Optical recording medium reproducing apparatus using edge detecting technique

摘要

A demodulation device for use with an optical recording medium comprises an edge detector for detecting edges of a binary signal corresponding to marks written onto the optical recording medium as information, an edge interval measuring circuit for measuring a value for the interval between two successive edges detected by the edge detector, a storage device for storing a table that relates thresholds representing upper and lower limits on at least one of a length of the mark and an interval between the marks to demodulated bit strings, and a data converter for comparing an edge interval value obtained by the edge interval measuring circuit with the thresholds representing upper and lower limits to thereby determine one of corresponding a length of the mark and an interval between marks and obtain a demodulated bit string corresponding to the edge interval value measured from the table.