| 摘要 |
PURPOSE:To quickly put a magnetic head on the first track by utilizing a mechanical position detecting mechanism when the magnetic head is transferred from the original returning position to the first track, by transferring the magnetic head from a position by a prescribed distance when a significant envelope level is detected. CONSTITUTION:As a magnetic head 26 is transferred from the original returning position HP of the magnetic head to track No. 1, signals having the envelope conceptually indicated by the solid line 500 are recorded on a magnetic disk 10. A control device 60 transfers the magnetic head 26 in the forward direction R1 one unit (d) by one unit and detects the envelope of signals fetched from the head 26 at locations shown by black circles ''.''. When, for example, the envelope does not exceed a prescribed value Vth at a time t4 but exceeds the prescribed value Vth at another time t5, the control device 60 judges that the magnetic head 26 approaches the first track No. 1. Then the control device 60 commands a driving circuit 50 to move the magnetic head 26 by a prescribed number of pulses, for example, either pulses.
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