Light-emitting device, distance-imaging device, and monitoring device

Abstract

A plurality of light sources (21) emit light to be used in distance imaging. An electronic component (22) is associated with the operation of the plurality of light sources (21). A shield member (23) blocks the spatial conduction of noise to the electronic component (22). An optical member (24) has a plurality of lenses that allow the passage of the aforementioned light. The shield member (23) has a plurality of openings (231). The plurality of openings (231) are disposed so as to allow the passage of at least a portion of the light emitted from each of the plurality of light sources (21) toward a corresponding lens among the plurality of lenses.

Description

Light emitting device, distance imaging device, and monitoring device

[0001] The present disclosure relates to a light emitting device including a plurality of light sources that emit light used for distance imaging. The present disclosure also relates to a distance imaging device and a monitoring device that include the light emitting device.

[0002] Patent Document 1 discloses a range imaging device mounted on a vehicle, which is an example of a monitoring device. The range imaging device includes a light emitting device, an imaging device, and a computing device. The light emitting device emits light toward an area located in front of the vehicle, which is an example of a monitoring area. The imaging device captures an image of an object located in the area based on the light reflected by the object. The computing device calculates the distance to the object based on the time between when light is emitted from the light emitting device and when the light enters the imaging device.

[0003] Japanese Patent Application Publication No. 2009-257983

[0004] There is a demand for improving the light distribution of emitted light while suppressing an increase in the size of a light emitting device having a plurality of light sources for distance imaging.

[0005] A first example embodiment provided by the present disclosure is a light-emitting device comprising: a plurality of light sources that emit light used for distance imaging; electronic components associated with the operation of the plurality of light sources; a shielding member that blocks spatial conduction of noise to the electronic components; and an optical member having a plurality of lenses that allow the light to pass through, wherein the shielding member has a plurality of openings that are arranged to allow at least a portion of the light emitted from each of the plurality of light sources to pass toward a corresponding one of the plurality of lenses.

[0006] A second example embodiment provided by the present disclosure is a distance imaging device comprising: a light emitting device according to the first example embodiment; an imaging device that acquires an image of a subject based on the light reflected by the subject; and a computing device that calculates the distance to the subject based on the time from when the light is emitted from the light emitting device to when the light is incident on the imaging device.

[0007] A third example embodiment provided by the present disclosure is a monitoring device that includes the distance imaging device according to the second example embodiment, and causes the light emitting device according to the first example embodiment to emit light toward a predetermined monitoring area.

[0008] Multiple light sources are used to provide light for distance imaging over a wider range of subject areas. Because the final light distribution pattern is formed by combining the light emitted from each light source, the optical conditions that must be considered to achieve the desired light distribution characteristics are complex. Additionally, to prevent the light-emitting device from becoming larger, the spacing between multiple light sources and between multiple lenses tends to become smaller. This increases the possibility that part of the light emitted from a given light source will be incident on another lens adjacent to the lens associated with that light source. This can result in unexpected deviations from the desired light distribution characteristics.

[0009] According to the configurations of the above-described embodiments, the shielding member prevents light emitted from a light source from entering a lens other than the lens associated with that light source. This allows the individual light distribution characteristics obtained by the one-to-one correspondence between the light sources and the lenses to be reflected in the final composite light distribution pattern, simplifying the optical conditions that must be considered to obtain the desired light distribution characteristics. Additionally, the multiple apertures that pass at least a portion of the light emitted from each of the multiple light sources toward only one of the multiple lenses are formed as part of the shielding member used to block spatial conduction of noise to electronic components, thereby improving space utilization efficiency and minimizing the number of components. Therefore, the light distribution of the emitted light can be improved while minimizing the size of a light-emitting device having multiple light sources for distance imaging.

