Optical device

Abstract

To control the density of spots at a desired position to a desired density.SOLUTION: Provided is an optical device comprising a signal generation unit that generates a first drive signal to drive a movable reflection unit in a prescribed direction that reflects a beam irradiated from a light-emitting element. In a prescribed first period in which the first drive signal transitions from one of a maximum value and a minimum value of the first drive signal to the other of these, the first drive signal includes a period in which it has a first slope and a second slope that is different from the first slope, and the slope in the first period does not include a positive slope or does not include a negative slope, either of which applies.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an optical device. [Background technology]

[0002] In recent years, various optical devices such as LiDAR (Light Detection And Ranging) have been developed. For example, as described in Patent Document 1, the optical device includes a movable reflector that reflects a beam emitted from a light emitting element such as a laser diode (LD). The beam reflected by the movable reflector is irradiated onto an object to be measured by the optical device, thereby generating a spot. The irradiation position of the beam can be displaced in the horizontal direction by swinging the movable reflector around a predetermined first rotation axis. In addition, the irradiation position of the beam can be displaced in the vertical direction by swinging the movable reflector around a second rotation axis perpendicular to the first rotation axis. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 004514 Summary of the Invention [Problem to be solved by the invention]

[0004] In optical devices such as LiDAR, it may be desirable to control the density of spots at a desired location to a desired density, for example, to make the density of spots in a portion of the field of view of the optical device higher than the density of spots surrounding that portion.

[0005] One example of a problem to be solved by the present invention is how to control the density of spots at a desired position to a desired density. [Means for solving the problem]

[0006] The invention described in claim 1 is a signal generating unit that generates a first drive signal that drives a movable reflecting unit that reflects a beam emitted from a light emitting element in a predetermined direction; In a first predetermined period during which the first drive signal transitions from one of the maximum value and the minimum value of the first drive signal to the other, The first drive signal has a first slope and a period having a second slope different from the first slope, The optical device is one in which the tilt in the first period does not include a positive tilt or does not include a negative tilt. The invention described in claim 4 is a signal generating unit that generates a first drive signal that drives a movable reflecting unit that reflects a beam emitted from a light emitting element in a predetermined direction; An optical device in which there are at least three irradiation periods during a predetermined first period in which the first drive signal transitions from one of its maximum and minimum values ​​to the other during one period of the first drive signal, and the slope of at least one of the periods is different from the slopes of the other periods. [Brief description of the drawings]

[0007] [Figure 1] 1 is a diagram showing an optical device according to a first embodiment. [Diagram 2] 4 is a graph showing a vertical drive signal according to the first embodiment. [Diagram 3] 10 is a graph showing a vertical drive signal according to the second embodiment. [Figure 4] 11 is a graph showing a vertical drive signal according to the third embodiment. [Diagram 5] 11 is a graph showing a vertical drive signal according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In all the drawings, the same components are given the same reference numerals, and the description will be omitted as appropriate.

[0009] (Embodiment 1) FIG. 1 is a diagram showing an optical device 10 according to the first embodiment.

[0010] In FIG. 1, an arrow indicating the first direction X, the second direction Y, or the third direction Z indicates that the direction from the base end of the arrow to the tip end of the arrow is the positive direction of the direction indicated by the arrow, and that the direction from the tip of the arrow to the base end of the arrow is the negative direction of the direction indicated by the arrow.

[0011] The first direction X is a direction parallel to the horizontal direction. The second direction Y is perpendicular to the first direction X. The second direction Y is a direction parallel to the vertical direction. Specifically, the positive direction of the second direction Y is a direction from the bottom to the top in the vertical direction, and the negative direction of the second direction Y is a direction from the top to the bottom in the vertical direction. The third direction Z is perpendicular to both the first direction X and the second direction Y. The third direction Z is a direction parallel to the horizontal direction. Specifically, the positive direction of the third direction Z is a direction from the side where the movable reflector 120 described later is located to the side where the virtual surface IS described later is located, and the negative direction of the third direction Z is a direction from the side where the virtual surface IS is located to the side where the movable reflector 120 is located.

