| 摘要 |
<p>PURPOSE:To prevent the position of noise band from moving on a screen and to reduce the number of noise band, by exercising the phase control so that the ratio of a disc circuit frequency to a reproduced control signal frequency is a specified relation. CONSTITUTION:At recording, servo drive is given by taking a signal frequency- dividing a vertical synchronizing signal to 1/2 as a reference. At reproduction, the rotation of a head motor 64 is controlled with an output of a phase comparator 68 phase-comparing an output frequency-dividing a signal from a reference signal generator 62 with a frequency divider 63 and an output of a flip- flop 66, a capstan motor 12 is phase-compared at a phase comparator 55 for a frequency-divided reference signal and a control signal, and the rotation is controlled with the summing of the output and a signal from a speed detection circuit 51 at an adder 57. At high speed reproduction, a signal from a reference signal generator 62 is applied to the phase comparator 55, phase-comparison is made with the control signal and the output is applied to the capstan motor 12 via the adder 57 and a DC amplifier 58.</p> |
