Light-emitting module and optical device

Abstract

Provided are a light-emitting module and the like with which it is possible to suppress decrease in frame rate and point cloud distortion in a frame. A light beam emitted in the z direction (third designated direction) from an i-th light-emitting unit Ei (i=1 to n) is condensed in the x direction (first designated direction) by an i-th light-condensing unit Li1 of an i-th optical element Li. The light beam is deflected by an i-th deflection unit Li2 of the i-th optical element Li in an i-th direction that forms a variable angle with respect to the y direction (second designated direction). Accordingly, an i-th area (FOI) is irradiated with the light beam. For example, light beam emission by a first light-emitting unit E1, ..., light beam emission by the i-th light-emitting unit Ei, ..., and light beam emission by an n-th light-emitting unit En are sequentially executed. As a result of light beam emission of n times, reception information for one frame is acquired. An emission surface Li22 of the i-th deflection unit Li2 of the i-th optical element Li has a shape along a plane that forms an i-th angle θi with respect to the y direction (second designated direction).

Description

Light-emitting module and optical device

[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 etc. that can reduce the frame rate and suppress point cloud distortion in frames.

[0007] The light emitting module of the present invention comprises: first to nth light emitting units arranged at a distance from each other in the first designated direction among a first designated direction, a second designated direction, and a third designated direction which are perpendicular to each other, and each emitting a light beam in the third designated direction; and first to nth optical elements arranged at a distance from each other in the first designated direction, wherein each of the first to nth optical elements has: first to nth focusing units respectively that focus the light beam emitted in the third designated direction from each of the first to nth light emitting units in the first designated direction; and first to nth deflecting units respectively that deflect the light beam focused in the first designated direction by each of the first to nth focusing units in the first to nth directions through first to nth emission surfaces respectively that are shaped along planes that form different angles with respect to the second designated direction.

[0008] According to this light-emitting module, a light beam emitted from an ith light-emitting unit (i = 1 to n) in a third designated direction is focused in a first designated direction by an ith focusing unit of an ith optical element. The light beam is deflected in an ith direction that forms a different angle with respect to the second designated direction by an ith deflection unit of the ith optical element, thereby irradiating the ith area (FOI). For example, light beam emission from the first light-emitting unit → light beam emission from the ith light-emitting unit → light beam emission from the nth light-emitting unit is sequentially performed, thereby acquiring one frame of light reception information through n light beam emission cycles. This can avoid a decrease in frame rate. Furthermore, because the ith emission surface of the ith optical element is shaped along a plane that forms an ith angle with respect to the second designated direction, point cloud distortion in each frame is suppressed.

[0009] 1 is an explanatory diagram of the configuration of an optical device according to one embodiment of the present invention. An explanatory diagram of the configuration of a light emitting module. An explanatory diagram of the configuration of a light emitting unit. A cross-sectional view of the light emitting module taken along line IV-IV in FIG. 2. A cross-sectional view of the light emitting module taken along line V-V in FIG. 2. An explanatory diagram of the configuration of a vehicle (mobile device) according to one embodiment of the present invention. An explanatory diagram of an FOI formed by a light emitting module. An explanatory diagram of the irradiation intensity distribution in the x direction in the FOI formed by a light emitting module. An explanatory diagram of the difference in irradiation intensity distribution in the FOI formed by a light emitting module depending on whether or not the exit surface of the deflection unit has an uneven structure.

[0010] (Optical Device) An optical system 1 according to one embodiment of the present invention, as shown in FIG. 1, includes a light-emitting module 110, a light-receiving module 20, and a control device 100. The light-emitting module 110 and the light-receiving module 20 constitute the "optical device" of the present invention. The optical device is used as a detection device and an imaging device that detects and captures an object OBJ by receiving light reflected from the object OBJ, as well as a distance measuring device that acquires distance information to the object OBJ. The optical 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] 1, the light emitting module 10 includes a light source 11 and a light emitting optical system 12. The light source 11 includes, for example, n light emitting units E arranged in the x direction (first specified direction) as shown in FIG. i (i=1 to n). i emits light in a third designated direction (+z direction) perpendicular to each of the x direction (first designated direction) and the y direction (second designated direction). In Fig. 2, a light-emitting module in which four (n = 4) light-emitting units E1 to L4 are arranged is illustrated, but n may be changed to various numbers (e.g., n = 2, 6, 8, 12, etc.).

