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. 25, 1983
Filed:
Mar. 02, 1981
Mitsuo Uzuka, Urawa, JP;
Sony Corporation, Tokyo, JP;
Abstract
A drive circuit for an alternate-phase brushless DC motor is arranged to minimize the torque ripple normally occurring with such motors. The motor has rotor magnets and at least two stator coils, and has a torque relationship in which the rotational torque for each coil extends over an electrical angle of more than 180 degrees and has gradual rising and falling portions intersecting with respective falling and rising portions of the torque of the other coil. The drive circuit includes a rotary position sensor, such as a Hall element, switching transistors for driving the stator coils, and switching signal forming circuitry responsive to the sensor to switch the switching transistors on and off alternately. In order to reduce the torque ripple, the drive circuit is made to energize the stator coils in the region of the intersections of the rotational torque, so that the coils are energized for more than 180 electrical degrees. In one preferred embodiment, a pair of additional switching transistors coupled to the stator coils are switched on by a circuit formed of a pair of differential amplifiers coupled to the Hall element and, through a logic gate, to the additional switching transistors.