Optical disk system with delay-difference detector without delay lines

Abstract

Optical disk systems comprising photo detectors () for detecting optical disks comprising amplifiers and slicers (-) and delay-difference detectors () for detecting delay differences in sliced amplified detection signals are improved by installing delaylineless delay-difference detectors () comprising combinatorial-logic circuits () like inverters, ORs, NORs, ANDs, NANDs and sequential-logic circuits (-) like SetResetFlipFlops. Without the prior art delay lines, said delay-difference detectors () are of a lower complexity and low costly and can be well integrated. By introducing a first pair of sequential-logic circuits () for detecting delay differences between rising edges and a second pair of sequential-logic circuits () for detecting delay differences between falling edges, both kinds of edges are being used and the influence of time-jitter is less compared to the situation where just one kind of edge is used. Said delay-difference detector () further comprises an analog adder/subtracter () for adding/subtracting-logic circuit output signals and low pass filter(s) () located before or after said adder/subtracter ().