| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical disk which has information for obtaining a position in the circumferential direction and an optical disk unit which obtains the position in the circumferential direction by the disk. SOLUTION: When the widths of black zones of non reflective parts of a SPOKE10 set in the inner periphery of the optical disk are increased, outputs of photo detectors 8A and 8B are changed, and an output of a differential amplifier, or a SPOKE detecting signal 15, is changed as well. Moreover, the widths of white zones of the reflective parts of the SPOKE10 are increased, the outputs of the photo detectors 8A and 8B are changed, and the output of the differential amplifier, or the SPOKE detecting signal 15, is changed as well, and a waveform whose phase is shifted in the reverse direction is obtained. The index 0 of the optical disk can be detected. COPYRIGHT: (C)2009,JPO&INPIT
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