| 摘要 |
<p>PURPOSE:To obtain the CTL detection signal of a constant level, not containing a false signal by setting the level of the false signal contained in the output signal of a control amplifier at a lower level than a threshold set by a slice circuit. CONSTITUTION:The signal detected by a head 1 is supplied to the CTL amplifier 2, but the output level V2 of it is kept constant by an AGC circuit 14 and a transistor 5 and the CTL detection signal is sliced by diodes 12, 13, and is supplied to an index signal detection circuit 3. Because the level of the false signal Id is lower than that of the CTL signal I, when the voltage dividing ratio of resistors 6, 7 is made so that the false signal level in the output signal of the amplifier 2 comes lower than the conducting voltage Vd of the diodes 12, 13, the signal to be inputted to the circuit 3 comes to be only a regular signal I. Thus, by making the signal pass through the slice circuit with the higher threshold than the false signal level, the CTL signal of the constant level, not containing the false signal can be obtained.</p> |
