WO2023153212A1

WO2023153212A1 - Projector, and measuring device

Info

Publication number: WO2023153212A1
Application number: PCT/JP2023/002296
Authority: WO
Inventors: 義朗伊藤
Original assignee: 株式会社小糸製作所
Priority date: 2022-02-09
Filing date: 2023-01-25
Publication date: 2023-08-17
Also published as: JP2023116281A

Abstract

This projector comprises a light emitting unit having a plurality of surface light emitting elements including a first surface light emitting element and a second surface light emitting element, and a control device for controlling a light emission intensity of the surface light emitting elements by controlling a current flowing to each surface light emitting element, wherein the control device performs control such that the current flowing to the first surface light emitting element is increased more than the current flowing to the second surface light emitting element, and a length of an ON-period per unit of time of the current flowing to the first surface light emitting element is shorter than a length of an ON-period per unit time of the current flowing to the second surface light emitting element.

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), light beams (laser beams) have become one of the measuring devices used for understanding the surrounding environment and estimating self-location. Research/development of a device (hereinafter referred to as “LiDAR” (Light Detection and Ranging)) that irradiates an object and uses the reflected light to measure the distance is underway. There is a wide range of requirements for LiDARs mounted on ADs and ADASs, and various specifications and accuracy such as irradiation methods and stability are required for projectors that generate and scan the above light beams.

Patent Document 1 describes a LIDAR system mounted on a vehicle. A LIDAR system consists of an illuminator (laser projector) that projects a light beam generated by a light source toward a target scene, a receiver that receives the light reflected from an object, and a controller that calculates distance information about the object from the reflected light ( processor), which scans a particular pattern of light across a desired range and field of view (FOV). Convert measurements to represent a point-by-point 3D map of an environment.

Japanese special table 2020-527724

A surface emitting element array (VCSEL (Vertical Cavity Surface Emitting Laser) array, etc. used as a light source for a projector that projects (irradiates) a light beam (scan beam) from LiDAR (Light Detection and Ranging) toward the area to be measured. ), there is a surface emitting element array (hereinafter referred to as an “addressable VCSEL array”) in which specific light emitting elements can be independently turned on and off. By using the surface emitting element array as the light source of the projector, it is possible to realize a space-saving projector capable of high-speed beam scanning with high reliability.

In the addressable VCSEL array, it is also possible to individually control the emission intensity (optical density) of each light emitting element. It is possible to increase the measuring distance for the area where the light beam is projected by .

Here, when the emission intensity of a specific light-emitting element is increased as described above, the amount of heat generated by the light-emitting element increases, and as a result, the wavelength of the light beam emitted from the light-emitting element shifts to the longer wavelength side. This wavelength shift reduces the measurement accuracy of LiDAR. For example, when the wavelength of the light beam shifts to the long wavelength side, the LiDAR light receiver receives reflected light (return light) in a wavelength region with low sensitivity, which lowers the measurement accuracy of the LiDAR. In addition, when a band-pass filter is installed in the LiDAR receiver for the purpose of reducing solar noise, it is necessary to expand the transmission wavelength range of the band-pass filter according to the amount of wavelength shift. The solar noise that gets mixed in increases and the measurement accuracy of LiDAR decreases.

The above Patent Document 1 describes that an illuminator is configured using a two-dimensional VCSEL array. However, this document does not specifically describe increasing the emission intensity of a specific light-emitting element, the above problems caused by increasing the emission intensity of a specific light-emitting element, and methods for solving the problems.

The present disclosure is a projector capable of increasing the intensity of a light beam irradiated toward a specific measurement area while suppressing a wavelength shift caused by an increase in the amount of heat generated by a specific light emitting device of a surface emitting device array. and to provide a measuring device.

One aspect of the present disclosure is a floodlight, which includes a light emitting unit having a plurality of surface light emitting elements including a first surface light emitting element and a second surface light emitting element, and controlling a current flowing through each of the surface light emitting elements. a control device for controlling the light emission intensity of the surface light-emitting element, the control device increasing the current flowing through the first surface light-emitting element more than the current flowing through the second surface light-emitting element; Control is performed so that the length of the ON period per unit time of the current flowing through the first surface emitting element is shorter than the length of the ON period per unit time of the current flowing through the second surface emitting element.

