WO2023153139A1

WO2023153139A1 - Projector, and measuring device

Info

Publication number: WO2023153139A1
Application number: PCT/JP2023/000814
Authority: WO
Inventors: 和也本橋
Original assignee: 株式会社小糸製作所
Priority date: 2022-02-09
Filing date: 2023-01-13
Publication date: 2023-08-17
Also published as: JP2023116280A

Abstract

This projector comprises a light emitting unit (111) provided with a plurality of laser light sources capable of being controlled to be turned on/off individually, and a control device for controlling the turning on/off of each laser light source, wherein the control device simultaneously turns on a combination of two or more laser light sources with which a total energy of laser light that may enter an eye of a person when the laser light sources are each turned on simultaneously is at most equal to a predetermined threshold.

Description

Projector and measuring device

The present disclosure relates to projectors and measuring devices.

With the progress of AD (Autonomous Driving) and ADAS (Advanced Driver Assistance System), LiDAR (Light Detection and Ranging) is one of the measuring devices used for understanding the surrounding environment and estimating self-location. called. ) are being researched/developed. LiDAR consists of a projector (irradiator) that irradiates an object with projected light (irradiation light, light beam (laser light)) and reflected light (return light) that returns the projected light to the object to be measured. The difference between the timing when the projector emits the projected light and the timing when the receiver receives the reflected light (time of flight of the laser beam. Hereinafter referred to as "TOF" (Time Of Flight) ) to get the distance to the object.

The laser light emitted from the LiDAR projector may be harmful to the human body due to its small emission area and high energy density. In Japan, the Japanese Industrial Standards (JIS) stipulate the "radiation safety standards for laser products" (JIS C 6802). must be designed to meet the conditions specified in

WO 2005/010000 is designed to flexibly adjust the balance between the parameters of a laser source (illumination range for eye safety, repetition rate, duty cycle, pulse power, reference to operating temperature, etc.). discloses a LIDAR system. The LIDAR system operates a laser source of a laser scanner that emits a first laser pulse from a plurality of angular regions to a specific angular region, performs LIDAR measurements based on the reflection of the first laser pulses, and performs a LIDAR measurement based on the LIDAR measurements. to selectively activate the laser source of the laser scanner to emit a second laser pulse in a particular angular region.

Japanese special table 2020-509389

One type of LiDAR is flash LiDAR. Flash LiDAR does not include mechanical components such as motors and MEMS (Micro Electro Mechanical Systems), and is a leading LiDAR in fields where durability is required, such as when used for in-vehicle purposes to realize AD and ADAS. considered as a candidate.

By the way, for example, as illustrated in FIG. 6A, the entire light source 60 (for example, When all the light emitting elements 601) of the light source are controlled to light up at the same time, as shown in FIG. more likely to exceed the threshold (safety value, upper limit value, allowable value, etc.) based on In addition, when long-distance measurement is required, such as when measuring a vehicle in the opposite lane in the distance, it is necessary to irradiate a high-intensity laser beam, and it is required to reduce the effects on the human body. Note that FIG. 6B is a graph showing the above control, in which the horizontal axis is time and the vertical axis is the light emission intensity of the light emitting element 601, and the amount of light emitted (energy of the light emitted) and the amount of exposure (energy to which a person is exposed) are different. The size is shown schematically.

As one of the methods for solving the above problems, for example, as illustrated in FIG. 601 (for example, an addressable VCSEL (Vertical Cavity Surface Emitting Laser) array). In this case, the light projection target areas 61a to 61d of the individual light emitting elements 601a to 601d are set to be different, and the individual light emitting elements 601a to 601d are turned on sequentially (turned on at different times). It is possible to irradiate the entire area 61 with laser light and reduce the influence on the human body.

However, the above method inevitably increases the number of times the light-emitting elements 601a to 601d are turned on/off (the number of times they are turned on and off). It becomes difficult to secure the scanning speed for the entire areas 61a to 61d.

Patent Document 1 discloses adjusting the balance with other parameters considering the irradiation range for ensuring eye safety as a parameter of the laser light source. However, Patent Literature 1 does not particularly describe a method for preventing frame rate reduction.

