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:
Apr. 01, 1997
Filed:
Oct. 27, 1994
Li-Hsin D Lu, San Jose, CA (US);
Karl M Schlager, Campbell, CA (US);
SGS-Thomson Microelectronics, Inc., Carrollton, TX (US);
Abstract
A method and apparatus for switching a motor between bipolar and unipolar mode. During each phase of the bipolar mode, one of the coils floats and has a back emf. In the method, first, a mode change signal requesting a change between the bipolar mode and the unipolar mode is received. Second, the back emf across the floating coil is monitored. Third, a point in time when the back emf equals the center tap voltage is detected. Last, the motor is switched between the bipolar mode and the unipolar mode at a point away from point in time when the back emf across the floating coil equals the center tap voltage. Various circuitry is also disclosed for switching a motor between a bipolar mode and a unipolar mode.