Optical scanning device, driving method for optical scanning device, and image drawing system

Abstract

To provide an optical scanner which can suppress the reduction in the quality of an image to be drawn, a driving method of the optical scanner and an image drawing system.SOLUTION: A drive control unit derives, on the basis of an output signal of an optical scanner, a first deviation time at the time point at which the angle around a first axis of a mirror part for the output signal of a first angle detection sensor becomes a first reference angle with respect to the time point at which the angle around the first axis of the mirror part becomes the first reference angle, being the deviation time used for correction of generation timing of a first reference signal expressing that the angle around the first axis of the mirror part becomes the first reference angle.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to an optical scanning device, a driving method for an optical scanning device, and an image drawing system. [Background technology]

[0002] A micromirror device (also called a microscanner) is known as one of the Micro Electro Mechanical Systems (MEMS) devices fabricated using silicon (Si) microfabrication technology. Optical scanning devices equipped with this micromirror device are small and consume low power, so they are expected to be applied to image drawing systems such as laser displays and laser projectors.

[0003] In a micromirror device, a mirror portion is formed so as to be able to swing around a first axis and a second axis that are perpendicular to each other, and the light reflected by the mirror portion is scanned two-dimensionally as the mirror portion swings around each axis. Also, a micromirror device is known that enables Lissajous scanning of light by resonating the mirror portion around each axis.

[0004] Patent Document 1 discloses a micromirror device that includes a protective member that protects a mirror portion and is disposed in the direction of reflection of light by the mirror portion to transmit the light reflected by the mirror portion, and a photodetector that is disposed within the protective member from within the range through which the light reflected by the mirror portion transmits to outside the range. This micromirror device controls the amplitude of the mirror portion according to the state of light detection by the photodetector.

[0005] Patent Document 2 discloses an optical scanning device that includes a photodetector for detecting angle information of a mirror portion. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2010-256774 A [Patent Document 2] International Publication No. 2014 / 097683 Summary of the Invention [Problem to be solved by the invention]

[0007] In the above optical scanning device, the timing of irradiating the mirror with light from the light source is controlled based on a reference signal (e.g., a zero-cross signal) indicating that the angle of the mirror has reached the reference angle. In other words, if the accuracy of detecting the timing at which the angle of the mirror has reached the reference angle by the optical scanning device decreases, the image quality of the drawn image will decrease.

[0008] However, the techniques described in Patent Documents 1 and 2 do not take into consideration using a photodetector to improve the accuracy of detecting the timing at which the angle of the mirror portion reaches the reference angle.

[0009] The present disclosure has been made in consideration of the above circumstances, and aims to provide an optical scanning device, a driving method for an optical scanning device, and an image drawing system that can suppress deterioration in image quality of a drawn image. [Means for solving the problem]

[0010] The optical scanning device disclosed herein is an optical scanning device including: a mirror section having a reflective surface that reflects incident light; a first actuator that oscillates the mirror section around a first axis that is in a plane including the reflective surface of the mirror section when stationary; a second actuator that oscillates the mirror section around a second axis that is in a plane including the reflective surface of the mirror section when stationary and that intersects with the first axis; a first angle detection sensor that outputs a signal according to the angle of the mirror section about the first axis; a second angle detection sensor that outputs a signal according to the angle of the mirror section about the second axis; at least one photodetector provided at a position capable of receiving reflected light from the mirror section; and at least one processor, wherein the processor applies a first drive signal having a first drive frequency to the first actuator and applies a second drive signal having a second drive frequency to the second actuator. a second drive signal that detects the angle of the mirror unit about the first axis becoming the first reference angle is applied, and a first deviation time at which the angle of the mirror unit about the first axis becomes the first reference angle relative to the time when the output signal of the first angle detection sensor indicates that the angle of the mirror unit about the first axis becomes the first reference angle is derived based on the output signal of the photodetector; and a second deviation time at which the angle of the mirror unit about the second axis becomes the second reference angle is derived based on the output signal of the photodetector, which is a deviation time used to correct the generation timing of a first reference signal that indicates that the angle of the mirror unit about the first axis becomes the first reference angle relative to the time when the output signal of the first angle detection sensor indicates that the angle of the mirror unit about the second axis becomes the second reference angle.

[0011] In the optical scanning device of the present disclosure, one optical detector may be provided in the center of the area where an image is drawn by the light reflected from the mirror portion.

[0012] In the optical scanning device of the present disclosure, the photodetector may be provided on an axis corresponding to the first axis and an axis corresponding to the second axis in a region where an image can be drawn by light reflected from the mirror portion.

[0013] In addition, the optical scanning device of the present disclosure may have at least one optical detector provided at each end on an axis corresponding to a first axis and at each end on an axis corresponding to a second axis in an area where an image can be drawn by reflected light from the mirror portion.

[0014] In addition, in the optical scanning device disclosed herein, the processor derives a first average phase delay time by averaging a first phase delay time of the output signal of the first angle detection sensor for multiple periods of the first drive signal, and derives a second average phase delay time by averaging a second phase delay time of the output signal of the second angle detection sensor for multiple periods of the second drive signal, and the time at which the output signal of the first angle detection sensor indicates that the angle about the first axis of the mirror unit has become the first reference angle may be a time at which the first average phase delay time has elapsed since the first drive signal indicates that the angle about the first axis of the mirror unit has become the first reference angle, and the time at which the output signal of the second angle detection sensor indicates that the angle about the second axis of the mirror unit has become the second reference angle may be a time at which the second average phase delay time has elapsed since the second drive signal indicates that the angle about the second axis of the mirror unit has become the second reference angle.

[0015] In addition, in the optical scanning device disclosed herein, the processor may derive a first average phase delay time by averaging a first phase delay time at a time when the output signal of the first angle detection sensor is zero, and derive a second average phase delay time by averaging a second phase delay time at a time when the output signal of the second angle detection sensor is zero.

[0016] In addition, the optical scanning device disclosed herein may be configured such that the processor derives a first average phase delay time by averaging a first phase delay time from a time when the first drive signal in a corresponding period is zero to a time when the output signal of the first angle detection sensor is zero, and derives a second average phase delay time by averaging a second phase delay time from a time when the second drive signal in a corresponding period is zero to a time when the output signal of the second angle detection sensor is zero.

[0017] In addition, in the optical scanning device disclosed herein, the first reference angle and the second reference angle are zero, the first deviation time is the time from the time when the output signal of the first angle detection sensor indicates that the angle of the mirror section about the first axis has become zero to the time when the output signal of the photodetector indicates that the angle of the mirror section about the first axis has become zero, and the second deviation time may be the time from the time when the output signal of the second angle detection sensor indicates that the angle of the mirror section about the second axis has become zero to the time when the output signal of the photodetector indicates that the angle of the mirror section about the second axis has become zero.

[0018] In addition, in the optical scanning device disclosed herein, the processor may generate a first reference signal when a first deviation time has elapsed from the time when the output signal of the first angle detection sensor indicates that the angle of the mirror section about the first axis has become the first reference angle, and generate a second reference signal when a second deviation time has elapsed from the time when the output signal of the second angle detection sensor indicates that the angle of the mirror section about the second axis has become the second reference angle.

[0019] In addition, the optical scanning device disclosed herein is provided with a delay time derivation mode for deriving a first delay time and a second delay time, and the processor executes the delay time derivation mode during calibration to obtain the first delay time and the second delay time for each preset condition, and when generating the first reference signal and the second reference signal, the first delay time and the second delay time obtained in advance during calibration may be used.

[0020] In the optical scanning device of the present disclosure, the above conditions may include a first phase delay time and a second phase delay time.

[0021] In the optical scanning device of the present disclosure, the above conditions may further include a drive voltage of the first drive signal and a drive voltage of the second drive signal.

[0022] In the optical scanning device of the present disclosure, the above conditions may further include a first drive frequency and a second drive frequency.

[0023] In the optical scanning device according to the present disclosure, the above conditions may further include an environmental temperature.

[0024] In the optical scanning device according to the present disclosure, the optical detector may be a photodiode.

[0025] In the optical scanning device according to the present disclosure, the optical detector may be in an inactive state while an image is being drawn.

[0026] In addition, the optical scanning device disclosed herein may be such that the first angle detection sensor is a pair of angle detection sensors arranged at opposing positions across a first axis or a second axis, and the output signal of the first angle detection sensor is an output signal obtained by adding or subtracting a pair of output signals output from the pair of angle detection sensors, and the second angle detection sensor is a pair of angle detection sensors arranged at opposing positions across the first axis or the second axis, and the output signal of the second angle detection sensor is an output signal obtained by adding or subtracting a pair of output signals output from the pair of angle detection sensors.

[0027] An image drawing system according to the present disclosure includes any one of the optical scanning devices described above and a light source that irradiates light onto the mirror portion.

