| 摘要 |
<p>PURPOSE:To quickly shift a reproducing head to a normal track when the reproducing head largely gets out of the normal track, by obtaining an auxiliary tracking signal which performs control for putting the reproducing head onto the normal track. CONSTITUTION:After a pilot signal frequency component is extracted from a signal reproduced by a head 23 through a switch 22, regenerative amplifier 24, and LPF26, the signal is mixed with a four frequency reference signal 28 supplied from a control circuit 13 through a filter 17 at a mixer 27. An output signal containing the component of fH-4fH frequencies is inputted into level discriminating circuits 44-46 through BPFs41-43 having center frequencies fH, 2fH, and 4fH, respectively and, when the output signal exceeds a fixed threshold, a high-level signal is inputted into a condition detecting circuit 47. When it is discriminated that the reproducing head is not on a normal track, an auxiliary tracking control signal 48 is generated and a capstan motor is controlled by a capstan controlling circuit 37, and then, the head 23 is quickly shifted to the normal track.</p> |