In addition, the problems of the present disclosure and their solutions will be clarified in the section of the description of the mode for carrying out the invention and the drawings.

According to the present disclosure, it is possible to increase the intensity of the light beam irradiated toward the specific measurement area while suppressing the wavelength shift caused by the increase in the amount of heat generated by the specific light emitting element of the surface emitting element array.

It is a figure which shows the schematic structure of a measuring apparatus. It is a figure which shows an example of a surface emitting element array. It is the figure which drew typically an example of the optical path of the floodlight emitted from the surface emitting element which belongs to each group. FIG. 4 is a diagram showing an example of light distribution by a light projector mounted on a vehicle; 4 is a graph showing an example of emission intensity (optical density) of surface emitting elements of each group. FIG. 4 is a diagram showing an example of waveforms of currents that flow through the surface emitting elements of each group. FIG. 4 is a diagram showing an example of waveforms of currents that flow through the surface emitting elements of each group. It is an example of the heat dissipation structure provided in the light emitting part. It is an example of the heat dissipation structure provided in the light emitting part. It is an example of the heat dissipation structure provided in the light emitting part. It is an example of the heat dissipation structure provided in the light emitting part. It is an example of the heat dissipation structure provided in the light emitting part.

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.

[First embodiment]
FIG. 1 shows a schematic configuration (block diagram) of a measuring device 100 shown as one embodiment. The exemplified measurement device 100 includes functions as a LiDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging). The measurement apparatus 100 measures the time (hereinafter referred to as “TOF” (Time Of Flight) from the time the light beam irradiated toward the measurement area is reflected by the object 50 until the reflected light (return light, scattered light) returns. ), the distance to the object 50 is measured. 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 projected light is reflected by the object 50 and returns. The incoming light is called "reflected light".

In the present embodiment, if the measurement device 100 is a flash LiDAR (Flash LiDAR) mounted on a vehicle equipped with AD (Autonomous Driving) or ADAS (Advanced Driver Assistance System) will be described as an example. The measuring device 100, for example, assists in the detection of people, vehicles, and objects, ensures the safety of the driver of the vehicle and those around the vehicle, and reduces damage to objects around the vehicle while driving. provide a variety of useful information for

As shown in the figure, the exemplified measuring apparatus 100 includes a light emitting unit 111, a light projection control device 112, a current source 113, a light projecting optical system 114, a light receiving optical system 115, a light receiving unit 116, a TOF measuring device 117, and an arithmetic unit. 150, and communication I/F 160. 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 that constitutes the light projector has a plurality of surface-emitting type laser light-emitting elements arranged one-dimensionally or two-dimensionally on a substrate, and it is possible to independently turn on and off specific light-emitting elements. It is configured using a surface emitting element array (addressable VCSEL array). The surface emitting type laser light emitting device is, for example, a VCSEL (Vertical Cavity Surface Emitting Laser). A surface emitting type laser emitting device is hereinafter referred to as a “surface emitting device”. A substrate on which a plurality of surface emitting devices are arranged is, for example, a semiconductor substrate, a ceramic substrate, or the like. The surface emitting element of the light emitting unit 111 generates a light beam (laser light) that serves as projection light. The arrangement form of the surface emitting elements in the substrate is not necessarily limited. are arranged in a grid pattern, a hexagonal grid pattern, etc.).

The light projection control device 112 generates a control signal for controlling the current source 113 that supplies the driving current of the surface light emitting element of the light emitting unit 111 and inputs it to the current source 113 , so that the light emitting unit 111 is driven from the current source 113 . controls the current (driving current) supplied to the surface emitting element. The light projection control device 112 also inputs a signal indicating the timing at which the surface light emitting element emits light (the timing at which the projected light is emitted from the surface light emitting element; hereinafter referred to as “projection timing”) to the TOF measuring device 117. do. The light projection control device 112, for example, periodically and repeatedly causes the surface light emitting elements to emit light by controlling the on/off of the current flowing through each of the surface light emitting elements of the light emitting section 111 periodically.

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

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 is 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 is configured using, for example, optical components such as various lenses such as a condenser lens, various optical filters, and reflectors (mirrors). The light receiving optical system 115 of this embodiment includes a bandpass filter (wavelength filter) for removing sunlight noise included in the reflected light.

The light receiving unit 116 is configured using a light receiving element such as a SPAD (Single Photon Avalanche Diode), a photodiode, or a photodetector such as a balanced photodetector. 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 is 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 .