[0028] The present disclosure also provides a driving method for an optical scanning device including a mirror section having a reflective surface that reflects incident light, a first actuator that oscillates the mirror section around a first axis that is in a plane including the reflective surface of the mirror section when stationary, a second actuator that oscillates the mirror section around a second axis that is in a plane including the reflective surface of the mirror section when stationary and that intersects with the first axis, a first angle detection sensor that outputs a signal according to the angle of the mirror section about the first axis, a second angle detection sensor that outputs a signal according to the angle of the mirror section about the second axis, and at least one photodetector provided at a position capable of receiving reflected light from the mirror section, the driving method including applying a first driving signal having a first driving frequency to the first actuator and applying a second driving signal having a second driving frequency to the second actuator. a first deviation time used to correct the generation timing of a first reference signal indicating that the angle of the mirror unit about the first axis has become the first reference angle, relative to the time point when the output signal of the first angle detection sensor indicates that the angle of the mirror unit about the first axis has become the first reference angle, is derived based on the output signal of the photodetector; and a second deviation time used to correct the generation timing of a second reference signal indicating that the angle of the mirror unit about the second axis has become the second reference angle, relative to the time point when the output signal of the second angle detection sensor indicates that the angle of the mirror unit about the second axis has become the second reference angle, is derived based on the output signal of the photodetector. Effect of the Invention

[0029] According to the present disclosure, degradation in image quality of a drawn image can be suppressed. [Brief description of the drawings]

[0030] [Figure 1] FIG. 1 is a schematic diagram of an image drawing system. [Diagram 2] FIG. 1 is a perspective view of the appearance of a micromirror device. [Diagram 3] 4 is a graph showing an example of a first drive signal. [Figure 4]6 is a graph showing an example of a second drive signal. [Diagram 5] 3 is a block diagram showing an example of a functional configuration of a drive control unit. FIG. [Figure 6] 4A to 4C are diagrams illustrating an example of signals output from a pair of first angle detection sensors. [Figure 7] 6A to 6C are diagrams illustrating an example of signals output from a pair of second angle detection sensors. [Figure 8] 4 is a circuit diagram showing an example of a configuration of a first signal processing unit. FIG. [Figure 9] FIG. 4 is a diagram illustrating an example of a first signal processing. [Figure 10] FIG. 11 is a diagram illustrating an example of a second signal processing. [Figure 11] 6 is a diagram for explaining deviations in timing at which the first angle detection signal crosses zero. FIG. [Figure 12] 11 is a diagram for explaining a process of deriving a first average phase delay time. FIG. [Figure 13] 11 is a diagram for explaining a process of deriving a second average phase delay time. FIG. [Figure 14] 11 is a diagram illustrating an example of a relationship between a first average phase delay time and a first deviation time. FIG. [Figure 15] 13 is a diagram illustrating an example of a relationship between a second average phase delay time and a second deviation time. FIG. [Figure 16] 4A to 4C are diagrams for explaining a generation process of a first zero cross pulse. [Figure 17] 10 is a diagram for explaining a generation process of a second zero cross pulse. FIG. [Figure 18] 13 is a flowchart showing an example of a first delay time derivation process. [Figure 19] 13 is a flowchart showing an example of a second delay time derivation process. [Figure 20] 13 is a flowchart showing an example of a first zero cross pulse generating process. [Figure 21] 13 is a flowchart showing an example of a second zero cross pulse generating process. [Figure 22] FIG. 13 is a diagram for explaining the arrangement position of a photodetector during calibration. [Diagram 23] 10 is a flowchart showing an example of a first calibration process. [Figure 24] FIG. 11 is a diagram for explaining a first calibration process. [Diagram 25] 10 is a flowchart showing an example of a second calibration process. [Figure 26] FIG. 11 is a diagram for explaining a second calibration process. [Figure 27] FIG. 13 is a plan view of a micromirror device according to a modified example. [Figure 28] FIG. 11 is a circuit diagram showing a configuration of a first signal processing unit according to a modified example. [Figure 29] FIG. 13 is a diagram showing the arrangement position of a photodetector according to a modified example. [Diagram 30] 13A to 13C are diagrams for explaining a first calibration process according to a modified example. [Diagram 31] 13A to 13C are diagrams for explaining a second calibration process according to a modified example. [Diagram 32] FIG. 13 is a diagram showing the arrangement position of a photodetector according to a modified example. [Diagram 33] FIG. 13 is a diagram showing the arrangement position of a photodetector according to a modified example. [Diagram 34] 13 is a diagram showing an example of the relationship between a first average phase delay time and a first deviation time when the drive voltage of a first drive signal is changed. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Hereinafter, examples of embodiments for carrying out the technology of the present disclosure will be described in detail with reference to the drawings.

[0032] First, the configuration of an image drawing system 10 according to this embodiment will be described with reference to Fig. 1. As shown in Fig. 1, the image drawing system 10 has an optical scanning device 2 and a light source 3. The optical scanning device 2 includes a micro mirror device (hereinafter referred to as "MMD (Micro Mirror Device)") 4, a drive control unit 5, and a photodetector 7. The drive control unit 5 is an example of a processor according to the disclosed technology.

[0033] The image drawing system 10 draws an image by reflecting a light beam L emitted from a light source 3 by an MMD 4 and optically scanning a scanned surface 6 under the control of a drive control unit 5. The scanned surface 6 is, for example, a screen for projecting an image, or the retina of a human eye.

[0034] The image rendering system 10 is applied to, for example, a Lissajous scanning laser display. Specifically, the image rendering system 10 is applicable to a laser scan display such as an Augmented Reality (AR) glass or a Virtual Reality (VR) glass.

[0035] MMD4 is the first axis a 1 and the first axis a 1 The second axis a perpendicular to 2 The micromirror device is a piezoelectric two-axis drive type that can oscillate the mirror section 20 (see FIG. 2) around the second axis a. 2 The direction parallel to is the X direction, and the first axis a 1 The direction parallel to is the Y direction, and the first axis a 1 and the second axis a 2 The direction perpendicular to the first axis a is called the Z direction. 1 and the second axis a 2 The example shows that the first axis a is perpendicular to the first axis a. 1 and the second axis a 2 The angle may be other than 90 degrees. The intersection here means within a certain angle range including a tolerance around 90 degrees.

[0036] The light source 3 is a laser device that emits, for example, a laser beam as the light beam L. The light source 3 outputs, for example, three-color laser beams of R (Red), G (Green), and B (Blue). When the mirror section 20 of the MMD 4 is stationary, the light source 3 preferably irradiates the light beam L perpendicularly to the reflecting surface 20A (see FIG. 2) of the mirror section 20. When the light beam L is irradiated perpendicularly from the light source 3 to the reflecting surface 20A, the light source 3 may become an obstacle when the light beam L is scanned and drawn on the scanned surface 6. For this reason, it is preferable to control the light beam L emitted from the light source 3 by an optical system and irradiate it perpendicularly to the reflecting surface 20A. The optical system may include a lens or may not include a lens. The angle at which the light beam L emitted from the light source 3 is irradiated to the reflecting surface 20A is not limited to perpendicular, and the light beam L may be irradiated obliquely to the reflecting surface 20A.

[0037] The drive control unit 5 outputs drive signals to the light source 3 and the MMD 4 based on the optical scanning information. The light source 3 generates a light beam L based on the input drive signal and irradiates the MMD 4. The MMD 4 rotates the mirror unit 20 along the first axis a based on the input drive signal. 1 and the second axis a 2 Rock it around.

[0038] The drive control unit 5 drives the mirror unit 20 along the first axis a 1 and the second axis a 2 By resonating around each of these, the light beam L reflected by the mirror portion 20 scans the surface to be scanned 6 so as to draw a Lissajous waveform. This light scanning method is called a Lissajous scanning method.

[0039] The photodetector 7 photoelectrically converts the incident light and outputs a signal according to the amount of light. Although details will be described later, the photodetector 7 is not used when drawing an image on the scanned surface 6 with the reflected light from the MMD 4 based on drawing data, but is used during calibration. An example of the photodetector 7 is a photodiode.

[0040] Next, the configuration of the MMD 4 according to this embodiment will be described with reference to Fig. 2. As shown in Fig. 2, the MMD 4 has a mirror section 20, a first support section 21, a first movable frame 22, a second support section 23, a second movable frame 24, a connection section 25, and a fixed frame 26. The MMD 4 is a so-called MEMS scanner.

[0041] The mirror section 20 has a reflecting surface 20A that reflects incident light. The reflecting surface 20A is provided on one surface of the mirror section 20, and is formed of a metal thin film such as gold (Au), aluminum (Al), silver (Ag), or a silver alloy. The shape of the reflecting surface 20A is, for example, a first axis a 1 and the second axis a 2 It is a circle with the intersection point of and as its center.

[0042] 1st axis a 1 and the second axis a 2 The MMD 4 has a rectangular planar shape and is aligned along the first axis a. 1 Axisymmetric with respect to the second axis a 2 It is linearly symmetric with respect to .

[0043] The first support portion 21 is provided on the outer side of the mirror portion 20 along the second axis a. 2 The first support portion 21 is disposed at a position facing each other with the first axis a 1 The mirror unit 20 is connected to the first axis a 1 In this embodiment, the first support portion 21 is supported so as to be swingable around the first axis a 1 It is a torsion bar extending along.

[0044] The first movable frame 22 is a rectangular frame that surrounds the mirror unit 20 and is aligned along a first axis a 1 The first movable frame 22 is connected to the mirror unit 20 via the first support unit 21. 1 The piezoelectric elements 30 are formed at positions facing each other with the piezoelectric element 30 sandwiched therebetween. In this manner, by forming the two piezoelectric elements 30 on the first movable frame 22, a pair of first actuators 31 are configured.

[0045] The pair of first actuators 31 are 1 The first actuator 31 is disposed on the mirror unit 20 at a position facing each other with the first axis a 1 By applying a rotational torque around the first axis a, the mirror unit 20 is rotated around the first axis a. 1 Swing it around.

[0046] The second support portion 23 is provided on the outer side of the first movable frame 22 along the first axis a. 1 The second support portion 23 is disposed at a position facing the second axis a. 2 The first movable frame 22 and the mirror unit 20 are connected to the second axis a 2 In this embodiment, the second support portion 23 supports the second axis a 2 It is a torsion bar extending along.

