JP2022025315A - Light projection device, object detection device, and moving body - Google Patents

Abstract

To enable projection of scanning light at a wide angle when a transmission member is provided.SOLUTION: Disclosed is a light projection device according to an aspect of the present invention, which projects scanning light. The light projection device includes: a light source part for emitting light; an optical scanning part for scanning the light emitted from the light source part in a predetermined scanning direction; and a transmission member which is provided in an optical path of the scanning light by the optical scanning part and transmits the scanning light therethrough. The transmission member includes the scanning curved surface having the curvature in the scanning direction.SELECTED DRAWING: Figure 1

Description

The present application relates to a light projection device, an object detection device, and a moving body.

Conventionally, an object detection device such as an LIDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging) device that detects an object in front of a moving body such as a vehicle, and an object detection device used in the object detection device, scanning light in front of the moving body. A light projection device is known (see, for example, Patent Document 1).

Further, the optical projection device discloses a configuration in which a transmitting member that transmits scanning light is provided in the optical path of the scanned scanning light to be projected (see, for example, Patent Document 2).

However, in the configurations of Patent Documents 1 and 2, if the transmitting member is provided, the scanning light may not be projected at a wide angle.

An object of the present invention is to make it possible to project scanning light at a wide angle when a transmissive member is provided.

The light projection device according to one aspect of the present invention is a light projection device that projects scanning light, and includes a light source unit that emits light and an optical scanning unit that scans the emitted light of the light source unit in a predetermined scanning direction. A transmission member provided in the optical path of the scanning light by the optical scanning unit and transmitting the scanning light, and the transmitting member includes a scanning curved surface having a curvature in the scanning direction.

According to the present invention, when the transmissive member is provided, the scanning light can be projected at a wide angle.

It is a figure which shows the structural example of the optical scanning part which concerns on 1st Embodiment, (a) is the figure which looked at the light projection device from the X-axis direction, (b) is the figure which looked at the light projection device from the Y-axis direction. It is a figure. It is a figure which shows the structural example of the object detection apparatus which concerns on 1st Embodiment. It is a block diagram of the hardware configuration example of the control part which concerns on 1st Embodiment. It is a block diagram of the functional structure example of the control part which concerns on 1st Embodiment. It is a figure which shows the relationship example of the incident angle of a window surface, and the reflectance. It is a figure explaining the miniaturization example of the light projection apparatus. It is a figure which shows the structural example of the object detection apparatus which concerns on 2nd Embodiment. It is a block diagram of the functional structure example of the control part which concerns on 3rd Embodiment. It is a figure of the structural example of the moving body which concerns on 4th Embodiment. It is a block diagram of the hardware configuration example of the moving body which concerns on 4th Embodiment.

Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In each drawing, the same components are designated by the same reference numerals, and duplicate description will be omitted as appropriate.

Further, the embodiments shown below exemplify an image forming apparatus for embodying the technical idea of the present invention, and the present invention is not limited to the embodiments shown below. Unless otherwise specified, the shapes of the components, their relative arrangements, the values of the parameters, etc. described below are not intended to limit the scope of the present invention to that alone, but are intended to be exemplified. Is. In addition, the size and positional relationship of the members shown in the drawings may be exaggerated in order to clarify the explanation.

The light projection device according to the embodiment is a light projection device used in an object detection device such as LIDAR that detects an object in front of a moving body such as a vehicle. In the embodiment, a transmitting member that transmits scanning light is provided in an optical path of scanning light by an optical scanning unit, and the transmitting member includes a scanning curved surface having a curvature in a predetermined scanning direction. With this configuration, when the transmissive member is provided, the incident angle of the scanning light incident on the transmissive member is reduced in the angle region where the scanning angle is large, thereby ensuring the light utilization efficiency of the scanning light transmitted through the transmissive member. Allows scanning light to be projected at a wide angle.

[First Embodiment]
Hereinafter, an embodiment will be described by taking an object detection device 100 having a light projection device 300 as an example. In the embodiment, in the XYZ three-dimensional Cartesian coordinate system, the scanning direction of light by the optical scanning unit is the X-axis direction (an example of a predetermined direction), and the direction intersecting the X-axis direction is the Y-axis direction (an example of the crossing direction). The direction that intersects both the X-axis direction and the Y-axis direction is defined as the Z-axis direction.

<Configuration example of light projection device 300>
First, the configuration of the light projection device 300 will be described with reference to FIG. FIG. 1 is a diagram illustrating an example of the configuration of the light projection device 300 according to the present embodiment. (A) is a view of the light projection device 300 viewed from the X-axis direction, and (b) is a view of the light projection device 300 viewed from the Y-axis direction. Note that FIG. 1 shows only the main elements of the light projection device 300 for the sake of clarity.

As shown in FIG. 1, the light projection device 300 includes a semiconductor laser 11, a projection lens 12, a MEMS (Micro Electro Mechanical Systems) mirror 13, a window 16, and a control unit 200. The light projection device 300 incidents the light emitted by the semiconductor laser 11 on the MEMS mirror 13 via the projection lens 12, and projects the scanning light by the MEMS mirror 13 onto the detection region 500 via the window 16. The detection area 500 is a three-dimensional spatial area in which an object to be detected may exist.

The semiconductor laser 11 is an example of a light source unit that emits light. The semiconductor laser 11 emits a laser beam 11a having a predetermined light intensity at a predetermined timing in the positive direction of the Y axis in response to a control signal from the control unit 200. The laser beam 11a is an example of the emitted light of the light source unit. The laser beam 11a may be a pulsed laser beam or a CW (Continuous Wave) laser beam.

