JPH06342922A - Reflection type light-receiving device - Google Patents

Abstract

PURPOSE:To provide a reflection type light-receiving device, in which incident light projected on the light-receiving device can be made incident efficiently on a photodetector. CONSTITUTION:A reflection type light-receiving device has the plane of incidence 33, a first reflecting plane 31 reflecting light projected through the plane of incidence 33, a second reflecting plane 32 further reflecting light reflected by the first reflecting plane 31 and a photodetector 21 receiving light reflected by the second reflecting plane 32. According to the constitution, the angle of incidence of light projected onto the light-receiving plane of the photodetector 21 can be set at 70 deg. or less, thus efficiently making incident light on the photoreceptor incident on the photodetector.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type light receiver used for a sensor or the like.

[0002]

2. Description of the Related Art A conventional photodetector will be described with reference to FIGS. 4 is a schematic side view of a conventional lens type light receiver, FIG. 5 is a schematic side view of a conventional reflection type light receiver, and FIG. 6 is a schematic cross-sectional view of the reflection type light receiver shown in FIG.
FIG. 7 is a diagram showing the interface transmittance characteristic with respect to the incident angle.

A conventional lens type photodetector 60 shown in FIG.
The light receiving element 61, lead frames 62a and 62b, a light transmissive material 63, and a lens surface 64 are provided. The light receiving element 61 is arranged at the tip of the lead frame 62a,
The wire 65 is electrically connected to the lead frame 62b. The light receiving element 61, the lead frame 62a,
The tip portion of 62b and the wire 65 are integrally sealed with a light transmissive material 63. The lens surface 64 is formed in a convex shape on the surface of the light transmissive material 63, and is arranged at a position facing the light receiving surface of the light receiving element 61.

The lens-type optical receiver 60 having the above-described structure collects the light incident from the outside through the lens surface 64 near the light receiving surface of the light receiving element 61 and then receives the light by the light receiving element 61. In the lens type light receiver 60, in order to effectively collect parallel light incident from the outside on the light receiving element 61, the light receiving element 61 is separated from the center of the lens surface 64 by at least approximately the same distance as the outer diameter of the lens surface 64. In order to hold the lead frames 62a and 62b, the tips of the lead frames 62a and 62b must be sealed with a light-transmissive material 63. Therefore, the thickness of the lens type light receiver 60 needs to be at least twice the outer diameter of the lens surface 64 or more.

A conventional reflection type light receiver 70 shown in FIG. 5 includes a light receiving element 71, lead frames 72a and 72b, a light transmitting material 73, a concave reflecting surface 74, and an incident surface 75. The light receiving element 71 is arranged at the tip of the lead frame 72a, and is connected to the lead frame 72 by the wire 76.
It is electrically connected to b. The light receiving element 71, the tips of the lead frames 72a and 72b, and the wire 76 are integrally sealed with a light transmissive material 73. The concave reflection surface 74 is formed by mirror-finishing the surface of the light transmissive material 73 by plating, metal deposition, or the like, and is arranged on the side facing the light receiving surface of the light receiving element 71. Incident surface 75
Is formed in a flat shape on the back surface side of the light receiving element 71.

The reflection type photoreceiver 70 having the above-described structure is shown in FIG.
As shown in FIG. 3, light incident from the outside through the incident surface 75 is reflected by the concave reflecting surface 74, condensed near the light receiving surface of the light receiving element 71, and then received by the light receiving element 71. The reflection-type light receiver 70 can have a thickness within 1 times the outer diameter of the concave reflection surface 74, and can be thinner and smaller than the lens-type light receiver 60.

[0007]

By the way, in the reflection type light receiver 70 having the above structure, as shown in FIG. 6, the light reflected in the vicinity of the outer periphery of the concave reflection surface 74 is received by the light receiving element 71.
The light is incident on the light receiving surface of at an angle close to parallel. FIG. 7 shows an incident rate characteristic when light is incident on the light receiving surface of the light receiving element 71 from the light transmissive material 73, and whether or not the light is polarized when the incident angle on the light receiving surface exceeds 70 degrees. It can be seen that the incidence rate decreases extremely. Therefore, in the conventional reflection type light receiver, there is a problem that the light incident on the light receiver cannot be efficiently incident on the light receiving element.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a reflection type light receiver capable of efficiently making light incident on a light receiver enter a light receiving element.

