Light-emitting module

Abstract

Provided is a light-emitting module with which a frame rate can be reduced and point group distortion in a frame can be suppressed. A light-emitting module 1 comprises: first to n-th light-emitting element arrays; a first optical element 121; and a second optical element 122. The first to n-th light emitting element arrays are arranged in parallel so as to be separated from each other in a y-direction (first designated direction). An i-th light emitting element array is composed of a plurality of light emitting elements Li1 to Lim arranged in an x-direction (second designated direction). The first optical element 121 has a first incident surface 1211 and a plurality of first emission surfaces 1212i (i = 1 to n). The first incident surface 1211 has a plurality of light condensing element arrays arranged in parallel so as to be separated from each other in the y-direction. Each of the light condensing element arrays is composed of a plurality of light condensing elements arranged in the x-direction. The plurality of first emission surfaces 1212i respectively deflect light beams that are emitted after being condensed respectively by the i-th light condensing element arrays toward i-th directions which form mutually different angles with respect to the first designated direction. The second optical element 122 diffuses and emits the light beams emitted from the first optical element 121 in the x-direction.

Description

Light-emitting module

[0001] The present invention relates to optical devices such as LiDAR (Light Detection and Ranging) systems.

[0002] Illumination devices that irradiate an object with a light beam are used for applications such as distance measurement and / or object shape recognition using time of flight (ToF) and / or structured light. Illumination devices have been proposed that focus a light beam emitted from a vertical cavity surface emitting laser (VCSEL) as a light source using a lens array to form a virtual light-emitting point (see, for example, Patent Document 1).

[0003] The illumination device includes a plurality of light-emitting units arranged in an array, each emitting a substantially parallel light beam, a focusing unit (e.g., a microlens array) that focuses the light beams emitted from the light-emitting units, and a conversion unit (e.g., an optical lens) that converts the diverging light beams into substantially parallel beams and changes the emission direction of each light beam. The illumination device further includes an optical element (e.g., a diffuser) that converts the light beams emitted from the conversion unit into a linear light beam.

[0004] International Publication WO2023 / 248729

[0005] However, if the active area of ​​the light-emitting unit is smaller than the active area of ​​the light-receiving unit, the frame rate will be low. Furthermore, since the diffuser is curved depending on the direction in which the light beam (light ray) emitted from the conversion unit is incident on the diffuser, point cloud distortion will occur in the frame, which may lead to problems such as a decrease in distance measurement accuracy.

[0006] Therefore, an object of the present invention is to provide a light-emitting module that can reduce the frame rate and suppress point cloud distortion in frames.

[0007] The light-emitting module of the present invention comprises: a plurality of light-emitting element rows arranged parallel to and spaced apart from each other in a first designated direction, with first to nth light-emitting element rows composed of a plurality of light-emitting elements arranged in a second designated direction perpendicular to the first designated direction; a plurality of light-collecting element rows arranged parallel to and spaced from each other in the first designated direction, with a first optical element having a first incident surface having first to nth light-collecting element rows arranged in the second designated direction and each composed of a plurality of light-collecting elements that collect light rays emitted from each of the plurality of light-emitting elements, and first to nth first exit surfaces that deflect light rays that diverge after being collected by each of the first to nth light-collecting element rows into first to nth directions that form mutually different angles with respect to the first designated direction; and a second optical element having a second incident surface that receives the light rays emitted from the first optical element and diffuses them in the second designated direction, and a planar second exit surface that emits the light rays diffused in the second designated direction.

[0008] In this light-emitting module, light rays (line-shaped light rays) are emitted simultaneously or simultaneously from the i-th light-emitting element row (i = 1 to n). The light rays are deflected by the first optical element in the i-th direction, which forms different angles with respect to the first designated direction, and then diffused by the second optical element in the second designated direction, thereby irradiating the i-th area with the light rays. For example, light rays are emitted from the first light-emitting element row → light rays from the i-th light-emitting element row → light rays from the n-th light-emitting element row sequentially, thereby acquiring one frame of received light information through n light-ray emission. This can avoid a decrease in frame rate. Furthermore, since the emission surface of the second optical element is configured as a planar surface and is configured as a substantially flat plate overall, point cloud distortion in each frame is suppressed.

[0009] 2 is an explanatory diagram of the configuration of a light emitting module according to one embodiment of the present invention; FIG. 2 is an explanatory diagram of the configuration of a light emitting module; FIG. 2 is a cross-sectional view of the light emitting module taken along line III-III in FIG. 2; FIG. 2 is a cross-sectional view of the light emitting module taken along line IV-IV in FIG. 2; FIG. 2 is an explanatory diagram of the irradiation intensity distribution in a first designated direction by the light emitting module; FIG. 2 is an explanatory diagram of the irradiation intensity distribution in a second designated direction by the light emitting module; and FIG. 2 is an explanatory diagram of the irradiation efficiency of the light emitting module.

