| 摘要 |
Optical disk systems comprising photo detectors ( 1 ) for detecting optical disks comprising amplifiers and slicers ( 2 - 5 ) and delay-difference detectors ( 6 ) for detecting delay differences in sliced amplified detection signals are improved by installing delaylineless delay-difference detectors ( 6 ) comprising combinatorial-logic circuits ( 7,8 ) like inverters, ORs, NORs, ANDs, NANDs and sequential-logic circuits ( 11 - 18 ) like SetResetFlipFlops. Without the prior art delay lines, said delay-difference detectors ( 6 ) are of a lower complexity and low costly and can be well integrated. By introducing a first pair of sequential-logic circuits ( 11,12,15,16 ) for detecting delay differences between rising edges and a second pair of sequential-logic circuits ( 13,14,17,18 ) 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 ( 6 ) further comprises an analog adder/subtracter ( 9 ) for adding/subtracting-logic circuit output signals and low pass filter(s) ( 10 ) located before or after said adder/subtracter ( 9 ).
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