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. 07, 2009
Filed:
Apr. 24, 2007
Isao Yoneda, Kanagawa, JP;
Kazuyuki Ishibashi, Kanagawa, JP;
Takeshi Chawanya, Kanagawa, JP;
Hiroshi Uchida, Kanagawa, JP;
Isao Yoneda, Kanagawa, JP;
Kazuyuki Ishibashi, Kanagawa, JP;
Takeshi Chawanya, Kanagawa, JP;
Hiroshi Uchida, Kanagawa, JP;
Hitachi Global Storage Technologies Netherlands B.V., Amsterdam, NL;
Abstract
Embodiments in accordance with the present invention provide a magnetic disk drive with sufficiently low noise. A digital/analog converter supplies to a voice coil motor (VCM) driver a control voltage comprising a first preset voltage value, a second preset voltage value, and a transition voltage value of a substantially cosine wave that interconnects the first preset voltage value and the second preset voltage value. A driving current is supplied from the VCM driver to a voice coil of an actuator assembly. Since a current not containing higher-harmonic components in a transition period flows as a VCM current that flows into the voice coil, vibromotive force can be easily suppressed by shifting a structural resonance point of the entire disk drive including the actuator assembly. In addition, since the back electromotive force occurring in an inductance element is cleared to zero during a half wavelength of period of the cosine wave, speed electromotive force can be measured by immediate shifting from a setting period to a measuring period.