The wavelength of the laser beam 11a is not particularly limited, but when the light projection device 300 is mounted on an automobile or the like, a wavelength longer than 760 nm or an invisible wavelength that cannot be seen by the naked eye is preferable. The laser beam 11a emitted from the semiconductor laser 11 is incident on the projection lens 12.

Although the semiconductor laser 11 is shown as an example of the light source unit, the present invention is not limited to this. A solid-state laser such as a VCSEL (Vertical Cavity Surface Emitting LASER) or a YAG laser, which is a semiconductor laser having a plurality of light emitting units, a gas laser, a fiber laser, or the like can also be used. Further, the light source is not limited to a laser light source, and an LED (Light Emitting Diode) light source, a lamp light source, or the like can also be used.

The projection lens 12 is a non-axisymmetric lens having different curvatures in the X-axis direction and the Z-axis direction, and is configured to include a glass material, a plastic material, or the like. The projection lens 12 converts the laser beam 11a into substantially parallel light in the X-axis direction, and converts the laser beam 11a into focused light focused toward the focusing position fy in the Z-axis direction. Then, the converted laser beam 11a is emitted in the positive direction of the Y-axis.

The laser beam 11a emitted from the projection lens 12 is once focused at the focusing position fy in the Z-axis direction, and then spread (diverges) at the spreading angle θy. After that, the laser beam 11a is deflected and scanned by the MEMS mirror 13, and the scanning laser beam 11b by the MEMS mirror 13 is projected onto the detection region 500 through the window 16.

The scanning laser beam 11b is substantially parallel light in the X-axis direction (see FIG. 1B), and is light that spreads at a spreading angle θy in the Y-axis direction (see FIG. 1A). As described above, the projection lens 12 corresponds to an example of an optical magnifying unit that expands the laser beam 11a in the crossing direction (Y-axis direction) in the scanning direction (X-axis direction). By making the scanning laser beam 11b substantially parallel in the X-axis direction, the scanning laser beam 11b can be projected with higher position resolution than in the Y-axis direction.

In this embodiment, the configuration in which the function of the light magnifying unit is realized by one projection lens 12 is exemplified, but the function of the light magnifying unit can also be realized by a plurality of spherical lenses or aspherical lenses. Further, the light magnifying unit may be configured by including a light deflection element such as a mirror. Further, a diffusing plate may be included, and the spreading angle of the laser beam may be adjusted by a diffusing action.

The MEMS mirror 13 is an example of an optical scanning unit that scans the emitted light of the semiconductor laser 11 in a predetermined scanning direction. The MEMS mirror 13 can be manufactured by finely processing silicon, glass, or the like by a micromachining technique applying a semiconductor manufacturing technique.

The MEMS mirror 13 has a movable portion 13b including a light deflection surface 13a, and a drive beam (not shown). The drive beam is connected to the movable portion 13b, and is configured by superimposing a thin-film piezoelectric material on an elastic beam having elasticity. The MEMS mirror 13 reciprocates the movable portion around the swing shaft 13c (in the direction of the arrow 13d) according to the applied voltage to change the angle of the light deflection surface 13a.

The MEMS mirror 13 is provided with the swing shaft 13c tilted with respect to the Z axis. The angle of this inclination is, for example, 45 degrees. The laser beam 11a incident on the light deflection surface 13a along the Y-axis direction is deflected to the Z-axis positive direction side. The MEMS mirror 13 scans the light that spreads in the Y-axis direction and spreads at an angle θy in the X-axis direction within the angle region of the scanning angle θx (see FIG. 1B). Note that FIG. 1B shows how the movable portion 13b of the MEMS mirror 13 swings around the swing shaft 13c.

The scanning laser light 11b by the MEMS mirror 13 corresponds to the scanning light by the optical scanning unit. The light projection device 300 can project the scanning laser beam 11b onto the detection region 500 defined by the scanning angle θx and the spreading angle θy.

In the present embodiment, the MEMS mirror 13 is shown as an example of the optical scanning unit, but the present invention is not limited to this. The optical scanning unit can also include a galvano mirror, a polygon mirror, an OPA (Optical Phased Array), and the like. As the MEMS mirror 13, not only the piezoelectric type but also the one driven by another drive method such as an electrostatic method can be applied.

Further, the inclination of the swing shaft 13c with respect to the Z axis is not limited to 45 degrees and can be appropriately selected.

The window 16 is an example of a transmission member provided in the optical path of the scanning laser beam 11b by the MEMS mirror 13 and transmitting the scanning laser beam 11b. The window 16 is a member made of a glass material or a plastic material having light transmittance with respect to the wavelength of the semiconductor laser 11.

In the light projection device 300, the semiconductor laser 11, the projection lens 12, and the MEMS mirror 13 are arranged in a housing (accommodation member) (not shown). The housing is provided with an opening. The window 16 is provided so as to close the opening, and the scanning laser beam 11b is transmitted through the window 16 and projected to the outside.

Here, if dust or dirt adheres to the semiconductor laser 11, the projection lens 12, and the MEMS mirror 13, the light intensity of the projected scanning laser beam 11b may fluctuate and the performance of the optical projection device 300 may deteriorate. In particular, since the MEMS mirror 13 has a movable element, the operation of the movable element is easily affected by dust, dirt, and the like. In the present embodiment, by providing the window 16 in the opening, it is possible to prevent dust and contaminants from entering the housing, and it is possible to suppress deterioration in the performance of the light projection device 300.

