| 摘要 |
PURPOSE:To detect accurately the number of signals crossing tracks and the crossing direction by sampling the signal showing the reflected light quantity from a disk at the rise and fall time points of a track error signal and comparing the signal levels with each other between sampling points. CONSTITUTION:A track error signal SB is supplied to a zero cross detector and converted into a binary coded signal. This binary coded signal is supplied to both rise and fall differentiators 3 and 4 respectively to be turned into differential signals. These differential signals SE and SF are supplied to delay circuits 5 and 6 and to sampling/holding circuits 7 and 8 in the form of sampling pulses respectively. A signal SC showing the reflected light quantity is supplied to the circuits 7 and 8 from a pickup 1 and sampled and held by signals SE and SF to be applied to the plus and minus terminals of a comparator 9 as signals SG and SH respectively. The comparator 9 delivers a detecting signal for track crossing irection. |
