| 摘要 |
PURPOSE:To shorten a leading time by applying an off-setting voltage to a control voltage, flowing quickly a mark signal to the trapezoidal wave made from a reference signal and starting a control action when a mark signal enters the inclination of the trapezoidal wave. CONSTITUTION:While the off-setting voltage is applied to the output of a speed control circuit system 18, the frequencies of the mark signal and the trapezoidal wave are different with each other, therefore, the mark signal flows in the A direction to the trapezoidal wave. The larger the frequency difference is, the faster the flowing speed is, and the flowing speed can be set by the value of the off-setting voltage. Consequently, the control can be executed so as to position quickly the mark signal to the prescribed position of the trapezoidal wave. By setting the time width at the upper side part of the trapezoidal wave by matching to a response delay from when the adding of the off-setting voltage is stopped and a changing-over circuit 38 is closed until a phase control circuit system 12 retreats, the smooth retreating action can be secured. Thus, a motor servo circuit with a short leading time can be obtained.
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