| 摘要 |
PURPOSE:To cope with a high speed rotation by obtaining a settling time of a laser light output with a laser light from a leading end of a prerecorded part of a sector as a recording or erasing light power. CONSTITUTION:A reproducing signal of a prerecorded part from an optical head 1 is set to a predetermined level by a reproducing amplifier 4, and applied to an ID detector 5. The detector 5 converts the signal to a binary signal to detect signals of the prerecorded part. It is compared with a set signal of a recording/erasing start sector from a controller to detect whether it is a reproduced sector or a target sector. The target sector is a sector before one to start recording or erasing. A timing generator 6 outputs a signal to a laser driver 2 based on the ID detection signal. A switching unit 7 is operated by a signal of the generator 6, and the driver 2 controls a driving current in response to an input of the unit 7. With the configuration, laser power setting accuracy at the time of recording or erasing can be obtained to maintain interchangeability with prior art disk of ISO standards. |
