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. 20, 1991
Filed:
Jun. 29, 1989
Hiroshi Iwai, Fujieda, JP;
Abstract
A dc motor apparatus with an index signal output comprises: a dc motor including: a stator having driving coils; a rotor having plural pairs of magnetic poles; plural magnetic sensors provided to the stator for sensing magnetic flux from the plural magnetic poles, one of the sensors producing a first signal; and a driving circuit responsive to output signals of the plural magnetic sensors for producing drive signals to energize the driving coils; and one of the magnetic poles magnetized to exhibit a different intensity of magnetic flux density from that of remaining poles; a peak level detecting circuit responsive to the first signal for detecting a peak level thereof and holding it for a predetermined interval to produce a reference signal; and comparing circuit for producing a second signal when the first signal has a predetermined relationship with the reference signal n. A level of the reference signal is changed in accordance with a detected peak level of the signal of the magnetic sensors to generate an index signal stably.