[0010] 6 illustrates the functional configuration of a range imaging device according to an embodiment. 6 illustrates a vehicle on which the range imaging device of FIG. 1 is mounted. 6 is an exploded perspective view illustrating the configuration of the light emitting device of FIG. 1. 6 is a front view illustrating the optical member of FIG. 3. 6 is a rear view illustrating the optical member of FIG. 3. 6 illustrates a cross section taken along line VI-VI in FIG. 4 as viewed from the direction of the arrows. 6 illustrates the positional relationship between the light source, optical member, and shield member of FIG. 3. 6 is a cross-sectional view illustrating the assembled state of the light emitting device of FIG. 3.

[0011] The following detailed description of exemplary embodiments will be given with reference to the accompanying drawings. In the drawings used in the following description, the scale has been changed as necessary to make each component recognizable.

[0012] 1 illustrates an example of the functional configuration of a range imaging device 1 according to one embodiment. The range imaging device 1 is a device that not only acquires an image IM in which a subject SB located within a subject area A is captured, but also acquires distance information to the subject SB.

[0013] The range imaging device 1 includes a light emitting device 2. The light emitting device 2 includes a light source that emits light L toward a subject area A. Examples of the light source include semiconductor light emitting elements such as light emitting diodes (LEDs) and laser diodes (LDs).

[0014] The distance imaging device 1 includes an imaging device 3. The imaging device 3 includes a light receiving element that outputs a signal corresponding to light arriving from a subject area A. An example of the light receiving element is a CMOS image sensor. The imaging device 3 is configured to capture an image of the subject SB based on light L reflected by the subject SB.

[0015] The range imaging device 1 includes a calculation device 4. The calculation device 4 is configured to calculate the distance to the subject SB based on the time from when light L is emitted from the light emitting device 2 until the light L is incident on the imaging device 3. A time of flight (TOF) method is used to calculate the distance. Either a direct TOF method or an indirect TOF method may be used. The TOF method itself is well known, so a detailed description thereof will be omitted.

[0016] As illustrated in Figure 2, the range imaging device 1 can be mounted on a vehicle 5. The position of the range imaging device 1 on the vehicle 5 is determined appropriately depending on the position of the subject area A. In this example, the range imaging device 1 is mounted on the right front corner of the vehicle 5. This makes it possible to monitor the subject area A set around the right corner of the vehicle 5. For example, the presence or absence of an object OB that requires the vehicle 5 to take avoidance action can be monitored. The vehicle 5 is an example of a moving body. The vehicle 5 is an example of a monitoring device. The subject area A is an example of a monitored area.

[0017] 3, the light-emitting device 2 includes a plurality of light sources 21. The light sources 21 are arranged to form a two-dimensional array. Each of the light sources 21 is configured to emit light used for distance imaging. In this embodiment, the light used for distance imaging includes an infrared wavelength range. In other words, the light used for distance imaging is invisible light.

[0018] The light-emitting device 2 includes electronic components 22. The electronic components 22 include various elements associated with the operation of the light sources 21. Examples of such elements include a switching element that controls the turning on and off of each of the multiple light sources 21, a temperature sensor that detects the temperature of the area where the multiple light sources 21 are arranged, and the like.

[0019] The light-emitting device 2 includes a shielding member 23. The shielding member 23 is disposed so as to block spatial conduction of noise to the electronic components 22. The noise includes electromagnetic noise and electrostatic noise. The shielding member 23 can be formed from a conductive material.

[0020] The shield member 23 has a plurality of openings 231. The plurality of openings 231 are arranged to form a two-dimensional array. The number of the plurality of openings 231 matches the number of the plurality of light sources 21. In other words, each of the plurality of openings 231 corresponds to one of the plurality of light sources 21.

[0021] The light-emitting device 2 includes an optical member 24. Fig. 4 illustrates an example of the appearance of the optical member 24 as viewed from the front. Fig. 5 illustrates an example of the appearance of the optical member 24 as viewed from the back. The back of the optical member 24 faces the shield member 23. Fig. 6 illustrates an example of a cross section of the optical member 24 as viewed from the direction of the arrow along line VI-VI in Fig. 4.

