The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 04, 2011
Filed:
May. 29, 2009
Masashi Kisaka, Kanagawa, JP;
Hiroshi Uchida, Kanagawa, JP;
Masashi Kisaka, Kanagawa, JP;
Hiroshi Uchida, Kanagawa, JP;
Hitachi Global Storage Technologies, Netherlands, B.V., Amsterdam, NL;
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/Fin z-transform space. The denominator of the transfer function of the peak filter that is represented by F, 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/F.