fy of the drive signals DX and DY.
　また、本実施例においては、駆動周波数調節部３３は、第１及び第２の共振周波数ｆｎｘ及びｆｎｙの比率が所定範囲（基準比率ｆ０ｘ：ｆ０ｙ）内である場合、第１及び第２の駆動信号ＤＸ及びＤＹの周波数ｆｘ及びｆｙがそれぞれ第１及び第２の共振周波数ｆｎｘ及びｆｎｙとなるように第１及び第２の駆動信号ＤＸ及びＤＹの周波数ｆｘ及びｆｙを調節する。 In the present embodiment, the drive frequency adjusting unit 33 performs the first and second drive when the ratio between the first and second resonance frequencies fnx and fny is within a predetermined range (reference ratio f0x: f0y). The frequencies fx and fy of the first and second drive signals DX and DY are adjusted so that the frequencies fx and fy of the signals DX and DY become the first and second resonance frequencies fnx and fny, respectively.
　一方、本実施例においては、駆動周波数調節部３３は、第１及び第２の共振周波数ｆｎｘ及びｆｎｙの比率が所定範囲から外れた場合（例えば比率ｆ１ｘ：ｆ１ｙとなった場合）、第１及び第２の駆動信号ＤＸ及びＤＹの周波数ｆｘ及びｆｙが当該共振周波数ｆｎｘ及びｆｎｙとは異なる周波数ｆｔｘ及びｆｔｙとなるように第１及び第２の駆動信号ＤＸ及びＤＹの周波数ｆｘ及びｆｙを調節する。 On the other hand, in the present embodiment, the drive frequency adjusting unit 33 is configured such that when the ratio between the first and second resonance frequencies fnx and fny is out of a predetermined range (for example, when the ratio becomes f1x: f1y), The frequencies fx and fy of the first and second drive signals DX and DY are adjusted so that the frequencies fx and fy of the second drive signals DX and DY become frequencies ftx and fty different from the resonance frequencies fnx and fny. .
　従って、揺動ミラー２０は、第１及び第２の共振周波数ｆｎｘ及びｆｎｙが変化して両者の比率が基準範囲から外れた場合においても、その揺動周波数の比率は、当該基準範囲内であることが維持される。従って、安定して揺動ミラー２０が揺動するミラー装置１２並びにこれを含む光走査装置ＳＣ及び測距装置１０を提供することができる。 Therefore, even when the first and second resonance frequencies fnx and fny change and the ratio of the two deviates from the reference range, the oscillation mirror 20 has a ratio of the oscillation frequency within the reference range. Is maintained. Therefore, it is possible to provide the mirror device 12 in which the oscillating mirror 20 is stably oscillated, and the optical scanning device SC and the distance measuring device 10 including the mirror device 12.
　なお、本実施例においては、駆動周波数調節部３３が駆動周波数ｆｘ及びｆｙの両方を調節する場合について説明した。しかし、駆動周波数ｆｘ及びｆｙの比率が基準範囲内となることを考慮すると、駆動周波数ｆｘ及びｆｙの一方のみが調節されてもよい。 In the present embodiment, the case where the drive frequency adjusting unit 33 adjusts both the drive frequencies fx and fy has been described. However, considering that the ratio between the drive frequencies fx and fy falls within the reference range, only one of the drive frequencies fx and fy may be adjusted.
　すなわち、駆動周波数調節部３３は、第１及び第２の共振周波数ｆｎｘ及びｆｎｙの比率が所定範囲内である場合、第１及び第２の駆動信号ＤＸ及びＤＹの周波数ｆｘ及びｆｙがそれぞれ第１及び第２の共振周波数ｆｎｘ及びｆｎｙとなるように第１及び第２の駆動信号ＤＸ及びＤＹの周波数ｆｘ及びｆｙを調節し、第１及び第２の共振周波数ｆｎｘ及びｆｎｙの比率が当該所定範囲から外れた場合、第１及び第２の駆動信号ＤＸ及びＤＹのいずれかの周波数が当該共振周波数とは異なる周波数となるように第１及び第２の駆動信号ＤＸ及びＤＹの周波数を調節してもよい。 That is, when the ratio between the first and second resonance frequencies fnx and fny is within a predetermined range, the drive frequency adjusting unit 33 sets the frequencies fx and fy of the first and second drive signals DX and DY to the first. The frequencies fx and fy of the first and second drive signals DX and DY are adjusted so as to be the second resonance frequencies fnx and fny, and the ratio of the first and second resonance frequencies fnx and fny is within the predetermined range. If the frequency is out of the range, the frequency of the first and second drive signals DX and DY is adjusted so that one of the first and second drive signals DX and DY has a frequency different from the resonance frequency. Also good.