Further, the window 16 has a first surface 16a facing the MEMS mirror 13 and a second surface 16b facing the first surface 16a. Each of the first surface 16a and the second surface 16b is formed into a curved surface having curvatures in the X-axis direction and the Y-axis direction as a whole.

Specifically, as shown in FIG. 1A, the respective curvature center Cys of the first surface 16a and the second surface 16b substantially coincide with the focusing position fy in the Y-axis direction. As a result, the scanning laser beam 11b spreading from the focusing position fy at the spreading angle θy is configured to be substantially perpendicular to each of the first surface 16a and the second surface 16b in the Y-axis direction.

However, the center of curvature Cy of each of the first surface 16a and the second surface 16b does not necessarily have to coincide with the focusing position fi, and may be arranged in the vicinity of the focusing position fi. By arranging them in the vicinity, it is possible to reduce the angle at which the scanning laser beam 11b spreading at the spreading angle θy is incident on the first surface 16a and the second surface 16b in the Y-axis direction.

The small incident angle means that the incident angle is close to perpendicular to the incident surface. For example, when the scanning laser beam 11b is vertically incident on the first surface 16a, the incident angle of the scanning laser beam 11b is 0 degrees. And as the inclination with respect to the vertical increases, the angle of incidence increases.

Strictly speaking, the center of curvature of the first surface 16a and the center of curvature of the second surface 16b are displaced by the thickness of the window 16, but this deviation is the radius of curvature of the first surface 16a and the second surface 16b. Etc. and small. Therefore, in FIG. 1A, the center of curvature of both the first surface 16a and the second surface 16b in the Y-axis direction is displayed as the center of curvature Cy.

On the other hand, as shown in FIG. 1 (b), the center of curvature Cx of each of the first surface 16a and the second surface 16b is located substantially on the swing axis 13c in the X-axis direction. As a result, in the X-axis direction, the scanning laser beam 11b scanned by the swing of the light deflection surface 13a around the swing axis 13c is incident on each of the first surface 16a and the second surface 16b substantially perpendicularly. It is configured.

However, the center of curvature Cx of each of the first surface 16a and the second surface 16b does not necessarily have to be located on the swing shaft 13c, and may be configured to be located in the vicinity of the swing shaft 13c. By being located in the vicinity, the angle of incidence of the scanning laser beam 11b on the first surface 16a and the second surface 16b can be reduced in the X-axis direction.

Strictly speaking, the center of curvature of the first surface 16a and the center of curvature of the second surface 16b are displaced by the thickness of the window 16, but this deviation is caused by the radius of curvature of the first surface 16a and the second surface 16b, etc. Small compared to. Therefore, in FIG. 1B, the center of curvature of both the first surface 16a and the second surface 16b in the X-axis direction is displayed as the center of curvature Cx.

In the present embodiment, the curvature of the first surface 16a in the X-axis direction and the curvature in the Y-axis direction are different, and the curvature in the X-axis direction is larger than the curvature in the Y-axis direction. Therefore, the first surface 16a is formed as a non-axisymmetric surface. The curved surface of the first surface 16a in the X-axis direction corresponds to an example of a scanning curved surface having a curvature in the scanning direction. Further, the curved surface of the first surface 16a in the Y-axis direction corresponds to an example of an intersecting curved surface having a curvature in the intersecting direction.

Similarly, the curvature of the second surface 16b in the X-axis direction and the curvature in the Y-axis direction are different, and the curvature in the X-axis direction is larger than the curvature in the Y-axis direction. Therefore, the second surface 16b is also formed as a non-axisymmetric surface. The curved surface of the second surface 16b in the X-axis direction corresponds to an example of a scanning curved surface having a curvature in the scanning direction. Further, the curved surface of the second surface 16b in the Y-axis direction corresponds to an example of an intersecting curved surface having a curvature in the intersecting direction.

The manufacturing method of the window 16 can be appropriately selected, but when the first surface 16a or the second surface 16b is formed by non-axisymmetric surfaces having different curvatures in the X-axis direction and the Y-axis direction, a mold is used. The molding process of the existing plastic material is particularly suitable.

The control unit 200 is a control device that controls the semiconductor laser 11, controls the MEMS mirror 13, and performs processing for acquiring object information, which will be described later.

<Configuration example of object detection device 100>
Next, the configuration of the object detection device 100 will be described with reference to FIG. FIG. 2 is a diagram illustrating an example of the configuration of the object detection device 100. As shown in FIG. 2, the object detection device 100 includes a light projection device 300, a condenser lens 14, and a photodiode 15.

The condensing lens 14 is a lens that condenses at least one of the reflected light or scattered light (hereinafter collectively referred to as return light 502) of the scanning laser light 11b by the object 501 existing in the detection region 500. The condenser lens 14 is an axially symmetric lens configured to include a glass material or a plastic material.

The condenser lens 14 concentrates the return light 502 on the light receiving surface of the photodiode 15. With this configuration, the return light 502 is received with a higher light intensity. However, it is not always necessary to collect light on the light receiving surface of the photodiode 15. Further, the condenser lens 14 is not limited to the configuration having one lens, and may be configured to include an optical element such as a plurality of lenses, a reflection mirror, and a prism.

The photodiode 15 is an example of a light receiving unit that receives at least one of the reflected light or the scattered light of the scanning laser light 11b by the object 501 existing in the detection region 500. The photodiode 15 receives the return light 502 focused by the condenser lens 14, and outputs a light receiving signal, which is a voltage signal corresponding to the received light intensity, to the control unit 200.

The light receiving unit is not limited to the photodiode 15, and an APD (Avalanch Photo Diode), a Geiger mode APD SPAD (Single Photo Avalanch Photo Diode), a TOF (Time of Flight), or the like can also be used. ..

