JPH05226689A - Optically coupled device - Google Patents

Abstract

PURPOSE:To obtain an optically coupled device having a high current transmission rate and a high coupling efficiency by providing a protrusion wall for reflecting a light of a light emitting element toward photodetector at a part of an inner wall of light shielding resin and providing a reflecting film having a high reflectivity on the wall in the optically coupled device of a double molding structure having light transmitting and shielding properties. CONSTITUTION:A light emitting element 1 and a photodetector 2 are mounted on lead frames 3a, 3b. The element 1 is covered with transparent resin 4. Both the elements are covered with an inner transparent resin mold 5. Further, an outer shell is covered to be sealed by a light shielding resin mold 6 so as to prevent an erroneous operation due to an incoming light. The mold 6 has a protrusion wall 7, and a reflecting miller 8 is provided on a boundary to the mold 5. A light emitted from the element 1 is emitted directly to the photodetector 2. A laterally emitted light is reflected on the wall 7, and absorbed by the photodetector 2. Thus, a current transmission rate of about 1.3 times as large as that of conventional optically coupled devices is 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, and more particularly to an optical coupling device having an improved coupling efficiency.

[0002]

2. Description of the Related Art Examples of conventional optical coupling devices are shown in FIGS.

In FIG. 3, light emitted from the light emitting element 1 mounted on the lead frame 3a reaches the light receiving element 2 mounted on the lead frame 3b through the transparent resin 4 and the translucent resin mold 5. To do.

At this time, the whole is covered with the light-shielding resin mold 6 in order to avoid the influence of ambient light.

Further, in FIGS. 4 and 5, a projection wall 7 is provided for the purpose of reflecting the light emitted in the lateral direction and absorbing it by the light receiving element.

[0006]

The above-described conventional optical coupling device has the following drawbacks.

(I) In the case of FIG. 3, the light receiving element can receive only the light that directly strikes the light receiving element out of the light emitted from the light emitting element. That is, of the light emitted from the light emitting element, the light emitted in the lateral direction does not reach the light receiving element.

(Ii) In the case of FIGS. 4 and 5, a projection wall is used for the light-shielding resin in order to reflect the light emitted in the lateral direction and hit the light-receiving element. However, since the light-shielding resin mold is black, light is absorbed, and light emitted in the lateral direction hardly reaches the light receiving element.

For the above reasons, it has been difficult to obtain high coupling efficiency.

[0010]

The optical coupling device of the present invention comprises:
A light emitting element and a light receiving element mounted on a lead frame, a translucent resin mold for sealing them, a light shielding resin mold further sealed from the outside, and a part of the inner wall of the light shielding resin, The projection wall that reflects the light of the light emitting element toward the light receiving element and the reflective film having a high reflectance with respect to the light of the light emitting element are provided on the projection wall.

[0011]

The present invention will be described below with reference to the drawings.

FIG. 1 is a vertical sectional view showing a first embodiment of the present invention. The light emitting element 1 and the light receiving element 2 are mounted on the lead frames 3a and 3b, respectively. The light emitting element 1 is covered with a transparent resin 4, and both elements are covered with an inner transparent resin mold 5. Further, the outer shell is covered and sealed with a light-shielding resin mold 6 for the purpose of preventing malfunction due to external light. This light-shielding resin mold 6 has a projection wall 7, and a reflective film 8 is provided at the interface with the light-shielding resin mold 5 inside. The light emitted from the light emitting element 1 directly strikes the light receiving element 2, and the light emitted in the lateral direction is reflected by the projection film 7 and absorbed by the light receiving element 2. Therefore, the optical coupling device of the present invention is an optical coupling device having high coupling efficiency. That is, about 1.3 of the conventional optical coupling device.
Double current transfer rate is obtained.

FIG. 2 is a vertical sectional view showing a second embodiment of the present invention. In the second embodiment, not only the light emitting element 1 but also the light receiving element side is provided with the reflection film 8 at the interface with the light blocking resin mold 5. Also in this case, an optical coupling device with high coupling efficiency can be obtained as in the case of the first embodiment, and the current transfer rate is about 1.5 times that of the conventional coupling device.

[0014]

As described above, the optical coupling device of the present invention has a light-emitting element mounted on a lead frame, a light-receiving element, a light-shielding resin mold for sealing them, and a light-shielding characteristic further sealed from the outside. The resin mold, the projection wall for reflecting the light of the light emitting element toward the light receiving element on a part of the inner wall of the light blocking resin, and the reflective wall having a high reflectance for the light of the light emitting element on the projection wall. . With such a structure, an optical coupling device having an electric current transfer rate can be obtained.

[Brief description of drawings]

FIG. 1 shows a vertical sectional view of a first embodiment of the present invention.

FIG. 2 shows a vertical sectional view of a second embodiment of the present invention.

FIG. 3 shows a first example of a vertical sectional view of a conventional optical coupling device.

FIG. 4 shows a second example of a vertical sectional view of a conventional optical coupling device.

FIG. 5 shows a third example of a vertical sectional view of a conventional optical coupling device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light emitting element 2 Light receiving elements 3a, 3b Lead frame 4 Transparent resin 5 Translucent resin mold 6 Light-shielding resin mold 7 Projection wall 8 Reflective film

Claims (1)

[Claims] 1. An optical coupling device having a double mold structure in which a light emitting element and a light receiving element are arranged to face each other, sealed with a resin mold having a light-transmitting property, and then further molded with a resin having a light-shielding property, Characterized in that a projection wall for reflecting the light of the light emitting element toward the light receiving element is provided on a part of the inner wall of the conductive resin, and a reflective film having a high reflectance with respect to the light of the light emitting element is attached to the projection wall. Optical coupling device.