[0012] The relationships among the first direction X, the second direction Y, the third direction Z, the horizontal direction, and the vertical direction are not limited to the above example. The relationships change depending on the arrangement of the optical device 10 with respect to the horizontal direction and the vertical direction. For example, the first direction X or the third direction Z may be parallel to the vertical direction.

[0013] The optical device 10 includes a light emitting element 110, a movable reflecting unit 120, a light receiving element 130, a beam splitter 140, a driving unit 210, and a signal generating unit 220. The driving unit 210 and the signal generating unit 220 shown in Fig. 1 are functional block diagrams. Therefore, the driving unit 210 and the signal generating unit 220 shown in Fig. 1 do not suggest the actual size or actual position of the driving unit 210 and the signal generating unit 220.

[0014] The light emitting element 110 is, for example, a laser diode (LD). The light emitting element 110 is driven by a driving unit 210. The driving unit 210 is, for example, a laser driver. The driving unit 210 is controlled by a control unit such as a microcomputer (not shown). The light emitting element 110 emits a beam B at a predetermined repetition period. As shown by the dashed line extending from the light emitting element 110 to the movable reflecting unit 120 via the beam splitter 140, the beam B is emitted from the light emitting element 110, reflected by the beam splitter 140, and irradiated onto the movable reflecting unit 120.

[0015] In the first embodiment, the movable reflector 120 is a MEMS (Micro Electro Mechanical Systems) mirror. The movable reflector 120 reflects the beam B toward the positive side of the movable reflector 120 in the third direction Z. In the example shown in FIG. 1, a virtual surface IS exists on the positive side of the movable reflector 120 in the third direction Z. The virtual surface IS is virtually provided to explain the optical device 10 according to the first embodiment. Therefore, the virtual surface IS does not need to exist in the actual optical device 10. The virtual surface IS is perpendicular to the third direction Z. When the beam B is irradiated onto the virtual surface IS as shown by the dashed line extending from the movable reflector 120 to the virtual surface IS in FIG. 1, a spot S is generated on the virtual surface IS.

[0016] The signal generating unit 220 inputs a horizontal drive signal and a vertical drive signal SA, which will be described later with reference to FIG. 2, to the movable reflector 120. The signal generating unit 220 is, for example, an arbitrary signal generator. In one example, the horizontal drive signal drives the movable reflector 120 in the horizontal direction. Specifically, the movable reflector 120 oscillates around a predetermined first rotation axis AX at the resonant frequency of the movable reflector 120. In addition, the vertical drive signal SA drives the movable reflector 120 in the vertical direction. Specifically, the movable reflector 120 oscillates around a second rotation axis AY perpendicular to the first rotation axis AX at a frequency having a fundamental frequency lower than the resonant frequency of the movable reflector 120. However, the driving of the movable reflector 120 is not limited to this example.

[0017] When the light emitting element 110 emits the beam B at a predetermined repetition period, a plurality of spots S are generated along the scanning line L by the oscillation of the movable reflecting part 120 about the first rotation axis AX and the oscillation of the movable reflecting part 120 about the second rotation axis AY. This makes it possible to measure the distance to an object in the field of view F. The field of view F shown in Fig. 1 is a field of view projected onto a virtual plane IS. The scanning line L exists within the field of view F projected onto the virtual plane IS.

[0018] After being reflected by the movable reflector 120, the beam B is irradiated to an object (not shown) located on the positive side of the movable reflector 120 in the third direction Z. When the beam B is reflected or scattered by the object, the reflected or scattered light of the beam B is irradiated to the movable reflector 120 as received light. As shown by the dashed line extending from the movable reflector 120 to the light receiving element 130 via the beam splitter 140, the received light is reflected by the movable reflector 120, passes through the beam splitter 140, and is irradiated to the light receiving element 130. As a result, the light receiving element 130 receives the received light. The light receiving element 130 is, for example, an avalanche photodiode (APD). For example, the light receiving element 130 is electrically connected to a light receiving circuit (not shown). The light receiving circuit generates a received signal by receiving the received light by the light receiving element 130. The optical device 10 includes a computer such as a microcomputer (not shown) electrically connected to the light receiving circuit. The computer measures the time from when beam B is emitted from light emitting element 110 to when the light is received by light receiving element 130, thereby measuring the distance to the object irradiated with beam B.