[0047] The second movable frame 24 is a rectangular frame that surrounds the first movable frame 22 and is aligned along a second axis a. 2 The second movable frame 24 is connected to the first movable frame 22 via the second support portion 23. 2 The piezoelectric elements 30 are formed at positions facing each other with the piezoelectric element 30 sandwiched therebetween. In this manner, by forming two piezoelectric elements 30 on the second movable frame 24, a pair of second actuators 32 are configured.

[0048] The pair of second actuators 32 are 2 The second actuator 32 is disposed at a position facing the mirror unit 20 and the first movable frame 22 with the second axis a 2 By applying a rotational torque around the second axis a 2 The mirror portion 20 is swung around the

[0049] The connection portion 25 is provided on the outside of the second movable frame 24 with the first axis a 1 The connecting portion 25 is disposed at a position facing the second axis a. 2 It is connected to the second movable frame 24 at the top.

[0050] The fixed frame 26 is a rectangular frame body that surrounds the second movable frame 24 and is aligned along the second axis a. 2 It is connected to the second movable frame 24 via a connection portion 25 at the top.

[0051] In addition, the first movable frame 22 has a first axis a 1 A pair of first angle detection sensors 11A and 11B are provided at positions facing each other with the first axis a of the mirror unit 20 in between. Each of the pair of first angle detection sensors 11A and 11B is configured with a piezoelectric element. 1 The force applied by the deformation of the first support part 21 accompanying the rotation around the first axis a of the mirror part 20 is converted into a voltage and output as a signal. 1 It outputs a signal according to the surrounding angle.

[0052] In addition, the second movable frame 24 has a second axis a in the vicinity of the second support portion 23. 2 A pair of second angle detection sensors 12A and 12B are provided at positions facing each other with the second axis a of the mirror unit 20 in between. Each of the pair of second angle detection sensors 12A and 12B is configured with a piezoelectric element. 2 The second angle detection sensors 12A and 12B convert the force applied by the deformation of the second support portion 23 accompanying the rotation around the second axis a of the mirror portion 20 into a voltage and output a signal. 2 It outputs a signal according to the surrounding angle.

[0053] 2, wiring and electrode pads for applying drive signals to the first actuator 31 and the second actuator 32 are omitted. Also, wiring and electrode pads for outputting signals from the first angle detection sensors 11A, 11B and the second angle detection sensors 12A, 12B are omitted. A plurality of electrode pads are provided on the fixed frame 26.

[0054] The first axis a of the mirror portion 20 1The swing angle around the circumference (hereinafter referred to as the "first swing angle") θ 1 is controlled by a drive signal (hereinafter referred to as the "first drive signal") that the drive control unit 5 gives to the first actuator 31. The first drive signal is, for example, a sinusoidal AC voltage. The first drive signal is a drive voltage waveform V 1A (t) and the driving voltage waveform V applied to the other 1B (t) and the driving voltage waveform V 1A (t) and the driving voltage waveform V 1B (t) are in opposite phase to each other (i.e., the phase difference is 180°).

[0055] In addition, the first deflection angle θ 1 is the angle at which the normal to the reflecting surface 20A is inclined with respect to the Z direction on the XZ plane.

[0056] The second axis a of the mirror portion 20 2 The surrounding deflection angle (hereinafter referred to as the "second deflection angle") θ 2 is controlled by a drive signal (hereinafter referred to as the "second drive signal") that the drive control unit 5 gives to the second actuator 32. The second drive signal is, for example, a sinusoidal AC voltage. The second drive signal is a drive voltage waveform V 2A (t) and the driving voltage waveform V applied to the other 2B (t) and the driving voltage waveform V 2A (t) and the driving voltage waveform V 2B (t) are in opposite phase to each other (i.e., the phase difference is 180°).

[0057] In addition, the second deflection angle θ 2 is the angle at which the normal to the reflecting surface 20A is inclined with respect to the Z direction in the YZ plane.

[0058] FIG. 3 shows an example of the first drive signal, and FIG. 4 shows an example of the second drive signal. FIG. 3 shows a drive voltage waveform V 1A (t) and V 1B FIG. 4 shows the drive voltage waveform V 2A (t) and V 2B(t) is shown.

[0059] Drive voltage waveform V 1A (t) and V 1B (t) is expressed as follows, respectively: V 1A (t)=V off1 +V 1 sin(2πf d1 t) V 1B (t)=V off1 +V 1 sin(2πf d1 t+α)

[0060] Here, V 1 is the amplitude voltage. V off1 is the bias voltage. V off1 f may be zero. d1 is the drive frequency (hereinafter referred to as the "first drive frequency"); t is time; α is the drive voltage waveform V 1A (t) and V 1B In this embodiment, for example, α=180°.

[0061] Drive voltage waveform V 1A (t) and V 1B When the first actuator 31 is applied with the first drive frequency f d1 and the first axis a 1 Swings around.

[0062] Drive voltage waveform V 2A (t) and V 2B (t) is expressed as follows, respectively: V 2A (t)=V off2 +V 2 sin(2πf d2 t+φ) V 2B (t)=V off2 +V 2 sin(2πf d2 t+β+φ)

[0063] Here, V 2is the amplitude voltage. V off2 is the bias voltage. V off2 f may be zero. d2 is the drive frequency (hereinafter referred to as the "second drive frequency"); t is time; β is the drive voltage waveform V 2A (t) and V 2B In this embodiment, for example, β=180°. Also, φ is the phase difference of the driving voltage waveform V 1A (t) and V 1B (t) and the driving voltage waveform V 2A (t) and V 2B (t) is the phase difference.

[0064] Drive voltage waveform V 2A (t) and V 2B When the second actuator 32 is applied with the second drive frequency f d2 and the second axis a 2 Swings around.

[0065] First drive frequency f d1 is the first axis a of the mirror portion 20 1 The second drive frequency f is set to match the surrounding resonant frequency. d2 is the second axis a of the mirror portion 20 2 It is set to match the surrounding resonant frequency. In this embodiment, f d1 >f d2 That is, the mirror unit 20 is aligned along the first axis a 1 The oscillation frequency around the second axis a 2 The first driving frequency f d1 and the second driving frequency f d2 does not necessarily have to coincide with the resonant frequency. For example, the first driving frequency f d1 and the second driving frequency f d2 and may be frequencies within a frequency range near the resonant frequency (for example, a half-width range of a frequency distribution having a peak value at the resonant frequency). This frequency range is, for example, within the range of a so-called Q value.

[0066] Next, the functional configuration of the drive control unit 5 will be described with reference to Fig. 5. As shown in Fig. 5, the drive control unit 5 has a first drive signal generation unit 60A, a second drive signal generation unit 60B, a first signal processing unit 61A, a second signal processing unit 61B, a first phase shift unit 62A, a second phase shift unit 62B, a first derivation unit 63A, a second derivation unit 63B, a third derivation unit 64, a first zero cross pulse output unit 65A, a second zero cross pulse output unit 65B, and a light source drive unit 66.

[0067] The first drive signal generating section 60A, the first signal processing section 61A, and the first phase shifting section 62A may perform feedback control so that the oscillation of the mirror section 20 about the first axis a1 maintains a vibration state of a designated frequency. The second drive signal generating section 60B, the second signal processing section 61B, and the second phase shifting section 62B may perform feedback control so that the oscillation of the mirror section 20 about the second axis a2 maintains a vibration state of a designated frequency.

[0068] The first drive signal generating section 60A generates the above-mentioned drive voltage waveform V 1A (t) and V 1B The first drive signal including the first phase shift signal (t) is generated, and the generated first drive signal is applied to the pair of first actuators 31 via the first phase shift unit 62A. As a result, the mirror unit 20 rotates along the first axis a 1 Swings around.

[0069] The second drive signal generating section 60B generates the above-mentioned drive voltage waveform V 2A (t) and V 2B The second drive signal including the second phase shifter 62B is applied to the pair of second actuators 32 via the second phase shifter 62B. As a result, the mirror unit 20 rotates along the second axis a 2 Swings around.

[0070] The first drive signal generated by the first drive signal generating section 60A and the second drive signal generated by the second drive signal generating section 60B have a drive voltage waveform V 2A (t) and V 2BIn the equation for (t), the phase is synchronized as indicated by φ.

[0071] The first angle detection sensors 11A and 11B are arranged to detect the first axis a of the mirror unit 20. 1 The second angle detection sensors 12A and 12B detect the second axis a of the mirror unit 20 and output a signal according to the angle of the surroundings. 2 It outputs a signal according to the surrounding angle.

[0072] FIG. 6 shows an example of signals output from the pair of first angle detection sensors 11A and 11B. In FIG. 1 and S1a 2 The mirror unit 20 is aligned along the second axis a 2 Without swinging it around, the first axis a 1 The signal S1a represents the signals output from the pair of first angle detection sensors 11A and 11B when the sensor 11 is swung only in the circumferential direction. 1 , S1a 2 is the first driving frequency f d1 These are waveform signals that approximate sine waves having the same phase as each other.

[0073] The mirror portion 20 is aligned along the first axis a 1 and the second axis a 2 When the mirror unit 20 is swung around the second axis a at the same time, the output signals of the pair of first angle detection sensors 11A and 11B include 2 Vibration noise RN1 caused by surrounding vibrations is superimposed. S1b 1 is the signal S1a 1 The signal S1b has vibration noise RN1 superimposed on it. 2 is the signal S1a 2 6 represents a signal in which vibration noise RN1 is superimposed on the signal RN1. Note that in the example of Fig. 6, the vibration noise RN1 is emphasized for the purpose of explaining this embodiment.