[0010] 1, a light-emitting module 1 according to one embodiment of the present invention includes a light-emitting control device 10, a light source 11, and a light-emitting optical system 12. The light-emitting module 1, together with a light-receiving module 2, is used as a detection device and an imaging device that detects and images an object OBJ, as well as a distance measuring device that acquires distance information to the object OBJ. This device employs a technology called LiDAR (Light Detection and Ranging), which calculates the distance to the object OBJ based on the time it takes for reflected light from the object OBJ to be received and the phase of the reflected light.

[0011] The light-emitting control device 10 includes an arithmetic processing device (e.g., a CPU, a processor core, etc.) and a storage device (memory, etc.). The light-emitting control device 10 is configured so that the arithmetic processing device (hardware) reads a program (software) and data from the storage device, and performs arithmetic processing on the data in accordance with the program, thereby executing a designated task.

[0012] The light-emitting control device 10 is configured to switch between an emitting state and an emission-stop state of each light-emitting element L. The light-emitting control device 10 is configured to drive the light-emitting module 1 or each light-emitting element L at a specified drive voltage and / or a specified drive frequency, and to control the output (light intensity) of the light-emitting module 1. The light-emitting control device 10 may control the operation of the light-emitting module 1 to pulse the illumination light or to generate signal light by intensity-modulating the illumination light. The light-emitting control device 10 links the light-emitting module 1 and the light-receiving module 2, and the control device 100 may be configured to switch between a sensing state (a state in which a signal is output in response to received light) and a non-sensing state (a state in which a signal is not output even when light is received) of each light-receiving element.

[0013] The light source 11 includes, for example, n×m light-emitting elements L (L ) arranged in an n×m matrix in the y direction (first designated direction) and the x direction (second designated direction), as shown in FIG. ij (i = 1 to n, j = 1 to m). Each light emitting element L emits light in the +z direction (third specified direction) perpendicular to each of the y direction and the x direction. The light source 11 is, for example, a surface emitting laser (VCSEL). The semiconductor laser constituting the surface emitting laser emits, for example, infrared light (e.g., illumination light having a wavelength of 905 nm included in the near infrared range) that has little effect on the human eye. The first to nth light emitting element rows are arranged in parallel and spaced apart from each other in the y direction (first specified direction). The ith light emitting element row is made up of a plurality of light emitting elements L arranged in the x direction (second specified direction). i1 ~L im It is composed of:

[0014] Although FIG. 2 illustrates a two-dimensional array of light-emitting elements L where n=3 and m=3, each of n and m may be changed to various numbers such as 2, 4, 5, 6, . . .

[0015] The light-emitting optical system 12 is an optical system for irradiating the object OBJ with light emitted from the light source 11. As shown in each of Figures 2 to 4, the light-emitting optical system 12 includes a first optical element 121 and a second optical element 122.

[0016] The first optical element 121 has a first incident surface 1211 having n×m lens portions facing each of the n×m light-emitting elements L in the z direction, and a first first exit surface 12121, a second first exit surface 12122, and a third first exit surface 12123. As shown in FIGS. 3 and 4, the surfaces of the lens portions are formed as mathematically continuous convex curved surfaces. Each of FIGS. 3 and 4 uses multiple diagrams to show how light rays emitted from the light-emitting elements L travel through the first optical element 121 and the second optical element 122 in order. The first first exit surface 12121, the second first exit surface 12122, and the third first exit surface 12123 are each angled differently from one another with respect to the y direction (first designated direction). For example, the first first light emitting surface 12121 forms a first angle θ1 = 15° to 30° with respect to the y direction. The second first light emitting surface 12122 forms a second angle θ2 = 0° or -5° to 5° with respect to the y direction. The third first light emitting surface 12123 forms a third angle θ3 = -30° to -15° with respect to the y direction. The m=3 light emitting elements L constituting the i-th light emitting element row i1 , L i2 and L i3 The light rays collected by each of the three lens portions corresponding to each of the i-th first exit surfaces 1212i are deflected by the i-th first exit surface 1212i in a direction according to the angle the i-th first exit surface 1212i makes with respect to the first specified direction, and are then emitted from the first optical element 121.

[0017] The second optical element 122 is formed as a substantially flat light diffusion plate (diffuser), and includes a second incident surface 1221 onto which light rays emitted from the first optical element 121 are incident, and a substantially planar second exit surface 1222. As shown in Figures 2 and 4, the second incident surface 1221 is formed with a plurality of linear surface structures extending in the y direction and having a substantially semicircular or semielliptical cross section protruding in the -z direction. This causes light rays originating from the i-th light-emitting element row that are incident on the second incident surface 1221 to be diffused in the x direction (second specified direction) and emitted to the i-th area.

[0018] 5 shows the measurement results of the illumination intensity distribution in the y direction (first specified direction) of the light beams emitted from the light-emitting module 1 into each of the first to third areas or FOIs (Field of Illumination) (approximately 17.5°) using a dashed line, a two-dot dashed line, and a solid line. As is clear from FIG. 5, the illumination intensity distribution in the y direction of the FOI of the light beams emitted into each of the first to third areas is approximately uniform. Furthermore, the illumination intensity distributions in the y direction of the light beams emitted into adjacent areas overlap slightly (approximately 0.4°) in the y direction.