The arithmetic unit 150 is configured using 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.). be. 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 above 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 cloud information) 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.

FIG. 2 is a plan view of a surface emitting element array shown as an example of the light emitting section 111 shown in FIG. The illustrated surface emitting element array has a substrate 22 on which a plurality of surface emitting elements 10 are mounted, and a mounting substrate 24 which is a plate material on which the substrate 22 is mounted.

The exemplified surface emitting element array includes a plurality of groups arranged in a square lattice and belonging to a plurality of groups (hereinafter referred to as "groups 21a to 21e") partitioned into rectangular shapes of the same shape and size. It has a surface emitting element 10 . In the figure, a plurality of surface emitting elements 10 are provided so that their emission directions (optical axes) are directed in a direction perpendicular to the plane of the paper (+z direction shown in the figure).

In this example, 18 surface emitting elements 10 belong to one group, but the group setting method (the number of divided groups, the number of surface emitting elements 10 belonging to each group, the number of surface emitting elements 10 belonging to each group, and to which the surface emitting element 10 belongs) is not necessarily limited.

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 are electrically connected to the surface emitting element array. The surface emitting element array can control the emission intensity (optical density) of the surface emitting elements 10 on a group basis by controlling the current flowing through the surface emitting elements 10 on a group basis.

By the way, for example, in a vehicle to which AD or ADAS is applied, the measuring device 100 (LiDAR) mounted on the vehicle has a specific area (specific visual field range (visual field range)) among areas projected by the light emitting unit 111. There is a need to extend the measurement distance (detection distance, measurement range) for corners, FOV (Field Of View)). The specific area is, for example, a region of interest (ROI), such as a distant oncoming lane of a vehicle traveling on a highway.

As described above, the measuring apparatus 100 can adjust the emission intensity of the surface emitting elements 10 of the light emitting unit 111 on a group-by-group basis. It is possible to extend the measurement distance of a specific area among the areas projected by the light emitting unit 111 by increasing the light emission intensity by increasing the current flowing through the surface light emitting elements 10 belonging to .

FIG. 3 is a schematic diagram showing an example of optical paths of projected light (light beams) emitted from the surface emitting elements 10 belonging to each of the groups 21a to 21e of the light emitting section 111. FIG. As shown in the figure, projection light emitted from the surface light emitting elements 10 belonging to each of the groups 21a to 21e is adjusted in light distribution by the light projection optical system 114, and is projected onto different areas (light projection areas 51a to 51e). ) is projected (irradiated).

Here, in the configuration shown in the figure, for example, when it is desired to extend the measurement distance in the measurement area in charge of the group 21c, the current flowing through the surface emitting elements 10 belonging to the group 21c is changed to , is made larger than the current flowing through the surface emitting elements 10 belonging to .

FIG. 4 is a graph showing an example of the emission intensity (light density) of each of the surface emitting elements 10 of each group 21a to 21e shown in FIG. The vertical axis of the graph represents the emission intensity.

FIG. 5 shows the light distribution by each of the groups 21a to 21e when the current flowing through the surface emitting elements 10 belonging to the group 21c is made larger than the current flowing through the surface emitting elements 10 belonging to the

other groups

21a, 21b, 21d, and 21e. It is a figure which shows the state of. The figure shows the arrangement when the measurement device 100 having the light emitting unit 111 (surface light emitting element array) and the light projecting optical system 114 shown in FIG. It shows an example of light. As shown in the figure, the irradiation range 31 (measurable range) of the projected light emitted from the surface emitting elements 10 belonging to the group 21c is emitted from the surface emitting elements 10 belonging to the

other groups

21a, 21b, 21d, and 21e. It extends farther than the irradiation range 32 of the projected light.

Here, when more current is supplied to the surface emitting elements 10 belonging to the group 21c than the surface emitting elements 10 belonging to the

other groups

21a, 21b, 21d, and 21e as described above, the surface emitting elements 10 belonging to the group 21c The amount of heat generated is greater than that of the surface light emitting elements 10 belonging to the

other groups

21a, 21b, 21d, and 21e, and the temperature of each surface light emitting element 10 becomes non-uniform in the light emitting section 111 as a whole. The wavelength of the light emitted from the light-emitting element whose temperature has risen shifts to the longer wavelength side, and as a result, the light-receiving part receives the reflected light (return light) in a wavelength region with low sensitivity, resulting in a measurement device (flash LiDAR). Decreased measurement accuracy. In addition, by shifting the wavelength of light emitted from the light-emitting element whose temperature rises to the long wavelength side, the transmission wavelength range of the band-pass filter provided on the side of the light-receiving element for the purpose of reducing solar noise is expanded. Therefore, the measurement accuracy of the measurement device 100 is reduced due to the increase in solar noise contamination.

