| 摘要 |
PURPOSE:To improve reliability of a device and to always perform stable recording by adjusting a laser driving circuit so that the intensity of laser beams in over writing is modulated by a high intensity PH and a low intensity PL, relation between PH and PL is made specific, and the optimum conditions are always kept in spite of variation of PH. CONSTITUTION:PH and PL values obtained by a reference value setting circuit 5 are transmitted to a laser driving circuit 3 through a PH setting circuit 6 and a PL setting circuit 7, and modulated to binary codes of PH and PL based on binarization information from a data conversion circuit 4, then a laser diode 1 is driven by them. The intensity of laser beams irradiated from this diode 1 is converted to an electric signal by a photo diode 2 for monitoring and a laser beam intensity monitoring circuit 8, a PH value is monitored by a peak detecting circuit 9. This value is compared with the reference value by a comparator circuit 10, a control signal (b) is sent to the PL setting circuit 7 so that a deviation from the reference value has specific relation in a PL control circuit 14, then the optimum recording is performed. |