[0019] 6 shows the measurement results of the irradiation intensity distribution in the FOI (approximately 60°) in the x direction (second specified direction) of the light beam emitted to the i-th area (e.g., i=2) from the light-emitting module 1. As is clear from FIG. 6, the irradiation intensity distribution in the FOI in the x direction of the light beam emitted to the i-th area is approximately uniform.

[0020] 7 shows the measurement results of the irradiation intensity distribution in the FOI of the light beam emitted from the light-emitting module 1 to the i-th area (e.g., i=2). In FIG. 7, the higher the brightness of an area, the higher the irradiation intensity. If the maximum irradiation intensity of the i-th light-emitting element row is set to 100, the measurement result of the irradiation intensity shown in FIG. 7 is approximately 97.1%, confirming that the irradiation efficiency is very high.

[0021] (Light-receiving module) The light-receiving module 2 includes a light-receiving sensor 21 and a light-receiving optical system 22. The light-receiving sensor 21 is composed of light-receiving elements arranged two-dimensionally. For example, the light-receiving sensor 21 is composed of n' x m' light-receiving elements arranged in an n' x m' matrix. Of the n' x m' light-receiving elements, first to n-th light-receiving element groups that do not overlap or partially overlap each other form first to n-th light-receiving sections, respectively.

[0022] Each of n' and m' may be changed to various numbers. The light receiving element is an element that receives reflected light from the object OBJ, performs photoelectric conversion, and outputs a signal. The light receiving element is configured by a PD (Photo Diode), APD (Avalanche Photo Diode), SPAD (Single Photo Avalanche Diode), etc.

[0023] The light-receiving optical system 22 is an optical system for causing the light-receiving sensor 21 to receive the light reflected from the object OBJ. The light-receiving sensor 21 is disposed on the focal plane of the light-receiving optical system 22. The light-receiving optical system 22 focuses the light reflected from the object OBJ onto the light-receiving element of the light-receiving sensor 21. Each of the light-receiving optical systems 22 is made up of a lens group made up of a plurality of lenses (e.g., 5 to 7 lenses). The light-receiving optical system 22 may have an optical filter member (band-pass filter) that passes only desired light and blocks (absorbs) other unnecessary light.

[0024] (Mobile Device) The light-emitting module 1 having the above configuration is mounted together with a light-receiving module on a mobile device such as a vehicle (four-wheeled vehicle), a two-wheeled vehicle, or a robot with a mobile function (or an autonomous mobile function). The mobile device may be a vehicle V or the like.

[0025] (Object Detection Processing) During the object detection processing, the light-emitting control device 10 detects m=3 light-emitting elements L i1 ~L i3are simultaneously or all at once switched from a non-emission state to an emission state. When one light emitting element row that was in a non-emission state is switched to an emission state, the other light emitting element rows that were in an emission state up until then are switched to a non-emission state. For example, multiple light emitting element rows are switched from a non-emission state to an emission state in the order of the first light emitting element row → the second light emitting element row → the third light emitting element row → .... This order may be changed to another order.

[0026] (Effects) In this light-emitting module, light rays (line-shaped light rays) are emitted simultaneously or simultaneously from the i-th light-emitting element row (i = 1 to n). The light rays are deflected by the first optical element 121 in the i-th direction at different angles relative to the y direction (first designated direction) and then diffused by the second optical element 122 in the x direction (second designated direction), thereby irradiating the i-th area with the light rays. For example, light rays are emitted from the first light-emitting element row → light rays from the i-th light-emitting element row → light rays from the n-th light-emitting element row sequentially, thereby acquiring one frame of received light information through n light-ray emission. This can avoid a decrease in frame rate. Furthermore, since the second emission surface 1222 of the second optical element 122 is configured as a planar surface, resulting in a generally flat plate-like configuration, point cloud distortion in each frame is suppressed (see FIG. 2 ).

[0027] 1. Light emitting module 2. Light receiving module 10. Light emitting control device 11. Light source 12. Light emitting optical system 121. First optical element 1211. First incident surface 12121-12123. First exit surface 122. Second optical element 1221. Second incident surface 1222. Second exit surface 21. Light receiving sensor 22. Light receiving optical system L. Light emitting element OBJ. Object.

Claims

1. A light emitting module comprising: a plurality of light emitting element rows arranged parallel to and spaced apart from each other in a first designated direction, wherein the first to nth light emitting element rows are composed of a plurality of light emitting elements arranged in a second designated direction perpendicular to the first designated direction; a plurality of light condensing element rows arranged parallel to and spaced from each other in the first designated direction, wherein the first optical element has a first incident surface having the first to nth light condensing element rows arranged in the second designated direction, each composed of a plurality of light condensing elements that condense light rays emitted from each of the plurality of light emitting elements, and first to nth first exit surfaces that deflect light rays that diverge after being condensed by each of the first to nth light condensing element rows, into first to nth directions that form different angles with respect to the first designated direction; and a second optical element having a second incident surface that receives the light rays emitted from the first optical element and diffuses them in the second designated direction, and a planar second exit surface that emits the light rays diffused in the second designated direction.

Images