| 摘要 |
PURPOSE:To prevent a semiconductor laser from suffering damage due to an excess current by a method wherein a rectifying device is connected with the semiconductor laser in parallel and the same polarity. CONSTITUTION:A semiconductor laser driving circuit is composed of a semiconductor laser 1, a photodetector 2, a constant current circuit, and a rectifying device 4. The rectifying device 4 consists of plural bodies connected in series and has the same polarity as the semiconductor laser 1. Namely, a voltage, which increases a current rapidly, depends on number of the bodies connected in series. Therefore, by controlling the voltage, most of the current flows through the semiconductor laser when it is equal to or smaller than the rated current of the semiconductor laser and flows through the rectifying device 4 when it is larger than the rated current. Thereby, the semiconductor is prevented from an excess current. |
