Swinging device, electromagnetic wave irradiation device, and control device

Abstract

To minimize reductions in phase-shift and maximum drive angle.SOLUTION: A swinging device 10 is provided comprising a swinging unit, a detection unit 16, and a control unit 17. The swinging unit swings about a first axis in response to a drive signal having a first frequency. The detection unit 16 detects the angle of the swinging unit. The control unit 17 controls the first frequency of the drive signal according to a phase difference between a phase of the drive signal and a phase of the angle of the swinging unit.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a rocking device, an electromagnetic wave irradiation device, and a control device. [Background technology]

[0002] In distance measuring devices such as Lidar, a target is scanned by changing the radiation direction of a beam of light using a MEMS mirror. The MEMS mirror is a two-axis rotating mirror that is oscillated around one axis at a resonant frequency, thereby increasing the scanning speed and driving angle (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-048529 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a first frequency having the same period as the resonance frequency is applied so as to oscillate at the resonance frequency, a phase shift occurs and the maximum drive angle decreases.

[0005] Therefore, an object of the present disclosure, which has been made in consideration of the above-described problems of the conventional technology, is to reduce the phase shift and the reduction in the maximum drive angle. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, a rocking device according to a first aspect of the present invention is a swinging unit that swings around a first axis in response to a drive signal having a first frequency; a detection unit that detects the angle of the swing unit; and a control unit that controls the first frequency of the drive signal based on a phase difference between the phase of the drive signal and the phase of the angle of the oscillator.

[0007] An electromagnetic wave irradiation device according to a second aspect of the present invention comprises: a radiation unit that radiates electromagnetic waves; a scanning unit having a mirror unit that oscillates around a first axis in response to a drive signal having a first frequency, and that reflects the electromagnetic wave incident from the radiation unit on a reflecting surface of the mirror unit; a detection unit that detects the angle of the reflecting surface; and a control unit that controls the first frequency of the drive signal based on a phase difference between the phase of the drive signal that oscillates the mirror unit at the first frequency and the phase of the angle of the reflecting surface.

[0008] A control device according to a third aspect comprises: A control device for controlling an oscillating device having a mirror section that oscillates around a first axis in response to a drive signal having a first frequency, and a scanning section that reflects incident electromagnetic waves on a reflective surface of the mirror section, The control unit acquires the angle of the reflecting surface and controls the first frequency of the drive signal based on the phase difference between the phase of the drive signal that oscillates the mirror unit at the first frequency and the phase of the angle of the reflecting surface. [Effects of the Invention]

[0009] According to the oscillation device, electromagnetic wave irradiation device, and control device according to the present disclosure configured as described above, the phase shift and the decrease in the maximum drive angle are reduced. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a functional block diagram showing a schematic configuration of an electromagnetic wave detection device including a rocking device according to an embodiment. [Figure 2] FIG. 2 is a configuration diagram of the rocking device of FIG. [Figure 3] FIG. 3 is a configuration diagram of the scanning unit in FIG. 2. [Figure 4]FIG. 3 is a view of the slit plate in FIG. 2 as seen from the detection element side. [Figure 5] 10A and 10B are diagrams illustrating the swing of the reflecting surface in a first rotation direction caused by a first drive signal. [Figure 6] 10 is a diagram for explaining an angle change along a second rotation direction of the reflecting surface caused by a second drive signal. FIG. [Figure 7] 10 is a graph showing the relationship between the tilt direction around the first axis and time, for explaining a method of calculating the tilt directions around the first axis and the second axis based on the time of reception of the detection signal. [Figure 8] 3 is a flowchart for explaining a frequency adjustment process performed by the control unit of FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of a rocking device to which the present disclosure is applied will be described with reference to the drawings.

[0012] 1, an oscillating device 10 according to the first embodiment of the present disclosure may be used, for example, in an electromagnetic wave detecting device 11. The electromagnetic wave detecting device 11 may be configured to include the oscillating device 10, a measurement detecting unit 12, and a control device 13.

[0013] An overview of the electromagnetic wave detection device 11 will be described. Electromagnetic waves emitted from the oscillation device 10 are irradiated onto the object ob. The electromagnetic waves irradiated onto the object ob are reflected by the object ob, and the reflected waves are incident on the measurement detection unit 12. The control device 13 generates information about the object ob based on the electromagnetic waves radiated by the oscillation device 10 and the reflected waves detected by the measurement detection unit 12. The configuration of each part that makes up the electromagnetic wave detection device 11 will be described in detail below.

[0014] As shown in FIG. 2, the rocking device 10 includes a first radiation unit (radiation unit) 14, a scanning unit 15, a direction detection unit (detection unit) 16, and a control unit 17.

[0015] In this specification, a mirror reflecting an electromagnetic wave may mean that the mirror reflects the electromagnetic wave with a reflectance of more than 50%. Furthermore, the reflectance of the mirror to the electromagnetic wave is preferably more than 70%, more preferably more than 80%, even more preferably more than 90%, and most preferably substantially 100%.

[0016] In this specification, a mirror that transmits an electromagnetic wave may mean that the mirror transmits the electromagnetic wave at a transmittance of more than 50%. Furthermore, the transmittance of the mirror to the electromagnetic wave is preferably more than 70%, more preferably more than 80%, even more preferably more than 90%, and most preferably substantially 100%.

