READ SIGNAL DETECTION CIRCUIT FOR OPTICAL INFORMATION RECORDING AND REPRODUCING DEVICE

摘要

PURPOSE:To attain high density recording by monitoring the difference between the numbers of emergences of the polarities '1' or '0' of signals by an integration circuit and controlling a signal which is given to a comparator through a high pass filter by a D/A converter and a difference circuit according to the obtained difference. CONSTITUTION:When the integration circuit (up-and-down counter) 20 counts the numbers of emergences of '1' and '0' of output binarization signals DS from the comparator 13 and integrates the differences of the numbers of the respective emergences, the D/A converter 21 converts the integrated value into an analog value AS and gives it to the difference circuit (differential amplifier) 11. The difference circuit 1 gives a previously corrected signal obtained by subtracting the analog value AS from a read signal RS to the comparator 13 through the high pass filter 12. And the comparator 13 outputs the binarization signal DS having a stable time width from which the effect of the variation of the signal levels caused by the low frequency component of a modulated signal is removed. Thus, the width recording can be possible by using a modulating system which is not free of DC and the high density recording can be executed.