JP2022165971A - Scanning device and ranging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a scanning device and a ranging device capable of performing scanning in a scanning mode having a trajectory of a desired density distribution within an area to be scanned.

SOLUTION: A scanning device includes: an optical path control part that is arranged in a space area located in an irradiation direction of an optical scanning part, has a first reflection surface and a second reflection surface arranged so as to reduce a first angle that opposes a scanning object area as compared with a straight angle, and emits light toward the scanning object area; and a light reception part for receiving reflection light of the light reflected by an object existing in the scanning object area.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to scanning devices, and more particularly to scanning devices and ranging devices that perform optical scanning.

2. Description of the Related Art Ranging devices are known that scan a target area with light to measure the distance to an object. Such a rangefinder has, for example, a light source that emits a laser pulse, a scanning mechanism that reflects and scans the laser pulse, and a light receiving section that receives the laser pulse reflected by an object. . Then, the distance measuring device measures the distance to the object based on the emission time of the laser pulse emitted by the light source and the light reception time of the laser pulse received by the light receiving unit.

For example, Patent Literature 1 discloses a light scanning unit that has a light reflecting surface and can perform Lissajous scanning of light incident on the light reflecting surface within a target area, and a pulsed light emitted from a light source that is reflected by an object. a light-receiving unit for receiving the reflected light, and a distance measuring unit for measuring the distance to the object based on the timing of emitting the pulsed light from the light source unit and the timing of receiving the reflected light from the light-receiving unit. A range device is disclosed.

JP 2011-53137 A

In the distance measuring apparatus as described above, distance measurement is performed by so-called Lissajous scanning, in which pulsed light is emitted along the Lissajous locus. The Lissajous trajectory has a low scanning trajectory density in the central region of the scanning region and a high scanning trajectory density in the edge region.

For example, in range finding devices, it is often necessary to perform detailed range finding in the central area of the scanning area. In such a case, it is difficult to measure distances with the desired quality in areas with high scanning densities, such as the Lissajous trajectory. .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a scanning apparatus and a distance measuring apparatus capable of scanning in a scanning mode having a locus of a desired density distribution within a scanning area. I'm trying.

The invention according to claim 1 of the present application includes an optical scanning unit that scans light in a predetermined irradiation direction, and a first scanning unit disposed in a spatial region in the irradiation direction of the optical scanning unit and facing a scanning target region. an optical path control unit having a first reflective surface and a second reflective surface arranged so that the angle between the and a light receiving unit for receiving reflected light reflected by an object existing in the area.

According to an eighth aspect of the present invention, there is provided a scanning device according to any one of the first to seventh aspects, and measuring the distance to the object based on the reflected light received by the light receiving unit. and a distance measuring unit.

In the invention according to claim 9 of the present application, an optical scanning unit that scans light in a predetermined irradiation direction and a first angle facing the irradiation direction of the light scanned by the optical scanning unit is smaller than a flat angle. and an optical path control section for guiding the light to the scanning target area, the light guided by the optical path control means being directed to the scanning target area. and a light-receiving section for receiving reflected light reflected by an existing object.

The invention according to claim 10 of the present application forms a high-density region, which is a region where the locus density of the irradiation locus of light is a predetermined value or more, and a low-density region, which is a region where the locus density is lower than the high-density region. an optical scanning unit that continuously changes the emission direction of the light; and an area irradiated with the light that forms the high-density area in the scanning target area is irradiated with the light that forms the low-density area. an optical path control means for guiding the light emitted from the optical scanning unit to the scanning target area so as to be positioned between the areas, and the high density area in the light emitting direction of the optical scanning unit; The scanning device is characterized in that the positional relationship between the low-density areas and the positional relationship between the high-density area and the low-density area in the scanning target area are different.

FIG. 1 is a block diagram showing the configuration of a distance measuring device according to an embodiment. FIG. 2A is a top view of the optical scanning unit according to the example. FIG. 2B is a cross-sectional view of the optical scanning unit according to the example. FIG. 3 is an explanatory diagram showing a scanning mode of the optical scanning unit of the distance measuring device according to the embodiment. FIG. 4 is an explanatory diagram showing an example of the waveform of the driving signal applied to the optical scanning unit and the scanning locus of the pulsed light by the optical scanning unit according to the embodiment. FIG. 5 is an explanatory diagram showing how the scanning light is reflected by the reflecting mirror section. FIG. 6 is an explanatory diagram showing the mode of the scanning light reflected by the reflecting mirror section. FIG. 7 is a diagram showing the trajectory of the scanning light irradiated onto the scanning surface of FIG. FIG. 8 is a diagram showing the area of the trajectory of the scanning light irradiated onto the scanning plane of FIG. FIG. 9 is a diagram showing the area of the trajectory of the scanning light irradiated onto the scanning surface of FIG. FIG. 10A is a diagram showing the area of the trajectory of the scanning light irradiated onto the scanning surface of FIG. 6. FIG. FIG. 10B is a diagram showing the area of the trajectory of the scanning light irradiated onto the scanning surface of FIG. 6;

A configuration of a distance measuring device 10 according to an embodiment will be described with reference to FIG. The distance measuring device 10 is a distance measuring device that optically measures the distance to the object OB. Specifically, the distance measuring device 10 irradiates light toward a predetermined spatial region, that is, the scanning target region R. As shown in FIG. Further, the distance measuring device 10 receives the light reflected by the object OB and measures the distance to the object OB, that is, measures the distance.