[0074] FIG. 7 shows an example of signals output from the pair of second angle detection sensors 12A and 12B. In FIG. 1 and S2a 2 The mirror unit 20 is aligned along the first axis a 1 Without swinging it around, the second axis a2 The signal S2a represents the signals output from the pair of second angle detection sensors 12A and 12B when the sensor 12 is swung only in the circumferential direction. 1 , S2a 2 is the second driving frequency f d2 These are waveform signals that approximate sine waves having the same phase as each other.

[0075] The mirror portion 20 is aligned along the first axis a 1 and the second axis a 2 When the mirror unit 20 is swung around the first axis a at the same time, the output signals of the pair of second angle detection sensors 12A and 12B include 1 Vibration noise RN2 caused by surrounding vibrations is superimposed. S2b 1 is the signal S2a 1 S2b represents a signal with vibration noise RN2 superimposed on it. 2 is the signal S2a 2 7 shows a signal in which vibration noise RN2 is superimposed on the signal RN1. Note that in the example of Fig. 7, the vibration noise RN2 is emphasized for the purpose of explaining this embodiment.

[0076] The first signal processing unit 61A processes S1a output from the pair of first angle detection sensors 11A and 11B. 1 , S1a 2 The second signal processor 61B generates a signal S1c from which the vibration noise RN1 has been removed (hereinafter referred to as a "first angle detection signal") based on the S2a output from the pair of second angle detection sensors 12A and 12B. 1 , S2a 2 Based on this, a signal S2c from which the vibration noise RN2 has been removed (hereinafter referred to as a "second angle detection signal") is generated.

[0077] The first signal processing unit 61A can be realized, for example, by a circuit having a configuration shown in Fig. 8. As shown in Fig. 8, the first signal processing unit 61A is composed of a buffer amplifier 71, a variable gain amplifier 72, a subtraction circuit 73, and a gain adjustment circuit 74. The gain adjustment circuit 74 is composed of a first BPF (Band Pass Filter) circuit 75A, a second BPF circuit 75B, a first detection circuit 76A, a second detection circuit 76B, and a subtraction circuit 77. The subtraction circuit 73 and the subtraction circuit 77 are differential amplifier circuits composed of operational amplifiers.

[0078] Signal S1b output from the first angle detection sensor 11A 1 is input to a positive input terminal (non-inverting input terminal) of a subtraction circuit 73 via a buffer amplifier 71. The signal output from the buffer amplifier 71 is branched on the way to be input to the subtraction circuit 73, and is input to a first BPF circuit 75A in a gain adjustment circuit 74.

[0079] Signal S1b output from the first angle detection sensor 11B 2 is input to a negative input terminal (inverting input terminal) of a subtraction circuit 73 via a variable gain amplifier 72. The signal output from the variable gain amplifier 72 is branched on the way to be input to the subtraction circuit 73, and is input to a second BPF circuit 75B in a gain adjustment circuit 74.

[0080] The first BPF circuit 75A and the second BPF circuit 75B each have a second driving frequency f d2 The passband B1 has a center frequency of, for example, f d2 The vibration noise RN1 is in the frequency band of ±5 kHz. d2 , the signal passes through the passband B1. Therefore, the first BPF circuit 75A extracts and outputs the vibration noise RN1 from the signal input from the buffer amplifier 71. The second BPF circuit 75B extracts and outputs the vibration noise RN1 from the signal input from the variable gain amplifier 72.

[0081] The first detection circuit 76A and the second detection circuit 76B are each formed of, for example, an RMS-DC converter (Root Mean Squared value to Direct Current converter). The first detection circuit 76A converts the amplitude of the vibration noise RN1 input from the first BPF circuit 75A into a DC voltage signal and inputs it to the positive input terminal of the subtraction circuit 77. The second detection circuit 76B converts the amplitude of the vibration noise RN1 input from the second BPF circuit 75B into a DC voltage signal and inputs it to the negative input terminal of the subtraction circuit 77.

[0082] The subtraction circuit 77 subtracts the DC voltage signal input from the second detection circuit 76B from the DC voltage signal input from the first detection circuit 76A to obtain a value d 1 Output the value d 1 is the signal S1b output from the first angle detection sensor 11A. 1 and the amplitude of the vibration noise RN1 included in the signal S1b output from the first angle detection sensor 11B. 2 The subtraction circuit 77 calculates the value d 1 is input to the gain adjustment terminal of the variable gain amplifier 72 as the gain adjustment value.

[0083] The variable gain amplifier 72 adjusts the gain by adjusting the value d 1 The signal S1b input from the first angle detection sensor 11B 2 By multiplying by 2 In this way, the gain adjustment circuit 74 performs feedback control to adjust the amplitude level of the signal S1b after passing through the variable gain amplifier 72. 2 The amplitude of the vibration noise RN1 contained in the signal S1b after passing through the buffer amplifier 71 is 1 The amplitude of the vibration noise RN1 contained in the

[0084] The subtraction circuit 73 subtracts the signal S1b input to the positive input terminal. 1 From the signal S1b input to the negative input terminal 2The subtraction circuit 73 outputs a value obtained by subtracting the vibration noise RN1 from the first angle detection signal S1c (see FIG. 9), which is a signal from which the vibration noise RN1 has been removed, because the amplitudes of the vibration noise RN1 contained in both signals match due to the above feedback control.

[0085] FIG. 9 shows the S1b output from the pair of first angle detection sensors 11A and 11B. 1 , S1b 2 The first angle detection signal S1c is generated based on the signal S1b. 1 RN1 corresponds to a signal with double the amplitude of the signal from which the vibration noise RN1 has been removed.

[0086] The first axis a of the mirror portion 20 1 When the surrounding oscillation maintains a resonant state, as shown in FIG. 9, the first angle detection signal S1c output from the first signal processing unit 61A has a drive voltage waveform V 1A There is a phase lag of 90° relative to (t).

[0087] The second signal processing unit 61B can be realized by a configuration similar to that of the first signal processing unit 61A, and therefore a description thereof will be omitted.

[0088] FIG. 10 shows the S2b output from the pair of second angle detection sensors 12A and 12B. 1 , S2b 2 The second angle detection signal S2c is generated based on the signal S2b. 1 corresponds to a signal with double the amplitude of the signal from which vibration noise RN2 has been removed.

[0089] The second axis a of the mirror portion 20 2 When the surrounding oscillation maintains a resonant state, as shown in FIG. 10, the second angle detection signal S2c output from the second signal processing unit 61B has a drive voltage waveform V 2A There is a phase lag of 90° relative to (t).

[0090] The first angle detection signal S1c generated by the first signal processing unit 61A is fed back to the first drive signal generating unit 60A. The first phase shifting unit 62A shifts the phase of the drive voltage waveform output from the first drive signal generating unit 60A. The first phase shifting unit 62A shifts the phase by, for example, 90°.

[0091] The second angle detection signal S2c generated by the second signal processing unit 61B is fed back to the second drive signal generating unit 60B. The second phase shifting unit 62B shifts the phase of the drive voltage waveform output from the second drive signal generating unit 60B. The second phase shifting unit 62B shifts the phase by, for example, 90°.

[0092] The first angle detection signal S1c generated by the first signal processing unit 61A is ideally a sine wave, but in many cases it is not a smooth sine wave. This is because, in the processing by the first signal processing unit 61A, the second axis a of the mirror unit 20 is not smooth. 2 This is because the effects of surrounding fluctuations cannot be completely eliminated. In this case, the timing at which the first angle detection signal S1c crosses zero will shift slightly depending on the period, as shown in Fig. 11 as an example. Fig. 11 shows an example in which waveforms of the timing at which the first angle detection signal S1c crosses zero over multiple periods are superimposed.

[0093] Therefore, the first derivation unit 63A reduces the influence of the deviation for each period by averaging the first angle detection signal S1c for a plurality of periods. The process by the first derivation unit 63A will be described below.

[0094] The first derivation unit 63A derives the first average phase delay time by averaging the phase delay time of the first angle detection signal S1c relative to the first drive signal over the most recent multiple cycles (hereinafter referred to as the "first phase delay time"). Specifically, as shown in FIG. 12 as an example, the first derivation unit 63A derives the first average phase delay time by averaging the first phase delay time t1 from the point in time when the first drive signal in the corresponding cycle is zero to the point in time when the first angle detection signal S1c is zero for the most recent multiple cycles of the first drive signal and the first angle detection signal S1c. In this embodiment, the first drive signal is a bias voltage V off1 Therefore, the point when the first drive signal is zero is when the first drive signal is V off1 It means a point in time.

[0095] Similarly, the second angle detection signal S2c generated by the second signal processing unit 61B is also ideally a sine wave. 1 Since the influence of the surrounding vibrations remains, the sine wave is often not smooth. Therefore, the second derivation unit 63B reduces the influence of the deviation for each period by averaging the second angle detection signal S2c for multiple periods. The process by the second derivation unit 63B will be described below.

[0096] The second derivation unit 63B derives the second average phase delay time by averaging the phase delay time of the second angle detection signal S2c relative to the second drive signal over the most recent multiple cycles (hereinafter referred to as the "second phase delay time"). Specifically, as shown in FIG. 13 as an example, the second derivation unit 63B derives the second average phase delay time by averaging the second phase delay time t2 from the point in time when the second drive signal in the corresponding cycle is zero to the point in time when the second angle detection signal S2c is zero for the most recent multiple cycles of the second drive signal and the second angle detection signal S2c. In this embodiment, the second drive signal is a bias voltage V off2 Therefore, the point when the second drive signal is zero is when the second drive signal is V off2 It means a point in time.

[0097] In the above processing by the first derivation unit 63A and the second derivation unit 63B, the time point at which the sine wave becomes zero from negative to positive is used, but is not limited to this. For example, the time point at which the sine wave becomes zero from positive to negative may be used, or both the time point at which the sine wave becomes zero from negative to positive and the time point at which the sine wave becomes zero from positive to negative may be used.

