| 摘要 |
PROBLEM TO BE SOLVED: To prevent occurrence of erroneous recording stop and reproducing stop by discriminating accurately disturbance of a binary signal caused by scratch, dirt of an optical disk or the like and disturbance of a binarization signal caused by true off-track, and stabilizing off-track detection processing. SOLUTION: The value of the number of edges of a binary signal obtained by binarizing a track error signal output from a servo unit 4 and an edge interval time value are obtained, and it is discriminated whether the value of the number of edges and the edge interval time value satisfy first criterion, second criterion, and third criterion or not, and it is discriminated whether the off-track is caused or not on the basis of this discrimination result. COPYRIGHT: (C)2008,JPO&INPIT
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