In the present embodiment, the return light 502 is configured to be deflected by the light deflection surface 13a of the MEMS mirror 13 and then to be received by the photodiode 15 through the condenser lens 14.

<Hardware configuration example of control unit 200>
Next, with reference to FIG. 3, the hardware configuration of the control unit 200 included in the object detection device 100 will be described. Here, FIG. 3 is a block showing an example of the hardware configuration of the control unit 200.

As shown in FIG. 3, the control unit 200 includes a CPU (Central Processing Unit) 21, a ROM (Read Only Memory) 22, a RAM (Random Access Memory) 23, an SSD (Solid State Drive) 24, and a light source drive. It has a circuit 25, a scanning drive circuit 26, a sensor I / F (Interface) 27, and an input / output I / F 28. These are electrically connected to each other via the system bus B.

The CPU 21 is a processor, and realizes control and functions of the entire control unit 200 by reading programs and data from memories such as ROM 22 and SSD 24 onto RAM 23 and executing processing. A part or all of the functions of the CPU 21 may be realized by an electronic circuit such as an ASIC (application specific integrated circuit) or an FPGA (Field-Programmable Gate Array).

The ROM 22 is a non-volatile semiconductor memory capable of holding programs and data even when the power is turned off. The ROM 22 stores programs and data such as BIOS (Basic Input / Output System) and OS settings that are executed when the control unit 200 is started.

The RAM 23 is a volatile semiconductor memory that temporarily holds programs and data.

The SSD 24 is a non-volatile memory in which a program for executing processing by the control unit 200 and various data are stored. An HDD (Hard Disk Drive) may be provided instead of the SSD.

The light source drive circuit 25 is an electric circuit that is electrically connected to the semiconductor laser 11 and outputs a drive signal such as a drive voltage to the semiconductor laser 11 in response to a control signal from the CPU 21 or the like. As the drive signal, a rectangular wave, a sine wave, or a voltage waveform having a predetermined waveform shape can be used. The light source drive circuit 25 can modulate the frequency of the drive signal by changing the frequency of the voltage waveform.

The scanning drive circuit 26 is an electric circuit that is electrically connected to the MEMS mirror 13 and outputs a drive signal such as a drive voltage to the MEMS mirror 13 in response to a control signal from the CPU 11 or the like.

The sensor I / F 27 is an interface that is electrically connected to the photodiode 15 and inputs a light receiving signal of the photodiode 15.

The input / output I / F 28 is connected to an external controller mounted on a moving body such as a vehicle or an external device such as a PC (Personal Computer) to receive data such as detection conditions and to receive data such as detected object information. It is an interface for sending. It can also be configured to connect to a network such as the Internet to send and receive data.

<Example of functional configuration of control unit 200>
Next, the functional configuration of the control unit 200 will be described with reference to FIG. Here, FIG. 4 is a block showing an example of the functional configuration of the control unit 200. Note that FIG. 4 shows only the main elements of the control unit 200 for the sake of clarity.

As shown in FIG. 4, the control unit 200 includes a light source control unit 201, a scanning control unit 202, a light receiving signal acquisition unit 203, an object information acquisition unit 204, and an object information output unit 205. Of these, the respective functions of the light source control unit 201, the scan control unit 202, and the object information acquisition unit 204 are realized by the CPU 21 executing a predetermined program or the like. Further, the function of the light receiving signal acquisition unit 203 is realized by the sensor I / F27 or the like, and the function of the object information output unit 205 is realized by the input / output I / F28 or the like.

The control unit 200 is between the object in the detection region 500 and the object detection device 100 due to the time difference between the emission timing (injection timing) of the laser beam by the semiconductor laser 11 and the light reception timing (light reception timing) of the return light 502 by the photodiode 15. The distance information of can be acquired by calculation and the acquired distance information can be output. Further, when the object does not exist in the detection region, information indicating that the object determined based on the light receiving signal of the photodiode 15 does not exist can be output.

The light source control unit 201 controls the emission of laser light by the semiconductor laser 11. The light source control unit 201 can control the timing at which the semiconductor laser 11 emits laser light according to a reference signal based on the clock of the CPU 21 or the like.

The light receiving signal acquisition unit 203 acquires (inputs) the light receiving signal of the photodiode 15 according to the light intensity of the return light, and outputs it to the object information acquisition unit 204. The scanning control unit 202 controls the rotational drive of the MEMS mirror 13.

The object information acquisition unit 204 acquires the timing information from the light source control unit 201 when the semiconductor laser 11 emits the laser beam, and acquires the timing information from the light receiving signal acquisition unit 203 when the photodiode 15 receives the return light.

Then, the distance information between the object and the object detection device 100 in the detection region is acquired by calculation from the time difference between the injection timing and the light receiving timing. When the object does not exist in the detection area, the information indicating that the object does not exist determined from the light receiving signal output by the photodiode 15 is acquired. For example, when the received signal level is lower than a predetermined threshold level, the object information acquisition unit 204 can determine that the object does not exist.

The object information acquisition unit 204 can output object information including distance information between the object and the object detection device 100 and information indicating that the object does not exist to the external device via the object information output unit 205.

Specific examples of object information include distance images and the like. Here, the distance image is an image generated by arranging distance data indicating the distance to an object acquired for each pixel in two dimensions according to the position of the pixel. For example, the distance is converted into the brightness of the pixel. It is an image generated by. In other words, the distance image is three-dimensional information indicating the position of the object in the detection area.

A specific example of the object detection method is a TOF (Time of Flight) method. A known technique can be applied to the TOF method.

