| 摘要 |
PROBLEM TO BE SOLVED: To provide a drive circuit with which a laser diode can be reliably protected from surge breakdowns. SOLUTION: A pair of transistors 10A and 10B are formed into a collector grounding circuit by connecting resistors 11A and 11B to an emitter, a laser diode 12 is connected to between both emitters, and a light is emitted or erased by on-off driving with mutually opposite phases, using transistors 14A, 14B, 16A and 16B. The laser diode is protected from surge breakdowns by the resistors 11A and 11B. A light output control circuit 13 detects the light output of the laser diode, and the collector voltage of the transistors 10A and 10B is automatically controlled in a direction in which the light output becomes constant. |
