| 摘要 |
<p>PURPOSE:To track a head accurately in the center of a track by providing a comparator which compares a tracking error voltage with an equal reference voltage and a control circuit which varies the reference voltage for determining the rotating speed of the capstan of an automatic frequency control system. CONSTITUTION:The comparator 23 compares the tracking error signal with a reference voltage 22 equal to a tracking error signal obtained in the absence of a tracking deviation or compares two levels of pilot signals obtained from both adjacent tracks to detect whether the head deviates in a leading or lagging direction. A control circuit 24 varies the reference voltage for determining the speed of the capstan motor 3 of an AFC(automatic frequency control) loop based on the output of the comparator 23. Therefore, the rotating speed of the capstan motor 3 can securely be made constant to compensate speed variation due to disturbance such as variation in temperature variation. Consequently, the head can be tracked accurately in the center of the track.</p> |