[0019] FIG. 2 is a graph showing the vertical drive signal SA according to the first embodiment.

[0020] The horizontal axis of the graph shown in Fig. 2 represents time. The arrow representing the horizontal axis indicates that time passes from the base end on the left side of the arrow to the tip end on the right side of the arrow.

[0021] The vertical axis of the graph shown in FIG. 2 indicates the voltage value of the vertical drive signal SA. The arrow indicating the vertical axis indicates that the voltage value increases from the base end of the arrow on the lower side to the tip end of the arrow on the upper side. The voltage value of the vertical drive signal SA is 0 on the horizontal axis indicating time. When the beam B is irradiated to the movable reflector 120 when the voltage value of the vertical drive signal SA is 0, the spot S is generated at approximately the center of the second direction Y of the field of view F. As the voltage value of the vertical drive signal SA increases, the position where the spot S is generated when the beam B is irradiated to the movable reflector 120 is displaced upward in the positive direction of the second direction Y of the field of view F. As the voltage value of the vertical drive signal SA decreases, the position where the spot S is generated when the beam B is irradiated to the movable reflector 120 is displaced downward in the negative direction of the second direction Y of the field of view F.

[0022] The vertical drive signal SA changes periodically. Each period of the vertical drive signal SA includes a falling period DA and an rising period UA. The falling period DA and the rising period UA are repeated alternately. In the falling period DA, the vertical drive signal SA transitions from the maximum value of the vertical drive signal SA to the minimum value. In the rising period UA, the vertical drive signal SA transitions from the minimum value of the vertical drive signal SA to the maximum value.

[0023] The falling period DA will now be described.

[0024] Throughout the entire fall period DA, the driving unit 210 causes the light emitting element 110 to emit the beam B at a predetermined repeating cycle. Therefore, a plurality of spots S are generated along the scanning line L throughout the second direction Y of the field of view F. Therefore, the fall period DA is a main distance measurement period in which distance measurement is performed over a wider range in the second direction Y of the field of view F than distance measurement during the rise period UA described below.

[0025] The gradient of the descending period DA is substantially constant throughout the entire descending period DA. Therefore, during the descending period DA, the density of the spots S in the second direction Y is substantially constant throughout the entire second direction Y of the field of view F.

[0026] The up period UA will now be described.

[0027] 2, for the sake of explanation, a virtual line LA is added to the rising period UA. The virtual line LA is a line segment connecting the minimum value of the vertical drive signal SA at the start of the rising period UA and the maximum value of the vertical drive signal SA at the end of the rising period UA. The slope of the virtual line LA is substantially constant throughout the entire rising period UA.

[0028] The rising period UA includes a first non-irradiation period NA1, an irradiation period MA, and a second non-irradiation period NA2. The first non-irradiation period NA1, the irradiation period MA, and the second non-irradiation period NA2 are successive in order.

[0029] In the first non-irradiation period NA1 and the second non-irradiation period NA2, the driving unit 210 stops emitting the beam B from the movable reflecting unit 120. Therefore, in the first non-irradiation period NA1 and the second non-irradiation period NA2, the spot S is not generated. In contrast, in the irradiation period MA, the driving unit 210 causes the light emitting element 110 to emit the beam B at a predetermined repeating cycle. Therefore, in the irradiation period MA, a plurality of spots S are generated along the scanning line L. Therefore, the rising period UA is a sub-distance measurement period in which distance measurement is performed in a narrower range in the second direction Y of the field of view F than the distance measurement in the falling period DA.

[0030] The irradiation period MA according to the first embodiment corresponds to a period during which the voltage value of the vertical drive signal SA switches from negative to positive and the surrounding period. Therefore, during the irradiation period MA, the spots S are generated at the center of the second direction Y of the field of view F and the surrounding area in the second direction Y. Therefore, the density of the spots S at the center of the second direction Y of the field of view F and the surrounding area in the second direction Y can be increased compared to the case where the spots S are not generated during the irradiation period MA.