The present disclosure has been made in view of such a background, and an object thereof is to provide a projector and a measurement device that can prevent a frame rate from dropping while reducing the effects of laser light on the human body. and

In order to achieve the above object, a projector according to an aspect of the present disclosure includes:
a light emitting unit having a plurality of laser light sources that can be individually controlled to be turned on/off;
a control device for controlling lighting/extinguishing of each of the laser light sources;
with
The control device controls two of the laser light sources such that the total amount of energy of the laser light that may enter the human eye when the laser light sources are turned on at the same time is equal to or less than a preset threshold value. The above combinations are lit at the same time.

In addition, the problems disclosed by the present application and their solutions will be clarified by the section of the form for carrying out the present disclosure and the drawings.

According to the present disclosure, it is possible to prevent a decrease in frame rate (scan speed) while reducing the effects of laser light on the human body.

FIG. 1 is a diagram illustrating a schematic configuration of a measuring device. FIG. 2 is a plan view of a surface emitting element array shown as an example of a light emitting section. FIG. 3A is a schematic diagram showing a configuration example of a light projector used for explaining control of a surface emitting element by a light projection control device. FIG. 3B is a graph showing an example of control of the light emitting unit by the light projection control device. FIG. 4A is a schematic diagram showing an example of a combination of surface emitting elements that are lit at the same time. FIG. 4B is a schematic diagram showing an example of a combination of surface emitting elements that are lit at the same time. FIG. 4C is a schematic diagram showing an example of a combination of surface emitting elements that are lit at the same time. FIG. 5A is a diagram for explaining a method of calculating an angle at which the surface emitting element sees the aperture stop in the case of "measurement condition 1". FIG. 5B is a diagram illustrating a method of calculating the angle at which the surface emitting element looks into the aperture stop in the case of "measurement condition 3". FIG. 6A is a schematic diagram showing a configuration example of a light projector used for explaining control of light emitting elements. FIG. 6B is a graph showing an example of light source control. FIG. 7A is a schematic diagram showing a configuration example of a light projector used for explaining control of light emitting elements. FIG. 7B is a graph showing an example of light source control.

Embodiments for carrying out the present disclosure will be described below with reference to the drawings. In the following description, the same or similar configurations may be denoted by common reference numerals, and redundant description may be omitted.

FIG. 1 illustrates a schematic configuration (block diagram) of a measuring device 100 shown as one embodiment. The measurement device 100 is, for example, a flash LiDAR (Flash Light Detection and Ranging, Laser Imaging) installed in a vehicle equipped with AD (Autonomous Driving) or ADAS (Advanced Driver Assistance System). Detection and Ranging).

The measurement apparatus 100 measures the time (hereinafter referred to as “TOF” (hereinafter referred to as “TOF” ( The distance to the object 50 is measured by measuring the Time Of Flight).

In the following description, the light beam (irradiation light) that the measurement apparatus 100 irradiates toward the object 50 is referred to as "projected light", and the light that is reflected by the object 50 and returns. is called "reflected light".

For example, the measuring device 100 assists the detection of people, vehicles, objects, etc., as well as ensuring the safety of the driver of the vehicle and people around the vehicle, and the damage caused to objects around while driving the vehicle. Provide various information useful for reducing

As illustrated in FIG. 1, the measuring apparatus 100 includes a light emitting unit 111, a light projection control device 112 (an example of a control device), a current source 113, a light projecting optical system 114, a light receiving optical system 115, a light receiving unit 116, a TOF measurement A device 117 , an arithmetic device 150 and a communication I/F 160 are included. Among them, the light emitting unit 111, the light projection control device 112, the current source 113, and the light projection optical system 114 constitute a "projector" that generates projection light. The light receiving optical system 115 and the light receiving unit 116 constitute a "light receiver" that receives the reflected light.

