| 摘要 |
PROBLEM TO BE SOLVED: To attain sure signal detection by controlling DC offset in accordance with an optical disk at the time when information is reproduced from an optical disk of different kind. SOLUTION: Laser beams emitted toward the optical disk and reflected on the optical disk are received by a plurality of photoelectric conversion elements, and a current signal is outputted from each photoelectric conversion element. These current signals are added by an adding circuit 16 and outputted as reproduction signals after converted into voltage signals. Differential amplifiers 26, 28, 30 having different DC offset levels each other are included in the adding circuit 16 and used while changing over switches 32, 34, 36 in accordance with the kind of an optical disk. Thus, the reproduction signal having always appropriate offset level is supplied to a signal processing circuit even though a gain of the rear stage is changed for adjusting a signal level in accordance with the optical disk, then the reproduction signal is properly detected.
|
