Light-emitting module

Abstract

To provide a light-emitting module or the like capable of suppressing reduction of a frame rate and point group distortion in a frame.SOLUTION: Light-emitting module 1 includes first to n-th light-emitting element arrays, first optical element 121, and second optical element 122. The first to n-th light-emitting device arrays are arranged in parallel to be spaced apart from each other in the y direction, and the i-th light-emitting device array includes a plurality of light-emitting devices Li1 to Lim arranged in the x direction. The first optical elements 121 each have a first light incident surface 1211 and a plurality of first light exiting surfaces 1212i, and the first light incident surface 1211 has a plurality of rows of light collecting elements arranged in parallel to one another and spaced apart from one another in the y direction. The plurality of first emission surfaces 1212i deflect the light beams, which diverge after being condensed by the respective i-th condensing device arrays, in respective i-th directions that form mutually different angles with respect to the y-direction, and the second optical device 122 diffuses and emits the light beams emitted from the first optical device 121 in the x-direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an optical device such as a LiDAR (Light Detection and Ranging) system. [Background technology]

[0002] Illumination devices that irradiate an object with a light beam are used for applications such as measuring the spatial propagation time of light (ToF: Time of Flight) and / or measuring distances using structured light and / or recognizing the shape of an object. An illumination device has been proposed in which a light beam emitted from a vertical cavity surface emitting laser (VCSEL: Vertical Cavity Surface Emitting Laser) as a light source is focused by 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 after focusing 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. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication WO2023 / 248729 Summary of the Invention [Problem to be solved by the invention]

[0005] However, if the active area of ​​the light-emitting unit is smaller than that 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. [Means for solving the problem]

[0007] The light-emitting module of the present invention comprises: a plurality of light-emitting element rows arranged parallel to and spaced apart from one another in a first designated direction, the first to n-th light-emitting element rows being composed of a plurality of light-emitting elements arranged in a second designated direction perpendicular to the first designated direction; a first optical element having a first entrance surface having first to n-th light-collecting element rows arranged in parallel to and spaced apart from each other in the first designated direction, the first optical element having first to n-th light-collecting element rows arranged in the second designated direction, each row being 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 n-th first exit surfaces that deflect light rays that diverge after being collected by each of the first to n-th light-collecting element rows, respectively, in first to n-th directions that form mutually different angles with respect to the first designated direction; The optical element has a second entrance surface onto which the light beam emitted from the first optical element is incident and which diffuses the light beam in the second specified direction, and a second optical element having a planar second exit surface from which the light beam diffused in the second specified direction is emitted.

[0008] In this light-emitting module, light beams (line-shaped light beams) are emitted simultaneously or simultaneously from the i-th light-emitting element row (i = 1 to n). The light beams are deflected by the first optical element in the i-th direction at different angles relative 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 beams. For example, light beams are emitted from the first light-emitting element row → light beams from the i-th light-emitting element row → light beams from the n-th light-emitting element row sequentially, thereby acquiring one frame of received light information through n light beam emissions. 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. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating the configuration of a light-emitting module according to an embodiment of the present invention; [Figure 2] FIG. 2 is a diagram illustrating the configuration of a light-emitting module. [Figure 3] FIG. 3 is a cross-sectional view of the light-emitting module taken along line III-III in FIG. 2. [Figure 4] FIG. 4 is a cross-sectional view of the light-emitting module taken along line IV-IV in FIG. 2. [Figure 5] FIG. 4 is an explanatory diagram of the irradiation intensity distribution in the first specified direction by the light-emitting module. [Figure 6] FIG. 10 is an explanatory diagram of the irradiation intensity distribution in the second specified direction by the light-emitting module. [Figure 7] FIG. 10 is an explanatory diagram regarding the irradiation efficiency of the light-emitting module. DETAILED DESCRIPTION OF THE INVENTION

[0010] (light emitting module) 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 imaging device that detects and captures an object OBJ, as well as a distance measuring device that acquires information about the distance 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 to receive reflected light from the object OBJ 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 illumination light) 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, for example, 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 is, for example, as shown in FIG. 2, a light source having n×m light-emitting elements L (L ij(i=1 to n, j=1 to m)). Each light-emitting element L emits light in the +z direction (third designated direction) perpendicular to the y direction and the x direction. The light source 11 is, for example, a vertical cavity 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 designated direction). The ith light-emitting element row is made up of a plurality of light-emitting elements L arranged in the x direction (second designated direction). i1 ~L im It is composed of:

