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:
Jan. 28, 1997
Filed:
Aug. 03, 1994
Naoyuki Maeda, Inuyama, JP;
TRW Steering Systems Japan Co., Ltd., Aichi-ken, JP;
Abstract
A device for detecting asynchronization or stepping out of a stepping motor without making the stepping motor large in size. Parallel resonance circuit LC is provided in a recovery circuit of stator coil RL of the stepping motor for detecting linking current IX. If the stepping motor is out of step, the magnetic resistance between stator and rotor increases while the reactance of stator coil RL decreases. When motor drive current ID is turned off, a large transient current is momentarily generated yet is quickly dampened. While the motor drive current ID is off, linking current IX approaches zero. Consequently, if the stepping motor is out of step, there is no substantial difference in the linking current IX when motor drive current ID is turned on from when motor drive current ID was off. Also, the amplitude of the transient or resonance waveform is smaller than the amplitude when the stepping motor is operating normally. By thus detecting the resonance waveform of the parallel resonance circuit when motor drive current ID is turned on, it can be precisely determined whether or not the stepping motor is out of step.