<Action and effect of the light projection device 300>
Next, the operation and effect of the light projection device 300 will be described.
As described above, it is preferable to provide a window (transmissive member) in the opening of the housing that accommodates the MEMS mirror (optical scanning unit) because it is possible to prevent the intrusion of contaminants into the housing. However, when the scanning angle by the MEMS mirror becomes large, the incident angle of the scanning laser light with respect to the window surface becomes large, and the light utilization efficiency of the scanning laser light transmitted through the window may decrease.

Here, FIG. 5 is a diagram showing an example of the relationship between the angle of incidence on the window surface and the reflectance on the window surface. FIG. 5 shows the reflectance of the scanning laser beam incident on a window made of a material having a refractive index of 1.57 for each incident angle. The solid line graph 51 shows the case where the scanning laser beam is S-polarized, and the broken line graph 52 shows the case where the scanning laser beam is P-polarized. The polarization state of the scanning laser beam can be predetermined by the direction of installation of the semiconductor laser that emits the linearly polarized laser beam.

As shown in FIG. 5, when the angle of incidence on the window surface is small (incident in substantially vertical), the reflectance is about 5% for both S-polarized light and P-polarized light. Therefore, 95% of the light passes through the window surface. As the angle of incidence increases, the reflectance gradually increases with S-polarization, and when the angle of incidence exceeds 75 degrees, the reflectance increases significantly. With P-polarization, the reflectance remains low until the incident angle is about 60 degrees, but the reflectance gradually increases when it exceeds 60 degrees, and as with S-polarization, the reflectance greatly increases when it exceeds 75 degrees. As the reflectance increases, the transmittance decreases, and the light intensity of the scanning laser beam transmitted through the window surface decreases. FIG. 5 shows the reflectance on one surface (front surface) of the window, but since the other surface (back surface) also has the same characteristics, the decrease in transmittance is more than doubled due to the transmission on both sides.

Therefore, when the scanning angle of the scanning laser light by the MEMS mirror becomes large, the light utilization efficiency of the transmitted light decreases, and the light projection device cannot project light with sufficient light intensity. This limits the scanning angle by the MEMS mirror. For example, when the scanning laser light is S-polarized, the transmittance is about 80% because the incident angle is 60 degrees and the reflectance is about 20% as shown in FIG. Due to the reflection on both sides of the window, the light utilization efficiency of the scanning laser beam after passing through the window becomes about 60%. In this case, the required scanning laser light intensity may not be obtained, and the scanning angle may be limited to ± 60 degrees or less.

In this embodiment, the window includes a scanning curved surface having a curvature in the X-axis direction (scanning direction). Since the scanning curved surface in the window has a curvature, the incident angle of the scanning laser light incident on the window can be reduced in the angle region where the scanning angle is large, and the reflectance on the window surface can be suppressed. As a result, it is possible to secure the light utilization efficiency of the scanning laser light transmitted through the window, relax the limitation of the scanning angle, and project the scanning laser light at a wide angle.

Note that FIG. 5 is an example showing the characteristics of a window without an antireflection film, but even when the window is provided with an antireflection film, the angle of incidence on the window surface and the angle of incidence on the window surface are shown. Similar characteristics can be obtained as characteristics indicating the relationship of reflectance.

Further, in the present embodiment, both the first surface facing the MEMS mirror in the window and the second surface facing the first surface include the scanning curved surface. As a result, the incident angle of the scanning laser light can be reduced on both the first surface and the second surface, and the limitation of the scanning angle can be further relaxed, so that the scanning laser light can be projected at a wider angle.

Further, in the present embodiment, the projection lens (light magnifying unit) that spreads the laser beam in the Y-axis direction (crossing direction) is provided, and the window has a crossing curved surface having a curvature in the Y-axis direction. As a result, the incident angle of the scanning laser beam incident on the window can be reduced even in the Y-axis direction, and the light utilization efficiency of the scanning laser beam transmitted through the window can be further improved.

Further, in the present embodiment, both the first surface and the second surface of the window are configured to include a scanning curved surface and an intersecting curved surface, respectively. As a result, the reflectance on both sides of the window can be suppressed, and the light utilization efficiency of the scanning laser light transmitted through the window can be further improved.

Further, in the present embodiment, the curvature of the first surface of the window in the X-axis direction is larger than the curvature in the Y-axis direction. In other words, the radius of curvature of the first surface of the window in the X-axis direction is smaller than the radius of curvature in the Y-axis direction. Even when the scanning angle of the MEMS mirror is large with respect to the spreading angle in the Y-axis direction of the projection lens, the incident angle of the scanning laser beam incident on the window is reduced to improve the light utilization efficiency of the scanning laser beam transmitted through the window. Can be improved.

Further, in the present embodiment, the MEMS mirror scans the laser beam by swinging the light deflection surface around the swing axis, and the center of curvature of the scanning curved surface is arranged on the swing axis. As a result, the scanning laser beam from the MEMS mirror is incident on the window surface substantially perpendicular to the window surface in the X-axis direction, so that the light utilization efficiency of the scanning laser beam transmitted through the window can be further improved.

In addition, by making the center of curvature of the intersecting curved surface substantially the same as the focusing position of the laser beam by the projection lens, the scanning laser beam expanded by the projection lens is incident on the window surface almost perpendicular to the window surface in the Y-axis direction. The light utilization efficiency of the transmitted scanning laser beam can be further improved.

Further, by including the scanning curved surface in which the window has a curvature in the X-axis direction, it is possible to obtain the effect of miniaturizing the light projection device. Here, FIG. 6 is a diagram illustrating an example of miniaturization of the light projection device.