The light source 20 is, for example, a light emitting element such as a laser diode capable of emitting pulsed light.

The optical system OS is provided on the optical path of the pulsed light L1. The optical system OS is an optical system including an optical member such as a collimator lens, and converts the pulsed light L1 emitted from the light source 20 into parallel light.

A beam splitter BS is provided on the optical path of the pulsed light L1. Specifically, the pulsed light L1 emitted from the light source 20 is converted into parallel light by the optical system OS and passes through the beam splitter BS. The beam splitter BS is arranged so as to transmit or reflect the incident light incident on the beam splitter BS in a predetermined direction. In this embodiment, the beam splitter BS transmits the pulsed light L1 emitted from the light source 20. As shown in FIG.

A MEMS (Micro Electro Mechanical Systems) mirror device 30 is provided on the optical path of the pulsed light L1. Specifically, the pulsed light L1 is applied to the MEMS mirror device 30 after passing through the optical system OS and the beam splitter BS. The MEMS mirror device 30 has a reflective surface 30S that reflects the pulsed light L1. The reflecting surface 30S is made of, for example, a light reflecting film 33 that reflects the pulsed light L1.

The MEMS mirror device 30 reflects the pulsed light L1 with a reflecting member to generate the scanning light L2. Further, the MEMS mirror device 30 continuously changes the emission direction of the scanning light L2 by swinging the reflecting member.

The light source controller 13 is a drive circuit that drives the light source 20 . The light source controller 13 has a timing table (not shown) for emitting the pulsed light L1 from the light source 20 . The light source controller 13 provides a drive signal to the light source 20 with reference to the timing table.

The scanning control unit 14 generates a drive signal for swinging the reflecting member of the MEMS mirror device 30 and supplies the generated drive signal to the MEMS mirror device 30 .

The reflective member of the MEMS mirror device 30 swings based on the driving signal generated by the scanning control unit 14 . Therefore, the direction in which the pulsed light L1 is reflected by the MEMS mirror device 30, that is, the irradiation direction, changes successively. Thus, the MEMS mirror device 30 reflects the pulsed light L1 to generate the scanning light L2. That is, the light source 20 and the MEMS mirror device 30 function as an optical scanning section that scans the scanning light L2 in a predetermined irradiation direction.

The reflecting mirror section 40 is a mirror member arranged in the irradiation range of the scanning light L2 generated by the MEMS mirror device 30 . The reflecting mirror section 40 has a first reflecting surface 41R and a second reflecting surface 41L on the surface facing the MEMS mirror device 30 . The scanning light L2 is reflected by the first reflecting surface 41R and the second reflecting surface 41L of the reflecting mirror section 40 and emitted toward the scanning target region R. As shown in FIG. Therefore, the reflecting mirror section 40 functions as an optical path control section (reflection section) that controls the optical path of the scanning light L2.

Here, in FIG. 1, a virtual surface separated from the MEMS mirror device 30 by a predetermined distance in the scanning target region R is shown as the scanning target surface S1. It should be noted that the scanning target surface S1 does not actually exist, but is illustrated for explanation of this embodiment.

The MEMS mirror device 30 emits the scanning light L<b>2 to the scanning target region R via the reflecting mirror section 40 . The emission direction of the scanning light L2 changes continuously over time. Therefore, the trajectory of the scanning light L2 is drawn on the scanning target surface S1. The predetermined irradiation range is determined according to the angular range in which the reflecting member of the MEMS mirror device 30 can swing.

When an object OB (an object having the property of reflecting the scanning light L2) exists on the optical path of the scanning light L2 in the scanning target region R, the scanning light L2 is reflected by the object OB.

The reflected light L3, which is the scanning light L2 reflected by the object OB, is reflected again by the first reflecting surface 41R and the second reflecting surface 41L of the reflecting mirror section 40 and enters the MEMS mirror device 30. FIG. The reflected light L3 reflected by the reflecting surface 30S of the MEMS mirror device 30 is reflected again by the beam splitter BS and enters the light receiving section 50. FIG.

The light receiving section 50 is arranged on the optical path of the reflected light L3 reflected by the beam splitter BS. The light receiving section 50 is a photodetector that generates a light receiving signal based on the intensity of light incident on the light receiving section 50 . As such a photodetector, a light receiving element such as an avalanche photodiode can be used.

