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:
Aug. 09, 2005
Filed:
May. 13, 2003
Takenori Atsumi, Ushiku, JP;
Takenori Atsumi, Ushiku, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A magnetic disk apparatus includes a following compensator for measuring a frequency characteristic of an under-control object to stabilize a vibration mode of the under-control object with phase condition and a resonance filter having a resonance point in the vicinity of a frequency at which positioning accuracy is to be enhanced, being coupled in parallel to the under-control object. Polarity of mode constant of the resonance filter is so determined as to stabilize a vibration mode brought about by the resonance filter on the basis of a relation between the frequency stabilized by a control system and the phase-180° crossover frequency. Positioning accuracy at a specific frequency can be enhanced without involving unstability in the control system even in a frequency range where sensitivity function of the control system is higher than 0 dB inclusive.