[0017] The first emitter 14 emits electromagnetic waves em. The electromagnetic waves em may include, for example, at least one of infrared rays, visible light, ultraviolet rays, and radio waves. In this embodiment, the electromagnetic waves em may be invisible light such as infrared rays. The first emitter 14 may emit the electromagnetic waves em in a narrow beam shape, for example, 0.5°. Alternatively, the first emitter 14 may emit the electromagnetic waves em in pulses. The first emitter 14 may switch between emitting and stopping the electromagnetic waves em based on the control of the control unit 17, which will be described later. The first emitter 14 includes a radiation source, for example, an LD (Laser Diode) and an LED (Light Emitting Diode). The first emitter 14 may further include an optical element that collimates the electromagnetic waves em emitted by the radiation source.

[0018] The scanning unit 15 may be located in the radiation path of the electromagnetic waves em radiated by the first radiator 14. For example, the scanning unit 15 may be located in the radiation direction of the electromagnetic waves em radiated by the first radiator 14. Alternatively, the scanning unit 15 may be located in a direction in which the electromagnetic waves em radiated by the first radiator 14 are deflected using at least one mirror.

[0019] 3, the scanning unit 15 has a reflecting surface rs that reflects the electromagnetic wave em. The reflecting surface rs may reflect monitor light ml, which will be described later. The reflecting surface rs may be capable of reflecting both the electromagnetic wave em and the monitor light ml.

[0020] The scanning unit 15 oscillates the reflecting surface rs around a first axis ax1 in accordance with a first frequency. The first frequency may be the frequency of a sinusoidal first drive signal sent from the control unit 17, which will be described later. The scanning unit 15 may oscillate the reflecting surface rs around a second axis ax2. The second axis ax2 may intersect with or be perpendicular to the first axis ax1. The scanning unit 15 may change the radiation direction of the electromagnetic wave em and monitor light ml incident on the reflecting surface rs by combining the oscillation of the reflecting surface rs around the first axis ax1 and the oscillation of the reflecting surface rs around the second axis ax2.

[0021] The scanning unit 15 has a first resonance frequency with respect to the oscillation of the reflecting surface rs about the first axis ax1. In the scanning unit 15 of the present application, the first resonance frequency changes in response to the oscillation about the second axis ax2.

[0022] The scanning unit 15 may be, for example, a MEMS (Micro Electro Mechanical Systems) mirror and may include a frame 18, a first mirror 19, a first holding unit 20, a second holding unit 21, and driving units (first driving unit, second driving unit) not shown. The frame 18 may be, for example, a rectangular frame or may have any shape such as a ring. In this embodiment, the frame 18 is a rectangular frame. The first mirror 19 may have a reflecting surface rs. The scanning unit 15 oscillates the first mirror 19 around a first axis ax1 in accordance with the first frequency, causing the reflecting surface rs to oscillate around the first axis ax1. The scanning unit 15 oscillates the first mirror 19 around a second axis ax2, causing the reflecting surface rs to oscillate around the second axis ax2.

[0023] The first holding unit 20 may be fixed to the frame 18. The first holding unit 20 may be fixed to the inside of the frame 18 on both sides of the center thereof. The first holding unit 20 may hold the first mirror 19 via the second holding unit 21. A first driving unit is provided in the first holding unit 20. The first holding unit 20 may oscillate the reflecting surface rs around a first axis ax1. The first driving unit is, for example, a piezoelectric element.

[0024] The second holding unit 21 is connected to the first mirror 19. The second holding unit 21 may also be connected to the first holding unit 20. A second driving unit is installed on the second holding unit 21. The second holding unit 21 may oscillate the reflecting surface rs around the second axis ax2. The second holding unit 24 holds the first mirror 19 (reflecting surface rs) so that it can oscillate around the second axis ax2. The second driving unit is, for example, a piezoelectric element.

[0025] The direction detection unit 16 detects the tilt direction (angle) of the reflecting surface rs. Specifically, the direction detection unit 16 may detect the tilt angle of the reflecting surface rs from a reference direction as the tilt direction. The reference direction is, for example, the normal direction of the reflecting surface rs when the signal strength of the drive signal to the scanning unit 15 is zero. The tilt angle is, for example, an angle around the first axis ax1.

[0026] The direction detection unit 16 may detect the tilt direction directly or indirectly. The direction detection unit 16 may include, for example, an angle sensor that directly detects the tilt direction. Alternatively, the direction detection unit 16 may indirectly detect the tilt direction based on the detection result of the monitor light ml irradiated onto the reflecting surface rs. In this embodiment, the configuration of the direction detection unit 16 that indirectly detects the tilt direction is described below.

[0027] As shown in FIG. 2, the direction detection unit 16 may include a second emitting unit 23 , a second mirror 24 , a third mirror 25 , a slit plate 26 , and a detection element 27 .

[0028] The second emitter 23 may emit monitor light ml. The monitor light ml may include, for example, at least one of infrared light, visible light, and ultraviolet light. The band of the monitor light ml may be different from the band of the electromagnetic waves em.