The reflected light L3 reflected by the beam splitter BS is converted into a received light signal by the light receiving section 50 . The changed received light signal is supplied to the distance measuring section 60 .

The distance measurement unit 60 measures the distance between the light receiving unit 50 and the object OB based on the pulsed light L1 emitted by the light source 20 and the reflected light L3 received by the light receiving unit 50 . For example, the distance measuring unit 60 includes a signal processing circuit and calculates distance data of the object OB by calculation. A time-of-flight method can be used as an example of calculating the distance data.

Specifically, the light source control unit 13 supplies an emission signal including the time (timing) at which the light source 20 emits the pulsed light L1 to the distance measurement unit 60 . In addition, the received light signal generated by the light receiving unit 50 includes the timing of receiving the reflected light L3. The distance measuring unit 60 measures the distance from the distance measuring device 10 to the object OB based on the difference between the timing when the light source 20 emits the pulsed light L1 and the timing when the light receiving unit 50 receives the reflected light L3. do.

A configuration example of the MEMS mirror device 30 will be described with reference to FIGS. 2A and 2B. FIG. 2A is a schematic top view of the MEMS mirror device 30. FIG. FIG. 2B is a cross-sectional view along line VV of FIG. 2A.

As shown in FIGS. 2A and 2B, the fixed portion 31 includes a fixed substrate B1 and a fixed frame B2 which is an annular frame formed on the fixed substrate B1. As shown in FIG. 2B, the fixed substrate B1 has, on the top surface B1S of the fixed substrate B1, a projecting portion B1P having a frame-like planar shape in a region facing the fixed frame B2, and fixed on the projecting portion B1P. It has a configuration in which a frame B2 is placed.

The movable portion 32 is arranged inside the fixed frame B2 and includes a swing plate SY and a swing frame SX surrounding the swing plate SY. A circular light reflecting film 33 is provided on the rocking plate SY as a reflecting member. Hereinafter, the upper surface of the light reflecting film 33, that is, the center of the reflecting surface 30S will be described as AC.

The swing frame SX is connected to the fixed frame B2 by a first torsion bar TX. The first torsion bar TX is a pair of long plate-like structural portions extending along a first swing axis AX passing through the center AC of the reflecting surface 30S and extending in the in-plane direction of the reflecting surface 30S. When a force around the swing axis AX is applied to the swing frame SX, the first torsion bar TX is twisted, and the swing frame SX moves around the first swing axis AX, that is, the first swing axis AX. It oscillates as the central axis of oscillation. The swing frame SX has a line-symmetrical shape about the first swing axis AX.

The swing plate SY is connected to the swing frame SX by a second torsion bar TY. The second torsion bar TY passes through the center AC of the reflective surface 30S, extends in the in-plane direction of the reflective surface 30S, and extends along a second swing axis AY perpendicular to the first swing axis AX. It is a pair of long plate-shaped structural parts that extend.

When a force around the swing axis AY is applied to the swing plate SY, the second torsion bar TY is twisted, and the swing plate SY is rotated about the second swing axis AY, that is, the second swing axis AY. It oscillates as the central axis of oscillation. The rocking plate SY has a line-symmetrical shape about the rocking axis AY.

Therefore, the rocking plate SY rocks around the rocking axes AX and AY that are perpendicular to each other. The direction in which the reflection surface 30S faces is changed by the oscillation of the oscillation plate SY.

As described above, the movable portion 32 is connected to the fixed frame B2, and the fixed portion B2 is placed on the projecting portion B1P of the fixed substrate B1. Therefore, the movable portion 32 is separated from the upper surface B1S of the fixed substrate B1. Then, when the swing frame SX swings about the swing axis AX and the swing plate SY swings about the swing axis AY, the movable portion 32 swings so as to be inclined with respect to the fixed frame B2. The projecting portion B1P is formed with a sufficient height such that the movable portion 32 does not come into contact with the upper surface B1S due to the swinging. Note that, for example, the fixed frame B2 and the movable portion 32 may be an integral structure formed by processing one semiconductor substrate.

The driving force generation unit 34 includes a permanent magnet MG1 and a permanent magnet MG2 arranged outside the projecting portion B1P on the fixed substrate B1, and a metal wire routed on the swing frame SX along the outer periphery of the swing frame SX. It includes a wiring (first coil) CX and a metal wiring (second coil) CY that is routed on the oscillating plate SY along the outer circumference of the oscillating plate SY.

The permanent magnet MG1 is a pair of magnet pieces arranged on the swing axis AX and facing each other with the movable portion 32 interposed therebetween. The permanent magnet MG2 is a pair of magnet pieces arranged on the swing axis AY and facing each other with the movable portion 32 interposed therebetween. Therefore, in this embodiment, four magnet pieces are arranged so as to surround the movable portion 32 .

