JP2022186075A - Light emitting device and distance measuring device - Google Patents

Abstract

To provide a novel structure that suppresses a laser beam that is emitted to sides of a light emitting device.SOLUTION: A light emitting device 10 includes: a substrate 12; a light source 14 on the substrate, the light source emitting a laser beam; a frame part 12c surrounding the light source; a cover member 16 covering an upper opening 12d of the frame part, the cover member transmitting a laser beam; and a connection member 18 for joining the frame part 12c and the cover member 16 to each other. The connection member 18 has a light reflecting material for reflecting a laser beam or a light absorbing material for absorbing a laser beam, and covers an outer circumferential side surface 16a of the cover member.SELECTED DRAWING: Figure 1

Description

The present invention relates to a light emitting device used in a distance measuring device.

In recent years, a system called LiDAR (Light Detection And Ranging) has been devised as a device for measuring the distance to an object existing in the surroundings. LiDAR emits light from a light source toward an object, measures reflected light from the object, and measures the distance and direction to the object. Also, a laser is known as a light source used for LiDAR. For example, Patent Document 1 discloses a VCSEL (Vertical Cavity Surface Emitting Laser) element composed of a compound semiconductor that emits light in the 980 nm band.

JP 2021-64743

However, in the VCSEL element described above, there is a possibility that part of the laser light propagates inside the cover member and is emitted sideways from the side surface of the cover member. Therefore, glare may occur when the VCSEL element is used as a light source. Further, in a system in which a light receiving sensor is arranged adjacent to the side of the VCSEL element, there is a possibility that the light receiving sensor may make an erroneous detection due to the laser light emitted sideways from the side surface of the cover member.

The present invention has been made in view of such circumstances, and one of the objects thereof is to provide a new configuration for suppressing laser light emitted to the side of a light emitting device.

In order to solve the above problems, a light-emitting device according to one aspect of the present invention includes a substrate, a light source mounted on the substrate and emitting laser light, a frame provided to surround the light source, a frame a cover member that covers an upper opening of the part and transmits laser light; and a joining member that joins the frame part and the cover member. The joining member has a light reflecting substance that reflects laser light or a light absorbing substance that absorbs laser light, and covers the outer peripheral side surface of the cover member.

According to this aspect, it is possible to suppress the laser light emitted sideways from the cover member.

The light absorbing material may be carbon black. Accordingly, even if a laser beam is emitted from the outer peripheral side surface of the cover member, the laser beam is absorbed by the carbon black of the joining member, so that the leakage of the laser beam to the outside of the light emitting device can be suppressed.

The light reflecting material may be metal solder. Accordingly, even if a laser beam is emitted from the outer peripheral side surface of the cover member, the laser beam is reflected by the metal solder of the joining member, so that leakage of the laser beam to the outside of the light emitting device can be suppressed.

The light source may emit infrared light. This facilitates use as a light source for an all-weather camera.

The light source may comprise a VCSEL element. As a result, it is possible to realize a light-emitting device that is relatively inexpensive and can irradiate a laser beam over a long distance.

Another aspect of the present invention is a rangefinder. This distance measuring device includes the above-described light emitting device and a light receiving device that receives laser light emitted from the light emitting device and reflected by an object.

According to this aspect, since the laser light emitted sideways from the cover member of the light emitting device is suppressed, it is possible to reduce erroneous detection of the light receiving device caused by the laser light emitted from the light emitting device entering the light receiving device as it is. .

Arbitrary combinations of the above constituent elements, and conversions of expressions of the present invention between manufacturing methods, devices such as lamps and lighting, light-emitting modules, light sources, etc. are also effective as aspects of the present invention.

According to the present invention, it is possible to suppress the laser light emitted to the side of the light emitting device.

1 is a schematic diagram showing a schematic configuration of a light emitting device according to an embodiment; FIG. 1 is a schematic diagram showing a schematic configuration of a distance measuring device according to an embodiment; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on preferred embodiments with reference to the drawings. The same or equivalent constituent elements, members, and processes shown in each drawing are denoted by the same reference numerals, and duplication of description will be omitted as appropriate. Moreover, the embodiments are illustrative rather than limiting the invention, and not all features and combinations thereof described in the embodiments are necessarily essential to the invention.

FIG. 1 is a schematic diagram showing a schematic configuration of a light-emitting device according to this embodiment. The light emitting device 10 includes a substrate 12 having a recess 12a formed thereon, a light source 14 placed on the bottom 12b of the recess 12a, a rectangular frame 12c provided so as to surround the light source 14, and the frame 12c. A cover member 16 that covers the upper opening 12d and a joining member 18 that joins the frame portion 12c and the cover member 16 are provided.

The substrate 12 is preferably a sinterable ceramic substrate such as aluminum nitride or aluminum oxide. Further, the substrate 12 according to the present embodiment is a plate-shaped member with a recess formed in a part thereof, and the bottom portion 12b and the frame portion 12c are formed as one piece. Electrode patterns are formed on the front and rear surfaces of the bottom portion 12 b of the substrate 12 . This electrode pattern and the electrode of the light source 14 are connected by a power feeding wire 20 made of gold or the like.