[0029] The second radiator 23 may emit monitor light ml in the form of a narrow beam, for example, 0.5°. Alternatively, the second radiator 23 may emit a continuous wave of the monitor light ml. The second radiator 23 includes a radiation source such as an LD (Laser Diode) or an LED (Light Emitting Diode). The second radiator 23 may further include an optical element that collimates the second electromagnetic wave em1 emitted by the radiation source.

[0030] The second mirror 24 may be located on the radiation path of the electromagnetic wave em from the first radiation unit 14 and on the radiation path of the monitor light ml from the second radiation unit 23. The second mirror 24 may transmit the electromagnetic wave em. The second mirror 24 may reflect the monitor light ml toward the scanning unit 15. Therefore, the monitor light ml may be irradiated onto the reflecting surface rs.

[0031] The third mirror 25 may be located closer to the object than the scanning unit 15. The third mirror 25 may further be located so as to overlap the traveling path of at least a part or all of the electromagnetic waves deflected by the scanning unit 15. The third mirror 25 may transmit the electromagnetic waves em. The third mirror 25 may reflect the monitor light ml.

[0032] The slit plate 26 may overlap the entire first corresponding direction cd1 and the second corresponding direction cd2 in the reflection range rr of the monitor light ml by the third mirror 25. In other words, the slit plate 26 may cover the entire reflection range rr in both the first corresponding direction cd1 and the second corresponding direction cd2. The first corresponding direction cd1 is a direction corresponding to the first rotation direction rd1 of the monitor light ml about the first axis ax1, reflected by the third mirror 25. The second corresponding direction cd2 is a direction corresponding to the second rotation direction rd2 of the monitor light ml about the second axis ax2, reflected by the third mirror 25. As shown in FIG. 4 , the slit plate 26 may be formed with a slit sl that is inclined with respect to both the first corresponding direction cd1 and the second corresponding direction cd2.

[0033] 2, the detecting element 27 may be positioned so as to be able to detect the monitor light ml passing through the slit sl. When the detecting element 27 detects the monitor light ml, it may transmit a detection signal to the control unit 17. Specifically, the detecting element 27 may include a single element such as an APD (Avalanche PhotoDiode) or a PD (PhotoDiode).

[0034] The control unit 17 includes one or more processors and a memory. The processor may include at least one of a general-purpose processor that loads a specific program to execute a specific function and a dedicated processor specialized for a specific process. The dedicated processor may include an application-specific integrated circuit (ASIC). The processor may include a programmable logic device (PLD). The PLD may include a field-programmable gate array (FPGA). The control unit 17 may include at least one of a system-on-a-chip (SoC) and a system in a package (SiP) in which one or more processors work together.

[0035] The control unit 17 may further include a storage unit. The storage unit may include any storage device, such as a RAM (Random Access Memory) or a ROM (Read Only Memory). The storage unit may store various programs that cause the control unit 17 to function and various information used by the control unit 17.

[0036] The control unit 17 controls the first radiation unit 14 and the scanning unit 15 .

[0037] The control unit 17 may control the oscillation of the scanning unit 15 about the first axis ax1 and the second axis ax2 by transmitting a drive signal to the scanning unit 15. Specifically, the drive signal may include a first drive signal transmitted to a first drive unit installed in the first holding unit 20 and a second drive signal transmitted to a second drive unit installed in the second holding unit 21.

[0038] As shown in FIG. 5, the first drive signal has a continuous sinusoidal waveform. The continuous sinusoidal first drive signal causes the first mirror 19 to continuously oscillate around the first axis ax1. The continuous oscillation of the first mirror 19 causes the radiation direction of the electromagnetic wave em to continuously change back and forth along the first rotation direction rd1. The control unit 17 may resonantly drive the reflecting surface rs around the first axis ax1 by generating the first frequency of the sinusoidal drive signal so that it is the same as the resonant frequency of the scanning unit 15 around the first axis ax1. Here, resonant driving refers to resonating at a natural vibration frequency (resonant frequency) determined by the structure, mass, spring constant, etc. of the MEMS mirror.

[0039] As shown in FIG. 6, the second drive signal may repeatedly increase and decrease in a stepped manner. This stepwise increase and decrease in the second drive signal causes the first mirror 19 to oscillate discretely around the second axis ax2. In other words, the first mirror 19 performs non-resonant driving, which gradually changes the reflecting surface rs around the second axis ax2 to an angle corresponding to the signal strength of the second drive signal. Here, non-resonant driving refers to oscillating the reflecting surface rs around the second axis ax2 without resonating at a natural vibration frequency (resonant frequency) determined by the structure, mass, spring constant, etc. of the MEMS mirror. The discrete oscillation of the first mirror 19 causes the radiation direction of the electromagnetic wave em to discretely change back and forth along the second rotation direction rd2. The frequency of the second drive signal, which repeatedly increases and decreases the signal strength in a stepped manner, may be fixed based on a fixed frame rate or may vary depending on an adjustable frame rate. The period of the second drive signal may be longer than the period of the first drive signal.

[0040] Furthermore, the control unit 17 may calculate the deflection direction of the electromagnetic waves em and the monitor light ml based on the drive signal to the scanning unit 15 and the detection signal obtained from the direction detection unit 16. The deflection direction corresponds to the orientation of the reflecting surface rs at which the scanning unit 15 changes the radiation direction of the electromagnetic waves em and the monitor light ml. The control unit 17 may calculate the deflection direction of the electromagnetic waves em and the monitor light ml as the directions of the first rotation direction rd1 and second rotation direction rd2 components. The method of calculating the deflection direction will be described in detail below.