[0014] Although FIG. 2 illustrates a two-dimensional array of light-emitting elements L in which 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 FIGS. 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 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 illustrate how light emitted from the light-emitting elements L travels through the first optical element 121 and the second optical element 122 in this 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 of 15° to 30° with respect to the y direction. The second first light emitting surface 12122 forms a second angle θ2 of 0° or -5° to 5° with respect to the y direction. The third first light emitting surface 12123 forms a third angle θ3 of -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 beams 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 ith 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 ith area.

[0018] In Fig. 5, the measurement results of the irradiation intensity distribution in the y direction (first specified direction) of the light beams emitted from the light-emitting module 1 to each of the first to third areas or Field of Illumination (FOI) (approximately 17.5°) are shown by the dashed-dotted line, the dashed-two-dotted line, and the solid line. As is clear from Fig. 5, the irradiation intensity distribution in the y direction of the light beams emitted to each of the first to third areas in the FOI is approximately uniform. Furthermore, the irradiation intensity distributions in the y direction of the light beams emitted to 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 from the light-emitting module 1 to the ith area (for example, i=2). As is clear from FIG. 6, the irradiation intensity distribution in the FOI in the x direction of the light beam emitted to the ith area is approximately uniform.

[0020] Figure 7 shows the measurement results of the irradiation intensity distribution in the FOI of light rays emitted from the light-emitting module 1 to the i-th area (for example, i=2). In Figure 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 Figure 7 is approximately 97.1%, confirming that the irradiation efficiency is very high.

[0021] (optical 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'×m' light receiving elements arranged in an n'×m' matrix. Of the n'×m' light receiving elements, first to n-th light receiving sections are composed of first to n-th light receiving element groups that do not overlap or partially overlap each other.

[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 composed of a PD (Photo Diode), APD (Avalanche Photo Diode), SPAD (Single Photon Avalanche Diode), etc.

[0023] The light receiving optical system 22 is an optical system for receiving light reflected from the object OBJ at the light receiving sensor 21. 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 multiple lenses (for example, 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 moving device such as a vehicle (four-wheeled vehicle), a two-wheeled vehicle, or a robot with a moving function (or an autonomous moving function). The moving device may be a vehicle V or the like.

[0025] (Object detection processing) During the detection process of the object, the light-emitting control device 10 controls m=3 light-emitting elements L constituting each of the i-th light-emitting element rows. i1 ~L i3 are 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] (effect) In the light-emitting module having this configuration, light beams (line-shaped light beams) are emitted simultaneously or simultaneously from the i-th light-emitting element row (i = 1 to n). The light beams 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 beams. For example, light beams are emitted from the first light-emitting element row → light beams from the i-th light-emitting element row → light beams from the n-th light-emitting element row sequentially, thereby acquiring one frame of received light information through n light beam emissions. This can prevent 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). [Explanation of symbols]

[0027] 1. Light-emitting module 2. Optical receiving module 10. Light-emitting control device 11‥Light source 12. Light-emitting optical system 121...First optical element 1211‥1st entrance plane 12121~12123...First exit surface 122...Second optical element 1221‥Second incidence plane 1222...Second exit surface 21. Light receiving sensor 22‥Optical system for light reception L: Light-emitting element OBJ: Object.

Claims

[Claim 1] a plurality of light-emitting element rows arranged parallel to and spaced apart from one another in a first designated direction, the first to n-th light-emitting element rows being composed of a plurality of light-emitting elements arranged in a second designated direction perpendicular to the first designated direction; a first optical element having a first entrance surface having first to n-th light-collecting element rows arranged in parallel to and spaced apart from each other in the first designated direction, the first optical element having first to n-th light-collecting element rows arranged in the second designated direction, each row being 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 n-th first exit surfaces that deflect light rays that diverge after being collected by each of the first to n-th light-collecting element rows, respectively, in first to n-th directions that form mutually different angles with respect to the first designated direction; a second optical element having a second incident surface onto which the light beam emitted from the first optical element is incident and which diffuses the light beam in the second specified direction, and a second planar exit surface from which the light beam diffused in the second specified direction is emitted. Light-emitting module.

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