　なお、本実施例において説明したように、相対的に周波数が高い駆動信号の駆動周波数（例えば駆動信号ＤＹの駆動周波数ｆｙ）を低くし、相対的に周波数が低い駆動信号の駆動周波数（例えば駆動信号ＤＸの駆動周波数ｆｘ）を高くすることで、両者の共振周波数（共振点）から大きく外れることなく揺動ミラー２０を共振させることができる。すなわち、揺動振幅の低下を抑制しつつ、安定して揺動ミラー２０を共振させることができる。 As described in the present embodiment, the drive frequency of a drive signal having a relatively high frequency (for example, the drive frequency fy of the drive signal DY) is lowered, and the drive frequency of a drive signal having a relatively low frequency (for example, drive) By increasing the driving frequency fx) of the signal DX, the oscillating mirror 20 can be resonated without greatly deviating from the resonance frequency (resonance point) of both. That is, it is possible to stably resonate the oscillating mirror 20 while suppressing a decrease in the oscillation amplitude.
　また、本実施例においては、駆動回路３０が揺動ミラー２０の第１及び第２の共振周波数ｆｎｘ及びｆｎｙの変化に応じて駆動信号ＤＸ及びＤＹの周波数ｆｘ及びｆｙを調節する場合について説明した。しかし、設計上の条件下で動作する場合、揺動ミラー２０の共振周波数及びこれに基づく基準範囲は大きく変化しない場合が多い。従って、駆動回路３０は、揺動ミラー２０の第１の揺動周波数と第２の揺動周波数との比率が基準範囲内となるように駆動信号ＤＸ及びＤＹを生成すればよい。 In the present embodiment, the case where the drive circuit 30 adjusts the frequencies fx and fy of the drive signals DX and DY according to changes in the first and second resonance frequencies fnx and fny of the oscillating mirror 20 has been described. . However, when operating under design conditions, the resonance frequency of the oscillating mirror 20 and the reference range based on it often do not change significantly. Therefore, the drive circuit 30 may generate the drive signals DX and DY so that the ratio between the first oscillation frequency and the second oscillation frequency of the oscillation mirror 20 is within the reference range.
　なお、駆動回路３０が調節する駆動信号ＤＸの周波数ｆｘと駆動信号ＤＹの周波数ｆｙの目標範囲である基準範囲は、絶対的な範囲であってもよいし、相対的な範囲であってもよい。例えば、当該基準範囲は、判定された第１及び第２の共振周波数ｆｎｘ及びｆｎｙ間の差異に基づいて変動してもよい。 Note that the reference range that is the target range of the frequency fx of the drive signal DX and the frequency fy of the drive signal DY adjusted by the drive circuit 30 may be an absolute range or a relative range. . For example, the reference range may vary based on the difference between the determined first and second resonance frequencies fnx and fny.
　また、本実施例においては、揺動ミラー２０が互いに直交する第１及び第２の揺動軸ＡＸ及びＡＹの周りを揺動する場合について説明した。しかし、第１及び第２の揺動軸ＡＸ及びＡＹは、互いに直交する場合に限定されず、互いに異なっていればよい。 In the present embodiment, the case where the oscillating mirror 20 oscillates around the first and second oscillating axes AX and AY orthogonal to each other has been described. However, the first and second swing axes AX and AY are not limited to being orthogonal to each other, and may be different from each other.
　このように、ミラー装置１２は、互いに異なる第１及び第２の揺動軸ＡＸ及びＡＹの周りを揺動する揺動ミラー２０と、揺動ミラー２０がそれぞれ第１及び第２の揺動軸ＡＸ及びＡＹの周りを揺動するための第１及び第２の駆動信号ＤＸ及びＤＹを生成する駆動回路３０と、を有する。また、駆動回路３０は、揺動ミラー２０の揺動状態に基づいて揺動ミラー２０のそれぞれ第１及び第２の揺動軸ＡＸ及びＡＹ周りの第１及び第２の揺動周波数を判定し、第１の揺動周波数と第２の揺動周波数との比率が所定範囲内となるように、第１及び第２の駆動信号ＤＸ及びＤＹを生成する。従って、安定して２つの揺動軸ＡＸ及びＡＹの周りを揺動する揺動ミラー２０を有するミラー装置１２を提供することができる。 As described above, the mirror device 12 includes the oscillating mirror 20 that oscillates around the first and second oscillating shafts AX and AY that are different from each other, and the oscillating mirror 20 includes the first and second oscillating shafts, respectively. And a drive circuit 30 that generates first and second drive signals DX and DY for swinging around AX and AY. Further, the drive circuit 30 determines first and second oscillation frequencies around the first and second oscillation axes AX and AY of the oscillation mirror 20 based on the oscillation state of the oscillation mirror 20, respectively. The first and second drive signals DX and DY are generated so that the ratio between the first oscillation frequency and the second oscillation frequency is within a predetermined range. Therefore, it is possible to provide the mirror device 12 having the oscillating mirror 20 that oscillates around the two oscillating axes AX and AY.
