| 摘要 |
PURPOSE:To prevent the deterioration of semiconductor layer, which is caused by the surge current generated when the power source is turned on and the excessive current in an instable circuit state, by a simple constitution. CONSTITUTION:The magnitude of the fixed potential Vr and the potential dropped from the source voltage Vcc to the fixed voltage Vr is compared by a potential comparing part 7, and when the fixed potential Vr side is larger, it is judged that the source voltage Vcc is still lower than the prescribed voltage, and a source voltage monitoring circuit 6, with which the driving current against a semiconductor laser 3 will be blocked, is provided. |