The light emitting unit 111 includes a plurality of surface emitting laser light sources (for example, VCSEL (Vertical Cavity Surface Emitting Laser)) arranged one-dimensionally or two-dimensionally on a substrate (semiconductor substrate, ceramic substrate, etc.). )). The light emitting unit 111 can be configured using a surface light emitting element array (addressable VCSEL array) capable of independently controlling on/off of each surface light emitting element 10 . The surface emitting element 10 generates a light beam (laser light) that serves as projection light.

FIG. 2 is a plan view of a surface emitting element array shown as an example of the light emitting section 111. FIG. The surface emitting element array has a plurality of surface emitting elements 10 arranged in a square lattice on one surface of the substrate 22 . In FIG. 2, each of the plurality of surface emitting elements 10 is provided with its emitting direction (optical axis) directed in a direction (+z direction in FIG. 2) perpendicular to the x direction and y direction in FIG. A plurality of current supply lines 23 for supplying a current (driving current) for causing the surface emitting elements 10 to emit light from a current source 113 (see FIG. 1) are electrically connected to the surface emitting element array. .

The arrangement form of the surface emitting elements 10 in the surface emitting element array is not necessarily limited to that illustrated in FIG. may be Further, the surface emitting elements 10 do not necessarily have to be two-dimensionally arranged on the substrate 22 and may be one-dimensionally arranged on the substrate 22 .

Returning to FIG. 1, the light projection control device 112 generates a control signal for controlling the current source 113 that supplies the drive current for the surface light emitting element 10 of the light emitting unit 111, and inputs it to the current source 113, whereby the current The current (driving current) supplied from the source 113 to the surface emitting element 10 is controlled. In addition, the light projection control device 112 outputs a signal indicating the timing at which the surface light emitting element 10 emits light (the timing at which the projected light is emitted from the surface light emitting element 10; hereinafter referred to as “projection timing”). to enter. The light projection control device 112 periodically and repeatedly causes the surface light emitting elements 10 to emit light by, for example, periodically repeating ON/OFF control of the electric current flowing through each of the surface emitting elements 10 .

The current source 113 supplies the surface emitting element 10 with a current corresponding to the control signal input from the light projection control device 112 . The current source 113 supplies, for example, a periodic square-wave current to the surface emitting elements 10 for turning on and off the current flowing through each of the surface emitting elements 10 .

The projection optical system 114 adjusts the light distribution of the projected light, for example, by applying an optical effect (refraction, scattering, diffraction, etc.) to the projected light emitted from the light emitting unit 111 . The projection optical system 114 can be configured using optical components such as various lenses such as a collimator lens, a diffraction grating, and a reflector (mirror).

The light-receiving optical system 115 collects the reflected light returning from the object 50 onto the light-receiving unit 116 . The light receiving optical system 115 can be configured using, for example, various lenses such as a condenser lens, various filters such as a wavelength filter, and optical components such as a reflector (mirror).

The light receiving unit 116 can be configured using a photodetector such as a SPAD (Single Photon Avalanche Diode), a photodiode, or a balanced photodetector, for example. The light receiving unit 116 photoelectrically converts the reflected light incident from the light receiving optical system 115 to generate a current (hereinafter referred to as “light receiving current”) corresponding to the intensity of the reflected light. The light receiving unit 116 inputs a signal indicating the timing of receiving the reflected light (hereinafter referred to as “light receiving timing”) and the generated light receiving current to the TOF measuring device 117 .

The TOF measurement device 117 obtains the TOF based on the signal indicating the light projection timing input from the light emission control device 112 and the signal indicating the light reception timing input from the light receiving unit 116 . The TOF measurement device 117 can be configured using, for example, a time measurement IC (Integrated Circuit) equipped with a TDC (Time to Digital Converter) circuit. The TOF measuring device 117 inputs the obtained TOF and the received light current input from the light receiving unit 116 to the arithmetic device 150 .