[0031] In the first embodiment, the slope of the vertical drive signal SA in the irradiation period MA is different from the slope of the vertical drive signal SA in the first non-irradiation period NA1 and the second non-irradiation period NA2. Specifically, the absolute value of the slope of the vertical drive signal SA in the irradiation period MA is smaller than the absolute value of the slope of the vertical drive signal SA in the first non-irradiation period NA1 and the second non-irradiation period NA2. Note that the positive and negative signs of the slope of the vertical drive signal SA are positive when the voltage value of the vertical drive signal SA increases over time, and are negative when the voltage value of the vertical drive signal SA decreases over time.

[0032] In the first embodiment, the absolute value of the slope of the vertical drive signal SA in the irradiation period MA is smaller than the absolute value of the slope of the virtual line LA. Therefore, the density of the spots S generated in the irradiation period MA in the second direction Y can be made higher than when the absolute value of the slope of the vertical drive signal SA in the irradiation period MA is equal to or larger than the absolute value of the slope of the virtual line LA.

[0033] In the first embodiment, it is preferable that the absolute value of the slope of the vertical drive signal SA in the first non-irradiation period NA1 and the second non-irradiation period NA2 is as large as possible under the constraints of the drive characteristics of the movable reflection unit 120. For example, the absolute value of the slope of the vertical drive signal SA in the first non-irradiation period NA1 and the second non-irradiation period NA2 may be set to the maximum absolute value allowed under the constraints of the drive characteristics of the movable reflection unit 120. In this case, the density of the spots S at the desired positions can be increased with a slight decrease in frame rate, compared to the case where the vertical drive signal SA transitions with a slope of the maximum absolute value over the entire range from the minimum value to the maximum value.

[0034] The waveform of the vertical drive signal SA is not limited to the waveform according to the first embodiment.

[0035] For example, the absolute value of the slope of the vertical drive signal SA in the irradiation period MA may be greater than the absolute value of the slope of the vertical drive signal SA in the first non-irradiation period NA1 and the second non-irradiation period NA2.

[0036] The rising period UA may include a period in which the slope of the vertical drive signal SA is 0 or negative. For example, the slope of the vertical drive signal SA may be 0 or negative in at least a part of at least one of the first non-irradiation period NA1, the irradiation period MA, and the second non-irradiation period NA2. As a result, for example, the positive and negative signs of the slope of the vertical drive signal SA in at least one of the first non-irradiation period NA1, the irradiation period MA, and the second non-irradiation period NA2 may be inverted from the positive and negative signs of the slope of the vertical drive signal SA in the irradiation period MA.

[0037] In addition, in the first embodiment, the rising period UA is a predetermined first period. As exemplified by the first non-irradiation period NA1 or the second non-irradiation period NA2, in a part of the predetermined first period, the beam B is not irradiated to the movable reflector 120 and the vertical drive signal SA has a predetermined first slope. Also, as exemplified by the irradiation period MA, in another part of the predetermined first period, the beam B is irradiated to the movable reflector 120 and the vertical drive signal SA has a second slope different from the first slope. However, the falling period DA may be a predetermined first period. In this example, in a part of the falling period DA, the beam B is not irradiated to the movable reflector 120 and the vertical drive signal SA has a predetermined first slope. Also, in another part of the falling period DA, the beam B is irradiated to the movable reflector 120 and the vertical drive signal SA has a second slope different from the first slope. In this example, the movable reflector 120 may be irradiated with the beam B emitted from the light emitting element 110 at a predetermined repetitive period throughout the entire rising period UA.