Also, the two magnet pieces forming the permanent magnet MG1 are arranged so that the portions exhibiting opposite polarities face each other. Similarly, the two magnet pieces forming the permanent magnet M2 are arranged such that the portions exhibiting opposite polarities face each other.

The scan controller 14 is connected to the metal wires CX and CY. The scanning control unit 14 supplies currents (driving signals) to the metal wires CX and CY. The drive force generation unit 34 generates an electromagnetic force for swinging the swing frame SX and the swing plate SY of the movable unit 32 by applying the drive signal.

Specifically, when a current flows through the metal wiring CX, interaction between the current and the magnetic field generated by the two magnet pieces of the permanent magnet MG1 arranged in the direction along the oscillation axis AY causes oscillation. A force around the swing axis AX is applied to the frame SX. Thereby, the first torsion bar TX is twisted around the swing axis AX, and the swing frame SX swings around the swing axis AX.

Further, when a current flows through the metal wiring CY, the interaction between the current and the magnetic field generated by the two magnet pieces of the permanent magnet MG2 arranged in the direction along the oscillation axis AX causes the oscillation plate SY to oscillate. A force is applied about the axis AY. Thereby, the second torsion bar TY is twisted around the swing axis AY, and the swing plate SY swings around the swing axis AY.

FIG. 3 shows how the scanning light L2 is emitted from the MEMS mirror device 30. As shown in FIG. In FIG. 3, when the pulsed light L1 is incident on the MEMS mirror device 30, it is reflected by the reflecting surface 30S to generate the scanning light L2.

The reflector section 40 is arranged in a spatial region in the irradiation direction when viewed from the MEMS mirror device 30 . Here, the position of the oscillating plate SY when no voltage is applied to the MEMS mirror device 30 is defined as a reference position. The axis of the scanning light L2 reflected by the reflection surface 30S from the pulsed light L1 at the reference position of the oscillating plate SY is defined as an optical axis AZ.

In FIG. 3, the scanning light L2 is emitted from the MEMS mirror device 30 on the back side of the first reflecting surface 41R and the second reflecting surface 41L of the reflecting mirror section 40 in the direction in which the scanning light L2 is emitted. A virtual surface SS1, which is a scanning surface assuming that light passes through the reflecting mirror section 40, is shown. Between the virtual surface SS1 and the reflecting mirror section 40, a transmitted light L2', which is the scanning light L2 when it is assumed that the scanning light L2 passes through the reflecting mirror section 40, is drawn. Note that the virtual surface SS1 and the transmitted light L2' do not actually exist, but are shown for explanation of this embodiment.

FIG. 4 shows the relationship between the driving signals DX and DY generated by the scanning control unit 14 when the MEMS mirror device 30 scans by Lissajous scanning, and the scanning trajectory of the scanning light L2 scanned by the MEMS mirror device 30 based thereon. is schematically shown.

In the following description, the drive signal DX is described as a drive signal generated by the scanning control section 14 and supplied to the metal wiring CX. As a result, the swing frame SX swings around the swing axis AX. Further, the drive signal DY will be described as a drive signal generated by the scanning control unit 14 and supplied to the metal wiring CY. Thereby, the rocking plate SY rocks around the rocking axis AY.

In the following description, it is assumed that the drive signal DX and the drive signal DY have the same amplitude (AMP=1 in the figure).

In FIG. 4, (a) shows the scanning trajectory TR of the transmitted light L2' drawn on the virtual plane SS1 shown in FIG. AX1 and AY1 in the drawing correspond to the swing axis AX and swing axis AY of the MEMS mirror device 30, respectively. That is, the oscillation of the MEMS mirror device 30 about the oscillation axis AX corresponds to the change in the scanning position in the direction along AY1 on the virtual surface SS1. Further, the swinging of the MEMS mirror device 30 about the swinging axis AY corresponds to the change in the scanning position in the AX1 direction on the virtual surface SS1.

FIG. 4(b) schematically shows the waveform of the drive signal DX during the Lissajous scanning shown in FIG. 4(a). _The drive signal DX in FIG. 4B is _a sine wave represented by the formula DX( _θ1 )=A1 sin( _θ1 + _B1 ) where A1 and _B1 are constants and θ1 is _a variable. is a signal of The variable θ ₁ corresponds to the natural frequencies of the swing frame SX and the swing plate SY supported by the fixed frame B2 by the first torsion bar TX of the MEMS mirror device 30, and the drive signal DX is the resonance frequency. It is set to be a sine wave of the frequency that

FIG. 4(c) schematically shows the waveform of the drive signal DY during the Lissajous scanning shown in FIG. 4(a). The drive signal DY is a sinusoidal signal represented by the formula DY ₍ θ2) _{= A2} sin ₍ θ2 ₊ B2) where _A2 and B2 _are constants and θ2 is a variable. The variable θ ₂ is set so that the drive signal DY becomes a sine wave with a frequency that corresponds to the natural frequency of the oscillation plate SY of the MEMS mirror device 30 and causes it to resonate.

