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. 14, 2009
Filed:
Aug. 21, 2007
Kazuaki Usui, Kanagawa, JP;
Masashi Kisaka, Kanagawa, JP;
Hidefumi Tominaga, Kanagawa, JP;
Koumei Hanaoka, Kanagawa, JP;
Masaki Nagashima, Kanagawa, JP;
Kazuaki Usui, Kanagawa, JP;
Masashi Kisaka, Kanagawa, JP;
Hidefumi Tominaga, Kanagawa, JP;
Koumei Hanaoka, Kanagawa, JP;
Masaki Nagashima, Kanagawa, JP;
Hitachi Global Storage Technologies Netherlands B.V., Amsterdam, NL;
Abstract
Embodiments in accordance with the present invention provide a drive unit that is capable of satisfactorily performing the positioning control with disturbance components included in a position error signal being effectively controlled. According to one embodiment, an error signal generator of a drive unit generates a position error signal (PES) on the basis of servo data read out from a magnetic disk. On the assumption that a frequency of a periodic variation component included in the PES is a target frequency, if a target frequency deviates from an effective frequency range of a digital filter, a downsampler down-samples the PES, and then supplies the PES to the digital filter so that the effective frequency range is shifted. As a result, within the shifted effective frequency range, a setting changing unit can control a setting frequency of the digital filter so that the setting frequency follows the target frequency. Therefore, it is possible to effectively reduce a signal component of the target frequency (a periodic variation component included in the PES).