| 摘要 |
PURPOSE:To prevent the misdetection of a sector mark and to shorten the address recognizing time by always performing the detection of the sector mark and recognition of an address with no switch of reference clocks, etc. CONSTITUTION:A sector mark 3 and an address part 4 are set by preformat at the head position of each sector 2 defined on an optical disk 1 over the entire surface of the disk by means of the reference clocks CLK1 of the same frequency. Then the light obtained from the irradiation light from an optical head 6 and reflected on the disk 1 is received by the head 6 and amplified by a reed amplifier 8. This amplified light is segmented by a sector mark identifying circuit 10 in synchronism with the CLK1 and decided by a sector mark detecting circuit 11 for output of a detection signal 15. While an address part VFO12 uses the CLK1 as a reference clock to discriminate the output of the amplifier 8. Then a data signal 13 and a data clock 14 are outputted and an address demodulation circuit 17 demodulates the signal 13 by the input timing of the signal 15. Then the obtained track number 18 is recognized by an MPU19.
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