JPH02288272A - Semiconductor light emitting device - Google Patents

Abstract

PURPOSE:To prevent a voltage from decreasing due to resistance by electrically connecting a collector, an emitter of a lateral phototransistor formed by using a collector region between the base and the emitter of a driving transistor. CONSTITUTION:In a device, a semiconductor light emitting element 2 and a driving transistor 30 are placed on a lead frame island 1, a phototransistor 50 of a lateral structure is formed in the collector region 31 of the transistor 30, and a collector 52, an emitter 41 of the phototransistor 50 are electrically connected to the base region 32, emitter region 33 of the transistor 30. Part of radiated light from the element 2 conducts the transistor 50 to reduce the base current of the transistor 30, thereby controlling the driving current of the element 2. Accordingly, a current limiting resistor is eliminated to obviate a voltage drop due to the resistor.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor light emitting device, and more particularly to a semiconductor light emitting device incorporating a drive transistor.

[Conventional technology]

Conventionally, semiconductor light emitting devices have used a method in which a semiconductor light emitting element 2 is driven by a drive transistor 30 via a current limiting resistor 60, as shown in FIG.

[Problem to be solved by the invention]

The above-mentioned conventional light-emitting device uses a current-limiting resistor, so when voltage is applied, the voltage drops due to the resistor, resulting in poor voltage utilization.Especially when used in a remote control device, the light-emitting side is portable and requires batteries. Since this method uses a current limiting resistor, the operating voltage fluctuates widely, and even if a current limiting resistor is used, the light intensity fluctuates greatly.

[Means to solve the problem]

In the semiconductor light emitting device of the present invention, a drive transistor is arranged near a semiconductor light emitting element, and between the base and emitter of the drive transistor, the collector and emitter of a lateral phototransistor are formed using the collector region of the drive transistor. are electrically connected to each other.

〔Example〕

Next, the present invention will be explained with reference to the drawings. FIG. 1 is a longitudinal sectional view of a first embodiment of the invention. A semiconductor light emitting device 2 and a drive transistor 30 are mounted on the lead frame island 1, and a phototransistor 50 with a lateral structure is formed in the collector region 31 of the drive transistor 30.

Collector 52 of phototransistor 50. Emitter 51
are the base regions 32 . of the drive transistor 30 , respectively.
It is electrically connected to the emitter region 33. Figure 2 is the first
The equivalent circuit of the figure is shown.

A portion of the light emitted from the light emitting element 2 is transmitted to the phototransistor 5.
By making 0 conductive, the base current of the drive transistor 30 is reduced and the drive current of the light emitting element 2 is controlled.

FIG. 3 shows a driving transistor 30 according to a second embodiment of the present invention.
FIG. In this embodiment, the area of the phototransistor 50 is at a depth 2 of the base area 32 of the drive transistor.
The depth is 5 μm or more, and the surface concentration is 10 μm or more.
Make it as thin as 110l7'. Phototransistor 50
By making the region as in this embodiment, a phototransistor with a relatively high hFE of 30 can be obtained, and the light receiving characteristics are improved, so that the controllability of the amount of light is improved.

〔Effect of the invention〕

As explained above, the present invention uses a part of the light from the semiconductor light emitting device to control the collector current of the drive transistor, thereby eliminating the need for a current limiting resistor to limit the light intensity and reducing the voltage drop caused by the resistor. It has the effect of eliminating Furthermore, miniaturization can be achieved by integrating the semiconductor light emitting element and the drive transistor.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of the first embodiment of the present invention, and FIG.
FIG. 1 is an equivalent circuit diagram, FIG. 3 is a vertical sectional view of a second embodiment of the present invention, and FIG. 4 is an equivalent circuit diagram showing a method of using a conventional light emitting element. DESCRIPTION OF SYMBOLS 1...Lead frame island, 2...Semiconductor light emitting element, 30...Drive transistor, 31...Collector region, 32...Base region, 33...Emitter region, 41...Base terminal , 42... Emitter terminal, 43... Anode terminal, 50... Lateral phototransistor, 51... Phototransistor emitter,
52... Phototransistor collector, 60... Current limiting resistor.

Claims (1)

[Claims] In a semiconductor light emitting device including a semiconductor light emitting element and a drive transistor having a base region and an emitter region formed on the same island of a lead frame, a lateral phototransistor having the same polarity as the transistor is provided in a collector region of the drive transistor. a vertical collector and a vertical emitter of the phototransistor are electrically connected to a base and an emitter of the drive transistor, respectively.