[0009]

In order to achieve the above object, the reflection type light receiver of the invention according to claim 1 comprises a light receiving element,
A concave-shaped first reflecting surface arranged around the light receiving element, and a second reflecting surface arranged at a position facing the light receiving element and the front first reflecting surface, and It is characterized in that it is configured to be incident on the light receiving element after being reflected by one reflecting surface, further reflected by the second reflecting surface.

According to a second aspect of the present invention, there is provided the reflection type light receiver according to the first aspect, wherein the second reflecting surface is convex.

According to a third aspect of the present invention, there is provided the reflection type light receiver according to the first aspect, wherein the second reflection surface is concave.

According to a fourth aspect of the present invention, there is provided the reflection type light receiver according to the first, second or third aspect, wherein the light receiving element is sealed with a light transmissive material.

According to a fifth aspect of the present invention, there is provided the reflection type light receiver according to the first, second, third or fourth aspect, in which a light transmitting material is provided between the first reflecting surface and the second reflecting surface. It is characterized by being filled.

[0014]

According to the first aspect of the present invention, there is provided a reflection-type light receiver in which light incident from the outside is reflected by the first reflecting surface, is condensed near the second reflecting surface, and is reflected by the first reflecting surface. Is further reflected by the second reflecting surface and condensed near the light receiving surface of the light receiving element, and then is incident on the light receiving element, so that the incident angle of light incident on the light receiving surface of the light receiving element is 70 degrees or less. Therefore, the light incident on the light receiver can be efficiently incident on the light receiving element.

In the reflection type light receiver of the second aspect of the present invention, the second reflection surface has a convex shape, and has the same effect as that of the first aspect of the invention.

In the reflection type light receiver of the third aspect of the present invention, the second reflection surface has a concave shape, and has the same effect as that of the first aspect of the invention.

According to a fourth aspect of the present invention, there is provided a reflection type light receiver in which the light receiving element is sealed with a light transmissive material, and has the same effect as that of the first aspect of the invention.

According to a fifth aspect of the present invention, the reflection type light receiver has a space between the first reflecting surface and the second reflecting surface filled with a light transmissive material. Exerts the action of.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic rear view of a reflection type light receiver which is a first embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view of the reflection type light receiver shown in FIG.

A reflection type light receiver 1 according to the first embodiment of the present invention.
Includes a light receiving unit 2 and a light collecting unit 3. The light receiving section 2 is
It has a light receiving element 21, lead frames 22 a and 22 b, and a first light transmissive material 23. The light receiving element 21 is a pin photodiode made of silicon, is arranged at the tip of the lead frame 22a, and is electrically connected to the lead frame 22b by a wire 24. The light receiving element 21, the tip portions of the lead frames 22a and 22b, and the wire 24 are integrally sealed by the first light transmissive material 23. An epoxy resin is generally used for the first light transmissive material 23. This must have a low shrinkage factor and thermal expansion coefficient during curing in order to reduce damage to the light-receiving element, and to prevent the light-receiving layer of the light-receiving element from being destroyed, it must contain impurity ions. This is because the amount should be small.

The light collecting portion 3 has a concave first reflecting surface 31 and
It has a convex second reflecting surface 32, an entrance surface 33, and a second light transmissive material 34. The first reflecting surface 31 is the light receiving element 2
It is arranged around the light receiving surface of No. 1 and has a paraboloid of revolution. The second reflecting surface 32 is arranged at a position facing the light receiving surface of the light receiving element 21 and the first reflecting surface 31, and is formed in a rotating hyperboloid shape. First reflecting surface 31 and second reflecting surface 3
2 is formed by mirror-finishing the surface of the second light transmissive material 34 by plating, metal deposition, or the like. Incident surface 33
Is formed in a planar shape around the second reflecting surface 32 at a position facing the light receiving surface of the light receiving element 21 and the first reflecting surface 31 around the second reflecting surface 32. For the second light transmissive material 34, a thermoplastic resin such as an acrylic resin is used. This enables injection molding, and even if the light collecting part has a complicated shape, it can be processed into a desired shape, and the light collecting part is prevented from yellowing and deteriorating due to ultraviolet rays from sunlight or the like. Can be prevented.