Therefore, the swing frame SX and the swing plate SY are swung while resonating about the swing axis AX by the drive signal DX. That is, it is driven in a resonance mode operation mode around the swing axis AX. Further, the rocking plate SY is rocked while resonating around the rocking axis AY by the drive signal DY. Accordingly, the rocking plate SY rocks about the rocking axis AX and rocks about the rocking axis AY. The direction in which the reflection surface 30S faces changes according to the oscillation of the oscillation plate SY. Therefore, the pulsed light L1 emitted from the light source 20 is reflected by the light reflecting film 33, and emitted as the scanning light L2 toward the reflecting mirror portion 40 while changing the emission direction according to the oscillation of the oscillation plate SY. .

As shown in FIG. 4A, the rocking plate SY rocks while resonating about the rocking axis AX and the rocking axis AY as described above. Therefore, the trajectory TR of the irradiation point (spot position) on the virtual plane SS1 of the transmitted light L2' is drawn along the Lissajous curve.

A high-density area in which the locus density is higher than a predetermined density is formed in the end area of the virtual surface SS1 in the direction along the axis AX1. High density areas are indicated as "high" in the figures (same for subsequent figures). A central region arranged near the center of the virtual surface SS1 in the direction along the axis AX1 forms a low-density region in which the locus density is lower than a predetermined density. Low density areas are indicated as "low" in the figures (the same applies to subsequent figures). That is, as the distance from the end region toward the center region increases, the distance between the tracks becomes wider than in the end region. Furthermore, when the pulsed light beams L1 are emitted at equal intervals, the scanning speed is slower in the end regions than in the central region. becomes lower.

Therefore, in each of the first reflecting surface 41R and the second reflecting surface 41L, the MEMS mirror device 30 has a high-density area, which is an area in which the density of the locus of scanning by the scanning light L2 is high, and The scanning light L2 is scanned so as to form a low-density area, which is an area with a low locus density.

Returning to FIG. 3, the reflecting mirror portion 40 is perpendicular to the first reflecting surface 41R and the second reflecting surface 41L and has a V-shaped cross section along the optical axis AZ. Specifically, the reflecting mirror portion 40 is bent along an axis AM that passes through the center MC of the reflecting mirror portion 40 and intersects the optical axis AZ. That is, the reflecting mirror portion 40 has a bent portion 42 formed along the axis AM. In other words, the first reflecting surface 41R and the second reflecting surface 41L are arranged with the bent portion 42 serving as a boundary adjacent to each other.

A first reflecting surface 41R and a second reflecting surface 41L are provided on the surface of the reflecting mirror section 40 facing the MEMS mirror device 30 . The first reflecting surface 41R and the second reflecting surface 41L are made of a light reflecting film. The first reflective surface 41R and the second reflective surface 41L are arranged to face the reflective surface 30S of the MEMS mirror device 30 .

The first reflecting surface 41</b>R is provided on one surface facing the MEMS mirror device 30 . A second reflecting surface 41L is provided on the other surface facing the MEMS mirror device 30 . In this embodiment, the first reflecting surface 41R and the second reflecting surface 41L are provided so as to be symmetrical with respect to a plane including the axis AM and the axis AZ.

Here, of the areas of the first reflecting surface 41R or the second reflecting surface 41L, the area close to the bent portion 42 is defined as a first reflecting area. In addition, of the regions of the first reflecting surface 41R or the second reflecting surface 41L, a region further away from the bent portion 42 than the first reflecting region is defined as a second reflecting region.

FIG. 5 shows the scanning light L2 reflected by the reflecting mirror section 40 as seen from the direction along the axis AM of the reflecting mirror section 40 . The thickness of the arrows in the figure corresponds to the density of the trajectory. That is, a thick arrow indicates a high density of trajectories, and a thin arrow indicates a low density of trajectories.

In FIG. 5, the scanning light L2 forming the scanning locus of the low-density area among the scanning loci is irradiated to the first reflecting areas of the first reflecting surface 41R and the second reflecting surface 41L. Further, the scanning light L2 forming the scanning trajectory of the high-density region among the scanning trajectories is irradiated onto the second reflective regions of the first reflective surface 41R and the second reflective surface 41L.

In addition, the first angle D1 between the first reflecting surface 41R and the second reflecting surface 41L, which faces the scanning target region R, is smaller than a flat angle (180 degrees). In this embodiment, the first reflecting surface 41R and the second reflecting surface 41L are provided so as to face the MEMS mirror device 30. As shown in FIG. That is, the first angle D1 is an angle that faces the irradiation direction of the scanning light L2 scanned by the MEMS mirror device 30, among the angles formed by the first reflecting surface 41R and the second reflecting surface 41L.

