| 摘要 |
PURPOSE:To remove an apparent position error by changing the format of the magnetic transition or magnetic zone written into a guard band and giving plural phases to a phase locking loop by the new guard band. CONSTITUTION:The format of a guard band is written together with two phases of the same phase magnetic zone as two phases in a servo code. Respective magnetic zones are arranged at the position separated in the circumferential direction of an adjoining track and the phase of the pulse read from the magnetic zone is mutually separated to 180 deg.. Since such the recording of two magnetic zones determines a magnetic cell on a servo disk, when the servo code of two corresponding phases is used to generate a position error signal, the influence due to a close guard band is the same concerning both phases of the servo code, and since the position error signal is the amplitude difference between two phases, the off-setting signal due to a near-by degree of the guard band is cancelled between both phases. Consequently, the apparent position error is eliminated.
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