The light source 14 is a semiconductor light emitting element that emits laser light, and is fixed at a predetermined position on the substrate 12 with a chip bonding material 15 . In this embodiment, the light source 14 emits infrared light with wavelengths from near infrared rays to infrared rays, specifically, infrared light with a peak wavelength in the range of 780 to 2000 nm, and for example, a VCSEL element is used. By using a VCSEL element, it is possible to realize a light-emitting device that can irradiate a laser beam to a long distance at a relatively low cost. Also, the light source 14 that emits infrared light is suitable for use as a light source for an all-weather camera.

What kind of peak wavelength is preferable for the semiconductor light emitting element that emits light may vary depending on the application of the light emitting device 10 . For example, when the light-emitting device 10 is used together with a light-receiving device of a distance measuring device, which will be described later, the light-receiving device can be equipped with A relatively inexpensive silicon device can be used for the light receiving sensor. A compound semiconductor light-emitting element capable of realizing light having a peak wavelength in the range of 1500 to 1600 nm may be used as the light source.

The cover member 16 is made of a material that transmits laser light. For example, a material having a transmittance of 80% or more, preferably 85% or more, for light in the wavelength range of 780 to 2000 nm is preferable. Specifically, materials that transmit near-infrared rays and infrared rays, such as sapphire, quartz glass, and borosilicate glass, are preferred.

The joining member 18 joins the frame portion 12 c and the cover member 16 and covers at least a portion of the outer peripheral side surface 16 a of the cover member 16 . Preferably, the entire outer peripheral side surface 16 a is covered with the joining member 18 . When the laser beam L1 emitted from the light source 14 is transmitted through the translucent cover member 16, a part of the laser beam L2 propagates inside the cover member 16 toward the outer peripheral side surface 16a. Therefore, the joining member 18 covering the outer peripheral side surface 16a contains a light reflecting substance that reflects the laser light or a light absorbing substance that absorbs the laser light. Thereby, the laser beam emitted sideways from the cover member 16 can be suppressed.

The joining member 18 may be made by dispersing a light-absorbing substance in a base material. The base material is epoxy resin, silicon resin, low-melting glass, or the like. The light-absorbing substance is a material having a transmittance of 80% or less, preferably 50% or less, for light having a wavelength in the range of 780 to 2000 nm. Indium Tin Oxide), antimony-added tin oxide (ATO: Antimony Tin Oxide), lanthanum hexaboride (LaB ₆ ), and the like. Accordingly, even if the laser beam L2 is emitted from the outer peripheral side surface 16a of the cover member 16, it is absorbed by the carbon black or the like of the bonding member 18, so that the laser beam that leaks to the outside of the light emitting device 10 can be suppressed.

Also, the joining member 18 may have metal solder as a light reflecting material. The metal solder is, for example, gold-tin (Au--Sn) solder, tin-silver-copper (Sn--Ag--Cu) solder, or the like. Accordingly, even if the laser beam L2 is emitted from the outer peripheral side surface 16a of the cover member 16, it is reflected by the metal solder of the joining member 18, so that the leakage of the laser beam to the outside of the light emitting device 10 can be suppressed.

In addition, in the light emitting device 10 shown in FIG. 1, the bottom portion 12b and the frame portion 12c of the substrate 12 are configured as a single component. In this case, since it is necessary to form the electrode pattern on the bottom portion 12b of the substrate 12, it is necessary to bake the substrate after forming the cavity shape (recess). Therefore, there is a tendency for the dimensional accuracy to decrease due to shrinkage during firing of the substrate.

Therefore, as a modification of the light-emitting device 10, a light-emitting device may be formed by forming a plate-like substrate and then mounting a separate frame portion on the substrate to integrate them. In this case, the material of the plate-like substrate is preferably aluminum nitride or aluminum oxide, and the material of the frame is preferably aluminum nitride, aluminum oxide, or silicon. Since the electrode pattern can be formed after firing by making the frame and the substrate separate parts, the dimensional accuracy of the electrode pattern is improved.

(ranging device)
Next, a distance measuring device will be described as an example of the application of the light emitting device described above. A distance measuring device according to the present embodiment is a LiDAR as an optical deflection device that deflects light to achieve scanning. FIG. 2 is a schematic diagram showing a schematic configuration of the distance measuring device according to this embodiment.

The distance measuring device 30 shown in FIG. 2 includes a light projecting section 32 , a scanning section 34 and a light receiving section 36 inside a housing 31 . The scanning unit 34 has a mirror module 38 , a light blocking plate 40 and a motor 42 . The mirror module 38 is a plate-like member having a pair of light-reflecting deflection mirrors attached to both sides thereof. The mirror module 38 has its rotation center fixed along the rotation axis R of the motor 42 and rotates as the motor 42 is driven. Note that the scanning unit may be not only the rotating type mirror module 38 but also a rocking or vibrating type mechanism.

