| 摘要 |
PURPOSE:To perform sure erasure even without using a high power laser, by pulse-driving a semiconductor laser by a pulse generation circuit to generate an erasing signal by an erasing pulse that channel bit clocks are summed. CONSTITUTION:A channel bit clock generation circuit 1, the pulse generation circuit 2 to generate the erase signal by the erasing pulse that the channel bit clocks are summed, and a pulse current driving circuit 3 to pulse-drive the semiconductor laser 4 by the pulse generation circuit 2, are provided. A disk clock 9 obtained from a recording medium is inputted to a pulse comparison circuit 14 from a terminal 7. Then, a bias current supplied from a bias current control circuit 6 and a current made flow in from the pulse current drive circuit 3 are summed. Thus, since the laser is pulse-driven at the time of the erasure when the largest power is required, the life of the semiconductor laser is prolonged, and the semiconductor laser of lower allowable power can be used. |