Thus, in this embodiment, the scanning light L2 emitted from the MEMS mirror device 30 is directly applied to the reflecting mirror section 40 . However, the scanning light L<b>2 emitted from the MEMS mirror device 30 may indirectly irradiate the reflecting mirror section 40 . For example, the scanning light L2 emitted from the MEMS mirror device 30 may be applied to the reflecting mirror section 40 via an optical member such as a mirror. That is, when the scanning light L2 is indirectly applied to the reflecting mirror section 40, the reflecting mirror section 40 has a first reflecting surface 41R and a second reflecting surface 41L on the surface facing the MEMS mirror device 30. You don't have to.

When the MEMS mirror device 30 reflects the pulsed light L1 for scanning the scanning target region R, at one of the two scanning light beams L2 emitted at the maximum swing angle of the swing plate SY, Let L2R be the ray of the emitted scanning light L2, and L2L be the ray of the emitted scanning light L2 at the other maximum swing angle.

The angle formed by the two rays L2R and L2L, that is, the irradiation angle, which is the irradiation range of the scanning light L2 around the swing axis AY, is defined as an angle 2θ. An angle obtained by subtracting the first angle D1 from 180 degrees is defined as a second angle 2Y. Furthermore, let the angle θ be half the angle 2θ. Let Y be the half angle of the second angle 2Y.

In this embodiment, when the scanning light L2R is reflected by the first reflecting surface 41R, it is emitted in the same direction as the axis AZ on the projection plane of FIG. 5 viewed from the direction along the axis AM. The angle of the reflecting surface 41R is set. Similarly, the angle of the second reflecting surface 41L is set so that the scanning light L2L, when reflected by the second reflecting surface 41L, is emitted in the same direction as the axis AZ on the projection plane of FIG. Specifically, the irradiation angle 2θ is set to twice the second angle 2Y. That is, the angle θ is set to be twice the angle Y in this embodiment.

The scanning light L2 reflected by the reflecting mirror portion 40 is emitted toward the scanning target region R. As shown in FIG. In this embodiment, the scanning light L2 is emitted toward the scanning target area R so that the density of the trajectory of the scanning light L2 is high in the central area of the scanning target surface S1. That is, of the scanning trajectory TR drawn by the transmitted light L2′ on the virtual surface SS1, the scanning light L1 that draws a high-density region with a high trajectory density is directed toward the central region of the scanning target region R, and the trajectory has a low density. The angles of the first reflecting surface 41R and the second reflecting surface 41L are set so that the scanning light L1 that draws the low-density area (the central portion of the scanning trajectory TR) is directed toward the edge of the scanning target area R.

FIG. 6 shows the emission mode of the scanning light L2 reflected by the reflecting mirror section 40 as seen from the direction along the axis AM. The thickness of the arrows in the figure corresponds to the density of the trajectories. That is, a thick arrow indicates a high density of trajectories, and a thin arrow indicates a low density of trajectories.

In FIG. 6, the distance between the MEMS mirror device 30 and the reflector section 40 is much shorter than the distance between the scanning target surface S1 and the reflector section 40 . Therefore, when viewed macroscopically, it can be said that the light is emitted from the reflecting mirror portion 40, that is, the light emitting point.

The scanning light L2 reflected by the reflecting mirror section 40 is irradiated toward the scanning target surface S1. Specifically, the scanning light L2 is irradiated so that the density of the trajectory is highest in the central region of the scanning target surface S1. Further, the scanning light L2 is applied so that the density thereof gradually decreases toward the end region along the axis AX1 of the scanning target surface S1.

FIG. 7 shows the trajectory of the scanning light L2 irradiated on the scanning plane S1 of FIG. In FIG. 7, the scanning target surface S1 includes a scanning trajectory region S1L drawn by the scanning light L2 reflected by the first reflecting surface 41R and a scanning light reflected by the reflecting surface 41L of the second reflecting surface 41. and a region S1R of the scanning trajectory delineated by L2.

The trajectory of the scanning light L2 reflected by the first reflecting surface 41R is drawn in the scanning area S1L with the positional relationship reversed. Similarly, the trajectory of the scanning light L2 reflected by the second reflecting surface 41L is drawn in the scanning region S1R with the positional relationship reversed. That is, in the locus of the scanning light L2 irradiated onto the scanning surface S1, the positional relationship between the low-density area and the high-density area of the locus changes from the positional relationship in the reflecting mirror section 40. FIG.