Arithmetic device 150 uses, for example, a processor (CPU (Central Processing Unit), MPU (Micro Processing Unit), ASIC (Application Specific Integrated Circuit), FPGA (Field Programmable Gate Array), DSP (Digital Signal Processor), etc.) can be configured. The calculation device 150 generates information used for various measurements such as detection of the target object 50 and distance measurement based on the received light current and the TOF input from the TOF measurement device 117 . The information is, for example, a histogram used in Time Correlated Single Photon Counting, a distance to each point (point) of the object 50, a point cloud (point group information: point cloud) etc. The computing device 150 also controls the light projection control device 112 and the light receiving section 116 . The calculation device 150, for example, controls the light projection control device 112 and the light receiving unit 116, thereby adjusting the light projection timing and the light reception timing so that the processing related to the generation of the histogram is speeded up or optimized. Control. The information generated by the computing device 150 is provided (transmitted) to devices that use the information (hereinafter referred to as “various devices 40”) via a communication I/F 160 (I/F: Interface). .

Various utilization devices 40, for example, create an environment map by point cloud, self-location estimation (SLAM (Simultaneous Localization and Mapping)) using a scan matching algorithm (NDT (Normal Distribution Transform), ICP (Iterative Closest Point), etc.) etc.

<Light emission control>
The light projection control device 112 controls the surface light emitting element 10 so that the total amount of laser light energy that may enter the human eye is equal to or less than a preset threshold value (safety value, upper limit value, allowable value, etc.). The current sources 113 are controlled to illuminate two or more combinations simultaneously. This reduces the effect (exposure dose) on the human body when the laser light is accidentally irradiated on the human body, and the measurement device 100 and the projector comply with the radiation safety standards (IEC: International Electrotechnical Commission) for laser products. 60825-1 of Japanese Industrial Standards (JIS: Japanese Industrial Standards) "Radiation Safety Standards for Laser Products" (JIS C 6802), etc.). Also, by simultaneously turning on two or more of the above combinations, it is possible to prevent a decrease in the frame rate (scanning speed of the light projection target area).

FIG. 3A is a schematic diagram showing a configuration example of a light projector used for explaining control of the surface light emitting element 10 by the light projection control device 112. FIG. The reference numerals in FIG. 3A correspond to the reference numerals attached to FIG. In the example shown in FIG. 3A, for convenience of explanation, the case where the light emitting section 111 has four surface light emitting elements 10a to 10d arranged one-dimensionally at equal intervals on the substrate is illustrated. It is assumed that the surface emitting elements 10a to 10d all have common specifications (for example, they are all products of the same model number).

As illustrated in FIG. 3A, the laser light emitted from the surface emitting element 10a out of the four surface emitting elements 10a to 10d is emitted from the surface emitting element 10b to the light projection area 51a via the light projecting optical system 114. The laser light emitted from the surface emitting element 10c is emitted from the surface light emitting element 10d to the light emitting area 51c via the light emitting optical system 114. The emitted laser light is distributed to the light projection area 51d via the light projection optical system 114, respectively.

Here, for example, each of two adjacent surface emitting elements 10 (any combination of

surface emitting elements

10a and 10b, surface emitting elements 10b and surface emitting elements 10c, surface emitting elements 10c and surface emitting elements 10d) , the two laser beams distributed toward the projection target area by the projection optical system 114 may enter the human eye at the same time and have a harmful effect on the human body. be. Therefore, the light projection control device 112 reduces the effect of the laser light on the human body by controlling the adjacent surface emitting elements 10 not to light at the same time, so that the measuring device 100 (projector) complies with the radiation safety standards for laser products. make it fulfill

FIG. 3B is a graph illustrating the above control. In this graph, the horizontal axis is time and the vertical axis is the light emission intensity of the surface light emitting element 10, and shows an example of the amount of projected light (energy of projected light) and the amount of exposure (energy to which a person is exposed). As illustrated in FIG. 3B, in this example, the combination of the

surface emitting elements

10a and 10c is lit at the same time, and then the combination of the

surface emitting elements

10b and 10d is lit at the same time. As understood from FIG. 3B, the exposure dose at each lighting timing is 1/2 of the exposure dose (FIG. 6B) in the method shown in FIG. 6A. In this case, the time required for one frame is half the time (FIG. 7B) in the method shown in FIG. scan speed) can be increased.