The light shielding plate 40 is a circular plate-shaped member provided near the center of the mirror module 38 in the vertical direction, integrally with the mirror module 38, and having a plate surface perpendicular to the rotational axis R of the rotational movement. A material that blocks the transmission of light is used for the light shielding plate 40 .

Hereinafter, in the mirror module 38, the reflecting portion above the light shielding plate 40 is referred to as a light projecting deflector 40a, and the reflecting portion below the light shielding plate 40 is referred to as a light receiving deflector 40b. The reflecting surface of the mirror module 38 is formed such that the light receiving deflector 40b has a wider width than the light projecting deflector 40a. , is set to about half that width.

The light projecting section 32 includes a light emitting module 44 . The light emitting module 44 is arranged so that the light emitting device 10 and the lens 46 face each other. The lens 46 is a lens that narrows the beam width of the laser light emitted from the light emitting device 10 . The light emitting module 44 is arranged so that the laser light L emitted from the light emitting module 44 is directly incident on the light projecting deflection section 40a.

The light receiving section 36 includes a light receiving element 48 , a light receiving lens 50 and a folding mirror 52 . The light receiving element 48 is formed by arranging a plurality of photodiodes in an array. The light-receiving lens 50 is a lens that narrows down the laser light reflected by the light-receiving deflector 40b. The folding mirror 52 is a mirror that changes the traveling direction of the laser beam. The light receiving element 48 is arranged below the folding mirror 52 .

The folding mirror 52 is arranged to bend the path of light downward by about 90° so that the light incident from the light-receiving deflector 40 b through the light-receiving lens 50 reaches the light-receiving element 48 . The light-receiving lens 50 is arranged between the light-receiving deflector 40 b and the folding mirror 52 . The light-receiving lens 50 constricts so that the beam diameter of the light beam incident on the light-receiving element 48 is about the width of the photodiode.

Distance measuring device 30 according to the present embodiment is configured such that, in the interior space of housing 31, upper light projecting space 101 in which light projecting unit 32 is installed and light receiving unit 36 are separated by light shielding plate 40 of scanning unit 34. It is divided into a lower light receiving space 102 to be installed.

The laser light L emitted from the light emitting module 44 arranged in the light projection space 101 is incident on the light projection deflector 40a. The laser light L incident on the light projection deflector 40a is reflected in a direction corresponding to the rotation angle of the mirror module 38, and emitted in a direction toward the viewer from the plane of FIG. The range irradiated with the laser light L via the mirror module 38 is the scanning range.

The laser beam L′ reflected by an object located in a predetermined direction (that is, the direction in which light is emitted from the light projecting deflector 40a) according to the rotational position of the mirror module 38 is reflected by the light receiving deflector 40b. and is received by the light receiving element 48 via the folding mirror 52 .

Then, the laser beam L emitted from the light emitting module 44 is reflected by an object and reaches the light receiving element 48 as reflected light (laser beam L′). The distance and direction to the object are calculated by performing calculations in the circuit. Therefore, if stray light is generated in the light emitting module 44 and part of the laser light L directly reaches the light receiving space 102 without being reflected by the mirror module 38, an object that does not actually exist will be detected at a close distance. Or, an object may be detected in a direction that does not actually exist, resulting in deterioration of detection performance.

However, in the distance measuring device 30 of the present embodiment, as shown in FIG. It is possible to reduce erroneous detection of the light receiving section 36 that occurs when the light enters the light receiving element 48 as it is. In other words, stray light can be prevented from going from the light projecting space 101 to the light receiving space 102 without providing a partition between the light projecting space 101 and the light receiving space 102 .

Although the present invention has been described with reference to the above-described embodiments, the present invention is not limited to the above-described embodiments, and can be applied to any suitable combination or replacement of the configurations of the embodiments. It is included in the present invention. Further, it is also possible to appropriately rearrange the combinations and the order of processing in the embodiments based on the knowledge of a person skilled in the art, and to add modifications such as various design changes to the embodiments. Embodiments described may also fall within the scope of the present invention.

REFERENCE SIGNS LIST 10 Light emitting device 12 Substrate 12a Recess 12b Bottom 12c Frame 12d Top opening 14 Light source 16 Cover member 16a Peripheral side 18 Joining member 30 Distance measuring device.

Claims (6)

a substrate;
a light source that emits laser light and is placed on the substrate;
a frame provided to surround the light source;
a cover member that covers the upper opening of the frame and transmits the laser light;
a joining member that joins the frame and the cover member,
The light-emitting device, wherein the bonding member includes a light reflecting material that reflects laser light or a light absorbing material that absorbs laser light, and covers the outer peripheral side surface of the cover member. 2. The light emitting device of claim 1, wherein the light absorbing material is carbon black. 2. The light emitting device of claim 1, wherein the light reflecting material is metal solder. 4. The light emitting device according to claim 1, wherein the light source emits infrared light. 5. The light emitting device according to claim 1, wherein said light source has a VCSEL element. A light emitting device according to any one of claims 1 to 5;
a light receiving device that receives laser light emitted from the light emitting device and reflected by an object;
A rangefinder with a

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