Specifically, in FIG. 4A, a low-density region having a low density of the trajectory of the scanning light L2 is arranged in the central region, and a high-density region having a high density of the trajectory of the scanning light L2 is arranged in the end region. It is This corresponds to the trajectory of the scanning light L2 on the virtual surface SS1. On the other hand, the scanning light L2 that draws a high-density region with a high locus density on the virtual surface SS1 is distributed to the central region of the scanning target surface S1, and the scanning light L2 that draws a high-density region with a high locus density on the scanning target surface S1 is distributed to the end region of the scanning target surface S1. The scanning light L2 is arranged to draw a low-density area with a locus of low density at . That is, the emission trajectory in the scanning target region R of the scanning light L2 forming the high-density region is arranged between the emission trajectories in the scanning target region R of the scanning light L2 forming the low-density region.

In other words, the area irradiated with the scanning light L2 forming the high-density area in the scanning target area R is positioned between the areas irradiated with the scanning light L2 forming the low-density area.

By the way, when the angle Y and the angle θ shown in FIG. 5 satisfy the condition Y=θ/2, as shown in FIG. The regions S1R are arranged so as to be in contact with each other. In other words, the scanning trajectories in the scanning target region R by the scanning light L2 forming the high-density region are adjacent to each other in the scanning target region R. Under such a condition, the high-density area is arranged in the central area of the scanning target area R, so it is possible to improve the distance measurement accuracy of the object OB in the central area.

The emitted light L3 reflected by the reflecting mirror portion 40 is emitted toward the scanning target area R. As shown in FIG. In this embodiment, the optical path of the scanning light L2 reflected by the first reflecting surface 41R and the second reflecting surface 41L is set so as to go directly to the scanning target area R. As shown in FIG. However, the optical path of the scanning light L2 reflected by the first reflective surface 41R and the second reflective surface 41L does not have to be the optical path that goes directly to the scanning target area R. For example, an optical member such as a mirror is provided between the reflecting mirror section 40 and the scanning target area R, and the scanning light L2 reflected by the first reflecting surface 41R and the second reflecting surface 41L travels toward the scanning target area R. An optical path control means for indirectly setting the optical path may be provided.

The conditions of the angle Y and the angle θ are not limited to Y=θ/2, and may be appropriately adjusted according to the position that the user wishes to gaze at. For example, when aiming to further improve the distance measurement accuracy of the object OB in the central region of the scanning target region R, or to see the object OB more finely, in the central region of the scanning target region R, the scanning trajectory region S1L and It is preferable to scan the regions S1R of the scanning trajectories so as to overlap each other. Specifically, the condition should be set so as to satisfy Y<θ/2.

FIG. 8 shows a scanning trajectory region S1L and a scanning trajectory region S1R on the scanning target surface S1 of FIG. That is, of the scanning trajectory region S1L and the scanning trajectory region S1R, portions of the high-density regions where the scanning trajectory density is high overlap each other. FIG. 8 shows scanning locus areas in which the overlapping range of the scanning locus area S1L and the scanning locus area S1R (hereinafter referred to as the overlapping range) is set small. In the overlapping range, the distance measuring device 10 can obtain data for both the scanning trajectory region S1L and the scanning trajectory region S1R.

For example, even if some data cannot be obtained in one of the areas S1L and S1R of the scanning trajectories in the overlapping range, the distance measuring device 10 measures the data in the other area. It can be used for distance. Therefore, it is possible to reliably obtain distance measurement data in the overlapping range.

FIG. 9 shows a scanning trajectory region S1L and a scanning trajectory region S1R on the scanning surface S1 of FIG. FIG. 9 shows a region of scanning trajectories in which a large overlap range is set. In the overlapping range, the distance measuring device 10 can obtain data for both the scanning trajectory region S1L and the scanning trajectory region S1R.

In addition, as the overlapping range increases, the number of scanning light beams L2 that irradiate the range also increases. Therefore, it is possible to improve the detection rate of the object OB in the overlapping range.

By shortening the emission interval of the scanning light L2 irradiated in the overlapping range, it is possible to obtain more data. By shortening the emission interval of the scanning light L2 in this way, it is possible to obtain detailed information about the object OB in the overlapping range.

FIGS. 10A and 10B differ from FIGS. 8 and 9 in the overlapping range of the scanning trajectory regions S1L and S1R. In FIG. 10A, the low-density regions where the density of the scanning trajectory is low are overlapped between the regions S1L and S1R. That is, the scanning trajectories in the scanning target region R of the scanning light L2 forming the low-density regions on the first reflecting surface 41R and the second reflecting surface 41L are adjacent to each other in the scanning target region R. In FIG. 10B, the regions S1L and S1R are completely overlapped. In this way, by overlapping low-density areas with low scanning trajectory densities, it is possible to form high-density areas with high scanning trajectory densities. Moreover, the density of the scanning trajectory can be made nearly uniform over the entire scanning target region R. Note that the overlapping range of the regions S1L and S1R can be determined by changing the conditions of the angle Y and the angle θ. Specifically, the state shown in FIG. 10A is obtained when 0<Y<.theta./4, and the state shown in FIG. 10B is obtained when Y=.theta./4.