[0041] As described above, the first drive signal is a sine wave that oscillates the scanning unit 15 along the first rotation direction rd1. Furthermore, with the above-described configuration, the slit sl can cause the monitor light m1 to be incident on the detecting element 27 when the reflecting surface rs is tilted in a specific direction about the first axis ax1. The specific tilt direction about the first axis ax1 changes depending on the tilt direction about the second axis ax2. Furthermore, the oscillation about the second axis ax2 is a discrete oscillation. When the period of the second drive signal is longer than the period of the first drive signal, the monitor light m1 is incident on the detecting element 27 multiple times at a certain tilt direction about the second axis ax2. In this case, the tilt direction of the reflecting surface rs about the second axis ax2 is the same when multiple detection signals (e.g., three detection signals) are received. Therefore, the period of the second drive signal is set longer than the period of the first drive signal so that the monitor light m1 can be incident multiple times (for example, three times) consecutively on the detecting element 27 during a predetermined period in which the tilt direction about the second axis ax2 is constant. With this configuration, as shown in Fig. 7, in any tilt direction about the second axis ax2, a detection signal is transmitted from the detecting element 27 to the control unit 17 when the reflecting surface rs is tilted in a specific direction about the first axis ax1.

[0042] At the midpoint between two consecutive detection signals, the tilt direction about the first axis ax1 reaches an extreme value. For example, with respect to the first and second times t1 and t2 at which detection signals are consecutively received, the tilt direction about the first axis ax1 reaches a maximum or minimum at the first intermediate time mt1, which is the midpoint between the first and second times t1 and t2. Similarly, with respect to the second and third times t2 and t3 at which detection signals are consecutively received, the tilt direction about the first axis ax1 reaches a minimum or maximum at the second intermediate time mt2, which is the midpoint between the second and third times t2 and t3. Therefore, at the third intermediate time mt3, which is the midpoint between the first and second intermediate times, the tilt direction about the first axis ax1 is the reference direction. Therefore, the second time t2 relative to the third intermediate time mt3 corresponds to the tilt direction of the reflecting surface rs about the second axis ax2. The correspondence between the second point in time t2 relative to the third intermediate point in time mt3 and the tilt direction of the reflecting surface rs around the second axis ax2 may be calculated in advance based on the tilt angle of the slit sl relative to the second corresponding direction cd2 and the period of the second drive signal.

[0043] The control unit 17 may detect the tilt direction of the reflecting surface rs around the second axis ax2 based on the three consecutively detected detection signals, utilizing the events described above. As described above, the specific tilt direction around the first axis ax1 in which the monitor light ml is incident on the detection element 27 changes depending on the tilt direction around the second axis ax2. Therefore, the control unit 17 may recognize the specific tilt direction around the first axis ax1 depending on the detected tilt direction around the second axis ax2. The control unit 17 may calculate the tilt direction around the first axis ax1 based on the specific tilt direction, the first frequency, and the elapsed time since the most recent detection signal was received. The control unit 17 may calculate the deflection direction based on the tilt directions around the first axis ax1 and the second axis ax2 and the position of the first radiator 14 relative to the scanner 15.

[0044] The control unit 17 may transmit the estimated deflection directions in the first rotation direction rd1 and the second rotation direction to the control device 13 as information.

[0045] The control unit 17 controls the first frequency based on the phase of the first drive signal oscillated at the first frequency and the phase of the tilt direction. The phase of the tilt direction is a phase that orients the reflecting surface rs in an arbitrary tilt direction around the first axis ax1. Specifically, the control unit 17 may estimate a first resonant frequency based on the phase difference between the phase of the first drive signal oscillated at the first frequency and the phase of the tilt direction, and adjust the first frequency to the estimated first resonant frequency.

[0046] When the first frequency matches the first resonant frequency, the phase difference between the first drive signal and the tilt direction about the first axis ax1 is π / 2, or in other words, 1 / 4 period. Therefore, when the phase difference between the first drive signal and the tilt direction about the first axis ax1 deviates from π / 2, the control unit 17 changes the first frequency until the phase difference becomes π / 2. Furthermore, the first frequency may be changed, for example, so that the angular deviation in the direction of the first axis ax1 is 1 / 4 or less, or 1 / 8 or less, in one distance pixel that is the radiation range when the first emitter 14 emits a single pulse of electromagnetic waves em and that is the detection range in which the measurement detector 12 detects the reflected waves from the object ob.

[0047] The control unit 17 may determine, as the first resonant frequency, a first frequency at which the phase difference between the first drive signal and the tilt direction about the first axis ax1 is π / 2. The control unit 17 may store the determined first resonant frequency in a memory unit. The control unit 17 may generate the first drive signal using the first resonant frequency stored in the memory unit. Even after generating the first drive signal using the first resonant frequency stored in the memory unit, the control unit 17 may compare the phase of the first drive signal with the phase of the tilt direction to determine whether the first drive signal matches the first resonant frequency and adjust the first frequency. Note that before determining the first resonant frequency, a pre-measured first resonant frequency may be stored in the memory unit and used to generate the first drive signal.

