| 摘要 |
PURPOSE:To prevent deterioration and damage of a semiconductor laser in turning on and off a power source by making the base potential of one transistor higher than the base potential of the other transistor. CONSTITUTION:During the time a power source voltage -VEE, which is applied when the power source is turned on, is low and smaller than a voltage VZ of a Zener diode 5 in the reverse direction, the voltage at a reference voltage terminal A in a first reference voltage generating circuit 1 is about the ground potential due to a resistor R1. The base potential of the first transistor Tr1 is about the ground potential and higher than the base potential of the second transistor Tr2. Therefore the collector current of the first transistor Tr1 is small, and the overcurrent is not flowed in the semiconductor laser 4. |