[0012] i-th light-emitting unit E i is, for example, a plurality of light-emitting elements e arranged in an array or dots in the x and y directions as shown in FIG. i For example, the light emitting unit E i The size in the x direction is 1.2 to 1.8 mm, the size in the y direction is 0.3 to 0.6 mm, and the divergence angle is 18 to 24°. The semiconductor laser constituting the surface-emitting laser emits, for example, infrared light (for example, illumination light having a wavelength of 905 nm included in the near-infrared range) that has little effect on the human eye.

[0013] The light emitting optical system 12 is an optical system for irradiating the light emitted from the light source 11 toward the object OBJ. As shown in FIG. 2, the light emitting optical system 12 includes n light emitting units E i n optical elements L corresponding to each of the i (i=1 to n).

[0014] As shown in FIGS. 2, 4 and 5, the i-th optical element L i is a pair of support parts L i0 , the i-th light collecting portion L i1 and the i-th deflection unit L i2 4 and 5, the first optical element L1 (i=1) is illustrated. i0 Each end of the light emitting element E i As shown in FIG. i0 The other end of each of the deflection portions L is a substantially flat plate-shaped i-th deflection portion L i2 and the i-th deflection section L i2 As shown in FIG. 4, the i-th optical element L i In a cross section perpendicular to the x direction passing through the central axis of the pair of support parts L i0 and the i-th deflection unit L i2 As shown in FIG. 2, the i-th light-collecting portion L is shaped like an inverted bell or a semi-elliptical sphere. i1 is continuous with the approximate center of the i-th deflection portion Li2.

[0015] The i-th light collecting portion L shown in FIG. i1 is composed of a collimator lens, and the i-th light-emitting unit E i 4, the light beam emitted from the i-th optical element L in the z direction is converted into a collimated light beam that is parallel or approximately parallel in the y direction (second specified direction). i In a cross section perpendicular to the x direction passing through the central axis of the i-th light collecting portion L i1 The incident surface L i11 is approximately hyperbolic.

[0016] i-th light-emitting unit E i and the i-th light collecting portion Li1 The distance BF in the z direction is i Size l in the y direction (second specified direction) of ver and the size in the y direction of the i-th field of illumination (FOI ver is approximately expressed by the relation (14) using

[0017] BF = (l ver / 2)÷tan(FOI ver / 2) ...(14).

[0018] The i-th light collecting portion L shown in FIG. i1 is the i-th light-emitting element E i 5, the light beam emitted from the i-th optical element L in the z-direction is condensed in the x-direction (first specified direction). i In a cross section perpendicular to the y direction passing through the central axis of the i-th light collecting portion L i1 The incident surface L i11 has a curvature greater than that of an approximately hyperbolic curve.

[0019] As is clear from FIG. 5, the i-th optical element L i In a cross section perpendicular to the y direction (second specified direction) passing through the central axis of the i-th light collecting portion L i1 The incident surface L i11 has line symmetry with respect to the central axis parallel to the z direction (third specified direction), and the i-th light-emitting unit E i and a pair of concave curves continuing to both ends of the convex curve.

[0020] i-th deflection unit L i2 is the i-th light collecting portion L i1 4, the i-th optical element L i In a cross section perpendicular to the x direction passing through the central axis of the i-th deflection section L i2 The exit surface L i22 is the i-th angle θ with respect to the y direction (second specified direction) i It is a substantially linear shape.