[0098] The above processing by the first derivation unit 63A and the second derivation unit 63B can reduce the influence of the difference in the timing at which the first angle detection signal S1c and the second angle detection signal S2c cross zero from one period to the next. However, the timing at which the first angle detection signal S1c becomes zero and the timing at which the first deflection angle θ 1 There is a time lag of t3 between the time when 1 (hereinafter, "first delay time t3 1 Similarly, there may be a difference between the timing when the second angle detection signal S2c becomes zero and the timing when the second deflection angle θ 2 There is a time lag of t3 between the time when 2 (hereinafter, "second delay time t3 2 ") may occur.

[0099] FIG. 14 shows the first average phase delay time and the first deviation time t3 1 FIG. 15 shows an example of the relationship between the second average phase delay time and the second deviation time t3 2 As shown in FIG. 14, as the first average phase delay time becomes longer, the first deviation time t3 1 As shown in FIG. 15, as the second average phase delay time becomes longer, the second deviation time t3 2 becomes shorter.

[0100] Therefore, the third derivation unit 64 determines the first delay time t3 as a delay time according to a preset condition. 1 and the second delay time t3 2In the present embodiment, an example in which the first average phase delay time and the second average phase delay time are applied as the condition will be described. Note that, instead of the first average phase delay time, for example, the first phase delay time of the most recent period may be used. Also, instead of the second average phase delay time, for example, the second phase delay time of the most recent period may be used.

[0101] Specifically, the third derivation unit 64 calculates the first average phase delay time t1 according to the following function f1: avg The first shift time t3 according to 1 Derive. t3 1 =f1(t1 avg ) The third derivation unit 64 uses the first average phase delay time t1 instead of the function f1. avg and the first offset time t3 1 A first average phase delay time t1 is calculated using a lookup table in which avg The first shift time t3 according to 1 may be derived.

[0102] Moreover, the third derivation unit 64 calculates the second average phase delay time t2 according to the following function f2: avg The second shift time t3 according to 2 Derive. t3 2 =f2(t2 avg ) In addition, the third derivation unit 64 uses the second average phase delay time t2 instead of the function f2. avg and the second delay time t3 2 The second average phase delay time t2 is calculated using a lookup table in which the avg The second shift time t3 according to 2 may be derived.

[0103] The function f1 is a function of the first average phase delay time and the first deviation time t3 obtained by the calibration. 1 The function f2 is a function obtained by approximating the relationship between the second average phase delay time and the second deviation time t3 obtained by calibration. 2The calibration is a function obtained by approximating the relationship between the above and the following equation. The calibration will be described in detail later.

[0104] The first zero-cross pulse output unit 65A outputs the first drive signal, the first average phase delay time derived by the first derivation unit 63A, and the first deviation time t3 derived by the third derivation unit 64. 1 The first reference signal is generated based on the first axis a of the mirror portion 20. 1 This is a signal indicating that the angle around the center of the driving signal becomes a reference angle (hereinafter referred to as the "first reference angle"). In this embodiment, an example in which zero is applied as the first reference angle will be described. That is, the first zero cross pulse output unit 65A outputs the first drive signal, the first average phase delay time derived by the first derivation unit 63A, and the first deviation time t3 derived by the third derivation unit 64. 1 Based on this, a zero-cross pulse (hereinafter referred to as a "first zero-cross pulse") ZC1 as an example of a first reference signal is generated. The first zero-cross pulse output section 65A is configured with a zero-cross detection circuit. The first zero-cross pulse is generated when the first axis a of the mirror section 20 1 This is a zero-cross signal that indicates that the surrounding angle has become zero.

[0105] As shown in FIG. 16, the first zero-cross pulse output section 65A outputs a pulse when the first drive signal is zero (V off1 ) from the timing of crossing the first average phase delay time and the first deviation time t3 1 The first zero-cross pulse output section 65A outputs the generated first zero-cross pulse ZC1 to the light source driving section 66.

[0106] In this way, the first delay time t3 1 is a delay time used to correct the generation timing of the first reference signal. Also, the first delay time t3 1 The first angle detection signal S1c corresponds to the first axis a of the mirror unit 20. 1The rotational angle of the first axis a of the mirror section 20 relative to the time point indicating that the angle around the axis becomes the first reference angle (zero in this embodiment) (the time point when the first angle detection signal S1c crosses zero in this embodiment) 1 The first angle detection signal S1c is the time lag from the time when the angle around the first axis a of the mirror unit 20 actually becomes the first reference angle. 1 The point in time when the angle around the first axis a of the mirror section 20 becomes the first reference angle is the point in time when the first drive signal is applied to the first axis a of the mirror section 20. 1 The point in time when the angle around the center of the lens becomes the first reference angle (in this embodiment, the first drive signal is V off1 This is the point in time when the first average phase delay time has elapsed from the point in time when the signal crosses the line .

[0107] The second zero-cross pulse output unit 65B outputs the second drive signal, the second average phase delay time derived by the second derivation unit 63B, and the second deviation time t3 derived by the third derivation unit 64. 2 The second reference signal is generated based on the second axis a of the mirror portion 20. 2 This is a signal indicating that the angle around the center of the driving signal has become a reference angle (hereinafter referred to as the "second reference angle"). In this embodiment, an example in which zero is applied as the second reference angle will be described. That is, the second zero-cross pulse output unit 65B outputs the second drive signal, the second average phase delay time derived by the second derivation unit 63B, and the second deviation time t3 derived by the third derivation unit 64. 2 Based on this, a zero-cross pulse (hereinafter, referred to as a "second zero-cross pulse") ZC2 as an example of a second reference signal is generated. The second zero-cross pulse output section 65B is configured with a zero-cross detection circuit. The second zero-cross pulse is generated when the second axis a of the mirror section 20 is 2 This is a zero-cross signal that indicates that the surrounding angle has become zero.

[0108] As shown in FIG. 17, the second zero-cross pulse output section 65B outputs a zero-cross pulse when the second drive signal is zero (V off2 ) from the timing of crossing the second average phase delay time and the second deviation time t3 2The second zero-cross pulse output section 65B outputs the generated second zero-cross pulse ZC2 to the light source driving section 66.

[0109] In this way, the second delay time t3 2 is a delay time used to correct the generation timing of the second reference signal. 2 The second angle detection signal S2c corresponds to the second axis a of the mirror unit 20. 2 The second axis a of the mirror section 20 with respect to the time point indicating that the angle around the second axis a becomes the second reference angle (zero in this embodiment) (the time point when the second angle detection signal S2c crosses zero in this embodiment) 2 The second angle detection signal S2c is the time lag from the time when the angle around the second axis a of the mirror unit 20 actually becomes the second reference angle. 2 The time point when the angle around the second axis a of the mirror section 20 becomes the second reference angle is the time point when the second drive signal is applied to the second axis a of the mirror section 20. 2 The point in time when the angle around the center of the lens becomes the second reference angle (in this embodiment, the second drive signal is V off2 This is the point in time when the second average phase delay time has elapsed from the point in time when the signal crosses the line .

[0110] Although the first zero-cross pulse output section 65A and the second zero-cross pulse output section 65B output zero-cross pulses using both the time when the sine wave becomes zero from negative to positive and the time when the sine wave becomes zero from positive to negative, the present invention is not limited to this. For example, the first zero-cross pulse output section 65A and the second zero-cross pulse output section 65B may output zero-cross pulses using either the time when the sine wave becomes zero from negative to positive and the time when the sine wave becomes zero from positive to negative.

[0111] The light source driving unit 66 drives the light source 3 based on, for example, drawing data supplied from outside the image drawing system 10. In addition, the light source driving unit 66 controls the irradiation timing of the laser light from the light source 3 so that the irradiation timing is synchronized with the first zero cross pulse ZC1 and the second zero cross pulse ZC2.

[0112] Next, the flow of the first delay time derivation process will be described with reference to Fig. 18. The flow of the first delay time derivation process is executed at a predetermined time interval, for example, while the image is being drawn by the image drawing system 10. This time interval may be, for example, a time interval corresponding to one period of the first drive signal, a time interval corresponding to multiple periods, or a time interval set in advance regardless of the period.

[0113] 18, the first derivation unit 63A acquires, for each period, a first phase delay time from a point in time when the first drive signal in the corresponding period is zero to a point in time when the first angle detection signal S1c is zero. In step S12, the first derivation unit 63A derives a first average phase delay time by averaging the first phase delay times of the most recent multiple periods acquired in step S10.

[0114] In step S14, the third derivation unit 64 calculates the first deviation time t3 according to the first average phase delay time derived in step S12 in accordance with the above-mentioned function f1. 1 When the process of step S14 is completed, the first delay time derivation process is completed. By periodically executing the first delay time derivation process during drawing of the image, the first average phase delay time and the first delay time t3 1 will be updated.

[0115] Next, the flow of the second delay time derivation process will be described with reference to Fig. 19. The second delay time derivation process is executed at a predetermined time interval, for example, while the image is being drawn by the image drawing system 10. This time interval may be, for example, a time interval corresponding to one period of the second drive signal, a time interval corresponding to multiple periods, or a time interval set in advance regardless of the period.

[0116] 19, the second derivation unit 63B acquires, for each period, a second phase delay time from a point in time when the second drive signal in the corresponding period is zero to a point in time when the second angle detection signal S2c is zero. In step S22, the second derivation unit 63B derives a second average phase delay time by averaging the second phase delay times of the most recent multiple periods acquired in step S20.

