JPH05308151A - Optical coupler - Google Patents

Abstract

PURPOSE:To enhance a utility efficiency of a light and to reduce a thickness by forming a reflecting surface of an optical guide in a shape in which a stripelike recess surface is stepwisely connected, i.e., a shape equivalent to a lens surface of a Fresnel lens. CONSTITUTION:A light emitting element 1 and a photodetector 2 have a light emitting surface and a receiving surface which are disposed in the same direction. The element 1 and the photodetector 2 are sealed with transparent resin (optical guide) 4, and an outer surface of the resin 4 is covered with light shielding resin 5. A reflecting surface 4a for reflecting a light from the element 1 toward the photodetector 2 is formed in a shape in which a plurality of stripelike recess surfaces are stepwisely connected, i.e., a shape equivalent to a lens surface of a Fresnel lens on a boundary between the resins 4 and 5. Thus, even if a thickness of the resin 4 of the guide is reduced, a condensing efficiency similar to a concave mirror of an elliptical shape can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical coupling device (photocoupler) which is often used in various kinds of OA equipment such as copying machines and facsimile machines, and industrial equipment typified by robot equipment.

[0002]

2. Description of the Related Art Conventionally, as an optical coupling device, a light emitting element and a light receiving element are arranged so as to face each other, and a pair of these elements are primary-molded with a transparent resin. It is generally a structure that is secondarily molded with a resin.

However, in the optical coupling device having such a structure, there remains a problem that the light utilization efficiency, that is, the light receiving efficiency of the light receiving element is not so high as about 30%.

Therefore, the present applicant has already proposed (unpublished) an optical coupling device having a structure for improving the light receiving efficiency. The schematic structure will be described with reference to FIGS. 2 (a) and 2 (b). In addition, Fig. 2 (a) shows the central cross section of the optical coupling device.
Moreover, (b) shows the BB cross section of (a), respectively.

The light emitting element 7 and the light receiving element 8 are horizontally arranged on the heat-resistant resin substrate 9, and the pair of elements are resin-sealed with a transparent resin by a method such as transfer molding, and a light guide is provided on this portion. Forming 10. And
The reflecting surface of the light guide 10 is connected to the light emitting element 7 and the light receiving element 8.
The condensing efficiency is improved by making each of the positions to be the elliptical concave surface having the first and second focal points. A metal reflection film 12 having a high reflectance is formed on the outer surface of the reflection surface of the light guide 10 by a sputtering method or an aluminum vapor deposition method. Further, the light guide 10 is molded with a resin 11 having a high light blocking property for the purpose of blocking ambient light and protecting the metal reflection film 12.

[0006]

By the way, according to the previously proposed technique (the structure shown in FIG. 2), the light receiving efficiency is 70%.
%, It is possible to achieve a sufficient effect in terms of light utilization efficiency, but the reflecting surface of the light guide 10 is an elliptical concave surface, and the light emitting element and the light receiving element are arranged at the two focal points. However, since the distance between the elements cannot be shortened to secure the dielectric strength between the pair of elements, the light guide 10 becomes thick, and as a result, the shape and size of the entire device becomes large. There was a problem left.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a thin optical coupling device which has high light utilization efficiency.

[0008]

A structure for achieving the above object will be described with reference to FIG. 1 corresponding to an embodiment. According to the present invention, the light emitting element 1 and the light receiving element 2 have light emitting surfaces thereof. And the light receiving surface are arranged in the same direction, the elements 1 and 2 are sealed with a transparent resin (light guide) 4, and the outer surface of the transparent resin 4 is covered with a light shielding resin 5. At the boundary between the transparent resin 4 and the light-shielding resin 5, a plurality of band-shaped concave surfaces are arranged in a stepwise manner and a reflecting surface 4 that reflects light from the light emitting element 1 toward the light receiving element 2 is formed.
It is characterized by the formation of a.

[0009]

The thickness of the transparent resin 4 is reduced by forming the reflecting surface 4a of the transparent resin 4 serving as a light guide into a shape in which a plurality of belt-shaped concave surfaces are connected in a stepwise manner, that is, a shape equivalent to the lens surface of the Fresnel lens. Even if it is made thin, it is possible to obtain the same focusing effect as that of the elliptical concave mirror shown in FIG.

[0010]

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention, (a)
Is a central longitudinal sectional view, (b) is a view showing an AA cross section of the (a) view, and (c) is a plan view of the heat resistant resin substrate 3.

The optical coupling device of this embodiment is a horizontal type in which a light emitting element 1 and a light receiving element 2 are mounted side by side on a heat resistant resin substrate 3, and a pair of elements 1 and 2 are provided. The light emitting surface and the light receiving surface of are oriented in the same direction.

On the surface of the heat resistant resin substrate 3, electrode wirings 13 ... 13 made of Al or Au are formed. The electrode wirings 13 ... 13 and the light emitting element 1 and the light receiving element 2 are formed. And are connected by Au wires 14, respectively.

The above pair of light emitting / receiving elements 1 and 2 are sealed with a transparent resin, and the resin portion serves as a light guide 4. The reflecting surface 4a of the light guide 4 is formed on the basis of the ellipsoidal surface shown in FIG. 2 described above, and the elliptical surface is formed into a staircase shape in the same manner as the lens surface of a generally known Fresnel lens. The thickness of the reflecting surface portion is reduced.

On the outer surface of the reflecting surface 4a of the light guide 4, a reflecting film 6 made of metal such as Al, Au or Ag having a high reflectance is formed by sputtering, vapor deposition or plating. The entire light guide 4 is sealed with a light-shielding resin 5 for the purpose of blocking ambient light and protecting the metal reflection film 6. In addition,
A method such as transfer molding is used for forming the light-shielding resin 5 and the previous light guide 4.

[0015]

As described above, according to the present invention,
The reflecting surface of the light guide for performing the optical coupling between the light emitting element and the light receiving element placed horizontally, the shape in which the band-shaped concave surface is continuous stepwise
That is, since the shape is the same as the lens surface of the Fresnel lens, the dielectric strength and light utilization efficiency between the pair of light emitting / receiving elements remain the same as compared with the case where the shape of the reflecting surface is an elliptical concave surface. It is possible to reduce the thickness of the entire device.

[Brief description of drawings]

1A and 1B are diagrams showing a configuration of an embodiment of the present invention, in which FIG. 1A is a vertical sectional view, FIG. 1B is a sectional view taken along line AA of FIG. 1A, and FIG. Figure

2A and 2B are diagrams showing a configuration example of a horizontal optical coupling device, in which FIG. 2A is a vertical sectional view, and FIG. 2B is a sectional view taken along line BB of FIG. 2A.

[Explanation of symbols]

 1 ... ・ Light emitting element 2 ... ・ Light receiving element 3 ... Heat-resistant resin substrate 13 ... 13 ... Electrode wiring 14 ... 14 Au wire 4 ... (Transparent resin) 4a ... Reflective surface 5 ... Shading resin 6 ... Reflective film

Claims (1)

[Claims] 1. A light emitting element and a light receiving element are arranged with their light emitting surface and light receiving surface facing in the same direction, the elements are sealed with a transparent resin, and the outer surface of the transparent resin is a light shielding resin. Is covered with a transparent resin and a light-shielding resin, a plurality of band-shaped concave surfaces are formed in a staircase-like shape, and a reflecting surface that reflects light from the light-emitting element toward the light-receiving element An optical coupling device having a structure formed with.