[0048] The control unit 17 may change the first frequency based on the tilt direction of the reflecting surface rs about the second axis ax2. Specifically, the control unit 17 may change the first frequency so that it corresponds to each tilt direction of the reflecting surface rs caused by the rocking that changes stepwise about the second axis ax2. Depending on the drive method for rocking the reflecting surface rs about the first axis ax1 and the second axis ax2, the first resonant frequency changes depending on the rocking about the second axis ax2, in other words, the tilt direction of the reflecting surface rs about the second axis ax2. Therefore, specifically, the control unit 17 may change the first frequency so that it matches the first resonant frequency that corresponds to the tilt direction of the reflecting surface rs about the second axis ax2.

[0049] The control unit 17 may store in the storage unit a first resonance frequency for each tilt direction of the reflecting surface rs about the second axis ax2. Alternatively, the control unit 17 may store in the storage unit first resonance frequencies corresponding to each of some of the tilt directions of the reflecting surface rs about the second axis ax2. Each time the control unit 17 changes the tilt direction of the reflecting surface rs about the second axis ax2, the control unit 17 may read out from the storage unit a first resonance frequency corresponding to the changed tilt direction and generate a first drive signal. Even after generating a first drive signal using the first resonance frequency stored in the storage unit, the control unit 17 may compare the phase of the first drive signal with the phase of the tilt direction to determine whether the first drive signal matches the first resonance frequency and adjust the first frequency.

[0050] The control unit 17 may change the first frequency of the first drive signal at a predetermined time point.

[0051] The predetermined time point may be the time point when the angular velocity of the oscillation of the reflecting surface rs around the first axis ax1 becomes minimal. Specifically, the time point when the angular velocity of the oscillation becomes minimal is the time point when the electromagnetic wave em is reflected toward both ends of the oscillation along the first rotation direction rd1. Note that the predetermined time point may be set to a period when the angular velocity of the oscillation of the reflecting surface rs around the first axis ax1 becomes equal to or less than a first threshold value. The first threshold value may be set to, for example, an angular velocity at which the angular velocity of the oscillation of the reflecting surface rs around the first axis ax1 becomes 5 percent greater than the minimal value.

[0052] Alternatively, the predetermined time point may be the time point at which the deviation of the tilt direction of the reflecting surface rs about the first axis ax1 due to the swinging about the first axis ax1 is minimized. Specifically, the time point at which the deviation of the tilt direction of the reflecting surface rs about the first axis ax1 is minimized is the time point at which the electromagnetic wave em is reflected toward the center of the swinging along the first rotation direction rd1. The predetermined time point may also be set to a period during which the deviation of the angle of the reflecting surface rs about the first axis ax1 is equal to or less than a second threshold value. The first threshold value may be set to, for example, a deviation that is 5 percent greater than the value at which the deviation of the angle of the reflecting surface rs about the first axis ax1 is minimized.

[0053] In a configuration in which first resonance frequencies corresponding to some of all tilt directions changed stepwise around the second axis ax2 are stored in a memory unit, the control unit 17 may change the first frequency using a deviation of the first resonance frequency stored in the memory unit. The deviation of the first resonance frequency may be a deviation from a reference first resonance frequency. The reference first resonance frequency may be, for example, the first resonance frequency in a state in which no drive signal is applied to the second actuator 21.

[0054] Some of the tilt directions may include a tilt direction at a maximum change in the swing of the reflecting surface rs around the second axis ax2. Furthermore, some of the tilt directions may include tilt directions spaced at regular angular intervals in the swing around the second axis ax2. Furthermore, some of the tilt directions may be tilt directions corresponding to positions spaced at regular displacement intervals along the second rotation direction rd2 when the radial direction in the swing around the second axis ax2 is projected onto a plane.

[0055] The control unit 17 may estimate the first resonance frequency in the tilt direction by interpolation or extrapolation based on the first resonance frequencies stored in advance for some of the tilt directions and the tilt direction of the reflecting surface rs about the second axis ax2. The control unit 17 may change the first frequency so that it becomes the same as the estimated first resonance frequency.

[0056] Furthermore, the control unit 17 may change the first frequency so that it becomes a frequency according to the ambient temperature. The control unit 17 may obtain the first resonance frequency for any plurality of temperature values ​​in advance and store it in the storage unit. The control unit 17 may estimate the first resonance frequency at that temperature by interpolation or extrapolation based on the first resonance frequency measured in advance for any plurality of temperature values ​​and the ambient temperature. The control unit 17 may change the first frequency so that it becomes the same as the estimated first resonance frequency.

[0057] The control unit 17 switches the first emitter 14 between emitting and extinguishing light. As shown in FIG. 5 , the control unit 17 may cause the first emitter 14 to emit pulsed light while the reflecting surface rs is tilted so that a sampling area excluding the vicinity of both ends of the oscillation in the first rotation direction rd1 is aligned with the radiation direction. Furthermore, the control unit 17 may cause the first emitter 14 to emit pulsed light while the above-described conditions for oscillation in the first rotation direction rd1 are satisfied after a stabilization time has elapsed since the signal strength of the second drive signal was changed. The control unit 17 may output a command to the first emitter 14 to emit light to the first emitter 14, and simultaneously transmit radiation information indicating that radiation has been completed to the control device 13.

