| 摘要 |
<p>PURPOSE:To attain the accurate and stable servo control by measuring the width of a signal to be measured of a part to be controlled by calculating the front and rear edges of a clock pulse contained in said signal to be measured and using an obtained control signal to control the part to be controlled. CONSTITUTION:Signals Sa and Sb are supplied to a generating circuit 6 for signals to be measured from magnetic pickups 5a and 5b. Thus a signal Sx to be measured is obtained. For a clock pulse signal P supplied from a clock input terminal 7, a counter 14 counts pulses including that reaching first the back of the front edge of the signal Sx and that reaching first the back of the rear edge of the signal Sx. Then an analog output Vn is obtained in response to the count result of the counter 14. In addition, correcting analog outputs Vf and -Vr having the same and adverse polarities to the output Vn are obtained through LPFs 17 and 18 and then added together by an adder circuit 22. Thus a control signal Vx=Vn+Vf-Vr is obtained. This signal Vx is supplied to a motor 3 to keep the width of the signal Sx at the normal value.</p> |
