| 摘要 |
PURPOSE:To realize the accurate and stable detection of the information on the revolution initiation position of a disk surface, by detecting and storing the phase information on the disk surface which is detected by an optical head at the beginning of the system start and the phase difference of the output of a detector for revolution initiation position mark signal. CONSTITUTION:The comparison of phases is carried out only at the beginning of the system start between the disk position phase information obtained from a recording medium 103 and the disk position phase information obtained from a detector 104 for revolution initiation position mark signal. Thus a relative attachment error between an optical head and the detector 104 is detected and stored. The phase of the output signal of the detector 104 is shifted in response to the stored error signal. Based on this shifted output signal, the revolution phase of a disk is controlled again. As a result, the disk revolution initiation phase is coincident with the disk surface phase information read by the optical head regardless of the variance of the relative attachment position of a revolution initiation detector against the optical head.
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