Therefore, in order to solve such problems, the projection control device 112 of the present embodiment has a mechanism for uniformizing the temperature of each surface emitting element 10 as the entire light emitting section 111 . Specifically, the light projection control device 112 causes the surface emitting elements 10 belonging to the group 21c (hereinafter also referred to as "first surface emitting elements") to flow currents belonging to the

other groups

21a, 21b, 21d, and 21e. In order to increase the current flowing through the surface emitting element 10 (hereinafter also referred to as "second surface emitting element"), the ON period per unit time of the current flowing through the first surface emitting element is set to the second surface emitting element. By controlling the ON period of the current to be shorter than the ON period per unit time, the light emitting section 111 as a whole has a mechanism for uniformizing the temperature of each surface emitting element 10 .

Fig. 6A shows an example of the above mechanism. In this example, when controlling the lighting/extinguishing of the surface light-emitting elements by periodically turning on and off the current flowing through each of the surface light-emitting elements 10 provided in the light-emitting unit 111, the light projection control device 112 controls each cycle 3, the length of the ON period of the current of the first surface emitting element is controlled to be shorter than the length of the ON period of the second surface emitting element (hereinafter referred to as "first method").

According to the first method, the amount of heat generated by the first surface light emitting element is suppressed while the ON period of the first surface light emitting element is shortened and the light emission intensity is increased by increasing the current flowing through the first surface light emitting element. can be achieved, and the amount of heat generated by the first surface emitting element and the second surface emitting element can be made uniform over time.

In the first method, the length of the ON period of the first surface light-emitting element is determined by, for example, the ratio of the magnitudes of the currents flowing through the first surface light-emitting element and the second surface light-emitting element, or The temperature of each surface emitting element 10 as a whole of the light emitting section 111 is set so as to be efficiently uniformed while considering the ratio of the lengths of the ON periods of the second surface emitting elements.

Fig. 6B shows another example of the above mechanism. In this example, when controlling the lighting/extinguishing of the surface light-emitting elements 10 by periodically turning on and off the current flowing through each of the surface light-emitting elements 10 provided in the light emitting unit 111, the light projection control device 112 Control is performed so that the on/off period of the current of the first surface light emitting element is longer than the on/off period of the second surface light emitting element (hereinafter referred to as "second method").

According to the second method, the OFF period (heat dissipation period) of the first surface emitting element per unit time is longer than the OFF period (heat dissipation period) of the second surface emitting element per unit time, and the first surface emitting element emits light. It is possible to make the amount of heat generated by the element and the second surface emitting element uniform over time.

In the example of FIG. 6B, the timing to turn on the first surface emitting element and the timing to turn on the second surface emitting element are matched, but they do not necessarily have to match. Further, the on/off period of the current of the first surface light emitting element and the on/off period of the second surface light emitting element are, for example, the ratio of the magnitudes of the currents flowing through the first surface light emitting element and the second surface light emitting element, The temperature of each surface emitting element 10 as a whole of the light emitting section 111 is set so as to be efficiently homogenized while taking into consideration the ratio of the ON periods of the surface emitting element and the second surface emitting element.

Note that the first method has the advantage of increasing the number of light emissions per unit time of the first surface light-emitting element, compared to the second method, for example. Moreover, in the case of the second method, for example, there is an advantage that the ON period of the first surface emitting element and the ON period of the second surface emitting element can be made common. In the example of FIGS. 6A and 6B, the waveform of the current flowing through the first surface emitting element and the second surface emitting element is a square wave, but it does not necessarily have to be a square wave.

As described above, according to the measuring device 100 of the present embodiment, it is possible to make the amounts of heat generated by the first and second surface emitting elements uniform over time. Therefore, it is possible to suppress a wavelength shift caused by an increase in the amount of heat generated by a specific light emitting element of the surface emitting element array, and prevent deterioration in the sensitivity of the measurement apparatus 100 caused by the wavelength shift. In addition, it is possible to increase the intensity of the light beam that the measurement device 100 (projector) irradiates toward a specific measurement area.

