| 摘要 |
PROBLEM TO BE SOLVED: To provide a disk playback apparatus in which as a disk is vibrated and a servo error signal becomes unstable in detection of mass eccentricity and an eccentric disk, it can be detected if magnitude of the servo error signal is measured, but in a disk in which reflectance is low and applying servo is unstable and recording group media such as CD-R, CD-RW in which a recording state is bad and data are hard to read, trouble is caused in reading data only by incresing slightly reproduction speed prior to vibration due to high speed rotation of the disk; a disk in which when it is rotated at high speed, a reading error is easy to occur can be specified, such control can be performed that the rotation frequency of only this disk is lowered. SOLUTION: This apparatus is an optical disk in which a medium is rotated by switching rotation speed, the apparatus has such constitution that the number of reading errors at high rotation frequency and the number of reading errors at low rotation frequency can be stored in a memory respectively, the number of these reading errors are compared, when difference of the number of caused errors is the prescribed value or more, the medium is not rotated at high speed, when difference of the number of caused errors is less than the prescribed value, the medium is rotated at high speed. COPYRIGHT: (C)2006,JPO&NCIPI
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