[0117] In step S24, the third derivation unit 64 calculates the second deviation time t3 according to the second average phase delay time derived in step S22 in accordance with the above-mentioned function f2. 2 When the process of step S24 is completed, the second delay time derivation process is completed. By periodically executing the second delay time derivation process during the drawing of the image, the second average phase delay time and the second delay time t3 2 will be updated.

[0118] Next, the flow of the first zero cross pulse generation process will be described with reference to Fig. 20. For example, the first zero cross pulse generation process is executed while the image drawing system 10 is drawing an image.

[0119] In step S30 of Fig. 20, the first zero cross pulse output section 65A judges whether or not the first drive signal is zero. If this judgment is an affirmative judgment, the process proceeds to step S32, and if this judgment is a negative judgment, step S30 is executed again.

[0120] In step S32, the first zero cross pulse output unit 65A calculates the first average phase delay time and the first delay time t3 derived by the first delay time derivation process from the timing when the first drive signal becomes zero in step S30. 1 The first average phase delay time and the first shift time t3 are waited until the time has elapsed since the first drive signal became zero in step S30. 1 When the time period including the above has elapsed, the determination in step S32 becomes positive, and the process proceeds to step S34.

[0121] In step S34, the first zero cross pulse output unit 65A generates the first zero cross pulse ZC1 and outputs the generated first zero cross pulse ZC1 to the light source driving unit 66. When the process of step S34 ends, the process returns to step S30. When the image drawing process by the image drawing system 10 ends, the first zero cross pulse generation process ends.

[0122] Next, a flow of the second zero cross pulse generation process will be described with reference to Fig. 21. For example, the second zero cross pulse generation process is executed while the image drawing system 10 is drawing an image.

[0123] 21, the second zero-cross pulse output section 65B determines whether or not the second drive signal is zero. If this determination is positive, the process proceeds to step S42, and if this determination is negative, step S40 is executed again.

[0124] In step S42, the second zero cross pulse output unit 65B calculates the second average phase delay time and the second delay time t3 derived by the second delay time derivation process from the timing when the second drive signal becomes zero in step S40. 2 The second average phase delay time and the second deviation time t3 are waited until the time has elapsed from the time when the second drive signal becomes zero in step S40. 2 When the time period including the above has elapsed, the determination in step S42 becomes positive, and the process proceeds to step S44.

[0125] In step S44, the second zero cross pulse output unit 65B generates the second zero cross pulse ZC2 and outputs the generated second zero cross pulse ZC2 to the light source driving unit 66. When the process of step S44 ends, the process returns to step S40. When the image drawing process by the image drawing system 10 ends, the second zero cross pulse generation process ends.

[0126] Next, a process for obtaining the above-mentioned functions f1 and f2 by calibration will be described. FIG. 22 is a diagram for explaining the arrangement position of the photodetector 7 during calibration. The photodetector 7 is provided at a position where it can receive reflected light from the mirror section 20. In this embodiment, as shown in FIG. 22 as an example, one photodetector 7 is provided at the center of an area R1 where an image is drawn by reflected light from the mirror section 20 (hereinafter referred to as "drawing area"). When the mirror section 20 is stationary, that is, when the first axis a of the mirror section 20 is rotated, the photodetector 7 is positioned at a position where it can receive reflected light from the mirror section 20. 1 Angle around and second axis a 2 When the circumferential angle is zero, the light beam L reflected from the mirror unit 20 is irradiated onto the photodetector 7. In this case, the photodetector 7 outputs a signal indicating that the light beam L has been irradiated (hereinafter referred to as an "irradiation signal") to the drive control unit 5.

[0127] The optical scanning device 2 according to this embodiment has a first deviation time t3 1 and the second delay time t3 2 The optical scanning device 2 has a delay time derivation mode for deriving the delay time. During calibration, the first calibration process shown in FIG. 23 and the second calibration process shown in FIG. 25 are executed by executing the delay time derivation mode. Examples of the timing for executing the calibration include the start-up of the optical scanning device 2 and the timing when the user inputs an instruction to execute the calibration. The calibration may also be executed before the optical scanning device 2 is shipped from the factory. In this case, the data obtained by the calibration is stored in, for example, a non-volatile storage unit provided in the drive control unit 5. In this case, the light detector 7 may not be included in the image drawing system 10 at the user's base to which the optical scanning device 2 is shipped. In addition, during the execution of the first calibration process and the second calibration process, the light beam L is continuously irradiated from the light source 3 to the reflecting surface 20A of the mirror unit 20.

[0128] 23, the first drive signal generating unit 60A generates the first drive signal as described above, and applies the generated first drive signal to the pair of first actuators 31 via the first phase shifting unit 62A. 2 Without swinging it around, the first axis a 1 Only rock around.

[0129] In step S52, the first derivation unit 63A acquires, for each period, a first phase delay time from the point in time when the first drive signal in the corresponding period is zero to the point in time when the first angle detection signal S1c is zero. At this time, as shown in FIG. 24 as an example, the first derivation unit 63A also acquires, for each period, a delay time t4 from the point in time when the first angle detection signal S1c is zero to the point in time when the irradiation signal is input from the photodetector 7. The point in time when the irradiation signal is input is the point in time when the output signal of the photodetector 7 is aligned with the first axis a of the mirror unit 20. 1 This represents the point in time when the angle around it becomes zero.

[0130] In step S54, the first derivation unit 63A derives a first average phase delay time by averaging the first phase delay times of the most recent multiple periods acquired in step S52. In step S56, the first derivation unit 63A derives a first average phase delay time by averaging the delay times t4 of the most recent multiple periods acquired in step S52. 1 Derive.

[0131] The above-mentioned processes from step S50 to step S56 are executed multiple times while changing the first drive frequency. When the first drive frequency is changed, the first average phase delay time and the first deviation time t3 1 In other words, the first average phase delay times and the first shift times t3 1 As a result, the combination of the first average phase delay time and the first shift time t3 shown in FIG. 1 The relationship is obtained.

[0132] In step S58, the third derivation unit 64 calculates the first average phase delay time and the first deviation time t31 The function f1 is derived by approximating the relationship between the first average phase delay time and the first delay time t3. This function f1 is used in step S14 of the first delay time derivation process (see FIG. 18). 1 The relationship may be stored as a lookup table. When the process of step S58 ends, the first calibration process ends.

[0133] 25, the second drive signal generating unit 60B generates the second drive signal as described above, and applies the generated second drive signal to the pair of second actuators 32 via the second phase shifting unit 62B. That is, in the second calibration process, the mirror unit 20 is rotated about the first axis a 1 Without swinging it around, the second axis a 2 Only rock around.

[0134] In step S72, the second derivation unit 63B acquires, for each period, a second phase delay time from the time when the second drive signal in the corresponding period is zero to the time when the second angle detection signal S2c is zero. At this time, as shown in FIG. 26 as an example, the second derivation unit 63B also acquires, for each period, a delay time t5 from the time when the second angle detection signal S2c is zero to the time when the irradiation signal is input from the photodetector 7. The time when the irradiation signal is input is the time when the output signal of the photodetector 7 is aligned with the second axis a of the mirror unit 20. 2 This represents the point in time when the angle around it becomes zero.

[0135] In step S74, the second derivation unit 63B derives a second average phase delay time by averaging the second phase delay times of the most recent multiple periods acquired in step S72. In step S76, the second derivation unit 63B derives a second average phase delay time by averaging the delay times t5 of the most recent multiple periods acquired in step S72. 2 Derive.

[0136] The above-mentioned processes from step S70 to step S76 are executed multiple times while changing the second drive frequency. When the second drive frequency is changed, the second average phase delay time and the second deviation time t3 2 In other words, the second average phase delay times and the second shift times t3 2 As a result, the combination of the second average phase delay time and the second shift time t3 shown in FIG. 2 The relationship is obtained.

[0137] In step S78, the third derivation unit 64 calculates the second average phase delay time and the second deviation time t3 2 The function f2 is derived by approximating the relationship between the second average phase delay time and the second delay time t3. The function f2 is used in step S24 of the second delay time derivation process (see FIG. 19). 2 The relationship may be stored as a lookup table. When the process of step S78 ends, the second calibration process ends.

[0138] As described above, according to this embodiment, the detection accuracy of the timing at which the angle of the mirror portion 20 by the optical scanning device 2 becomes the reference angle can be improved by using the optical detector 7, thereby suppressing deterioration in the image quality of the drawn image.

[0139] The configuration of the MMD 4 shown in the above embodiment is merely an example. The configuration of the MMD 4 can be modified in various ways. For example, 1 The first actuator 31 that swings the mirror unit 20 around the second axis a is disposed on the second movable frame 24. 2 A second actuator 32 for swinging the periphery may be disposed on the first movable frame 22 .

[0140] In the above embodiment, the pair of first angle detection sensors 11A and 11B are aligned along the first axis a 1In the above embodiment, the first angle detection sensors 11A and 11B are disposed at positions facing each other across the second axis a. For example, as shown in FIG. 27, the pair of first angle detection sensors 11A and 11B may be disposed at positions facing each other across the second axis a. 2 27, the pair of first angle detection sensors 11A, 11B are disposed on the first movable frame 22 near the first support section 21. The first angle detection sensor 11A is disposed near the first support section 21 connected to one side of the mirror section 20. The first angle detection sensor 11B is disposed near the first support section 21 connected to the other side of the mirror section 20. Therefore, the pair of first angle detection sensors 11A, 11B detects the second axis a 2 The pair of first angle detection sensors 11A and 11B are disposed at positions facing each other across the first axis a 1 27 in the -X direction.