[Second embodiment]
In the first embodiment, the temperature of each surface emitting element 10 is made uniform in the entire light emitting section 111 by controlling the waveform of the current flowing through the surface emitting element. In the second embodiment, by providing a heat dissipation structure in the light emitting section 111, the temperature of each surface light emitting element 10 in the entire light emitting section 111 is made uniform. The basic configurations of the measuring device 100 and the surface emitting device 10 in the second embodiment are the same as those shown in FIGS. 1 to 5. FIG.

Specific examples of the heat dissipation structure are shown in FIGS. 7A to 7E. 7A to 7E are views of the light emitting unit 111 shown in FIG. 2 as viewed from the side (+y direction). These figures show a substrate 22 on which the surface emitting element 10 is mounted and a mounting substrate 24 which is a plate material on which the substrate 22 is mounted. The mounting substrate 24 is provided on the rear surface side (−z side) of the substrate 22 with a heat dissipating agent 42 (silicon grease or the like) interposed therebetween.

In the example shown in FIG. 7A,

other groups

21a, 21b, 21d, and 21e are used as the material 24a of the mounting substrate 24 in the vicinity of the surface emitting elements 10 belonging to the group 21c (hereinafter also referred to as "first surface emitting elements"). A material (for example, a material with high thermal conductivity) having a higher heat dissipation effect than the material 24b of the mounting board 24 in the vicinity of the surface emitting element 10 (hereinafter also referred to as a "second surface emitting element") belonging to the . According to this method, since there is no need to separately provide a special configuration, for example, the light emitting unit 111 can be configured compactly. Although two types of

materials

24a and 24b with different heat dissipation effects are used as materials for the mounting board 24 in the example of FIG. good too. By increasing the types of materials, it becomes possible to more finely adjust the temperature of each part of the substrate 22 .

In the example shown in FIG. 7B, a plurality of types of heat dissipating agents (

heat dissipating agents

42a and 42b) having different heat dissipating effects are prepared as the heat dissipating agent 42, and the heat dissipating agent 42a having a high heat dissipating effect is applied near the first surface light emitting element, By applying the heat-dissipating agent 42b having a lower heat-dissipating effect than the heat-dissipating agent 42a near the second surface-emitting elements, the heat-dissipating effect near the first-surface light-emitting elements is greater than the heat-dissipating effect near the second-surface light-emitting elements. I'm trying to get higher. In this example, the back surface of the substrate 22 near the first surface light-emitting elements is coated with a heat radiation agent 42a having a high heat radiation effect, and the back surface of the substrate 22 near the second surface light emitting elements is coated with a heat radiation agent 42a having a higher heat radiation effect than the heat radiation agent 42a. A low heat radiation agent 42b is applied. According to this method, since there is no need to separately provide a special configuration, for example, the light emitting unit 111 can be configured compactly. In the example shown in the figure, two types of heat dissipating agents 42 are used, but three or more types of heat dissipating agents 42 having different heat dissipating effects may be used. By finely changing the type of the heat dissipation agent 42 depending on the application position, the temperature of each part of the substrate 22 can be adjusted more finely.

In the example shown in FIG. 7C, the rear surface of the mounting board 24 (the -z side surface of the mounting board 24) is arranged so that the heat dissipation effect in the vicinity of the first surface light emitting element is higher than the heat dissipation effect in the vicinity of the second surface light emitting element. ) is provided with a plurality of radiation fins 43 . In the example shown in the figure, the closer to the first surface light-emitting element, the higher the radiation effect (larger surface area) the radiation fins are arranged. It should be noted that the position of the mounting board 24 and the degree of heat dissipation effect of the heat dissipation fins 43 is determined according to the amounts of heat generated by the first and second surface light emitting elements.

In the example shown in FIG. 7D, a Peltier element 44 is provided as a cooling mechanism in the vicinity of the first surface emitting element. In this example, a Peltier element 44 is provided on the rear surface of the mounting substrate 24 in the vicinity of the first surface emitting element. By providing a plurality of Peltier elements 44 on the mounting board 24 and controlling the current flowing through each Peltier element 44, the temperature of each part of the board 22 may be adjusted more finely.