[0058] 1, the measurement detector 12 may be provided so that the electromagnetic waves emitted by the oscillating device 10 can be incident on the object ob. The measurement detector 12 may detect the reflected electromagnetic waves em. The measurement detector 12 may transmit detection information indicating that the reflected waves from the object have been detected to the control device 13.

[0059] More specifically, the measurement detection unit 12 includes elements that constitute a distance measurement sensor. For example, the measurement detection unit 12 includes a single element such as an APD (Avalanche PhotoDiode), a PD (PhotoDiode), or a distance measurement image sensor. Alternatively, the measurement detection unit 12 may include an element array such as an APD array, a PD array, a distance measurement imaging array, or a distance measurement image sensor.

[0060] The control device 13 may generate three-dimensional position information of any object point on the object ob based on the deflection direction and radiation information acquired from the oscillating device 10 and the detection information acquired from the measurement detection unit 12.

[0061] Specifically, the control device 13 may acquire distance information of any object point on the target ob using ToF (Time of Flight) based on the time when the first radiator 14 radiates the pulsed electromagnetic wave em and the time when the measurement detector 12 detects the electromagnetic wave em after radiation.

[0062] The control device 13 may generate three-dimensional position information of any object point based on the deflection direction to the object point and distance information calculated as described above.

[0063] Next, the frequency adjustment process executed by the control unit 17 in this embodiment will be described with reference to the flowchart of Fig. 8. The frequency adjustment process starts, for example, when the signal strength of the second drive signal changes.

[0064] In step S100, the control unit 17 determines the tilt direction about the second axis ax2 that corresponds to the second drive signal after the change in signal strength. After the determination, the process proceeds to step 101. Note that the signal strength of the second drive signal corresponds to the tilt direction of the reflecting surface rs about the second axis ax2, and this correspondence may be measured in advance and stored in the storage unit. However, the actual correspondence may deviate from the previously measured correspondence.

[0065] In step S101, the control unit 17 reads out the first resonance frequency corresponding to the tilt direction about the second axis ax2 determined in step S100 from the storage unit. After reading, the process proceeds to step .

[0066] In step S102, the control unit 17 determines a first frequency based on the first resonant frequency read in step S101 or the change in step S106. The control unit 17 then generates a first drive signal having the determined first frequency. After generation, the process proceeds to step S103.

[0067] In step S103, the control unit 17 calculates the tilt directions about both the first axis ax1 and the second axis ax2 based on the detection signals obtained from the direction detection unit 16. After the calculation, the process proceeds to step S104.

[0068] In step S104, the control unit 17 calculates the phase of the first drive signal generated in step S102. Furthermore, the control unit 17 calculates the phase of the tilt direction about the first axis ax1 based on the tilt directions about both the first axis ax1 and the second axis ax2 calculated in step S103. After the calculation, the process proceeds to step S105.

[0069] In step S105, the control unit 17 determines whether the reflecting surface rs is resonating around the first axis ax1 based on the phase difference between the phase of the first drive signal calculated in step S104 and the phase of the tilt direction around the first axis ax1. If the reflecting surface rs is not resonating, the process proceeds to step S106. If the reflecting surface rs is resonating, the process proceeds to step S107.

[0070] In step S106, the control unit 17 changes the first frequency. After the change, the process proceeds to step S102.

[0071] In step S107, the control unit 17 determines the first frequency of the first drive signal generated in step S102 to be the first resonance frequency corresponding to the tilt direction about the second axis ax2 calculated in step S103. Furthermore, the control unit 17 stores the determined first resonance frequency in the storage unit as the first resonance frequency corresponding to the tilt direction about the second axis ax2 calculated in step S103. After storing, the frequency adjustment process ends.

[0072] The oscillating device 10 of this embodiment, configured as described above, includes an oscillating unit that oscillates around a first axis ax1 in response to a drive signal having a first frequency, a direction detection unit 16 that detects the angle of the oscillating unit, and a control unit 17 that controls the first frequency of the drive signal based on the phase difference between the phase of the drive signal and the phase of the angle of the oscillating unit. As described above, the scanning speed and drive angle are increased by oscillating the reflecting surface rs using a first drive signal having a first resonant frequency. However, deviations may occur in the first resonant frequency determined by the structure or design of the scanning unit 15 (oscillating unit). To address such issues, the oscillating device 10 configured as described above controls the frequency of the drive signal based on a comparison between the phase of the angle of the oscillating reflecting surface rs and the phase of the drive signal, thereby correcting the deviation in the resonant frequency. Therefore, the oscillating device 10 can reduce phase deviations and a decrease in the maximum drive angle.

[0073] Furthermore, in the oscillating device 10, the control unit 17 estimates a change in the first angle of the reflecting surface rs oscillating around the first axis ax1 based on the time from the first time point t1 to the second time point t2 and the time from the second time point t2 to the third time point t3, among the first time point t1, the second time point t2, and the third time point t3, at which the direction detection unit 16 continuously detected the angle during a predetermined period, and controls the first frequency based on the phase difference between the phase of the drive signal and the phase of the first angle of the reflecting surface rs. With this configuration, the oscillating device 10 obtains information about the phase of the angle of the reflecting surface rs oscillating around the first axis ax1 based on the angle of the reflecting surface rs oscillating around the first axis ax1 estimated by using the three time points at which the direction detection unit 16 continuously detected the angle. Therefore, the frequency of the drive signal is controlled based on a comparison of the phase of the angle of the reflecting surface rs oscillating around the first axis ax1 with the phase of the drive signal, thereby correcting a deviation in the resonant frequency.

