JPH04257275A - Optical coupling device - Google Patents

Abstract

PURPOSE:To use outputs of different input/output current characteristics in response to the use of a circuit using one optical coupling device. CONSTITUTION:An LED 7, a single phototransistor 8 optically coupled with the LED and a Darlington phototransistor 9 are accommodated in the same package.

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 in which a light emitting element and a light receiving element are optically coupled within the same package.

0002

2. Description of the Related Art FIG. 5 is a block diagram of a conventional optical coupling device of this type, and FIG. 6 is a sectional view thereof. 5 and 6, 1 is an anode terminal, 2 is a cathode terminal, 3 is an NC terminal, 4 is an emitter terminal, 6c is a collector terminal, and 7 is an LED
, 8 is a phototransistor, 10 is a lead frame to which the phototransistor 8 is die-bonded, 11 is an LE
D7 is a die-bonded lead frame, 12 is a bonding wire, 13 is a transparent protective resin, 14 is a transparent epoxy resin, and 15 is a black epoxy resin.

In this optical coupling device, a constant forward current is passed through the LED 7 to cause the LED to emit light, and the light reaches a phototransistor 8 to which a constant voltage is applied between the collector and emitter. This light is converted into a current by the phototransistor 8, and a signal is transmitted.

0004

[Problems to be Solved by the Invention] In this conventional optical coupling device, only one light-receiving element and one light-emitting element are housed in the same package, so the input current to the LED and from the light-receiving element are The ratio to the output current, that is, the current transfer ratio, was fixed. Therefore, in conventional optical coupling devices, the current transfer ratio cannot be changed depending on the application of the circuit, which limits the degree of freedom in device design.

[0005]

[Means for Solving the Problems] The optical coupling device of the present invention includes:
A light emitting device and a plurality of light receiving devices optically coupled to the light emitting device and having different optical input-output characteristics are housed in the same package, or a light receiving device and the light receiving device are housed in the same package. A plurality of light emitting devices having mutually different input current-light output characteristics are optically coupled to each other.

[0006]

Embodiments Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing a first embodiment of the present invention, and FIG. 2 is a sectional view thereof.

In FIGS. 1 and 2, 1 is an anode terminal of the LED 7, 2 is a cathode terminal of the LED 7, 3 is an NC terminal, 4 is an emitter terminal of a single photodiode 8, and 5 is a cathode terminal of the LED 7.
is the emitter terminal of Darlington phototransistor 9,
6a is a common collector terminal of both phototransistors, 1
0 is a lead frame to which both phototransistors are die-bonded, 11 is a lead frame to which the LED 7 is die-bonded, 12 is a bonding wire, 13 is a transparent protective resin, 14 is a transparent epoxy resin, and 15 is a black epoxy resin.

FIG. 3 is a characteristic diagram showing the relationship between VCE (collector-emitter voltage) and IC (output collector current) of each phototransistor when the input current to the LED 7 is 1 mA. As shown in the figure, a larger output current can be obtained from the Darlington phototransistor than from a single phototransistor. Therefore, when using the optical coupling device of this embodiment, by selecting terminals 5 and 6a, it is possible to support both circuits that require a large output current and circuits that require a small output current. It becomes like this.

FIG. 4 is a block diagram showing a second embodiment of the present invention. In the same figure, the same reference numerals are given to the same parts as those in the previous embodiment, so a duplicate explanation will be omitted, but in this embodiment, one phototransistor 8 and one phototransistor 8 are provided in the same package. LED optically coupled with this
7 and an LED array 17 are housed therein. Figure 4
, 6b is a collector terminal that also serves as an anode terminal of the LED array 17, and 16 is a cathode terminal of the LED array 17.

In this embodiment, assuming that the characteristics of the individual LEDs of the LED array 17 are equal to those of the LED 7, by selecting and inputting the input current to the terminals 1 and 2 or the terminals 6b and 16, the same characteristics can be obtained. The optical output can be made different with respect to the input current, and therefore the output current can be made different.

[0011]

As explained above, the present invention provides a method for connecting a plurality of light receiving elements having different optical input-output current characteristics optically coupled to the same light-emitting element or input current optically coupled to the same light-receiving element. Since a plurality of light emitting devices with different optical output characteristics are housed in the same package, according to the present invention, signals with different input-output current characteristics can be obtained from the same optical coupling device, and one The optical coupling device can now be used in various application circuits.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a sectional view of the first embodiment of the invention.

FIG. 3 is an output characteristic diagram of the first embodiment of the present invention.

FIG. 4 is a configuration diagram showing a second embodiment of the present invention.

FIG. 5 is a configuration diagram of a conventional example.

FIG. 6 is a sectional view of a conventional example.

[Explanation of symbols]

1 to 5, 6a to 6c, 16 terminal 7 LED 8 (single) phototransistor 9 Darlington phototransistor 10, 11 lead frame 12 bonding wire 13 transparent protective resin 14 transparent epoxy resin 15 black epoxy resin 17 LED array

Claims (1)

[Claims] 1. A light emitting device and a plurality of light receiving devices optically coupled to the light emitting device and having mutually different optical input-output characteristics, or a light receiving device and a plurality of light receiving devices optically coupled to the light receiving device having mutually different input currents. An optical coupling device in which a plurality of light emitting devices having light output characteristics are housed in the same package.