In the example shown in FIG. 7E, a cooling fan 45 that blows air from the rear surface (-z side) of the mounting board 24 toward the vicinity of the first surface light emitting element is provided as a cooling mechanism. A plurality of cooling fans 45 may be provided on the rear surface of the mounting board 24 and the number of revolutions of each cooling fan 45 may be individually controlled to more finely adjust the temperature of each part of the board 22 .

As described above, even with the measurement apparatus 100 of the second embodiment, the amount of heat generated by each of the first and second surface emitting elements can be made uniform over time, and the surface emitting element array can have a specific characteristic. A wavelength shift caused by an increase in the amount of heat generated by the light emitting element can be suppressed. Also, it is possible to prevent a decrease in sensitivity of the measuring device 100 . In addition, it is possible to increase the intensity of the light beam that the measurement device 100 (projector) irradiates toward a specific measurement area.

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.

For example, by appropriately combining and applying both the configuration of the first embodiment and the configuration of the second embodiment, it is possible to suppress the wavelength shift more effectively.

This application is based on Japanese Patent Application No. 2022-019001 filed on February 9, 2022, the contents of which are incorporated herein by reference.

Claims

a light emitting unit having a plurality of surface emitting elements including a first surface emitting element and a second surface emitting element;
a control device for controlling the light emission intensity of the surface light-emitting elements by controlling the current flowing through each of the surface light-emitting elements;
has
The control device increases the current flowing through the first surface light-emitting element more than the current flowing through the second surface light-emitting element, and increases the length of the ON period per unit time of the current flowing through the first surface light-emitting element. controlling the current flowing through the second surface emitting element to be shorter than the length of the ON period per unit time;
floodlight.
The plurality of surface emitting elements can be controlled to turn on and off on a group-by-group basis,
2. The light projector according to claim 1, wherein said first surface emitting element is a surface emitting element group belonging to one said group, and said second surface emitting element is a surface emitting element group belonging to another said group.
The control device controls lighting and extinguishing of the surface light-emitting element by periodically turning on and off the current flowing through the surface light-emitting element, and determines the length of the on period of the current of the first surface light-emitting element in each cycle. is shorter than the length of the ON period of the second surface emitting element,
A light projector according to claim 1.
The control device controls lighting and extinguishing of the surface light-emitting element by periodically turning on and off the current flowing through the surface light-emitting element, and the on-off cycle of the current flowing through the first surface light-emitting element corresponds to the second surface light-emitting element. Control to be longer than the on/off period of the element,
A light projector according to claim 1.
a light projector according to any one of claims 1 to 4;
a light receiver that receives reflected light from a measurement target of the light projected from the light projector;
with
measuring the distance to the detection target based on the light reception result of the light receiver;
measuring device.
a light emitting unit disposed on a common substrate and having a plurality of surface emitting elements including a first surface emitting element and a second surface emitting element;
a control device for controlling the light emission intensity of the surface light-emitting elements by controlling the current flowing through each of the surface light-emitting elements;
a heat dissipation structure configured such that a heat dissipation effect in the vicinity of the first surface light emitting element is higher than in the vicinity of the second surface light emitting element;
has
The control device performs control to increase the current flowing through the first surface light-emitting element more than the current flowing through the second surface light-emitting element.
floodlight.
The heat dissipation structure includes a mounting substrate, which is a plate material on which the substrate is mounted,
In the mounting substrate, a portion in the vicinity of the first surface emitting element is made of a material having a higher heat dissipation effect than a material forming a portion in the vicinity of the second surface emitting element,
7. A light projector according to claim 6.
The heat dissipation structure includes a first heat dissipation agent applied to a portion of the substrate near the first surface light emitting device, and a portion of the substrate near the second surface light emitting device. and a second heat dissipating agent having a lower heat dissipating effect than
7. A light projector according to claim 6.
The heat dissipation structure includes a cooling mechanism provided near the first surface light emitting element,
7. A light projector according to claim 6.
The cooling mechanism includes a Peltier element or a cooling fan,
10. A light projector according to claim 9.
a light projector according to any one of claims 6 to 10;
a light receiver that receives reflected light from a measurement target of the light projected from the light projector;
with
measuring the distance to the detection target based on the light reception result of the light receiver;
measuring device.