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:
Sep. 14, 2010
Filed:
Aug. 23, 2006
Satoshi Miyajima, Kyoto, JP;
Hiroaki Hayashi, Kyoto, JP;
Tomofumi Mishima, Kyoto, JP;
Rohm Co., Ltd., , JP;
Abstract
A drive circuit of a fan motor is provided. In an embodiment of the drive circuit, a first PWM comparator compares a temperature detection voltage with a cyclic voltage, and outputs a first PWM signal. A second PWM comparator compares a minimum frequency setting voltage indicating a minimum frequency of the fan motor, with the cyclic voltage, and outputs a second PWM signal. The drive circuit combines the first PWM signal and the second PWM signal by a logical operation, to drive the fan motor. The drive circuit includes a first logic gate which generates a logical sum of the first PWM signal and the second PWM signal, and a second logic gate which generates a logical product of the first PWM signal and an inverted signal of the second PWM signal. The drive circuit switches drive mode based on the first logic gate and the second logic gate.