AUDIO SIGNAL PROCESSING CIRCUIT FOR OPTICAL INFORMATION RECORDING AND REPRODUCING DEVICE

摘要

PURPOSE:To eliminate a shift between playback audio signal at a join by digital processing and to improve sound quality by coupling an FM demodulator and an A/D converter together in terms of DC and shifting the DC level of a demodulated signal on the path between them. CONSTITUTION:An RF signal read out of a disk during reproduction is passed through a band-pass filter 22 added to an input terminal 21 and then demodulated by the FM demodulator 23. The demodulated signal is inputted to a low-pass filter 24 and becomes a signal having a DC component, and a signal (a) is inputted to a DC component shifting circuit 40 whose input and output are coupled together in terms of DC so that said DC component has an optimum DC level for the A/D converter 25. This DC component shifting circuit 40 has its input and output DC-coupled together and inputs the demodulation signal with the optimum DC level to the A/D converter 25 without waving the signal. Consequently, there is no step generated at a joint part during extension and a sound of high quality is reproduced.