[0022] 5 and 6 , the optical member 24 includes a plurality of lenses 241. The plurality of lenses 241 are arranged to form a two-dimensional array. The plurality of lenses 241 are configured to allow the passage of light emitted from the plurality of light sources 21. The number of the plurality of lenses 241 matches the number of the plurality of openings 231. That is, each of the plurality of lenses 241 corresponds to one of the plurality of openings 231 and one of the plurality of light sources 21.

[0023] 3, 4, and 6, the optical member 24 has an exit surface 242. The exit surface 242 has minute irregularities formed thereon, which are configured to scatter the light that has passed through the multiple lenses 241. As a result, light L is obtained as composite light emitted from the light-emitting device 2.

[0024] 7 illustrates an enlarged view of a portion of the shield member 23 and a portion of the optical member 24. The plurality of openings 231 are arranged to allow at least a portion of the light L0 emitted from each of the plurality of light sources 21 to pass toward a corresponding one of the plurality of lenses 241.

[0025] Specifically, the shape and size of each opening 231 are determined so that light L passing through the opening 231 does not enter another lens 241 adjacent to one of the plurality of lenses 241 associated with the opening 231. The distance between the incident surface of each lens 241 and the shield member 23 in the direction along the optical axis AX of each lens 241 is also set so as to satisfy this condition. As a result, of the light L0 emitted from the light source 21, light L0' that may enter another lens 241 adjacent to one of the plurality of lenses 241 associated with the light source 21 is blocked from traveling by the shield member 23.

[0026] Multiple light sources 21 are used to supply light L for distance imaging to a wider subject area A. Because the final light distribution pattern is formed by combining the light L0 emitted from each light source 21, the optical conditions that must be considered to obtain the desired light distribution characteristics are complex. In addition, to prevent the light-emitting device 2 from becoming larger, the spacing between the multiple light sources 21 and the spacing between the multiple lenses 241 tend to become smaller. This increases the possibility that part of the light L0 emitted from a certain light source 21 will be incident on another lens 241 adjacent to the lens 241 associated with that light source 21. In this case, there is a risk of unexpected deviation from the desired light distribution characteristics.

[0027] According to the configuration of this embodiment, the shield member 23 prevents light L0' emitted from a given light source 21 from entering a lens 241 other than the lens 241 associated with that light source 21. This allows the individual light distribution characteristics obtained by the one-to-one correspondence between the light sources 21 and the lenses 241 to be reflected in the final composite light distribution pattern, simplifying the optical conditions that must be considered to obtain the desired light distribution characteristics. Additionally, the multiple openings 231 that pass at least a portion of the light L0 emitted from each of the multiple light sources 21 toward only one of the multiple lenses 241 are formed as part of the shield member 23 used to block spatial conduction of noise to the electronic components 22. This improves space utilization efficiency while minimizing the number of components. Therefore, the light distribution of the emitted light L can be improved while minimizing the size of the light-emitting device 2 having multiple light sources 21 for distance imaging.

[0028] 3 , the light emitting device 2 includes a circuit board 25. The plurality of light sources 21 and the electronic components 22 are mounted on a common circuit board 25. The plurality of light sources 21 and the electronic components 22 are electrically connected through circuit wiring formed on the circuit board 25. The shielding member 23 is disposed between the optical member 24 and the circuit board 25, and allows the passage of light L0 through the plurality of openings 231 while blocking noise from reaching the electronic components 22.

[0029] According to this configuration, the space utilization efficiency can be further improved while further suppressing an increase in the number of components. However, if the shielding member 23 is interposed between the optical member 24 and the circuit board on which the plurality of light sources 21 are mounted and the circuit board on which the electronic components 22 are mounted can be separate bodies.

[0030] The light emitting device 2 includes a heat dissipation member 26. The heat dissipation member 26 is a component for dissipating heat generated from the plurality of light sources 21 and the electronic components 22. The heat dissipation member 26 includes a plurality of fins 261 for promoting heat dissipation.

[0031] The light emitting device 2 includes a fastening member 27. The fastening member 27 is a component for fastening the shielding member 23, the optical member 24, and the circuit board 25 to the heat dissipation member 26. The fastening member 27 has a head portion 271 and a shaft portion 272. The fastening member 27 can be, for example, a screw having a thread formed in the shaft portion 272.