[0021] First deflection section L 12 The exit surface L 122, second deflection section L 22 The exit surface L 222 , the third deflection section L 32 The exit surface L 322 and the fourth deflection section L 42 The exit surface L 422 The first deflection unit L extends along a plane that is at a different angle from the other deflection unit L with respect to the y direction (second specified direction). 12 The exit surface L 122 The second deflection portion L extends along a plane that forms a first angle θ1 = 10° to 15° with respect to the y direction. 22 The exit surface L 222 The third deflection section L extends along a plane that forms a second angle θ2=5° to 10° with respect to the y direction. 32 The exit surface L 322 The fourth deflection portion L extends along a plane that forms a third angle θ3=−15° to −10° with respect to the y direction. 42 The exit surface L 422 extends along a plane that forms a fourth angle θ4 = -10° to -5° with respect to the y direction. ｉ The i-th light collecting portion E corresponding to i1 The light beams collected by the i22 The light is deflected in the i-th direction by the first optical element 121 and emerges from the first optical element 121 .

[0022] As shown in FIG. 4, the i-th optical element L i In a cross section perpendicular to the x direction (first specified direction) of the i-th deflection unit L i2 The exit surface L i22 is the i-th angle θ in the y direction. i The i-th deflection section L is configured by a plurality of convex curves that are continuous along a plane. i2 The exit surface L i22 has a minute uneven structure or knurled structure in which a plurality of minute approximately semicircular cylinders or approximately semi-elliptical cylinders extending in the x direction, like a lenticular lens, are arranged in parallel along the plane.

[0023] 7, the first to fourth FOIs of the light-emitting module 10 are respectively indicated by dashed lines, dashed lines, solid lines, and dashed lines. From FIG. 7, it can be seen that each of the first to fourth FOIs has a horizontally elongated, generally rectangular or trapezoidal shape with a slightly bulging central portion in the x direction, and that adjacent FOIs in the y direction partially overlap.

[0024] 8 shows, by a solid line, the measurement result of the irradiation intensity distribution in the x direction (first specified direction) in the i-th FOI (approximately 100° in the x direction and approximately 17.5° in the y direction) from the light-emitting module 10 of one embodiment. Also shown in FIG. 8 is the measurement result of the irradiation intensity distribution in the x direction in the i-th FOI from the light-emitting module 10 of another embodiment, by a dashed line. In this other embodiment, the incident surface L has a cross-sectional shape consisting only of a substantially hyperbolic convex curve, and the pair of concave curves (see FIG. 5) are omitted. i11 The i-th light collecting portion L i1 As is clear from the comparison between the solid line and the broken line in FIG. 8, the incident surface L having a shape with a pair of concave curves as described above was used. i11 The i-th light collecting portion L i1 is used, the irradiation intensity distribution in the FOI in the x direction of the light beam emitted to each of the i-th areas is approximately uniform. i The light beams emitted from the VCSELs at both ends in the x direction among the VCSELs constituting the i-th light-collecting portion L i1 This is because the portion of the FOI corresponding to the concave curve is directed toward the central region of the FOI.

[0025] The upper side of Fig. 9 shows the measurement results of the irradiation intensity distribution in the i-th FOI from the light emitting module 10 of one embodiment. The lower side of Fig. 9 shows the measurement results of the irradiation intensity distribution in the i-th FOI from the light emitting module 10 of another embodiment. In this other embodiment, the light emitting module 10 has a substantially flat light output surface L that does not have the uneven structure as described above. i22 The i-th deflection unit L i2 As is clear from the comparison between the upper and lower sides of FIG. 9, the light exit surface L having the above-described uneven structure was i22 The i-th deflection unit L i2is used, the irradiation intensity distribution in the x direction in the i-th FOI is approximately uniform. i The dot pattern in the y direction (second specified direction) of the VCSEL constituting the i-th deflection unit L i2 The exit surface L i22 This is because the uneven structure of the image blurs the image.

