Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the head
Reexamination Certificate
2011-01-04
2011-01-04
Sniezek, Andrew L (Department: 2627)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the head
C360S077020, C360S078040
Reexamination Certificate
active
07864484
ABSTRACT:
A hard-disk drive (HDD). The HDD includes a main control circuit. The main control circuit includes a frequency-hunting peak filter. The frequency-hunting peak filter includes a peak filter wherein a gain at a center frequency becomes finite and a reciprocal of the transfer function is represented by z/FDin z-transform space. The denominator of the transfer function of the peak filter that is represented by FD, has a real part that becomes zero at the center frequency and an imaginary part that becomes a positive number at the center frequency. In addition, the frequency-hunting peak filter includes a frequency updating unit that updates the center frequency to converge onto a frequency of disturbance by obtaining a comparative relation between the center frequency and the frequency of disturbance acting on the control system in accordance with a phase difference between an input and output of the transfer function represented by z/FD.
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Kisaka Masashi
Uchida Hiroshi
Hitachi Global Storage Technologies - Netherlands B.V.
Sniezek Andrew L
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