| 摘要 |
A video tape playback device in which heads are tracking-controlled according to a predetermined tracking control value, in order to accomplish automatic tracking so that noise is not regenerated on the screen during an abnormal speed playback. The device has a direct-current (DC) envelope detector for detecting a direct-current (DC) envelop signal of a video signal read out a video tape via video heads; a comparator for comparing the detected DC envelop signal with a predetermined threshold value, and outputting a pulse signal representing the comparison result; a servo portion for performing a tracking operation according to a tracking control value, and generating a pulse of a head switching signal; and a controller for detecting a difference of time between a falling edge in the pulse signal output from the comparison means and a point of level alteration time of the head switching pulse, and controlling the predetermined tracking control value so that the detected time difference is within a range where noise is not regenerated on a screen to be displayed.
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