| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical disk device such that normal tracking control is performed even when a track error signal is distorted due to the defect such as the scratch on the optical disk. SOLUTION: The reflected light of the optical disk is entered onto the light receiving surface of photodetectors 24a-24d. The amplitude of an output sum signal V1 of the photodetectors 24a and 24c is limited to a specified value by a limiter circuit 33a. The amplitude of an output sum signal V1' of the photodetectors 24b and 24d is limited to the above specified value by a limiter circuit 33b. By binarization circuits 34a and 34b, input signals V2 and V2' are respectively binarized by using thresholds of specified rates with respect to the average of maximum amplitudes of these input signals. Phases of output signals V3 and V3' of the binarization circuits 34a and 34b are compared with each other by a phase comparator circuit 35 to provide a signal V4 showing the phase difference, an the track error signal. The tracking control is carried out by using this track error signal.
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