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:
Apr. 17, 2001
Filed:
Oct. 28, 1999
Yasuhito Shimizu, Yamato, JP;
Naoyuki Kagami, Fujisawa, JP;
Akira Tokizono, Fujisawa, JP;
Akihiro Ohyama, Funabaski, JP;
International Business Machines Corporation, Armonk, NY (US);
Abstract
A spindle motor start up method wherein a torque balance between the stator and rotor is broken so as to avoid startup malfunctions, and thereby improve motor startup time in spindle motors prone to startup malfunctions, such as hard disk drive motors having a 4:3 ratio of the number of rotor magnetic poles to the number of stator slots. Processes for breaking a torque balance according to the present invention include: (1) gradually decreasing an initial commutation (switching of each phase) frequency at the startup timing from a frequency higher than a commutation frequency in a conventional startup; (2) gradually decreasing an initial commutation frequency at the startup timing from a frequency higher than a commutation frequency in a conventional startup to a low frequency, and next, gradually increasing the initial frequency from the low frequency; (3) changing a drive current of the spindle motor so as to break a torque balance between the spindle motor stator and rotor; (4) monitoring a back electromotive force detection signal while commutating, and restarting commutation when the back electromotive force detection signal is not detected; and (5) monitoring a back electromotive force detection signal while commutating, resetting the commutation at a time in a commutation sequence after an initial commutation from a first phase to a second phase, and restarting the commutation from the first phase to the second phase.