[0074] Furthermore, in the oscillating device 10, the drive unit includes a first drive unit that is installed on the first holding unit 20 and oscillates the mirror unit about the first axis ax1, and a second drive unit that is installed on the second holding unit 21 and oscillates the mirror unit about the second axis ax2. With this configuration, the oscillating device 10 controls the drive frequency applied to the first drive unit that oscillates the mirror unit about the first axis ax1, thereby correcting the deviation of the resonance frequency. Therefore, the oscillating device 10 can reduce the phase deviation and the reduction in the maximum drive angle.

[0075] In the oscillating device 10, the direction detector 16 detects a second angle of the reflecting surface rs oscillating about the second axis ax2, and the controller 17 estimates a change in the first angle of the reflecting surface rs oscillating about the first axis ax1 based on the time from the first time point t1 to the second time point t2 and the time from the second time point t2 to the third time point t3, among the first time point t1, the second time point t2, and the third time point t3, at which the second angle within a predetermined range is continuously detected, and controls the first frequency based on the phase difference between the phase of the drive signal and the phase of the first angle of the reflecting surface rs. With this configuration, the oscillating device 10 obtains information about the phase of the angle of the reflecting surface rs oscillating about the first axis ax1 based on the angle of the reflecting surface rs oscillating about the first axis ax1 estimated by using the three time points at which the direction detector 16 continuously detected the angle. Therefore, the frequency of the drive signal is controlled based on a comparison between the phase of the angle of the reflecting surface rs oscillating around the first axis ax1 and the phase of the drive signal, so that the deviation of the resonance frequency can be corrected.

[0076] The electromagnetic wave irradiation device configured as described above includes an emitting unit 14 that emits electromagnetic waves, a scanning unit 15 that has a mirror unit that oscillates around a first axis ax1 in response to a drive signal having a first frequency and reflects the electromagnetic waves incident from the emitting unit 14 on a reflecting surface rs of the mirror unit, a direction detecting unit 16 that detects the angle of the reflecting surface rs, and a control unit 17 that controls the first frequency of the drive signal based on the phase difference between the phase of the drive signal that oscillates the mirror unit at the first frequency and the phase of the angle of the reflecting surface rs. With this configuration, the electromagnetic wave irradiation device controls the frequency of the drive signal in the scanning unit 15 based on a comparison between the phase of the angle of the oscillating reflecting surface rs and the phase of the drive signal, thereby correcting a shift in the resonant frequency. Therefore, the electromagnetic wave irradiation device can reduce phase shifts and a decrease in the maximum drive angle.

[0077] The electromagnetic wave irradiation device further includes a second detection unit that detects reflected waves that are generated when the electromagnetic waves are reflected by an object after being reflected by the scanning unit 15. With this configuration, the electromagnetic wave irradiation device can acquire distance information of any object point on the object, for example, by ToF, based on the time when the first radiating unit 14 radiates the electromagnetic waves and the time when the second detecting unit (measurement detecting unit 12) detects the electromagnetic waves after the radiation.

[0078] The control device 13 configured as described above controls an oscillating device 10 having a mirror unit that oscillates around a first axis ax1 in response to a drive signal having a first frequency and a scanning unit 15 that reflects incident electromagnetic waves em on the mirror unit's reflecting surface rs. The control device 13 also includes a control unit 17 that acquires the angle of the reflecting surface rs and controls the first frequency of the drive signal based on the phase difference between the phase of the drive signal that oscillates the mirror unit at the first frequency and the phase of the angle of the reflecting surface rs. With this configuration, the control device 13 controls the frequency of the drive signal in the scanning unit 15 of the oscillating device 10 based on a comparison between the phase of the angle of the oscillating reflecting surface rs and the phase of the drive signal, thereby correcting a shift in the resonant frequency. Therefore, the oscillating device 10 can reduce phase shifts and a decrease in the maximum drive angle.

[0079] The above has described an embodiment of the oscillating device 10, but the embodiment of the present disclosure can also be embodied as a method or program for implementing the device, as well as a storage medium on which a program is recorded (for example, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a CD-RW, a magnetic tape, a hard disk, or a memory card, etc.).

[0080] Furthermore, the implementation form of the program is not limited to application programs such as object code compiled by a compiler or program code executed by an interpreter, but may also be in the form of a program module incorporated into an operating system. Furthermore, the program may or may not be configured so that all processing is performed solely by the CPU on the control board. The program may also be configured so that part or all of it is executed by another processing unit mounted on an expansion board or expansion unit added to the board as needed.

[0081] The drawings illustrating the embodiments of the present disclosure are schematic, and the dimensional ratios and the like in the drawings do not necessarily correspond to the actual ones.

[0082] Although the embodiments of the present disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art could make various modifications or alterations based on the present disclosure. Therefore, it should be noted that these modifications or alterations are included in the scope of the present disclosure. For example, the functions included in each component can be rearranged so as not to cause logical inconsistencies, and multiple components can be combined or divided into one.