By the way, for example, when the bending portion 42 of the reflecting mirror portion 40 is irradiated with the scanning light L2, both the first reflecting surface 41R and the second reflecting surface 41L are irradiated with the scanning light L2. In such a case, the scanning light L2 is reflected in multiple directions, making it difficult to irradiate only a specific position of the scanning target region R with the scanning light L2. Therefore, the light source control unit 13 preferably performs control so that the bending portion 42 is not irradiated with the scanning light L2.

Further, in this embodiment, the reflecting mirror portion 40 is integrally formed of one rectangular plate-like body. However, the reflecting mirror section 40 is not limited to such a configuration, and for example, a first member having a first reflecting surface 41R and a second member having a second reflecting surface 41L are arranged. may be configured.

Even when the reflecting mirror section 40 is configured in this way, the scanning light beam L2 passes through the bending section 42 formed on the joint surface between the first member and the second member of the reflecting mirror section 40, for example, as described above. , both the first reflecting surface 41R and the second reflecting surface 41L are irradiated with the scanning light L2. Therefore, it is difficult to irradiate only a specific position of the scanning target area R with the scanning light L2.

Therefore, similarly to the above, the light source control unit 13 preferably performs control so as not to irradiate the bending portion 42 with the scanning light L2. In order to prevent such a problem, it is preferable to provide a space between the first member and the second member that is at least equal to or larger than the spot diameter of the scanning light L2.

In this embodiment, the reflecting mirror portion 40 is formed by bending such that the end portions of the first reflecting surface 41R and the second reflecting surface 41L irradiated with the scanning lights L2R and L2L are close to each other. However, the shape of the reflecting mirror portion 40 is not limited to this. 41L may be bent so as to be close to each other.

When the reflecting mirror unit 40 is configured in this manner, scanning can be performed by changing the positional relationship between the high-density region and the low-density region of the trajectory formed in the direction of the axis AY1 (or the direction of the axis AX1). .

Two examples of the bending directions of the first reflecting surface 41R and the second reflecting surface 41L of the reflecting mirror portion 40 are given. Here, the bent portions 42 of the reflector portion 40 may be provided at a plurality of locations. For example, the reflecting mirror section 40 may be configured by combining the two first reflecting surfaces 41R and the second reflecting surfaces 41L having different bending directions.

In these embodiments, the two scanning lights emitted at the maximum swing angle of the swing plate SY or the swing frame SX of the MEMS mirror device 30 are L2R and L2L. It is not denied that light is not emitted near the maximum swing angle and is emitted within the maximum emission angle that is smaller than the maximum swing angle. In this case, the two scanning lights emitted at the maximum emission angle may be read as L2R and L2L.

When the reflecting mirror section 40 is configured in this manner, scanning can be performed by changing the positional relationship between the high-density area and the low-density area of the trajectory formed in the directions of the axis AX1 and the axis AY1.

As described above, the distance measuring device 10 of the present invention scans the scanning target region R by reflecting the scanning light L2 emitted from the MEMS mirror device 30 by the reflecting mirror section 40 . Therefore, according to the distance measuring device 10 of the present invention, it is possible to freely set the density of the scanning trajectory of the scanning light L2 in the scanning target area R.

Specifically, when the trajectory of the scanning light L2 is a trajectory along the Lissajous curve, the trajectory of the scanning light L2 has a high-density region with a high density of the trajectory and a low-density region with a sparse density of the trajectory. may have. In such a case, by reflecting the scanning light L2 on the reflecting mirror section 40, it is possible to scan while changing the positional relationship between the high-density area and the low-density area.

Therefore, it is possible to perform distance measurement in a scanning mode having a locus of a desired density distribution within the scanning target area R, which is an area for distance measurement. Therefore, it is possible to obtain a good distance measurement condition, and to perform distance measurement of the object OB in the scanning target area R with higher accuracy.

10 distance measuring device 30 MEMS mirror device 40 reflector unit 50 light receiving unit 60 distance measuring unit

Claims (1)

an optical scanning unit that scans light in a predetermined irradiation direction;
It has a first reflecting surface and a second reflecting surface arranged in a spatial region in the irradiation direction of the optical scanning unit and arranged such that a first angle facing the scanning target region is smaller than a flat angle. , an optical path control unit for emitting the light toward the scanning target area;
a light-receiving unit that receives the light reflected by an object existing in the scanning target area;
has
The optical scanning unit includes, on the first reflecting surface and the second reflecting surface, a high-density area, which is an area in which the density of the scanning trajectory of the light is high, and an area in which the density of the scanning trajectory of the light is low. scanning the light to form a low-density region where
The optical path control unit is arranged such that an emission trajectory of the light forming the high-density area in the scanning target area is arranged between an emission trajectory of the light forming the low-density area in the scanning target area. and emitting the light toward the area to be scanned.

Images