Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the head
Reexamination Certificate
2005-05-31
2005-05-31
Tran, Sinh (Department: 2651)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the head
C360S025000
Reexamination Certificate
active
06900958
ABSTRACT:
A method is disclosed for improving head position accuracy in a disk drive during track following of concentric data storage tracks through real-time identification of external vibration and monitoring of write-unsafe (WUS) occurrences. In the method, after a seek operation to a predetermined data storage track, the track is followed using a servo control loop having a nominal gain and responsive to a position error signal (PES). After waiting a vibration detection delay period, occurrences of the PES exceeding a WUS limit are counted generating a WUS limit exception count. Also, a property of a variance is determined from spectral power values generated from the PES during track following. If the WUS limit exception count exceeds a first threshold, and if the property of the variance exceeds a second threshold, the nominal gain is increased to a vibration gain within a frequency band, to attenuate the effect of external vibration.
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Butt Arafat M.
McNab Robert J.
Nguyen David D.
Song Yanbin
Spaulding David A.
C. Kim, Esq. Won Tae
Fawcett, Esq. Robroy R.
Tran Sinh
Tzeng Fred F.
Western Digital Technologies Inc.
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