FIG. 6 schematically shows both the case where the scanning laser beam 11b transmits through the window 16 according to the present embodiment and the case where the scanning laser beam 11b transmits through the window 16x according to the comparative example. The window 16x is a flat plate-shaped transmissive member.

As shown in FIG. 6, the light projection device having the window 16 can be miniaturized by the amount that the window 16 has a curvature with respect to the light projection device having the window 16x. The miniaturized area 161 (lattice hatched portion) shown in FIG. 6 represents an area in which the light projection device having the window 16 can be miniaturized with respect to the light projection device having the window 16x.

In the description of the present embodiment, a configuration in which both the first surface and the second surface are formed on a curved surface is exemplified, but one of them may be formed on a curved surface and the other may be a flat surface. Further, although the configuration in which the shapes of the curved surfaces of the first surface and the second surface are substantially the same is illustrated, different shapes may be used. Examples of the different shapes include shapes having different curvatures on the first surface and the second surface. In this case as well, the light utilization efficiency can be ensured and the scanning laser beam can be projected at a wide angle as compared with the case where both are flat.

Further, the scanning laser light is light that spreads in the Y-axis direction, and the window exemplifies a configuration including a first surface and a second surface having curvatures in both the X-axis direction and the Y-axis direction, but is limited to this. is not it. The scanning laser light may be light substantially parallel in the Y-axis direction, and the window may be configured to include a first surface and a second surface having a curvature only in the X-axis direction.

Further, although the configuration in which the curved surface is formed on the entire first surface and the second surface is illustrated, only a part such as the portion through which the scanning laser light is transmitted is formed on the curved surface, and the other portion is formed on the plane. You can also.

Further, the configuration in which the curved surface is a spherical surface in the X-axis direction and the Y-axis direction is exemplified, but the present invention is not limited to this. Even if the curved surface has an aspherical surface such as a paraboloid, the effect of reducing the incident angle of the scanning laser beam can be obtained.

Further, although the configuration in which the projection lens (light magnifying unit) is arranged between the semiconductor laser (light source unit) and the MEMS mirror (optical scanning unit) is illustrated, the projection lens can also be arranged between the MEMSM mirror and the window. ..

[Second Embodiment]
Next, the object detection device 100a will be described in the second embodiment. FIG. 7 is a diagram illustrating an example of the configuration of the object detection device 100a.

As shown in FIG. 7, the object detection device 100a has a light projection device 300a. Further, the light projection device 300a has a MEMS mirror 13'. The MEMS mirror 13'includes a reflective diffraction structure 17 in the end region of the light deflection surface 13a.

The laser beam 11a emitted from the semiconductor laser 11 is converted into parallel light in the Z-axis direction by the projection lens 12 and incident on the reflective diffraction structure 17 formed on the MEMS mirror 13'. The laser beam 11a incident on the reflection type diffraction structure 17 may or may not be parallelized in the X-axis direction.

The reflection type diffraction structure 17 reflects the incident laser light 11a in the Z-axis direction and converts it into a laser light that focuses at the focusing position fy'in the Y-axis direction by a diffraction action. The laser beam is once focused at the focusing position fy'and then propagates in the Z-axis direction while spreading at a spreading angle θy in the Y-axis direction. The MEMS mirror 13'swings around the swing axis 13c in the direction of the arrow 13d and scans the incident laser beam 11a in the X-axis direction. The scanning laser beam 11b by the MEMS mirror 13'is scanned in the X-axis direction while spreading at an expansion angle θy in the Y-axis direction, and is projected onto the detection region 500.

By providing the reflection type diffraction structure 17 in the MEMS mirror 13', the configuration for expanding the laser beam 11a in the Y-axis direction can be simplified, and the light projection device 300a can be miniaturized.

However, when the reflective diffraction structure 17 is formed on the light deflection surface 13a of the MEMS mirror 13', scattered light is generated by the reflective diffraction structure 17, and the scattered light is returned light from an object that does not exist in the detection region 500. By acting as (ghost light), an object may be erroneously detected. Therefore, there is a trade-off between the miniaturization of the light projection device 300a by the reflective diffraction structure 17 and the false detection of an object. Therefore, the position and size of the reflective diffraction structure 17 are determined in consideration of the balance between the two. Is preferable.

The configuration and function of the window 16 are the same as those described in the first embodiment, but the center of curvature Cy of the crossed curved surface having curvature in the Y-axis direction on the first surface 16a and the second surface 16b is the focusing position fy. The difference is that it is configured to roughly match'. With this configuration, the scanning laser beam 11b incident on the window 16 can be incident on the first surface 16a and the second surface 16b substantially perpendicularly in the Y-axis direction. However, the center of curvature Cy and the focusing position fy'are not necessarily the same. By arranging both of them close to each other, it is possible to obtain an effect of reducing the incident angle of the scanning laser beam 11b incident on the first surface 16a and the second surface 16b in the Y-axis direction. Thereby, as in the first embodiment, the light utilization efficiency of the scanning laser beam 11b transmitted through the window 16 can be secured, the limitation of the scanning angle can be relaxed, and the scanning laser beam 11b can be projected at a wide angle.

The other effects are the same as those described in the first embodiment.

In the present embodiment, the configuration in which the MEMS mirror 13 has the reflection type diffraction structure 17 is exemplified, but the configuration of the MEMS mirror 13 is not limited to this, and various modifications are possible. For example, the MEMS mirror 13 may be provided with a light deflecting surface having a curvature. Further, as the MEMS mirror 13, a transmission type refraction means, one using rotation of a prism, one using diffraction or the like may be used.