[0141] As in the above embodiment, the pair of first angle detection sensors 11A and 11B are aligned along the first axis a 1 In contrast, when the pair of first angle detection sensors 11A and 11B are disposed at positions facing each other across the second axis a, the vibration noise can be removed by subtracting one of the output signals from the other. 2 When the two sensors are disposed at opposing positions across the sensor, the output signals of both sensors are added together to remove vibration noise.

[0142] An example of the configuration of the first signal processing unit 61A in this embodiment is shown in Fig. 28. As shown in Fig. 28, in this embodiment, the first signal processing unit 61A has an adder circuit 73A instead of the subtractor circuit 73. The adder circuit 73A receives the signal S1b input from the first angle detection sensor 11A via the buffer amplifier 71, 1 and a signal S1b input from the first angle detection sensor 11B via the variable gain amplifier 72. 2 The sum of and is output.

[0143] In the above embodiment, the pair of second angle detection sensors 12A and 12B are 2 In the above embodiment, the second angle detection sensors 12A and 12B are disposed at positions facing each other across the first axis a. For example, as shown in FIG. 27, the pair of second angle detection sensors 12A and 12B may be disposed at positions facing each other across the first axis a. 1 27, the pair of second angle detection sensors 12A, 12B are disposed on the second movable frame 24 near the second support portion 23. The second angle detection sensor 12A is disposed near the second support portion 23 connected to one side of the first movable frame 22. The second angle detection sensor 12B is disposed near the second support portion 23 connected to the other side of the first movable frame 22. Therefore, the pair of second angle detection sensors 12A, 12B are disposed near the second support portion 23 connected to the other side of the first movable frame 22. 1 The pair of second angle detection sensors 12A and 12B are disposed at positions facing each other across the second axis a 2 27, in the example of FIG. 27, the +Y direction.

[0144] As in the above embodiment, the pair of second angle detection sensors 12A and 12B are 2 In contrast, when the pair of second angle detection sensors 12A and 12B are disposed at positions facing each other across the first axis a, the vibration noise can be removed by subtracting one of the output signals from the other. 1 When the second signal processor 61B and the first signal processor 61A are disposed opposite each other with the output of the first signal processor 61A therebetween, the vibration noise can be removed by adding the output signals of the two. The configuration of the second signal processor 61B in this embodiment can be realized by the same configuration as that of the first signal processor 61A shown in FIG. 28, and therefore a description thereof will be omitted.

[0145] In the above embodiment, any one of the pair of first angle detection sensors 11A, 11B may be provided on the MMD 4. Similarly, any one of the pair of second angle detection sensors 12A, 12B may be provided on the MMD 4.

[0146] In the above embodiment, the case where one photodetector 7 is provided in the center of the drawing region R1 during calibration has been described, but the present invention is not limited to this. As an example, as shown in FIG. 29, the photodetector 7 detects the first axis a in a region where an image can be drawn by reflected light from the mirror section 20 (hereinafter, referred to as the "drawable region"). 1 Axis a corresponding to 3 Each end of the upper part and the second axis a 2 Axis a corresponding to 4 Alternatively, one may be provided at each end of the mirror section 20. Note that Fig. 29 shows an example in which the imaging area R1 is used as the imaging area. In this case, when the mirror section 20 is stationary, the shift times t4 and t5 are derived based on the distances A1 to A4 from the position P (the center of the imaging area R1 in the example of Fig. 29) where the light beam L reflected from the mirror section 20 is irradiated to the photodetector 7 and the input timing of the irradiation signal from the photodetector 7.

[0147] Specifically, in step S52 of the first calibration process, the first derivation unit 63A calculates the distance from the position P to the axis a as shown in FIG. 4 The ratio of the distances A1 and A2 to the photodetectors 7 on the axis a 4 Based on the time when the irradiation signals are input from the respective photodetectors 7 above, the first axis a of the mirror portion 20 is 1 In the example of FIG. 29, the distance A1 is equal to the distance A2, so the time T1 is the time when the angle of the axis a 4 The first derivation unit 63A uses the time from when the first angle detection signal S1c is zero to the derived time T1 as the offset time t4. The time T1 is the time when the output signal of the photodetector 7 is aligned with the first axis a of the mirror unit 20. 1 This represents the point in time when the angle around it becomes zero.

[0148] Similarly, in step S72 of the second calibration process, the second derivation unit 63B calculates the distance from the position P to the axis a as shown in FIG. 3The ratio of the distances A3 and A4 to the photodetectors 7 on the axis a 3 Based on the time when the irradiation signals are input from the respective photodetectors 7 above, the second axis a of the mirror portion 20 is 2 In the example of FIG. 29, the distance A3 is equal to the distance A4, so the time T2 is the time when the angle of the axis a 3 The second derivation unit 63B uses the time from when the second angle detection signal S2c is zero to the derived time T2 as the offset time t5. The time T2 is the time when the output signal of the photodetector 7 is aligned with the second axis a of the mirror unit 20. 2 This represents the point in time when the angle around it becomes zero.

[0149] The mirror section 20 may be capable of reflecting the light beam L to an area wider than the drawing area R1 based on the drawing data. That is, the mirror section 20 may be configured to reflect the light beam L at a first deflection angle θ 1 and the second swing angle θ 2 In this case, as shown in FIG. 32, the photodetector 7 is located outside the imaging region R1 and within the imaging region R2, and the axis a 3 Each end and axis a on 4 There may be one at each end on the top.

[0150] As an example, as shown in FIG. 33, the photodetector 7 detects the first axis a 1 Axis a corresponding to 3 Two points other than the ends on the top and the second axis a 2 Axis a corresponding to 4 Alternatively, one each of the first lead-out portions 63A may be provided at two points other than the ends on the upper side. In addition, FIG. 33 shows an example in which the drawing area R1 is applied as the drawing possible area. In this case, as in the case in which the photodetector 7 is provided at the ends, the first lead-out portion 63A is located at a position P along the axis a 4 The ratio of the distances A1 and A2 to the photodetectors 7 on the axis a 4Based on the time when the irradiation signals are input from the respective photodetectors 7 above, the first axis a of the mirror portion 20 is 1 In this case, the second lead-out portion 63B can derive the time T1 when the angle of the axis a becomes zero, as in the case where the photodetector 7 is provided at the end portion. 3 The ratio of the distances A3 and A4 to the photodetectors 7 on the axis a 3 Based on the time when the irradiation signals are input from the respective photodetectors 7 above, the second axis a of the mirror portion 20 is 2 The time T2 when the angle becomes zero can be derived.

[0151] In the above embodiment, the photodetector 7 may be in a non-operating state during drawing of an image. In this case, the supply of power to the photodetector 7 can be stopped, and as a result, power consumption can be reduced.

[0152] In the above embodiment, the first average phase delay time and the second average phase delay time are derived when an image is drawn, but the present invention is not limited to this. The first average phase delay time and the second average phase delay time may be acquired by executing an average phase delay time derivation mode for deriving the first average phase delay time and the second average phase delay time during calibration. In this case, when the first zero cross pulse ZC1 and the second zero cross pulse ZC2 are generated, the first average phase delay time and the second average phase delay time acquired in advance during calibration are used. In this case, the timing of execution of the calibration may be, for example, when the MMD4 is started up or when an instruction to execute the calibration is input by the user.

[0153] In the above embodiment, the third derivation unit 64 calculates the first delay time t3 according to the function f1. 1 34 shows the relationship between the first average phase delay time and the first deviation time t3 when the drive voltage V1 of the first drive signal is changed. 134 shows an example of the relationship between the driving voltage V1 of the first driving signal and the amplitude of the first driving signal. The solid line in FIG. 34 shows a case where the driving voltage V1 is higher than the dashed line. As shown in FIG. 34, the higher the driving voltage V1, the shorter the first delay time t3 1 In FIG. 34, the first average phase delay time and the first deviation time t3 are shown when the driving voltage V1 is changed. 1 The relationship between the first delay time t3 1 varies not only in response to the drive voltage V1 of the first drive signal but also in response to the first drive frequency.

[0154] Therefore, the third derivation unit 64 further calculates a first delay time t3 according to the first drive frequency F1 and the drive voltage V1 of the first drive signal in accordance with the following function f3: 1 may be derived. t3 1 =f3(t1 avg , F1, V1) Similarly, the third derivation unit 64 further calculates a second delay time t3 according to the second drive frequency F2 and the drive voltage V2 of the second drive signal in accordance with the following function f4: 2 may be derived. t3 2 =f4(t2 avg , F2, V2)

[0155] In addition, the third derivation unit 64 further derives the first delay time t3 according to the environmental temperature T in accordance with the following functions f5 and f6. 1 and the second delay time t3 2 In this case, the MMD 4 is provided with a temperature sensor that measures the environmental temperature. t3 1 =f5(t1 avg , T) t3 2 =f6(t2 avg , T)

[0156] In addition, the third derivation unit 64 further derives a first delay time t3 according to the first drive frequency F1, the drive voltage V1 of the first drive signal, and the environmental temperature T in accordance with the following function f7: 1 may be derived. t3 1 =f7(t1 avg , F1, V1, T) Similarly, the third derivation unit 64 further derives a second delay time t3 according to the second drive frequency F2, the drive voltage V2 of the second drive signal, and the environmental temperature T in accordance with the following function f8: 2 may be derived. t3 2 =f8(t2 avg , F2, V2, T) In the above functions f3 and f7, only one of the first drive frequency F1 and the drive voltage V1 of the first drive signal may be used. In the above functions f4 and f8, only one of the second drive frequency F2 and the drive voltage V2 of the second drive signal may be used.