[0038] In the first embodiment, as exemplified by the vertical drive signal SA, the control of the waveform of the drive signal that drives the movable reflector 120 in the vertical direction has been described. However, the control of the waveform according to the first embodiment is applicable not only to the waveform of the drive signal that drives the movable reflector 120 in the vertical direction, but also to the waveform of the drive signal that drives the movable reflector 120 in a predetermined direction different from the vertical direction. In this case, the control of the waveform according to the first embodiment is applicable to only one or both of the waveform of the drive signal that drives the movable reflector 120 in the vertical direction and the waveform of the drive signal that drives the movable reflector 120 in a direction different from the vertical direction.

[0039] Moreover, the irradiation of the beam B to the movable reflector 120 in the rising period UA is not limited to the aspect according to the embodiment 1. For example, the driving unit 210 may cause the light emitting element 110 to emit the beam B at a predetermined repeating period not only in the irradiation period MA but also in at least one of the first non-irradiation period NA1 and the second non-irradiation period NA2. Moreover, the irradiation of the beam B to the movable reflector 120 in the rising period UA may be performed not only in a single period of the irradiation period MA but also in a plurality of divided periods.

[0040] (Embodiment 2) 3 is a graph showing the vertical drive signal SB according to embodiment 2. The vertical drive signal SB according to embodiment 2 is similar to the vertical drive signal SA according to embodiment 1, except for the following points.

[0041] The vertical drive signal SB according to the second embodiment changes periodically, similar to the vertical drive signal SA according to the first embodiment. Each period of the vertical drive signal SB according to the second embodiment includes a fall period DB and a rise period UB. The rise period UB according to the second embodiment includes a first non-irradiation period NB1, an irradiation period MB, and a second non-irradiation period NB2. For the sake of explanation, a virtual line LB is added to the rise period UB according to the second embodiment.

[0042] The irradiation period MB according to the second embodiment is a period during which the voltage value of the vertical drive signal SB is positive. Therefore, in the second embodiment, the density of the spots S above the center of the second direction Y of the field of view F in the positive direction of the second direction Y can be increased compared to the first embodiment. The irradiation period MB may be a period during which the voltage value of the vertical drive signal SB is negative. In this case, the density of the spots S below the center of the second direction Y of the field of view F in the negative direction of the second direction Y can be increased compared to the first embodiment.

[0043] From the explanation of the first and second embodiments, the density of the spots S at the desired positions in the second direction Y of the field of view F can be controlled to the desired density according to the setting of the irradiation period. Specifically, the generation position of the spots S in the rising period can be controlled according to the value of the vertical drive signal in the irradiation period. For example, when the irradiation period includes a period in which the voltage value of the vertical drive signal switches from negative to positive, the spots S in the rising period are generated at the center of the second direction Y of the field of view F and its periphery. Furthermore, when the voltage value of the vertical drive signal is positive throughout the irradiation period, the spots S in the rising period are generated above the center of the second direction Y of the field of view F in the positive direction of the second direction Y. Furthermore, when the voltage value of the vertical drive signal is negative throughout the irradiation period, the spots S in the rising period are generated below the center of the second direction Y of the field of view F in the negative direction of the second direction Y.

[0044] Next, the DC component contained in the vertical drive signal SB will be described.

[0045] The vertical drive signal SB in each period in the second embodiment includes a positive DC component. The DC component included in each period of the vertical drive signal SB is positive when the integral value of each period of the vertical drive signal SB is positive, and is negative when the integral value of each period of the vertical drive signal SB is negative. If a positive or negative DC current flows steadily through the circuit constituting the signal generating unit 220, this may cause the circuit constituting the signal generating unit 220 to heat up or break down. For this reason, it is desirable to avoid the DC component included in the vertical drive signal SB from flowing steadily.

[0046] In the second embodiment, the vertical drive signal SB in a period different from the predetermined period shown in FIG. 3 may include a negative DC component. For example, the waveform of the vertical drive signal SB in the period different from the predetermined period may be modified from the waveform of the vertical drive signal SB in the predetermined period. This allows the vertical drive signal SB in the period different from the predetermined period to include a negative DC component. In this case, at least a part of the positive DC component in the predetermined period can be canceled by the negative DC component in the period different from the predetermined period. In this case, the absolute value of the positive DC component in the predetermined period and the absolute value of the negative DC component in the period different from the predetermined period may be equal to or different from each other. In addition, the positive DC component in the predetermined period may be canceled by the negative DC component in one period different from the predetermined period, or may be canceled by the negative DC components in multiple periods different from the predetermined period.

