| 摘要 |
<p>PURPOSE:To improve the response speed for control of a driving means as well as the rise characteristics of tracking when the driving speed of a recording medium is changed, by combining a shift of a magnetic head toward the side part with a shift element and the driving control of the recording medium. CONSTITUTION:The actuator control signals are alternatingly sampled and held in a capacitor 21 by switches 19 and 20 and by means of a timing pulse related to a head changeover pulse. Then the differential voltage between the output voltage of the capacitor 21 and the reference voltage that is set previously by a voltage source 22 is obtained by a differential amplifier 23. This differential voltage is added to a speed control loop 24-25-26 of a capstan motor 27 by an adder 25 to control the phase of the capstan. Thus the shift amounts of actuators 3 and 4 are set at 0 in the sampling timing. It is possible to always maintain a good tracking state of both reproduction heads 1 and 2 respectively and at the same time to reduce the maximum shift amount of both actuators 3 and 4 respectively.</p> |
