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. 09, 2004
Filed:
Apr. 17, 2002
Sunonwealth Electric Machine Industry Co., Ltd., Kaohsiung, TW;
Abstract
A speed-control drive circuit for a D.C. brushless fan motor includes a pulse width modulation input end for receiving an external pulse width modulation signal for controlling (and changing) the motor speed, and a motor winding drive circuit. The motor winding drive circuit and the pulse width modulation input end are connected to a set of motor windings. The pulse width modulation signal controls the motor winding drive circuit to cause excitation/unexcitation of the set of motor windings and to alternately changes a direction of current such that the set of motor windings adjusts a speed of the fan motor in response to excitation of the set of motor windings responsive to the pulse width modulation signal. The speed of the fan motor increases when an operational period of the pulse width modulation signal increases, and the speed of the fan motor decreases when the operational period of the pulse width modulation signal decreases.