[0047] (Embodiment 3) 4 is a graph showing the vertical drive signal SC according to embodiment 3. The vertical drive signal SC according to embodiment 3 is similar to the vertical drive signal SB according to embodiment 2, except for the following points.

[0048] The vertical drive signal SC according to the third embodiment changes periodically, similar to the vertical drive signal SB according to the second embodiment. Each period of the vertical drive signal SC according to the third embodiment includes a falling period DC and a rising period UC. The rising period UC according to the third embodiment includes a first non-irradiation period NC1, a second non-irradiation period NC2, a third non-irradiation period NC3, an irradiation period MC, and a fourth non-irradiation period NC4. The first non-irradiation period NC1, the second non-irradiation period NC2, the third non-irradiation period NC3, the irradiation period MC, and the fourth non-irradiation period NC4 are successive in order. In addition, a virtual line LC is added to the rising period UC according to the third embodiment for the purpose of explanation.

[0049] In the first non-irradiation period NC1, the second non-irradiation period NC2, the third non-irradiation period NC3, and the fourth non-irradiation period NC4, the driving unit 210 stops emitting the beam B from the movable reflecting unit 120. Therefore, no spot S is generated in the first non-irradiation period NC1, the second non-irradiation period NC2, the third non-irradiation period NC3, and the fourth non-irradiation period NC4. In contrast, in the irradiation period MC, the driving unit 210 causes the light emitting element 110 to emit the beam B at a predetermined repeating cycle. Therefore, a plurality of spots S are generated along the scanning line L in the irradiation period MC.

[0050] The irradiation period MC according to the third embodiment is a period during which the voltage value of the vertical drive signal SC is positive. Therefore, in the third embodiment, the density of the spots S above the center of the second direction Y of the field of view F in the positive direction of the second direction Y can be increased compared to the first embodiment.

[0051] In the third embodiment, the vertical drive signal SC in the third non-irradiation period NC3 has a predetermined first gradient. The voltage value of the vertical drive signal SC in the third non-irradiation period NC3 is switched from negative to positive. The vertical drive signal SC in the irradiation period MC has a second gradient different from the first gradient. Specifically, the absolute value of the second gradient is smaller than the absolute value of the first gradient. The voltage value of the vertical drive signal SC in the irradiation period MC is positive. The vertical drive signal SC in the second non-irradiation period NC2 has a third gradient different from the first gradient. Specifically, the absolute value of the third gradient is smaller than the absolute value of the first gradient. The voltage value of the vertical drive signal SC in the second non-irradiation period NC2 is negative. Therefore, the positive DC component of the vertical drive signal SC can be reduced compared to the case where the vertical drive signal SC fluctuates along the line segment connecting the start of the first non-irradiation period NC1 and the start of the irradiation period MC.

[0052] The irradiation of the beam B to the movable reflector 120 in the rising period UC is not limited to the aspect according to embodiment 3. For example, the driving unit 210 may cause the light emitting element 110 to emit the beam B at a predetermined repetition period not only in the irradiation period MC but also in periods other than the irradiation period MC in the rising period UC, such as the second non-irradiation period NC2 and the third non-irradiation period NC3.

[0053] (Embodiment 4) 5 is a graph showing the vertical drive signal SD according to embodiment 4. The vertical drive signal SD according to embodiment 4 is similar to the vertical drive signal SA according to embodiment 1, except for the following points.

[0054] The vertical drive signal SD according to the fourth embodiment changes periodically, similar to the vertical drive signal SA according to the first embodiment. Each period of the vertical drive signal SD according to the fourth embodiment includes a fall period DD and a rise period UD. The rise period UD according to the fourth embodiment includes a first non-irradiation period ND1, an irradiation period MD and a first non-irradiation period ND2. For the sake of explanation, a virtual line LD is added to the rise period UD according to the fourth embodiment.

