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:
Nov. 19, 2002
Filed:
Jul. 18, 2001
Shinichi Miyazaki, Suwa, JP;
Akihiko Ikegami, Okaya, JP;
Seiko Epson Corporation, , JP;
Abstract
When the brushless motor at rest is started, phase excitation is performed twice such that different phases are excited. A commutation reference point is set at a position at which a rotor has stopped after the second-time excitation. A position detector outputs pulse signals in response to a movement of an object driven by the brushless motor The pulse signals output from the position detector are monitored and commutation is controlled on the basis of the number of pulse edges of the pulse signals as counted starting from the commutation reference point. For example, the number of pulse edges output during a period starting from the commutation reference point and ending at a point of time at which commutation should be performed is measured in advance. When the number of pulse edges with reference to the commutation reference point becomes equal to the above predetermined number, it is determined that commutation timing has reached, and commutation is performed.