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:
Jun. 24, 2014
Filed:
Dec. 08, 2011
Ko Ishizuka, Saitama, JP;
Ko Ishizuka, Saitama, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
An absolute rotary encoder comprises: a rotary member which includes a cylindrical surface on which a plurality of marks are arranged at a predetermined pitch in a circumferential direction; a light source configured to emit a light toward the cylindrical surface; a detector configured to detect a predetermined number of marks of the plurality of marks; and a computing device configured to obtain an absolute rotation angle of the rotary member based on an output from the detector. The detector is configured to output a signal corresponding to the predetermined number of marks and having an uneven period resulting from a geometrical layout of the light source, the cylindrical surface, and the detector. The computing device is configured to correct the signal using correction data so as to reduce unevenness of the period, and to obtain the absolute rotation angle of the rotary member using the corrected signal.