[Third Embodiment]
Next, the object detection device 100b according to the third embodiment will be described. Here, FIG. 8 is a block diagram showing an example of the functional configuration of the control unit 200b included in the object detection device 100b. The hardware configuration of the control unit 200b is the same as that shown in FIG.

As shown in FIG. 8, the control unit 200b includes a distortion correction unit 206, an object image information acquisition unit 207, a complementary object information acquisition unit 208, and a complementary object information output unit 209.

Of these, the functions of the distortion correction unit 206, the object image information acquisition unit 207, and the complementary object information acquisition unit 208 are realized by the CPU 21 of FIG. 3 executing a predetermined program. Further, the function of the complementary object information output unit 209 is realized by the input / output I / O 28 and the like shown in FIG.

The distortion correction unit 206 inputs the right eye image captured by the right camera 181 included in the stereo camera 18 included in the object detection device 100b and the left eye image captured by the left camera 182, and inputs the right eye image and the left eye image. Correct each image distortion of. Examples of this image distortion include barrel-shaped or pincushion-shaped distortion around the outer edge of the image, trapezoidal distortion, and the like. The distortion correction unit 206 outputs the corrected right eye image and left eye image to the object image information acquisition unit 207, respectively.

Each of the right camera 181 and the left camera 182 is an example of an imaging unit that captures an image of an object.

The object image information acquisition unit 207 generates a distance image based on the parallax detected by image processing using the input right eye image and left eye image, and outputs the generated distance image to the complementary object information acquisition unit 208.

The complementary object information acquisition unit 208 acquires the complementary object information based on the object information input from the object information acquisition unit 204 and the distance image input from the object image information acquisition unit 207. Here, the complementary object information refers to object information in which one or both object information is complemented by using a plurality of object information acquired by different methods. In the present embodiment, one of the plurality of object information is the object information such as the distance information image detected by the TOF method, and the other is the object information such as the distance image detected by the stereo camera method.

In the TOF method, highly accurate distance detection is possible without depending on the distance to the object, but the in-plane spatial resolution is low because the return light from the object of the laser beam projected by expanding the beam is used. There is. Further, in the stereo camera method, high in-plane spatial resolution can be obtained according to the resolutions of the right camera 181 and the left camera 182, but the distance detection accuracy may be lowered depending on the distance to the object.

By combining the information obtained by both the TOF method and the stereo camera method, highly accurate distance detection with high in-plane spatial resolution becomes possible.

For example, one or more pixels corresponding to the distance image by the object information acquisition unit 204 and the distance image by the object image information acquisition unit 207 are defined. In this corresponding pixel, the distance detection value of the distance image by the object information acquisition unit 204 is used, and in the pixels other than the corresponding pixel, the distance detection of the distance image by the object image information acquisition unit 207 corrected based on the distance detection value in the corresponding pixel. The value is used to generate and acquire a complementary distance image. The complementary distance image is complementary object information obtained by complementing the in-plane spatial resolution of the TOF distance image using the stereo camera distance image.

The complementary object information acquisition unit 208 provides the acquired complementary distance image to the complementary object information output unit 209. The complementary object information output unit 209 can output complementary object information that complements the object information based on the image to an external device such as a vehicle controller.

As described above, in the present embodiment, the complementary distance image acquired based on the distance image by the TOF method and the distance image by the stereo camera method is output. As a result, it is possible to output a distance image with high distance detection accuracy with high in-plane spatial resolution in which the in-plane spatial resolution of the TOF distance image is complemented by using the stereo camera distance image.

In this embodiment, an example of complementing the in-plane spatial resolution of the distance image of the TOF method is shown, but the present invention is not limited to this, and the captured image is used for color information and the like that cannot be obtained by the TOF method. May be complemented. By complementing the color information, it becomes possible to use the color information such as a traffic signal and a traffic sign when the object detection device 100b is applied to the vehicle. In addition, other information other than these can be complemented.

Further, although a stereo camera is mentioned as an example of the image pickup unit, the camera is not limited to the stereo camera and may be a monocular camera.

The effects other than those described above are the same as those in the first embodiment.

[Fourth Embodiment]
Next, the moving body according to the fourth embodiment will be described. FIG. 9 is a diagram illustrating an example of the configuration of the moving body 1 including the object detection device 100 described in the first embodiment. The mobile body 1 is an automatic guided vehicle that unmannedly transports cargo to a destination.

The object detection device 100 is attached to the front portion of the moving body 1 and acquires object information such as a distance image on the positive Z direction side of the moving body 1. From the output of the object detection device 100, it is possible to detect object information such as the presence / absence of an object such as an obstacle on the positive Z direction side of the moving body 1 and the position of the object.

FIG. 10 is a block diagram showing an example of the hardware configuration of the mobile body 1. As shown in FIG. 10, the moving body 1 includes an object detection device 100, a display device 30, a position control device 40, a memory 50, and a voice / alarm generation device 60. These are electrically connected via a bus 70 capable of transmitting signals and data.

In the present embodiment, the travel management device 10 is composed of an object detection device 100, a display device 30, a position control device 40, a memory 50, and a voice / alarm generation device 60. The travel management device 10 is mounted on the moving body 1. Further, the travel management device 10 is electrically connected to the main controller 80 of the mobile body 1.