[0157] Moreover, the hardware configuration of the drive control unit 5 can be modified in various ways. The drive control unit 5 can be configured using at least one of an analog arithmetic circuit and a digital arithmetic circuit. The drive control unit 5 may be configured with one processor, or may be configured with a combination of two or more processors of the same type or different types. The processor includes a CPU (Central Processing Unit), a programmable logic device (PLD), a dedicated electric circuit, and the like. As is well known, a CPU is a general-purpose processor that executes software (programs) and functions as various processing units. A PLD is a processor such as an FPGA (Field Programmable Gate Array) whose circuit configuration can be changed after manufacture. A dedicated electric circuit is a processor having a circuit configuration designed specifically to execute a specific process such as an ASIC (Application Specific Integrated Circuit). [Explanation of symbols]

[0158] 2 Optical scanning device 3 light source 4. Micromirror Device (MMD) 5 Drive control section 6 Scanned surface 7. Photodetector 10 Image drawing system 11A, 11B First angle detection sensor 12A, 12B Second angle detection sensor 20 Mirror section 20A reflective surface 21 1st support part 22 First movable frame 23 Second support part 24 Second movable frame 25 Connection 26 Fixed Frame 30 Piezoelectric element 31 First actuator 32 Second actuator 60A First drive signal generator 60B second drive signal generating unit 61A First signal processing section 61B Second signal processing section 62A 1st phase shift section 62B Second phase shift section 63A 1st derivation part 63B 2nd derived part 64 Third Derivation 65A 1st zero cross pulse output section 65B Second zero cross pulse output section 66 Light source driver 71 Buffer Amplifier 72 Variable Gain Amplifier 73, 77 Subtraction circuit 73A Adding circuit 74 Gain adjustment circuit 75A 1st BPF circuit 75B 2nd BPF circuit 76A 1st detection circuit 76B Second detection circuit L Light beam P position R1 drawing area R2 drawable area RN1, RN2 vibration noise S1c First angle detection signal S2c Second angle detection signal ZC1 1st zero cross pulse ZC2 Second zero cross pulse a 1 1st axis a 2 2nd axis a 3 , a 4 shaft f d1 First Drive Frequency f d2 Second Drive Frequency

Claims

1. a mirror portion having a reflecting surface that reflects incident light; a first actuator that oscillates the mirror section around a first axis that is in a plane including the reflecting surface of the mirror section when the mirror section is stationary; a second actuator that oscillates the mirror section around a second axis that is within a plane that includes the reflecting surface of the mirror section when the mirror section is stationary and that intersects with the first axis; a first angle detection sensor that outputs a signal corresponding to an angle of the mirror portion about the first axis; a second angle detection sensor that outputs a signal corresponding to an angle of the mirror portion about the second axis; At least one photodetector provided at a position capable of receiving reflected light from the mirror portion; At least one processor; An optical scanning device comprising: The processor, applying a first drive signal having a first drive frequency to the first actuator; applying a second drive signal having a second drive frequency to the second actuator; a deviation time used for correcting a generation timing of a first reference signal indicating that the angle of the mirror part about the first axis has become a first reference angle, the first deviation time being a time at which the angle of the mirror part about the first axis has become the first reference angle relative to a time at which an output signal of the first angle detection sensor indicates that the angle of the mirror part about the first axis has become the first reference angle, based on an output signal of the photodetector; A deviation time used for correcting a generation timing of a second reference signal indicating that the angle of the mirror part about the second axis has become a second reference angle, the second deviation time being a time when the angle of the mirror part about the second axis has become the second reference angle relative to a time when an output signal of the second angle detection sensor indicates that the angle of the mirror part about the second axis has become the second reference angle, is derived based on an output signal of the photodetector. Optical scanning device.

2. The photodetector is provided at the center of an area where an image is drawn by the reflected light from the mirror portion.

2. The optical scanning device according to claim 1.

3. The photodetector is provided on an axis corresponding to the first axis and an axis corresponding to the second axis in a region in which an image can be drawn by reflected light from the mirror portion.

2. The optical scanning device according to claim 1.

4. At least one of the photodetectors is provided at each end on an axis corresponding to the first axis and at each end on an axis corresponding to the second axis in a region in which an image can be drawn by reflected light from the mirror portion.

4. The optical scanning device according to claim 3.

5. The processor, deriving a first average phase delay time by averaging a first phase delay time of an output signal of the first angle detection sensor with respect to a plurality of periods of the first drive signal; deriving a second average phase delay time by averaging a second phase delay time of an output signal of the second angle detection sensor with respect to a plurality of periods of the second drive signal; a time point when the output signal of the first angle detection sensor indicates that the angle of the mirror section about the first axis has reached the first reference angle is a time point when the first average phase delay time has elapsed from a time point when the first drive signal indicates that the angle of the mirror section about the first axis has reached the first reference angle, The time point when the output signal of the second angle detection sensor indicates that the angle of the mirror part about the second axis has reached the second reference angle is the time point when the second average phase delay time has elapsed from the time point when the second drive signal indicates that the angle of the mirror part about the second axis has reached the second reference angle.

5. The optical scanning device according to claim 1, wherein the optical scanning device is a light source.

6. The processor, deriving the first average phase delay time by averaging the first phase delay time at a time point when the output signal of the first angle detection sensor is zero; The second phase delay time is averaged at a time when the output signal of the second angle detection sensor is zero to derive the second average phase delay time.

6. The optical scanning device according to claim 5.

7. The processor, deriving the first average phase delay time by averaging the first phase delay time from a time when the first drive signal is zero to a time when the output signal of the first angle detection sensor is zero in a corresponding period; The second average phase delay time is derived by averaging the second phase delay time from a time when the second drive signal is zero to a time when the output signal of the second angle detection sensor is zero in a corresponding period.

7. The optical scanning device according to claim 6.

8. the first reference angle and the second reference angle are zero; the first deviation time is a time from a point in time when an output signal of the first angle detection sensor indicates that the angle of the mirror part about the first axis has become zero to a point in time when an output signal of the photodetector indicates that the angle of the mirror part about the first axis has become zero, the second deviation time is a time from a time when an output signal of the second angle detection sensor indicates that the angle of the mirror part about the second axis has become zero to a time when an output signal of the photodetector indicates that the angle of the mirror part about the second axis has become zero; 8. The optical scanning device according to claim 5, wherein the optical scanning device is a light source.

9. The processor, generating the first reference signal at a time when the first deviation time has elapsed from a time when an output signal of the first angle detection sensor indicates that the angle of the mirror part about the first axis has reached the first reference angle; The second reference signal is generated when the second deviation time has elapsed from the time when the output signal of the second angle detection sensor indicates that the angle of the mirror part about the second axis has reached the second reference angle.

9. The optical scanning device according to claim 5, wherein the optical scanning device is a light source.

10. A delay time derivation mode for deriving the first delay time and the second delay time, The processor, By executing the delay time derivation mode during calibration, the first delay time and the second delay time are obtained for each preset condition; When generating the first reference signal and the second reference signal, the first delay time and the second delay time acquired in advance in the calibration are used.

10. The optical scanning device according to claim 9.

11. The condition includes the first phase delay time and the second phase delay time. The optical scanning device according to claim 10.

12. The conditions further include a drive voltage of the first drive signal and a drive voltage of the second drive signal. The optical scanning device according to claim 11.

13. The conditions further include the first drive frequency and the second drive frequency.

13. An optical scanning device according to claim 11 or 12.

14. The conditions further include an environmental temperature. The optical scanning device according to any one of claims 11 to 13.

15. The photodetector is a photodiode. The optical scanning device according to any one of claims 1 to 14.

16. The photodetector is in a deactivated state during drawing of an image. The optical scanning device according to any one of claims 1 to 15.

17. the first angle detection sensor is a pair of angle detection sensors arranged at positions facing each other across the first axis or the second axis, the output signal of the first angle detection sensor is an output signal obtained by adding or subtracting a pair of output signals output from a pair of angle detection sensors, the second angle detection sensor is a pair of angle detection sensors arranged at positions facing each other across the first axis or the second axis, The output signal of the second angle detection sensor is an output signal obtained by adding or subtracting a pair of output signals output from a pair of angle detection sensors.

17. The optical scanning device according to claim 1.

18. An optical scanning device according to any one of claims 1 to 17; A light source that irradiates light onto the mirror portion; An image drawing system comprising:

19. a mirror portion having a reflecting surface that reflects incident light; a first actuator that oscillates the mirror section around a first axis that is in a plane including the reflecting surface of the mirror section when the mirror section is stationary; a second actuator that oscillates the mirror section around a second axis that is within a plane that includes the reflecting surface of the mirror section when the mirror section is stationary and that intersects with the first axis; a first angle detection sensor that outputs a signal corresponding to an angle of the mirror portion about the first axis; a second angle detection sensor that outputs a signal corresponding to an angle of the mirror portion about the second axis; At least one photodetector provided at a position capable of receiving reflected light from the mirror portion; A method for driving an optical scanning device comprising: applying a first drive signal having a first drive frequency to the first actuator; applying a second drive signal having a second drive frequency to the second actuator; a deviation time used for correcting a generation timing of a first reference signal indicating that the angle of the mirror part about the first axis has become a first reference angle, the first deviation time being a time at which the angle of the mirror part about the first axis has become the first reference angle relative to a time at which an output signal of the first angle detection sensor indicates that the angle of the mirror part about the first axis has become the first reference angle, based on an output signal of the photodetector; A deviation time used for correcting a generation timing of a second reference signal indicating that the angle of the mirror part about the second axis has become a second reference angle, the second deviation time being a time when the angle of the mirror part about the second axis has become the second reference angle relative to a time when an output signal of the second angle detection sensor indicates that the angle of the mirror part about the second axis has become the second reference angle, is derived based on an output signal of the photodetector. A method for driving an optical scanning device.

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