Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the head
Reexamination Certificate
2006-02-07
2008-03-18
Wong, K. (Department: 2627)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the head
C360S077040
Reexamination Certificate
active
07345841
ABSTRACT:
A magnetic recording disk drive has a disturbance sensor and a disturbance frequency identifier that are used to adjust the frequency of a peak filter as the disturbance frequency changes. The sensor and the frequency identifier are separate from the servo control loop and thus do not rely on the head position error signal (PES) to predict the disturbance frequency. The adjustable peak filter is coupled in parallel with the servo feedback controller. The peak filter modifies the open loop transfer function and the error rejection function of the servo control loop to provide a higher rejection at the identified frequency. The peak filter may be switched out of or uncoupled from the servo feedback controller during track-seeking or as desired, depending on the amplitude of the sensor signal or the amplitude of the PES.
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Baugh Eric Gordon
Semba Tetsuo
White Matthew T.
Berthold Thomas R.
Hitachi Global Storage Technologies - Netherlands B.V.
Wong K.
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