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. 21, 1995
Filed:
Sep. 08, 1993
Seiji Takei, Kanagawa, JP;
Kouji Obara, Kanagawa, JP;
Nippon Thompson Co., Ltd., Tokyo, JP;
Abstract
A direct current motor drive apparatus generating low levels of heat is described. A pulse width modulation signal, generated by a pulse width modulator corresponding to a torque command signal, is applied to a Hall effect element. The Hall effect element then generates an output corresponding to the number of lines of magnetic force of a field magnet on the moving side. After this output is amplified by an operational amplifier, waveform shaping is performed by first and second comparators. The resulting signals are then amplified by first and second power amplifiers and supplied to excitation coils. Since waveform shaping is performed on the signal applied to each of the power amplifiers mentioned above, the power amplifiers operate in a region of roughly complete switching, thereby suppressing the generation of heat.