　また、本実施例においては、ミラー装置１２は光走査装置ＳＣ以外のミラーとして動作することができる。また、光走査装置ＳＣは、測距以外の用途に用いられることができる。従って、本発明は、例えばミラー装置１２として実施することができ、また光走査装置ＳＣ又は測距装置１０として実施することもできる。なお、ミラー装置１２は、光走査装置ＳＣ及び測距装置１０のように、リサージュスキャンを行う走査装置又はこれを含む測距装置に搭載されることで、その走査軌道が安定し、大きな効果を得ることができる。 In this embodiment, the mirror device 12 can operate as a mirror other than the optical scanning device SC. Further, the optical scanning device SC can be used for purposes other than distance measurement. Accordingly, the present invention can be implemented as, for example, the mirror device 12, and can also be implemented as the optical scanning device SC or the distance measuring device 10. The mirror device 12 is mounted on a scanning device that performs Lissajous scanning, such as the optical scanning device SC and the distance measuring device 10, or a distance measuring device including the same, so that the scanning trajectory is stabilized and has a great effect. Can be obtained.
　また、本発明は、例えば図５に示したステップを実施することで、揺動ミラー２０を安定して揺動させる方法としても実施することができる。すなわち、例えば、本発明に係る方法は、第１及び第２の駆動信号ＤＸ及びＤＹを供給して、揺動ミラー２０を、互いに異なる第１及び第２の揺動軸ＡＸ及びＡＹの周りを揺動させるステップＳ１１と、揺動ミラー２０の揺動状態に基づいて揺動ミラー２０のそれぞれ第１及び第２の揺動軸ＡＸ及びＡＹ周りの第１及び第２の揺動周波数を判定するステップＳ１２と、第１の揺動周波数と第２の揺動周波数との比率が所定範囲内となるように、第１及び第２の駆動信号ＤＸ及びＤＹの周波数ｆｘ及びｆｙを調節するステップＳ１４及びＳ１５と、を有する。これによって、２つの揺動軸ＡＸ及びＡＹの周りを揺動する揺動ミラー２０を安定して駆動する方法を提供することができる。 The present invention can also be implemented as a method for stably oscillating the oscillating mirror 20, for example, by performing the steps shown in FIG. That is, for example, in the method according to the present invention, the first and second drive signals DX and DY are supplied, and the oscillating mirror 20 is moved around the first and second oscillating axes AX and AY which are different from each other. Based on the swinging step S11 and the swinging state of the swinging mirror 20, first and second swinging frequencies around the first and second swinging axes AX and AY of the swinging mirror 20 are determined. Step S14 and adjusting the frequencies fx and fy of the first and second drive signals DX and DY so that the ratio of the first oscillation frequency and the second oscillation frequency is within a predetermined range. And S15. Thus, it is possible to provide a method for stably driving the oscillating mirror 20 that oscillates around the two oscillating axes AX and AY.
