| 摘要 |
PROBLEM TO BE SOLVED: To provide a circuit which eliminates offsets included in the tracking signal error, which are computed by a push-pull system. SOLUTION: A tracking error signal computing circuit 20 has peak detection/multiplying circuits 22 and 26 which detect peaks of detection signals E and F of the left and the right regions of photodiodes to detect deviation of a beam light from the track of a disk recording medium and multiply a coefficient K, subtracting circuits 24 and 28 which subtract the multiplication results from the respective detection signals E and F to eliminate the offsets, and a subtracting circuit 30 which computes the difference of the signals from which offsets are eliminated (by conducting push-pull computations) so as to output a tracking error signal TPP(TE). The value of the coefficient K can be varied by adding an alignment signal AL to the detection signals E and F. In order to provide frequency dependency onto the coefficient K, the alignment signal AL is added to the signals E or F through a filter. COPYRIGHT: (C)2006,JPO&NCIPI
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