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:
Aug. 29, 2000
Filed:
Feb. 16, 1999
Kazuhiko Nishimura, Kyoto, JP;
Rohm Co., Ltd., Kyoto, JP;
Abstract
A sensorless motor driver receives the back electromotive forces appearing in the individual coils provided one for each phase in a brushless motor and the voltage at the node common to all of those coils, and produces square-wave signals including noise. These signals are then subjected to masking by a masking circuit in accordance with a noise masking signal produced by a masking signal producing circuit. In accordance with the thus masked signals, a driving current is supplied to the brushless motor. The driving current varies according to the load on the motor. The masking signal producing circuit monitors the driving current supplied to the motor, and outputs the masking signal in such a way that the length of the masking periods varies according to the driving current.