　また、本発明は、例えば、コンピュータに駆動回路３０として機能させるプログラムをインストールし、このコンピュータを揺動ミラー２０に接続することでも実施することができる。すなわち、本発明に係るプログラムは、例えば、コンピュータを、互いに異なる第１及び第２の揺動軸ＡＸ及びＡＹの周りを揺動する揺動ミラー２０に第１及び第２の駆動信号ＤＸ及びＤＹを供給し、揺動ミラー２０の揺動状態に基づいて揺動ミラー２０のそれぞれ第１及び第２の揺動軸ＡＸ及びＡＹ周りの第１及び第２の揺動周波数を判定し、第１の揺動周波数と第２の揺動周波数との比率が所定範囲内となるように、第１及び第２の駆動信号ＤＸ及びＤＹの周波数ｆｘ及びｆｙを調節する駆動回路３０として機能させる。従って、２つの揺動軸ＡＸ及びＡＹの周りを揺動する揺動ミラー２０を安定して駆動するプログラムを提供することができる。 The present invention can also be implemented, for example, by installing a program that causes a computer to function as the drive circuit 30 and connecting the computer to the oscillating mirror 20. That is, the program according to the present invention, for example, causes the computer to send the first and second drive signals DX and DY to the oscillating mirror 20 that oscillates around the first and second oscillating axes AX and AY that are different from each other. The first and second oscillation frequencies around the first and second oscillation axes AX and AY of the oscillation mirror 20 are determined based on the oscillation state of the oscillation mirror 20, respectively. The drive circuit 30 is configured to adjust the frequencies fx and fy of the first and second drive signals DX and DY so that the ratio between the swing frequency of the first drive signal and the second swing frequency falls within a predetermined range. Accordingly, it is possible to provide a program for stably driving the oscillating mirror 20 that oscillates around the two oscillating axes AX and AY.
１０　測距装置
ＳＣ　光走査装置
１２　ミラー装置
２０　揺動ミラー
３０　駆動回路
３３　駆動周波数調節部 DESCRIPTION OF SYMBOLS 10 Distance measuring device SC Optical scanning device 12 Mirror apparatus 20 Oscillating mirror 30 Drive circuit 33 Drive frequency adjustment part

Claims (8)

  1. 　互いに異なる第１及び第２の軸の周りを揺動する揺動ミラーと、
    　前記揺動ミラーがそれぞれ前記第１及び第２の軸周りを揺動するための第１及び第２の駆動信号を生成する駆動回路と、を有し、
    　前記駆動回路は、前記揺動ミラーの揺動状態に基づいて前記揺動ミラーの前記第１及び第２の軸周りの第１及び第２の揺動周波数を判定し、前記揺動ミラーの第１の揺動周波数と前記第２の揺動周波数との比率が所定範囲内となるように前記第１及び第２の駆動信号を生成することを特徴とするミラー装置。     An oscillating mirror that oscillates around different first and second axes;
    A drive circuit for generating first and second drive signals for swinging the swing mirror about the first and second axes, respectively;
    The drive circuit determines first and second oscillation frequencies around the first and second axes of the oscillating mirror based on the oscillating state of the oscillating mirror, and The mirror device characterized in that the first and second drive signals are generated so that a ratio between one oscillation frequency and the second oscillation frequency is within a predetermined range.
  2. 　前記駆動回路は、前記揺動ミラーの前記第１の軸周りの第１の共振周波数と前記第２の軸周りの第２の共振周波数とを比較し、前記第１の共振周波数と前記第２の共振周波数との比率の変化に基づいて前記第１及び第２の駆動信号の周波数を調節する駆動周波数調節部を有することを特徴とする請求項１に記載のミラー装置。 The drive circuit compares a first resonance frequency around the first axis of the oscillating mirror with a second resonance frequency around the second axis, and compares the first resonance frequency with the second resonance frequency. The mirror apparatus according to claim 1, further comprising a drive frequency adjusting unit that adjusts the frequency of the first and second drive signals based on a change in a ratio with a resonance frequency of the first and second drive signals.
  3. 　前記駆動周波数調節部は、前記第１の共振周波数と前記第２の共振周波数との比率が前記所定範囲内である場合、前記第１及び第２の駆動信号の周波数がそれぞれ前記第１及び第２の共振周波数となるように前記第１及び第２の駆動信号の周波数を調節し、前記第１の共振周波数と前記第２の共振周波数との比率が前記所定範囲から外れた場合、前記第１及び第２の駆動信号のいずれかの周波数が前記共振周波数とは異なる周波数となるように前記第１及び第２の駆動信号の周波数を調節することを特徴とする請求項２に記載のミラー装置。 The drive frequency adjusting unit may be configured to set the first and second drive signals to have a first frequency and a second frequency when the ratio between the first resonance frequency and the second resonance frequency is within the predetermined range. When the frequency of the first and second drive signals is adjusted to be a resonance frequency of 2, and the ratio of the first resonance frequency and the second resonance frequency is out of the predetermined range, the first 3. The mirror according to claim 2, wherein the frequency of the first and second drive signals is adjusted such that one of the first and second drive signals has a frequency different from the resonance frequency. apparatus.