In this example, in order not to light two adjacent surface light emitting elements 10 at the same time, every other combination of surface light emitting elements 10 is lighted at the same time. You may make it light simultaneously every 2 or more. Also, any combination of two or more surface emitting elements 10 that are not adjacent to each other may be lit at the same time.

Further, the plurality of surface emitting elements 10 constituting the light emitting section 111 are classified into a plurality of groups each having a plurality of adjacent surface emitting elements 10 as elements, and the surface emitting elements 10 belonging to two adjacent groups are simultaneously lit. You can choose not to let it happen. However, in this case, the total amount of energy of the laser light that may enter the human eye when all the surface emitting elements 10 in one group are turned on at the same time is set to a preset threshold value (safety value, upper limit value, permissible value, etc.).

4A to 4C are diagrams showing examples of combinations of surface emitting elements 10 that are simultaneously lit. 4A shows the case where every other surface light emitting element 10 is lit at the same time, FIG. 4B shows the case where every two surface light emitting elements 10 are simultaneously lit, and FIG. This is a case where the surface light-emitting elements 10 are turned on at the same time every other group in units of groups having surface light-emitting elements 10 (groups having two surface light-emitting elements 10 in this example).

It should be noted that how to select the combination of the surface light emitting elements 10 to be simultaneously lit among the surface light emitting elements 10 constituting the light emitting unit 111 (surface light emitting element array) depends on, for example, the arrangement interval of the surface light emitting elements 10, the surface light emitting element 10 Arrangement form of the elements 10 (for example, an orthorhombic lattice, a triangular lattice, a square lattice, a rectangular lattice, a hexagonal lattice, etc.), light beams emitted from the surface emitting elements 10 or the light beams emitted from the light emitting optical system 114 It is determined by considering the beam divergence angle (beam divergence angle, pitch) after passing through and the viewing angle of the human eye (viewing angle determined according to the aperture stop of the pupil).

For example, when the wavelength of the laser light is from 400 nm to 1400 nm, "Measurement conditions 1" (telescope, binoculars, etc. (hereafter referred to as "observation equipment") is listed in "Table 10" of "5.4 Measurement optical system" of JIS C 6802. for collimated beams where the risk is increased by the applied to the determination of the volume), "7 mm aperture stop at 100 mm" is stated.

In this case, under the above "measurement condition ₁ ", as illustrated in FIG. In addition, for example, under the above "measurement condition 3", as illustrated _in FIG. arctan(7/2/100)).

For this reason, for example, when the surface emitting element 10a and the surface emitting element 10c (or the surface emitting element 10b and the surface emitting element 10d) are turned on at the same time in the configuration shown in FIG. In order to prevent the light from entering the eye, under “measurement condition 1”, the light beam emitted from the surface emitting element 10 or the beam divergence angle (beam divergence angle) after the light beam has passed through the projection optical system 114 and The pitch should be 0.7° (=1.4°/2) or more. Further, in "measurement condition 3", the beam divergence angle (beam divergence angle) and the pitch after the light beam emitted from the surface emitting element 10 or the light beam passes through the projection optical system 114 is 2.0° (=4.0 °/2) or more.

As described above, in the measurement apparatus 100 of the present embodiment, the light projection control device 112 is preset with the total energy of laser light that may enter the human eye when each of them is turned on at the same time. The current source 113 is controlled so that a combination of two or more of the surface emitting elements 10 that are equal to or less than the threshold value (safety value, upper limit value, allowable value, etc.) is simultaneously turned on. For example, in the above "measurement condition 1", the light emission control device 112 controls the light emission unit 111 to have the plurality of light emitting units 111 so that the exposure dose to the human body when looking into the observation device is equal to or less than a preset threshold value. A laser light source to be turned on at the same time is selected from among the laser light sources. For example, in the above "measurement condition 3", the light projection control device 112 controls the number of laser light sources included in the light emitting unit 111 so that the radiation dose to the human body when looking into it with the naked eye is equal to or less than a preset threshold value. Among them, the laser light sources to be turned on at the same time are selected. Therefore, the influence (exposure dose) of the laser beam on the human body can be reduced, the measurement device 100 (projector) can meet the radiation safety standards for laser products, and the frame rate (scanning of the area to be projected) can be reduced. speed) can be prevented.

