INFORMATION REPRODUCING DEVICE

摘要

PURPOSE:To make the changing of emitted light quantity unnecessary and to reduce an error rate at the time of reproducing by controlling the amplitude and the DC potential of a signal inputted to a signal processing circuit so that they become an optimum value corresponding to the reflectance or the modulation factor of an information storage carrier, the light quantity of a light source and the like when they are changed. CONSTITUTION:A current signal from an optical head 2 is converted to a voltage signal by an I-V conversion circuit 3 and the amplitude of a reproduction signal 9 is detected by a gain control circuit 4. The amplitude of the output of the gain control circuit 4 is always made nearly constant by controlling gain so that the detected amplitude becomes sufficiently near a reference amplitude value. Besides, an offset control circuit 5 detects the offset level of a signal for detecting an offset level 54 and controls it so that it becomes sufficiently near a reference value. Then, the offset voltage of the output of the offset control circuit 5 is always made nearly constant. Thus, the amplitude or the offset level of the signal inputted to the signal processing circuit 6 can be made optimum without changing the laser light quantity and the error rate at the time when the signal is reproduced can be reduced.