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:
Oct. 08, 1996
Filed:
Feb. 21, 1995
Yasuhiro Okada, Tottori, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
A speed control system for brushless DC motors which maintains the rotational speed of the motor substantially constant even when the motor load and/or supply voltage fluctuates. Furthermore, by including a negative-resistance temperature coefficient thermistor in the speed control system, the rotational speed of the brushless DC motor may be varied as a function of ambient temperature. Thus, if the brushless DC motor is part of a motor fan and there is an increase in the ambient temperature, the rotational speed of the motor will increase to provide additional cooling. In contrast, if the ambient temperature decreases, the rotational speed of the brushless DC motor will be reduced thereby resulting in quieter operation of the motor.