Although the embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the above embodiments, and includes various modifications. In addition, the above-described embodiment describes the configuration in detail in order to explain the present disclosure in an easy-to-understand manner, and is not necessarily limited to those having all the described configurations. Moreover, it is possible to add, delete, or replace a part of the configuration of the above embodiment with another configuration.

As described above, this specification discloses the following matters.
(1) a light-emitting unit having a plurality of laser light sources that can be individually controlled to be turned on/off;
a control device for controlling lighting/extinguishing of each of the laser light sources;
with
The control device controls two of the laser light sources such that the total amount of energy of the laser light that may enter the human eye when the laser light sources are turned on at the same time is equal to or less than a preset threshold value. A floodlight that illuminates a combination of the above at the same time.
(2) According to (1), the control device selects the plurality of laser light sources to be turned on at the same time so that the exposure dose to the human body when looking into the observation device is equal to or less than a preset threshold. floodlight.
(3) The projector according to (1), wherein the control device selects the plurality of laser light sources to be lit simultaneously so that the exposure dose to the human body when looking into the laser with the naked eye is equal to or less than a preset threshold value.
(4) The light projector according to (1), wherein the control device simultaneously lights the plurality of laser light sources so that adjacent laser light sources are not lighted at the same time.
(5) The light projector according to (4), wherein the control device simultaneously lights every other combination of the laser light sources.
(6) Classify the plurality of laser light sources constituting the light emitting unit into a plurality of groups each having a plurality of adjacent laser light sources as elements, and prevent surface emitting elements of two adjacent groups from lighting at the same time. , the projector according to (1), wherein the laser light sources of the plurality of groups are turned on at the same time.
(7) any one of (1) to (6), wherein the light emitting unit is a surface emitting element array having a structure in which the surface emitting elements that are the laser light sources are arranged one-dimensionally or two-dimensionally; Floodlight as described.
(8) A measuring device configured using the projector according to any one of (1) to (7),
the light projector;
a light receiver that receives reflected light of the light projected from the light projector;
with
A measuring device that measures a distance to a detection target based on the light reception result of the light receiver.

This application is based on a Japanese patent application (Japanese Patent Application No. 2022-019000) filed on February 9, 2022, the contents of which are incorporated herein by reference.

Claims

a light emitting unit having a plurality of laser light sources that can be individually controlled to be turned on/off;
a control device for controlling lighting/extinguishing of each of the laser light sources;
with
The control device controls two of the laser light sources such that the total amount of energy of the laser light that may enter the human eye when the laser light sources are turned on at the same time is equal to or less than a preset threshold value. A floodlight that illuminates a combination of the above at the same time.
The floodlight according to claim 1, wherein the control device selects the plurality of laser light sources to be lit simultaneously so that the exposure dose to the human body due to peering using the observation device is equal to or less than a preset threshold value.
The floodlight according to claim 1, wherein the control device selects the plurality of laser light sources to be lit simultaneously so that the exposure dose to the human body when looking into the laser with the naked eye is equal to or less than a preset threshold value.
The floodlight according to claim 1, wherein said control device simultaneously turns on a plurality of said laser light sources so as not to turn on adjacent said laser light sources at the same time.
5. The floodlight according to claim 4, wherein said control device simultaneously turns on at least every other combination of said laser light sources.
The plurality of laser light sources constituting the light emitting unit are classified into a plurality of groups each having a plurality of adjacent laser light sources as elements, and the surface emitting elements of two adjacent groups are classified into a plurality of groups so as not to light up at the same time. 2. The light projector of claim 1, wherein the laser light sources of the group are illuminated simultaneously.
The light projector according to claim 1 or 2, wherein the light emitting unit is a surface emitting element array having a structure in which the surface emitting elements that are the laser light sources are arranged one-dimensionally or two-dimensionally.
A measuring device configured using the projector according to claim 1 or claim 2,
the light projector;
a light receiver that receives reflected light of the light projected from the light projector;
with
A measuring device that measures a distance to a detection target based on the light reception result of the light receiver.