| 摘要 |
PURPOSE:To always obtain prescribed outgoing light quantity even when the I-P characteristic of a laser element is changed by changing the driving current value of a semiconductor laser in correspondence to the irradiated position of an optical disk. CONSTITUTION:To a semiconductor laser element 1, a reproducing driving current IR is supplied from a reproducing driving current source 2 and a recording and erasing driving current IW is supplied from a recording and erasing driving current source 3 through a switch circuit 4. An outgoing light is incident from the element 1 to a light quantity detecting element 5 and inputted through an I/V converter to an APC circuit 7. Then, the current source 2 is controlled by an output and the stable prescribed outgoing light quantity of the laser 1 is obtained. On the other hand, the output of the circuit 6 is inputted to an A/D converter 8 and digital data Din of the outgoing light quantity are inputted to a CPU9. Data Dpx of the optimum outgoing light quantity at the time of erasing to correspond to the irradiated position on a magneto-optical disk are stored in a ROM10 and data Dxout of a driving current to obtain prescribed outgoing light quantity Px are stored in a RAM11. Then, these data are sent to a current source V/I3 by the CPU9 and the optimum current IW is outputted. |
