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:
Nov. 07, 2006
Filed:
Jan. 05, 2005
Nobuhisa Koide, Kanagawa, JP;
Gaku Ikedo, Kanagawa, JP;
Nobuhisa Koide, Kanagawa, JP;
Gaku Ikedo, Kanagawa, JP;
Hitachi Global Storage Technologies Netherlands B.V., Amsterdam, NL;
Abstract
Embodiments of the invention avoid erroneous drive current control at the time of a change in the drive waveform for a spindle motor. In one embodiment, a drive current setup section acquires the actual rotational speed from a rotational speed determination section. If the drive waveform is not changed, the feedback system for a first gain determines a drive current. Drive current data corresponding to the drive current is set in a register. If the drive waveform data switches to a curved wave during the next timing cycle, the feedback system does not perform any process, but the same drive current data as for the immediately preceding timing cycle is set in the register. During the next timing cycle, the actual rotational speed is acquired from the rotational speed determination section, and the feedback system for a second gain determines the drive current. When the drive waveform data changes, the feedback system process is skipped once. Therefore, erroneous drive current control can be avoided at the time of a drive waveform change.