| 摘要 |
<p>PURPOSE:To shorten time until tracking is turned to an optimum state by detecting a deviating direction immediately when a track on the magnetic tape of a magnetic head is deviated from the center line of the track recorded onto the magnetic tape in advance. CONSTITUTION:Discrimination circuits 10 and 11 respectively output signals 101 and 102 as the results of envelope detection to output signals from a preamplifier 4 and a delay circuit 9 and output discrimination signals 103 and 104 to decide whether the signal reaches a prescribed level or not. When scanning is executed while deviating the center of a magnetic head HA1 to the side of a track Bn-1 from the center line of a track An, a changeover switch 14 is turned to the state of connecting a 14a by detecting that time tS required for the scan of a logic circuit 12 shown by the difference of starting time for the discrimination signals 103 and 104 obtains difference more than the allowable error of prescribed time, and the signal 102 at a level in proportion to the envelope of the reproducing signal of an HB'3 from the discrimination circuit 11 is guided to a driving circuit 15. Thus, the speed of traveling the magnetic tape is increased and the track at the center of the HA1 is controlled to correctly trace the center line of the track An.</p> |