According to the first embodiment of the present invention having the above-mentioned structure, the light incident through the incident surface 33 is reflected by the first reflecting surface 31 and condensed near the second reflecting surface 32, and the first reflecting light is reflected. The light reflected by the surface 31 is further reflected by the second reflecting surface 32, is condensed near the light receiving surface of the light receiving element 21, and then is incident on the light receiving element 21, thereby being incident on the light receiving surface of the light receiving element 21. The incident angle of light can be 70 degrees or less. In the case of the present embodiment, since the second reflective surface 32 is located on the front surface of the reflective optical receiver 1, the entire front surface of the reflective optical receiver 1 cannot be used as the incident surface, but the second reflective surface 32 is used.
Is smaller in the front surface of the reflection type light receiver 1, the light incident on the light receiver can be made to enter the light receiving element more efficiently than in the conventional reflection type light receiver.

Further, in the conventional reflection type light receiver, since the light reflected by the concave reflecting surface is directly condensed in the vicinity of the light receiving element, when the incident angle of the incident parallel light with respect to the incident surface changes, the light is condensed. The points also move. On the other hand, according to the present embodiment, the light reflected by the first reflecting surface 31 is reflected by the second reflecting surface 32 and is then condensed in the vicinity of the light receiving element 21, so that compared with the conventional reflection type light receiver. There is little movement of the light condensing point when the incident angle of the incident parallel light with respect to the incident surface 33 changes. Therefore, a smaller light receiving element can be used as compared with the conventional reflection type light receiver.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a schematic cross-sectional view of a reflection type light receiver which is a second embodiment of the present invention, and is a view corresponding to FIG. 2 of the first embodiment. The schematic rear view of this embodiment is the same as that of FIG. 1 of the first embodiment, and will be omitted. Further, in the reflection type light receiver of the second embodiment, those having the same functions as those of the first embodiment are designated by the same reference numerals or corresponding reference numerals, and detailed description thereof will be omitted.

The optical receiver 4 shown in FIG. 3 differs from that of the first embodiment in that instead of the convex second reflecting surface 32, a concave elliptical reflecting surface is used for the second reflecting. The surface 42 is provided.

According to the second embodiment of the present invention having the above-described structure, the light incident through the incident surface 33 is reflected by the first reflecting surface 31 and is condensed near the second reflecting surface 42, and the first reflecting surface is formed. The light reflected by the surface 31 is further reflected by the second reflecting surface 42, is condensed near the light receiving surface of the light receiving element 21, and is then incident on the light receiving element 21, thereby achieving the same operation as that of the first embodiment.・ To be effective.

The present invention is not limited to the above embodiments, but various modifications can be made within the scope of the gist thereof. For example, although the first reflecting surface 31 is a paraboloid of revolution in each of the above-described embodiments, any light that is incident from the incident surface 33 may be reflected and condensed near the second reflecting surface. Further, the second reflecting surface is the convex reflecting surface 32 that is a hyperboloid of revolution in the first embodiment, and the concave reflecting surface 42 that is a spheroid in the second embodiment. Any light may be used as long as it reflects the light reflected by the one reflecting surface 31 and focuses it on the light receiving surface of the light receiving element 21.

Further, in each of the above embodiments, the light receiving portion 2 is formed by using the first light transmissive material 23, and the light collecting portion 3 is formed by using the second light transmissive material 34. The second light-collecting portion 3 and the light-collecting portion 3 may be integrally formed using the first light-transmissive material 23. Further, when there is no possibility that the light receiving element 21 will be damaged due to physical contact or the like,
The light receiving element 21, the lead frames 22a, 22b and the like may be used as they are without being integrally sealed with the first light transmissive material 23. Further, when there is no risk of soiling the reflective surface, the space between the first reflective surface 31 and the second reflective surfaces 32 and 42 is not filled with the second light transmissive material 34 and is used as it is. Good.