[0026] (Light-receiving module) The light-receiving module 20 includes a light-receiving sensor 21 and a light-receiving optical system 22. The light-receiving sensor 21 is configured, for example, with 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.

[0027] 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.

[0028] 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.

[0029] (Control Device) The control device 100 is configured to control the operation of the optical device as well as the operation of the onboard equipment of the vehicle V. The control device 100 includes an arithmetic processing device (e.g., a CPU, a processor core, etc.) and a storage device (memory such as ROM, RAM, etc.) communicatively connected to the arithmetic processing device via a network. The control device 100 is configured such 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.

[0030] The control device 100 controls each light-emitting unit E i The control device 100 may be configured to switch between a light-emitting state and a light-emitting stop state of each light-receiving element. The control device 100 may be configured to switch between a sensing state (a state in which a signal is output in response to light reception) and a non-sensing state (a state in which a signal is not output even when light is received). The control device 100 controls the light-emitting module 10 or each light-emitting unit E. i at a specified drive voltage and / or a specified drive frequency, and controls the output (light intensity of illumination light) of the light-emitting module 10. The control device 100 may control the operation of the light-emitting module 10 to pulse the illumination light or to generate signal light by performing intensity modulation of the illumination light.

[0031] 1, the control device 100 includes a distance information acquisition unit 110 and a contact determination unit 120. Each of the distance information acquisition unit 110 and the contact determination unit 120 is configured to execute a designated task by having an arithmetic processing device (hardware) read a program (software) and data from a storage device and perform arithmetic processing on the data in accordance with the program.

[0032] The distance information acquisition unit 110 is configured to acquire distance information of the object OBJ based on the time from when illumination light is emitted from the light-emitting module 10 (light-emitting time) to when the light-receiving module 20 receives the light reflected from the object OBJ (light-receiving time). The distance information acquisition unit 110 may acquire a signal from the light-receiving module 20 at a specified frequency. In addition to or instead of the time until the light reflected from the object OBJ is received, the distance information acquisition unit 110 may acquire distance information based on the phase of the light reflected from the object OBJ. Specifically, the distance information acquisition unit 110 may acquire the difference (phase difference) between the phase of the signal from the light-emitting module 10 and the phase of the signal output from the light-receiving module 20 and multiply the phase difference by the speed of light to acquire the distance information of the object OBJ.

[0033] The contact determination unit 120 is configured to determine the likelihood of contact between the object OBJ and the vehicle V, based on distance information of the object OBJ, such as traffic participants such as other vehicles and pedestrians, as well as roadside structures, acquired by the distance information acquisition unit 110. When the contact determination unit 120 determines that there is a high likelihood of contact between the vehicle V and the object OBJ, the control device 100 may be configured to decelerate, stop, or change direction (steer) the vehicle V, or to output an alert to alert passengers of the vehicle V.

[0034] (Mobile Device) The optical system 1 having the above configuration is mounted on, for example, a vehicle V (four-wheeled automobile) which is a mobile device shown in Fig. 6. The mobile device may be a two-wheeled automobile or a robot with a mobile function (or an autonomous mobile function), in addition to the vehicle V. The vehicle V may be a vehicle driven by a person or an automatically driven vehicle.

[0035] The light-emitting module 10 is housed inside the housing of the headlight HL of the vehicle V together with a headlight light source (a light source that illuminates the front with white visible light). The light-emitting module 10 may be attached to a location on the vehicle body below the headlight HL. The light-receiving module 20 is attached to the vehicle V or its body at a location below the headlight HL. The control device 100 is disposed in an appropriate location inside the vehicle V (such as the space below the floor of the cabin space).

