INFORMATION STORAGE DEVICE

摘要

PURPOSE:To record and reproduce the recording medium whose characteristics in different by detecting the output signal level of a gain variable means and varying the gain of the gain variable means based on the level of the detected output signal. CONSTITUTION:The detection signal of an optical pickup 1 is inputted to a gain switching circuit 3. It switches the gain in accordance with a control signal from a control circuit 4. It supplies the gain control signal in which the gain of the gain switching circuit 3 is set small to the gain switching circuit 3 in a signal recording period, an erasure period and at the time of reproducing a high reflecting film disk. It supplies a gain control signal in which the gain of the gain switching circuit 3 is set large to the gain switching circuit 3 at the time of reproducing an MO(magneto-optical) film disk. The output signal of the gain switching circuit 3 is supplied to a variable attenuator 5 and it changes an attenuation amount in accordance with an attenuation amount control signal from the control circuit 4. Thus, the optimum output signal level can be obtained even if the disk different in the characteristic is recorded or reproduced.