Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the head
Reexamination Certificate
2007-02-13
2007-02-13
Nguyen, Hoa T. (Department: 2627)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the head
Reexamination Certificate
active
11196874
ABSTRACT:
A magnetic recording disk drive with rotational vibration (RV) cancellation uses the position error signal (PES) and the signal from a RV sensor to determine when to enable and disable RV cancellation. An RV feedforward compensation signal to be summed with the VCM control signal is “switchable”, meaning that it can be enabled or disabled by the disk drive servo control processor. The determination to enable or disable is made from a comparison of the PES with a threshold PES, which may be an estimate of the off-track position of the head calculated from the RV sensor signal. The estimated off-track is compared to the absolute value of the actual or measured PES. If the estimated off-track is smaller than the actual PES, then the state of the RV cancellation is switched, i.e., if it is enabled it is disabled and if it is disabled it is enabled.
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Semba Tetsuo
Tzou Kevin I.
White Matthew T.
Berthold Thomas R.
Hitachi Global Storage Technologies - Netherlands B.V.
Nguyen Hoa T.
Slavitt Mitchell
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