Hard-disk drive

Details Hard-disk drive Hard-disk drive

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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patent: 6853512 (2005-02-01), Ozawa
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patent: 2004/0105294 (2004-06-01), Kisaka
patent: 2008/0007861 (2008-01-01), Park et al.
patent: 04038777 (1992-02-01), None
Kisaka, Masashi “Adaptive Notch Filter by Using a Frequency Chasing Filter”,IIC-06-136(Hitachi Global Storage Technologies), 27-30.
Kisaka, Masashi “Frequency Chasing Peak Filter”,IIC-04-70(Hitachi Global Storage Technologies), 1-5.

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