| 摘要 |
PURPOSE:To realize a small-sized low cost optical disc player in which information signals are reproduced with a high density from a high density optical disc and data is reproduced from a low density optical disc without deteriorating the error rate using a single optical pickup. CONSTITUTION:A detection voltage signal is fed from an optical pickup 1 through a current/voltage conversion circuit 2 and an amplifying circuit 3 to a DC cut section 4 where the DC component is removed from the detection voltage signal before the signal is fed to a comparator 5 to be binarized. Binary output from the comparator 5 is fed to a delay circuit 8 and an adder circuit 9, e.g. and OR gate. The delayed binary output from the delay circuit 8 is added to a binary output not delayed at the adder circuit 9. Output from the adder circuit 9 is fed to a demodulation circuit and an asymmetry correction circuit 6, e.g. a low-pass filter. The asymmetry correction circuit 6 corrects a comparison level being set on the mirror level side by an initial offset setting circuit 7. |
