| 摘要 |
<p>PURPOSE:To obtain improved phase control characteristics by comparing the phases of a signal which is subjected to 2/3-division from the output of the revolutionary phase detector of a head cylinder and of a signal which is subjected to 1/2-division of the vertical synchronizing signal output, to control by the output of the said comparison the head cylinder motor so that the both signals synchronize with each other. CONSTITUTION:The signal S22 from a PG7 that detects the revolutionary phase of a rotation head cylinder 3 is divided by a 1/3-dividing circuit 28 to make 1/3-division which is made to a signal S23. A signal S21 of 3.M.fv from an FG6 that detects the revolution information is inputted to the clock terminal of a 1/3-dividing circuit 29, and the signal S23 is inputted to the reset terminal of the same circuit 29. The output signal S24 from the circuit 29 is inputted to a delay circuit 30, and the signal is made to be a signal S25 by the charging time constant. By setting the primary, secondary, and tertiary threshold voltages, the 1st, 2nd, and 3rd delay-circuit output signals S26, S27, and S28 are obtained. The 2nd delay time output signal S27 of the delay circuit 30 is inputted to the clock terminal of a 1/2-dividing circuit 26. At the same time, the signal S23 is inputted to the reset terminal of the same circuit 26, and a signal S29 is obtained, which is supplied from the output terminal to the phase control circuit.</p> |