Further, in each of the above embodiments, the light receiving element 2
Although 1 is arranged on the lead frame 22a, it may be arranged directly on the circuit board, for example.

In each of the above embodiments, the light receiving element 21
Although the pin photodiode using silicon as the material has been described above, the present invention is not limited to this, and a phototransistor, a photo Darlington, or the like may be used. Incidentally, when a phototransistor or a photo Darlington is used, three terminals have to be drawn out, but in the reflection type light receiver according to the present invention, the terminals do not come in front of the reflection surface, which reduces the light receiving efficiency of the light receiver. There is nothing to do.

[0031]

As described above, according to the first aspect of the invention, the light incident from the outside is reflected by the first reflecting surface, is condensed near the second reflecting surface, and is reflected by the first reflecting surface. The light is further reflected by the second reflecting surface, condensed near the light receiving surface of the light receiving element, and then made incident on the light receiving element, so that the incident angle of the light incident on the light receiving surface of the light receiving element is 70 degrees or less. Therefore, it is possible to provide a reflection type light receiver that can efficiently make the light incident on the light receiver enter the light receiving element.

According to a second aspect of the present invention, in the first aspect of the invention, the second reflecting surface is a convex surface, and a reflection type light receiver having the same effect as that of the first aspect of the invention is provided. can do.

According to a third aspect of the present invention, in the first aspect of the invention, the second reflecting surface is a concave surface, and a reflection type light receiver having the same effect as that of the first aspect of the invention is provided. can do.

According to a fourth aspect of the present invention, in the first, second or third aspect of the invention, the light receiving element is sealed with a light transmissive material, and has the same effect as that of the first aspect of the invention. A reflective light receiver can be provided.

The invention as claimed in claim 5 is as follows.
Alternatively, in the invention described in claim 4, a space between the first reflective surface and the second reflective surface is filled with a light transmissive material, and a reflective light receiver having the same effect as that of the invention described in claim 1 is provided. be able to.

[Brief description of drawings]

FIG. 1 is a schematic rear view of a reflective light receiver that is a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view taken along the line AA of the reflection type light receiver shown in FIG.

FIG. 3 is a schematic cross-sectional view of a reflective light receiver that is a second embodiment of the present invention, and is a view corresponding to FIG. 2 of the first embodiment.

FIG. 4 is a schematic side view of a conventional lens type light receiver.

FIG. 5 is a schematic side view of a conventional reflection type light receiver.

6 is a schematic cross-sectional view of the reflection type light receiver shown in FIG.

FIG. 7 is a diagram showing an interface transmittance characteristic with respect to an incident angle.

[Explanation of symbols]

 1, 4 Reflection type light receiver 2 Light receiving part 3 Condensing part 21 Light receiving element 22a, 22b Lead frame 23 First light transmissive material 24 Wire 31 First reflecting surface 32, 42 Second reflecting surface 33 Incident surface 34 Second light Permeable material

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location 8422-4M H01L 31/10 Z

Claims (5)

[Claims] 1. A light-receiving element, a concave first reflecting surface arranged around the light-receiving element, and a second reflecting surface arranged at a position facing the light-receiving element and the front first reflecting surface. A reflection type light receiver, comprising: the incident light is reflected by the first reflection surface, further reflected by the second reflection surface, and then incident on the light receiving element. 2. The reflection type light receiver according to claim 1, wherein the second reflection surface is convex. 3. The reflection type light receiver according to claim 1, wherein the second reflecting surface is concave. 4. The reflection type light receiver according to claim 1, wherein the light receiving element is sealed with a light transmissive material. 5. The light transmissive material is filled between the first reflective surface and the second reflective surface.
2. The reflection type light receiver according to 2, 3, or 4.