[0055] The fall period DD according to the fourth embodiment includes a first fall period D1, a second fall period D2, and a third fall period D3. The first fall period D1, the second fall period D2, and the third fall period D3 are successive in order. In the first fall period D1, the voltage value of the vertical drive signal SD is positive. In the second fall period D2, the voltage value of the vertical drive signal SD switches from positive to negative. In the third fall period D3, the voltage value of the vertical drive signal SD is negative.

[0056] In the fourth embodiment, the gradient of the vertical drive signal SD in a part of the fall period DD is different from the gradient of the vertical drive signal SD in another part of the rise period UD. Specifically, the absolute value of the gradient of the vertical drive signal SD in the second fall period D2 is smaller than the absolute values ​​of the gradient of the vertical drive signal SD in the first fall period D1 and the third fall period D3. Therefore, the density of the spots S at the center of the second direction Y of the field of view F and its periphery can be increased compared to the case where the gradient of the vertical drive signal SD in the fall period DD is constant throughout the entire fall period DD.

[0057] Although the embodiments of the present invention have been described above with reference to the drawings, these are merely examples of the present invention, and various configurations other than those described above can also be adopted.

[0058] For example, in the embodiment, the beam B emitted from the light-emitting element 110 is a pulse beam emitted at a predetermined repeating period. However, the beam B emitted from the light-emitting element 110 may be continuous light. Even when the beam B is continuous light, the density of the spots S at a desired position can be controlled to a desired density by driving the movable reflector 120 in the same manner as in the embodiment.

[0059] This application claims priority based on Japanese Patent Application No. 2021-206822, filed on December 21, 2021, the disclosure of which is incorporated herein in its entirety. [Explanation of symbols]

[0060] 10 Optical equipment 110 Light emitting element 120 Movable reflector 130 Photodetector 140 Beam splitter 210 Drive unit 220 Signal Generator AX First rotation axis AY 2nd rotation axis B Beam D1 1st falling period D2 Second down period D3 3rd descending period DA falling period DB down period DC fall period DD down period F field of view IS Virtual Surface L scan line LA Virtual Line LB Virtual Line LC Virtual Line LD Virtual Line MA irradiation period MB irradiation period MC irradiation period MD irradiation period NA1 First non-irradiation period NA2 2nd non-irradiation period NB1 1st non-irradiation period NB2 Second non-irradiation period NC1 1st non-irradiation period NC2 2nd non-irradiation period NC3 Third non-irradiation period NC4 4th non-irradiation period ND1 First non-irradiation period ND2 1st non-irradiation period S Spot SA Vertical drive signal SB vertical drive signal SC Vertical drive signal SD vertical drive signal UA increase period UB rising period UC Rise Period UD Rise Period X 1st direction Y Second direction Z 3rd direction

Claims

1. a signal generating unit that generates a first drive signal for driving a movable reflecting unit that reflects a beam emitted from a light emitting element in a predetermined direction; In a first predetermined period during which the first drive signal transitions from one of the maximum value and the minimum value of the first drive signal to the other, The first drive signal has a first slope and a period having a second slope different from the first slope; An optical device, wherein the tilt in the first period is either one of: not including a positive tilt; and not including a negative tilt.

2. The first period is a period during which the light-emitting element emits a beam.

2. The optical device of claim 1.

3. a slope during a predetermined second period in which the first drive signal transitions from the other of the maximum value and the minimum value of the first drive signal to the one of the maximum value and the minimum value is the other of not including a positive slope and not including a negative slope.

3. The optical device according to claim 2.

4. a signal generating unit that generates a first drive signal for driving a movable reflecting unit that reflects a beam emitted from a light emitting element in a predetermined direction; An optical device in which there are at least three irradiation periods during a predetermined first period in which the first drive signal transitions from one of its maximum and minimum values ​​to the other during one period of the first drive signal, and the slope of at least one of the irradiation periods is different from the slopes of the other periods.

5. an absolute value of a slope of a second irradiation period of the at least three irradiation periods is smaller than an absolute value of a slope of a first irradiation period; 5. The optical device according to claim 4.

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