| 摘要 |
PROBLEM TO BE SOLVED: To detect an offset voltage at initial learning time due to phase offset of a phase comparison means (delay device, phase comparator) affected at high multiple speed (e.g. 20 multiple speed of DVD). SOLUTION: In the tracking error signal controller which is provided with a signal producing means 100 for projecting a convergence laser beam to a recording medium so as to produce two signals from reflected light, the phase comparison means 210 for comparing the phase between two signals so as to produce a tracking error signal and an offset voltage correction means 300 for storing the output offset voltage included in the tracking error signal at initial learning time to correct it at data reproducing time, a route to input a reference clock on a system to the phase comparison means 210 is arranged. In this constitution, an input signal of the phase comparison means 210 can function as the in-phase signal for no input of a reproduction signal of the initial learning time, then the output offset voltage due to the phase offset of the phase comparison means 210 can be detected. COPYRIGHT: (C)2003,JPO
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