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:
Apr. 18, 1990
Shoji Takahashi, Saitama, JP;
Citiaen Watch Co., Ltd., Tokyo, JP;
Abstract
A drive circuit for a stepping motor which seeks the read/write head of an FDD or the like to a predetermined track. The drive circuit includes a plurality of exciting coils for providing exciting fields to a rotor and supplies exciting currents in the forward or reverse direction by a predetermined combination to each of the exciting coils. A constant-current circuit is provided so as to cause the exciting current flowing on each exciting coil to have a constant value. The constant-current circuit includes a current mirror circuit with the slave branch connected to the exciting coils and the master branch contained in the constant-current circuit. The constant-current circuit further includes a constant-current source for supplying a constant current to the master branch of the current mirror circuit and a constant-current setting circuit for setting the constant current as desired. By making the currents flowing on the exciting coils uniform, the seeking positional accuracy of the read/write head is improved.