[0083] For example, in this embodiment, the direction detector 16 is configured to include a single detector element 27, but a plurality of detector elements may be used to detect the tilt direction of the reflecting surface rs.

[0084] All of the features described in this disclosure and / or all steps of all of the disclosed methods or processes may be combined in any combination except combinations in which these features are mutually exclusive. Furthermore, each feature described in this disclosure may be replaced by an alternative feature serving the same, equivalent, or similar purpose, unless expressly denied. Thus, unless expressly denied, each disclosed feature is only one example of a generic series of identical or equivalent features.

[0085] Furthermore, embodiments of the present disclosure are not limited to the specific configurations of any of the above-described embodiments, but rather extend to any novel feature or combination thereof described herein, or any novel method or process step or combination thereof described herein.

[0086] In this disclosure, descriptions such as "first" and "second" are identifiers for distinguishing the configuration. In this disclosure, the configurations distinguished by descriptions such as "first" and "second" can have their numbers exchanged. For example, the first radiating unit can exchange the identifiers "first" and "second" with the second radiating unit. The exchange of identifiers is performed simultaneously. The configurations remain distinguished even after the exchange of identifiers. The identifiers may be deleted. A configuration from which the identifiers have been deleted is distinguished by a symbol. The descriptions of identifiers such as "first" and "second" in this disclosure should not be used solely to interpret the order of the configurations or to justify the existence of an identifier with a smaller number. [Explanation of symbols]

[0087] 10. Oscillating device 11 Electromagnetic wave detection device 12 Measurement detector 13 Control device 14 First radiating part 15 Scanning unit 16 Direction detection unit 17 Control Unit 18 frames 19 The First Mirror 20 First holding part 21 Second holding part 23 Second radiating part 24 The Second Mirror 25 The Third Mirror 26 Slit plate 27 Detector element ax1 1st axis ax2 2nd axis cd1 First corresponding direction cd2 Second corresponding direction em electromagnetic wave ml Monitor light ob target rd1 First rotation direction rd2 Second rotation direction rs reflective surface

Claims

1. a swinging unit that swings around a first axis in response to a drive signal having a first frequency; a detection unit that detects the angle of the swing unit; a control unit that controls the first frequency of the drive signal based on a phase difference between a phase of the drive signal and a phase of an angle of the oscillator. Rocking device.

2. 2. The rocking device according to claim 1, The control unit a first time point, a second time point, and a third time point at which the angle is continuously detected by the detection unit during a predetermined period, and based on the time from the first time point to the second time point and the time from the second time point to the third time point, a change in the first angle of the reflecting surface that oscillates around the first axis is estimated; controlling the first frequency based on a phase difference between a phase of the drive signal and a phase of the first angle of the reflecting surface; Rocking device.

3. 2. The rocking device according to claim 1, The swinging portion is a second angle of the reflecting surface is changed by swinging the reflecting surface around a second axis different from the first axis; Rocking device.

4. 4. The rocking device according to claim 3, The swinging portion is a mirror portion that oscillates around the first axis in response to the drive signal, and reflects incident electromagnetic waves on a reflective surface of the mirror portion; a second holding portion that holds the mirror portion so that the mirror portion can swing around the second axis; a first holding portion that holds the mirror portion via the second holding portion so that the mirror portion can swing around the first axis; a drive unit that resonantly drives the mirror unit around the first axis and non-resonantly drives the mirror unit around the second axis in response to the drive signal, Rocking device.

5. 5. The rocking device according to claim 4, The drive unit is a first drive unit that is installed on the first holder and that swings the mirror unit around the first axis; a second drive unit that is installed on the second holder and that swings the mirror unit around the second axis, Rocking device.

6. The rocking device according to claim 3, the detection unit detects the second angle of the reflecting surface that swings around the second axis, The control unit a first time point, a second time point, and a third time point at which the second angle included in a predetermined range is successively detected, and based on the time from the first time point to the second time point and the time from the second time point to the third time point, a change in the first angle of the reflecting surface oscillating around the first axis is estimated; controlling the first frequency based on a phase difference between a phase of the drive signal and a phase of the first angle of the reflecting surface; Rocking device.

7. a radiation unit that radiates electromagnetic waves; a scanning unit having a mirror unit that oscillates around a first axis in response to a drive signal having a first frequency, and that reflects the electromagnetic wave incident from the radiation unit on a reflecting surface of the mirror unit; a detection unit that detects the angle of the reflecting surface; a control unit that controls the first frequency of the drive signal based on a phase difference between a phase of the drive signal that oscillates the mirror unit at the first frequency and a phase of an angle of the reflecting surface, Electromagnetic wave irradiation device.

8. The electromagnetic wave irradiation device according to claim 7, The scanning unit further includes a second detection unit that detects a reflected wave that is the electromagnetic wave reflected by an object. Electromagnetic wave irradiation device.

9. A control device for controlling an oscillating device including a mirror unit that oscillates around a first axis in response to a drive signal having a first frequency, and a scanning unit that reflects incident electromagnetic waves on a reflective surface of the mirror unit, a control unit that acquires an angle of the reflecting surface and controls the first frequency of the drive signal based on a phase difference between a phase of the drive signal that oscillates the mirror unit at the first frequency and a phase of the angle of the reflecting surface, Control device.

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