Patent ID: 6477131
Filing Date: 2002-11-05
Classification: G11B

Abstract:
An optical disk device for recording a signal onto or reproducing a signal from a disk having a track of land/groove structure, a pre-formatted area, and a mirror area, said optical disk including a head amplifier, said head amplifier comprising:a photodiode for performing light-current conversion and producing a detected current; a current-voltage conversion amplifier for converting the detected current into a voltage; a means for setting a plurality of gain values; and a circuit for switching a gain for a track field of said disk over to a gain for a pre-formatted area and vice versa and performing amplification, said circuit being included in said head amplifier; wherein when a detected current having a plurality of different direct current levels in time series is supplied, said setting means sets different gain values, so as not exceed a dynamic range of said current-voltage conversion amplifier, for intervals respectively having said different direct current levels, respectively.