| 摘要 |
PURPOSE:To recognize flag information with a high reliability and to improve a data processing efficiency by dividing a detecting level of various kinds of flag information. CONSTITUTION:When the equivalent track and a sector in a data area 30 of optical disk media 11 are searched and faulty sector flag information is not detected by flag detecting circuits 61-6n in a flag area 21, said data are trans ferred to a higher order device 1. At such a case, detecting levels 1-n are respectively set, the threshold of the faulty sector flag is changed, in case of the detecting level l(1<=l<=n) or above, said sector in the area 30 is judged to be faulty, a spare track area 32 is searched and said data are transferred. In case of the detecting level of less than l, said sector in the area 30 is not faulty, the omitted place is judged to be present on an optical disk 11 and said sector is transferred.
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