| 摘要 |
PURPOSE: To meet the demand of compatibility of miniaturization and power saving of a circuit configuration under a low power source voltage by providing a monitor light receiving element and controlling an offset amt. of an amplifier part. CONSTITUTION: An irradiating amt. of light irradiating a magneto-optical disk 1 from a laser light emitting element 2a via a mirror 2b is detected by a monitor light receiving element 2c. Reflected light from the disk 1 is detected by a photodetector part 2d, and the output from the photodetector part 2d is amplified by a head amplifier circuit 2g, and an offset amt. of a reference voltage is controlled based on the output from the monitor light receiving element 2c via a monitor amplifier circuit 2e and a comparing control circuit 2f by the input. Thus, under a low power source voltage, a C/N ratio can be raised at the reproducing time while a dynamic range can be extended, and the miniaturization and power saving of a circuit configuration can be performed. |
