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:
Jul. 01, 2008
Filed:
Feb. 03, 2006
Takenori Atsumi, Ibaraki, JP;
Atsushi Okuyama, Kanagawa, JP;
Takenori Atsumi, Ibaraki, JP;
Atsushi Okuyama, Kanagawa, JP;
Hitachi Global Storage Technologies Netherlands B.V., Amsterdam, NL;
Abstract
In one embodiment, the magnetic disk drive has a magnetic head, an actuator driving the magnetic head, and a control portion controlling a controlled object, including the magnetic head and the actuator, by creating a control signal based on a given target position signal and on a position signal played back by the magnetic head such that the magnetic head reaches a target position. The control portion is so configured that the phase of the open-loop transfer characteristic at the frequency of the resonant characteristics is arctangent ((Rop+1)/Iop) when (a) the resonant characteristics are present at frequencies other than the mechanical resonant frequency of the controlled object in the open-loop transfer characteristics when the control portion and the controlled object are connected, (b) the frequency of the resonant characteristics is higher than the frequency at which the gain characteristic of the open-loop transfer characteristics becomes 0 dB, and (c) the coordinates of a vector locus of the open-loop transfer characteristic at the frequency of the resonant characteristic are given by (Rop, Iop).