| 摘要 |
PURPOSE:To shorten a rotating phase changing time of a magnetic-sheet driving motor when a magnetic head moves from a track to another track, by directly controlling the producing timing of vertical synchronizing signals by using tack signals produced synchronously to the rotating of the motor at every rotation of the motor. CONSTITUTION:During track access operations at the time of reproduction, a track feeding signal A is outputted from a system control circuit 11 and inputted to a vertical synchronism resetting circuit 12. Then a gate signal generator 121 opens and AND circuit 123 for a previously fixed period T and tack signals E from a rotating position detector 5 are inputted to a vertical synchronizing signal generator 6. The tack signals E inputted to the generator 6 forcedly reset the generator 6 and make vertical synchronizing signal C outputted from the generator 6 synchronous to the tack signals E. Since the phases of the tack signals E can forcedly be matched to the phases of the vertical synchronizing signals C while the phases of the tack signals E fluctuate even when a change in the rotating phase of a sheet motor 1 takes place due to the movement of a magnetic head from a track to another track and the phases of the tack signals E fluctuate, the time required for pulling-in the phase can be made shorter.
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