| 摘要 |
PURPOSE:To limit an operation region of a transistor and speed up the ON-OFF operation of a semiconductor light emitting element by connecting a series connection between a Schottky barrier diode and a transistor with the semiconductor light emitting element in parallel. CONSTITUTION:A laser diode 1 is connected between a constant current source 18 connected to a current source terminal 4 and earth and then, a plurality of Schottky barrier diodes 2 are connected in parallel between a collector of a transistor 3 to which an emitter is earthed and the constant current source 18. Subsequently, an electric current always flows from the constant current source 18 to the laser side diodes 1, the Schottky barrier diodes 2, and the transistor side 3 separately and changes a base current of the transistor 3. As a result, such a variation of its base current permits electric currents flowing in the Schottky barrier diode 2 and the transistor side 3 as well as the laser diode side 1 to show a fluctuation and perform the On-OFF operation of a light output in the laser diode 1. The drive is so performed at a limited part of an active region of the transistor 3 that the laser diode can be driven at high speed. |
