| 摘要 |
PURPOSE:To control the rotation by counting a phase difference between a magnetic disk reproduced signal for adjustment and a rotation phase detection signal and varying the phase difference based on a counted result so that the leading edge of a recording gate generated from a reference signal coincides with that of a reproduced signal. CONSTITUTION:When the lock signal of a disk for adjustment goes to the low level, it is reported to a counting circuit 17 that rotation is stabilized, and a counting pulse TCK is counted in the counting circuit 17 synchronously with the PG signal (m) of a digital PG shifting circuit 19 while a switch SW 23 is turned on, and counting is stopped by the leading of a following detection signal (p) to obtain N1=T1/TCK. A prescribed constant value is added to obtain N5 as preset information, and this informa tion is written and stored in a latch circuit 18 by a time T8, which is required for this operation, from the detection signal and is sent as a preset value to the shifting circuit 19. A shift PG signal is issued by a counted value 0 of counting pulses, and the shift PG signal is repeatedly issued a time T5 after a second and following PG signals (m). The SW 23 is turned off by the end of adjustment, and the extent of shift of the PG signal is adjusted by the device when the recording disk is set and the SW 23 is turned on and an adjusting SW 9 is switched to perform recording.
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