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. 03, 2012
Filed:
Oct. 01, 2009
Takanori Watanabe, Shizuoka, JP;
Hiroshi Iwai, Shizuoka, JP;
Isamu Hashimoto, Shizuoka, JP;
Alphana Technology Co. Ltd., Fujieda-shi, Shizuoka, JP;
Abstract
In a brushless motor, the rotational frequency N (Hz) of the hub satisfies N<F/(3*P+2), where F(Hz) is an Eigen frequency of the second order rocking-mode resonance when not rotating in the situation where the recording disk is mounted on the hub. The recording disk is mounted on the hub. A base plate rotatably supports the hub. A laminated core is fixed to the base. The core has a ring portion and a plurality of teeth that extend radially from the ring portion. Coils are wound around the plurality of teeth. The coils are three-phase driven. A cylindrical magnet is fixed to the hub. The cylindrical magnet are magnetized for driving with P (P is a natural number) poles along the circumferential direction and are arranged to radially face the plurality of teeth.