[0036] (Object Detection Processing) In the object detection processing, the control device 100 controls the i-th light-emitting unit E i When one light-emitting element that was in the light-emitting stopped state is switched to the light-emitting state, the other light-emitting elements that were in the light-emitting state up until then are switched to the light-emitting stopped state. For example, the first light-emitting element E1 → the second light-emitting element E2 → the third light-emitting element E3 → the fourth light-emitting element E4 → ... are switched to the light-emitting state in the order of the plurality of light-emitting elements E1 to E. n The light emitting elements are switched from the non-light emitting state to the light emitting state. This order may be changed to another order.

[0037] The control device 100 controls the i-th light-emitting unit E i The i-th light receiving element corresponding to the i-th light receiving element may be switched from a non-sensing state (inactive state) to a sensing state (active state).

[0038] When the light receiving element in the sensing state receives the pulsed reflected light, a signal corresponding to the reflected light is transmitted to the control device 100. Based on the signal, the control device 100 controls each light emitting element E i and has the distance to the object OBJ as a pixel value, thereby generating a distance image.

[0039] (Effect) According to the light-emitting module having the above configuration, the i-th light-emitting unit E i (i=1 to n) in the z direction (third specified direction) passes through the i-th optical element L i The i-th light collecting portion L i1 The light beam is focused in the x direction (first specified direction) by the i-th optical element L i The i-th deflection unit L i2The light beam is deflected in an i-th direction that forms a different angle with respect to the y direction (second specified direction) by the first light-emitting element E1, and the light beam is irradiated onto the i-th area (FOI) (see FIG. 7). For example, the light beam emitted from the first light-emitting element E1 is deflected in an i-th direction that forms a different angle with respect to the y direction (second specified direction) by the first light-emitting element E2, and the i-th area (FOI) is irradiated with the light beam (see FIG. 7). i Light emission → nth light emitting element E ｎ By sequentially emitting the light beam n times, one frame of light reception information is acquired. This makes it possible to avoid a decrease in the frame rate. i The i-th deflection unit L i2 The exit surface L i22 is at the i-th angle θ with respect to the y direction (second specified direction). i Since the shape follows the plane that forms the point cloud, distortion of the point cloud in each frame is suppressed (see FIGS. 4 and 9).

[0040] REFERENCE SIGNS LIST 1 Optical system 10 Light-emitting module 11 Light source 12 Light-emitting optical system 20 Light-receiving module 21 Light-receiving sensor 22 Light-receiving optical system 100 Control device 110 Distance information acquisition unit 120 Contact determination unit E1 to E4 Light-emitting unit L1 to L4 Optical element L 10 ~L 40 ‥Support part L 11 ~L 41 ...Light collecting part L 111 ~L 411 ...incident surface of the light-collecting part L 12 ~L 42 ‥Deflection part L 122 ~L 422 ...Output surface of deflector V...Vehicle (moving device) HL...Headlight OBJ...Object.

Claims

1. A light emitting module comprising: first to n-th light emitting units arranged at intervals in the first designated direction among a first designated direction, a second designated direction, and a third designated direction which are perpendicular to one another, and each emitting a light beam in the third designated direction; and first to n-th optical elements arranged at intervals in the first designated direction, wherein each of the first to n-th optical elements has: first to n-th light collecting units that collect, in the first designated direction, the light beam emitted in the third designated direction from each of the first to n-th light emitting units; and first to n-th deflecting units that deflect, in the first to n-th directions, the light beam collected in the first designated direction by each of the first to n-th light collecting units, through first to n-th emission surfaces that are shaped along planes that form different angles with respect to the second designated direction.

2. An optical device in which, in a cross section perpendicular to the second designated direction of each of the first to nth optical elements, the incident surface of each of the first to nth light-collecting sections has line symmetry about a central axis parallel to the third designated direction, and is composed of a convex curve facing each of the first to nth light-emitting sections, and a pair of concave curves continuing from both ends of the convex curve.

3. An optical device in which, in a cross section perpendicular to the first specified direction of each of the first to nth optical elements, the exit surface of each of the first to nth deflection sections is configured by a plurality of convex curves that are continuous along the plane.

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