  4. 　前記駆動周波数調節部は、前記第１の共振周波数と前記第２の共振周波数との比率が前記所定範囲から外れた場合、前記第１及び第２の駆動信号のうち、周波数が相対的に高い駆動信号の周波数を前記共振周波数から下げ、周波数が相対的に低い駆動信号の周波数を前記共振周波数から上げるように、前記第１及び第２の駆動信号の各々の周波数を調節することを特徴とする請求項３に記載のミラー装置。 The drive frequency adjusting unit has a relatively high frequency among the first and second drive signals when the ratio between the first resonance frequency and the second resonance frequency is out of the predetermined range. The frequency of each of the first and second drive signals is adjusted so that the frequency of the drive signal is lowered from the resonance frequency and the frequency of the drive signal having a relatively low frequency is raised from the resonance frequency. The mirror device according to claim 3.
  5. 　請求項１乃至４のいずれか１つに記載のミラー装置と、
    　前記揺動ミラーに向けて光を出射する光源部と、を有し、
    　前記揺動ミラーは、前記光源部からの出射光を反射させることで前記出射光を用いて所定の領域をリサージュ曲線に沿った軌道で走査する走査部として機能することを特徴とする光走査装置。     The mirror device according to any one of claims 1 to 4,
    A light source unit that emits light toward the oscillating mirror;
    The oscillating mirror functions as a scanning unit that scans a predetermined region in a trajectory along a Lissajous curve using the emitted light by reflecting the emitted light from the light source unit. .
  6. 　請求項５に記載の光走査装置と、
    　前記所定の領域内に存在する対象物からの反射光に基づいて前記対象物までの距離を測定する測距部と、を有することを特徴とする測距装置。     An optical scanning device according to claim 5;
    A distance measuring device comprising: a distance measuring unit that measures a distance to the object based on reflected light from the object existing in the predetermined region.
  7. 　第１及び第２の駆動信号を供給して、揺動ミラーを、互いに異なる第１及び第２の軸の周りを揺動させるステップと、
    　前記揺動ミラーの揺動状態に基づいて前記揺動ミラーのそれぞれ前記第１及び第２の軸周りの第１及び第２の揺動周波数を判定するステップと、
    　前記第１の揺動周波数と前記第２の揺動周波数との比率が所定範囲内となるように、前記第１及び第２の駆動信号の周波数を調節するステップと、を有することを特徴とする方法。     Supplying first and second drive signals to cause the oscillating mirror to oscillate about different first and second axes;
    Determining first and second oscillating frequencies about the first and second axes of the oscillating mirror, respectively, based on the oscillating state of the oscillating mirror;
    Adjusting the frequencies of the first and second drive signals so that the ratio between the first oscillation frequency and the second oscillation frequency is within a predetermined range. how to.
  8. 　コンピュータを、
    　互いに異なる第１及び第２の軸の周りを揺動する揺動ミラーに第１及び第２の駆動信号を供給し、前記揺動ミラーの揺動状態に基づいて前記揺動ミラーのそれぞれ前記第１及び第２の軸周りの第１及び第２の揺動周波数を判定し、前記第１の揺動周波数と前記第２の揺動周波数との比率が所定範囲内となるように、前記第１及び第２の駆動信号の周波数を調節する駆動回路として機能させることを特徴とするプログラム。     Computer
    First and second drive signals are supplied to oscillating mirrors that oscillate around different first and second axes, and each of the oscillating mirrors is based on the oscillating state of the oscillating mirror. The first and second oscillation frequencies around the first and second axes are determined, and the first oscillation frequency and the second oscillation frequency are within a predetermined range so that the ratio is within a predetermined range. A program that functions as a drive circuit that adjusts the frequencies of the first and second drive signals.
PCT/JP2019/006051 2018-02-20 2019-02-19 Mirror device, optical scanning device, distance-measuring device, control method for mirror device, and program WO2019163754A1 (en)

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EP4099082A1 (en) * 2021-06-01 2022-12-07 FUJIFILM Corporation Optical scanning device, driving method of optical scanning device, and image drawing system

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US20110267501A1 (en) * 2010-04-28 2011-11-03 Microsoft Corporation Scanned beam display and image capture
JP2013003253A (en) * 2011-06-14 2013-01-07 Nippon Signal Co Ltd:The Optical scanner
JP2016156913A (en) * 2015-02-24 2016-09-01 日本信号株式会社 Optical scanning device

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EP4099082A1 (en) * 2021-06-01 2022-12-07 FUJIFILM Corporation Optical scanning device, driving method of optical scanning device, and image drawing system

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