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. 15, 2002
Filed:
Mar. 25, 1999
S. M. Sri-Jayantha, Ossining, NY (US);
Hien Dang, Nanuet, NY (US);
Arun Sharma, New Rochelle, NY (US);
Kiyoshi Satoh, Fujisawa, JP;
Tetsuo Ueda, Sagamihara, JP;
Hideki Ohzeki, Yokohama, JP;
Nayouki Kagami, Fujisawa, JP;
Kiochi Takeuchi, Yamato, JP;
International Business Machines Corporation, Armonk, NY (US);
Abstract
A hard disk has a servo loop and a rotating storage medium. The rotating storage medium has one or more significant flutter modes at frequencies below a zero cross frequency of a rejection transfer function of the servo loop. The effect of the forgoing is to allow the servo loop to better track a rotating medium that is subject to significant flutter. Peak filters with frequency bands that substantially overlap frequency bands of the significant flutter modes can also be added to the servo loop to further improve tracking. Multiple narrow band filters with frequency bands overlap can be used to cover the spectrum of a single flutter mode. Two lag-lead filters, the frequency responses of which overlap can be used to cover two adjacent significant flutter modes. At frequencies intermediate to the two adjacent flutter, modes, the lead caused by one filter, will be cancelled by the lag caused by the second.