Optical disc reproducing apparatus which employs a binary detector for

Abstract

An apparatus reproducing signals recorded on an optical disc rotated at a constant angular velocity. The apparatus employs a binary detector for forming digital data by comparing the reproduced signal with a predetermined threshold level, and a ternary detector for forming reproduced data from two series of digital data detected by comparing the reproduced signal with two different threshold levels of predetermined values. The reproduced data from an outer portion of the disc is detected by the binary detector, while the reproduced data from an inner portion of the disc is detected by the ternary detector. The playback output is selectively switched in response to an address signal of a specific track where the phase margin of the reproduced data detected by the binary detector and the phase margin of the reproduced data detected by the ternary detector becomes substantially equal to each other.