[0032] A first through hole 251 is formed in the circuit board 25. A second through hole 232 is formed in the shielding member 23. A third through hole 243 is formed in the optical member 24. The circuit board 25, the shielding member 23, and the optical member 24 are arranged in this order from the heat dissipation member 26 side so that the first through hole 251, the second through hole 232, and the third through hole 243 are arranged concentrically.

[0033] 8 , the fastening member 27 is attached from the side of the optical member 24 so that the shank 272 is positioned in the first through hole 251, the second through hole 232, and the third through hole 243. When the shank 272 is screwed into the receiving portion 262 formed in the heat dissipation member 26, the head portion 271 presses the optical member 24 toward the heat dissipation member 26. Accordingly, the shield member 23 and the circuit board 25 are also pressed toward the heat dissipation member 26, and are fastened together.

[0034] This configuration makes it easy to maintain the optical positional relationship between the light source 21, the opening 231, and the lens 241, as exemplified in Fig. 7. Therefore, it is possible to suppress a decrease in the light distribution of the light-emitting device 2.

[0035] The configurations described above are merely examples for facilitating understanding of the present disclosure. Each configuration example may be appropriately modified or combined with other configurations without departing from the spirit of the present disclosure.

[0036] In the above embodiment, the light L used for distance imaging is invisible light. However, visible light may also be used for distance imaging.

[0037] The light emitting device 2, the image capturing device 3, and the processing device 4 that make up the distance imaging device 1 do not need to be housed in a common housing. At least one of the image capturing device 3 and the processing device 4 can be mounted at an appropriate position on the vehicle 5 independently of the light emitting device 2.

[0038] The range imaging device 1 can also be mounted on a moving body other than the vehicle 5. Examples of other moving bodies include trains, flying bodies, aircraft, ships, etc. The moving body may not require a driver. The moving body is also an example of a monitoring device.

[0039] The range imaging device 1 does not need to be mounted on a moving object. As an example, the range imaging device 1 can be mounted on transportation infrastructure equipment such as street lights and traffic lights. In this case, the subject area A can be set to include the road. As another example, the range imaging device 1 can also be applied to a security system installed in a house or facility to detect an object that enters the subject area A.

[0040] The contents of Japanese Patent Application No. 2021-129919 filed on August 6, 2021 are incorporated by reference as part of this disclosure.

Claims

1. A plurality of light sources that emit light used for distance imaging, electronic components associated with the operation of the plurality of light sources, a shield member that blocks the spatial conduction of noise to the electronic components, an optical member having a plurality of lenses that allow the passage of the light, comprising: the shield member has a plurality of openings, the plurality of openings are arranged so as to allow at least a part of the light emitted from each of the plurality of light sources to pass toward a corresponding one of the plurality of lenses, a light emitting device.

2. comprising a circuit board on which the electronic components are mounted, the plurality of light sources are a plurality of semiconductor light emitting elements mounted on the circuit board, The light emitting device according to claim 1.

3. a heat radiating member that dissipates heat generated from the light source and the electronic components, a fastening member having a shaft portion, comprising: a first through hole formed in the circuit board, a second through hole formed in the shield member, and a third through hole formed in the optical member are concentrically arranged, by arranging the shaft portion of the fastening member in the first through hole, the second through hole, and the third through hole, the circuit board, the shield member, and the optical member are fastened to the heat radiating member, The light emitting device according to claim 2.

4. the light is non-visible light, The light emitting device according to any one of claims 1 to 3.

5. a light emitting device according to any one of claims 1 to 3, an imaging device that acquires an image of the subject based on the light reflected by the subject, an arithmetic device that calculates the distance to the subject based on the time from when the light is emitted from the light emitting device until the light enters the imaging device, comprising: a distance imaging device.

6. comprising the distance imaging device according to claim 5, and causing the light emitting device to emit the light toward a predetermined monitoring area, a monitoring device.

7. a moving body, The monitoring device according to claim 6.