| 摘要 |
PROBLEM TO BE SOLVED: To perform reproducing operation well without causing disablement of reproduction or reduction of reproduction processing speed even in the case of an optical disk being in a bad state in which pit shapes are different depending on a region in a disk. SOLUTION: After a reproduced RF signal S1 is sliced by a comparator 1, it is supplied to a slice level generator 2, and a slice level signal S2 is generated. An error rate of a binary signal S3 is obtained by an ECC processing section 4, supplied to an error rate monitor processing section 5, when an error rate is small, the signal S2 is suppled to the comparator 1 through a changeover switch 6 and a reference voltage generator 3 (operation of auto-slice function). When an error rate is large and it cannot be corrected, a slice level at which an error rate is reduced based on a signal 4 is decided by the monitor processing section 5, supplied to the comparator 1 through a changeover switch 6 and a reference voltage generator 3, also a region is specified in a disk region discriminating section 7 for an appropriate value of a slice level and the value is stored, and it is used for calling by access command at the time of reproduction.
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