The display device 30 is a display such as an LCD (Liquid Crystal Display) that displays three-dimensional information acquired by the object detection device 100, various setting information related to the moving body 1, and the like. The position control device 40 is an arithmetic unit such as a CPU that controls the position of the moving body 1 based on the object information acquired by the object detection device 100. The voice / alarm generator 60 is a device such as a speaker that determines whether or not obstacles can be avoided from the three-dimensional data acquired by the object detection device 100 and notifies the surrounding personnel when it is determined that the obstacles cannot be avoided. ..

In this way, it is possible to provide a moving body equipped with the object detection device 100.

The moving body provided with the object detection device 100 is not limited to the automatic guided vehicle. It can also be mounted on vehicles such as automobiles and flying objects such as drones. Further, it can be mounted not only on a mobile body but also on an information terminal such as a smartphone or a tablet.

Further, in the embodiment, an example in which the object detection device 100 includes the configuration and function of the control unit 200 is shown, but the present invention is not necessarily limited to this. Even if a device including an object detection device 100 such as an external controller included in the mobile body 1 or a device connected to the object detection device 100 is provided with a part or all of the configuration and functions of the control unit 200. good.

The effects other than the above-mentioned effects are the same as those in the first and second embodiments.

Although the embodiments have been described above, the present invention is not limited to the above-described embodiments specifically disclosed, and various modifications and changes can be made without departing from the scope of claims. be.

The light projected by the light projection device 300 is not limited to laser light, and may be light having no directivity, or electromagnetic waves having a long wavelength such as a radar. good.

Further, the numbers such as the ordinal number and the quantity used above are all exemplified for concretely explaining the technique of the present invention, and the present invention is not limited to the exemplified numbers. Further, the connection relationship between the components is exemplified for concretely explaining the technique of the present invention, and the connection relationship for realizing the function of the present invention is not limited to this.

Further, the division of blocks in the functional block diagram is an example, and even if a plurality of blocks are realized as one block, one block is divided into a plurality of blocks, and / or some functions are transferred to another block. good. Further, the functions of a plurality of blocks having similar functions may be processed by a single hardware or software in parallel or in a time division manner.

Each function of the embodiment described above can be realized by one or more processing circuits. Here, the "processing circuit" as used herein is a processor programmed to perform each function by software, such as a processor implemented by an electronic circuit, or a processor designed to execute each function described above. It shall include devices such as ASIC (Application Specific Integrated Circuit), DSP (digital signal processor), FPGA (field programmable gate array) and conventional circuit modules.

1 Mobile 100 Object detection device 11 Semiconductor laser (example of light source unit)
11a Laser light (an example of emitted light)
11b Scanning laser light (an example of scanning light)
12 Projection lens (an example of an optical magnifying unit)
13 MEMS mirror (an example of optical scanning unit)
13a Optical deflection surface 13b Moving part 13c Swinging shaft 14 Condensing lens 15 Photodiode (example of light receiving part)
16 window (example of transparent member)
16a First surface (an example of a scanning curved surface, an example of an intersecting curved surface)
16b Second surface (example of scanning curved surface, example of intersecting curved surface)
161 Miniaturized area 17 Reflective diffraction structure 18 Stereo camera 181 Right camera (example of image pickup unit)
182 Left camera (example of image pickup unit)
200 Control unit 201 Light source control unit 202 Scan control unit 203 Light receiving signal acquisition unit 204 Object information acquisition unit 205 Object information output unit 206 Distortion correction unit 207 Object image information acquisition unit 208 Complementary object information acquisition unit 209 Complementary object information output unit 500 Detection Region 501 Object 502 Return light fy, fy'Focusing position Cx Center of curvature in X-axis direction Cy Center of curvature in Y-axis direction θ x Scanning angle θy Spread angle X-axis direction Scanning direction Y-axis direction Crossing direction

Japanese Unexamined Patent Publication No. 2018-151278 Japanese Unexamined Patent Publication No. 2019-128221

Claims (9)

An optical projection device that projects scanning light.
The light source that emits light and
An optical scanning unit that scans the emitted light of the light source unit in a predetermined scanning direction,
It has a transmitting member provided in the optical path of the scanning light by the optical scanning unit and transmitting the scanning light.
The transmissive member is an optical projection device including a scanning curved surface having a curvature in the scanning direction. The transmissive member has a first surface facing the optical scanning unit and a second surface facing the first surface, and both the first surface and the second surface include the scanning curved surface. The light projection device according to claim 1. It further has an optical magnifying part that expands the emitted light in the intersecting direction of the scanning direction.
The light projection device according to claim 1 or 2, wherein the transmissive member includes a crossed curved surface having a curvature in the crossing direction. The transmissive member has a first surface facing the optical scanning unit and a second surface facing the first surface, and the scanning curved surface and the scanning curved surface are formed on both the first surface and the second surface. The light projection device according to claim 3, which includes the intersecting curved surface. The light projection device according to claim 3, wherein the curvature of the scanning curved surface in the scanning direction is larger than the curvature of the intersecting curved surface in the intersecting direction. The optical scanning unit scans the emitted light by swinging the light deflection surface around a predetermined swing axis.
The light projection device according to any one of claims 1 to 5, wherein the center of curvature of the scanning curved surface is arranged on the swing axis. The light projection device according to any one of claims 1 to 6, which projects the scanning light onto a predetermined detection area.
A light receiving unit that receives at least one of the reflected light or the scattered light of the scanning light by an object existing in the detection region, and a light receiving portion.
An object detection device including an object information output unit that outputs object information acquired based on the emission timing of the light source unit and the light reception timing of the light receiving unit. An image pickup unit that captures an image of the object,
The object detection device according to claim 7, further comprising a complementary object information output unit that outputs complementary object information that complements the object information based on the image. A mobile body having the object detection device according to claim 7 or 8.

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