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:
Mar. 31, 1992
Filed:
May. 23, 1990
Applicant:
Inventors:
Tetsuharu Nishimura, Kawasaki, JP;
Koh Ishizuka, Kawasaki, JP;
Assignee:
Canon Kabushiki Kaisha, Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G01D / ;
U.S. Cl.
CPC ...
25023116 ; 2502 / ; 356356 ;
Abstract
A rotary encoder wherein coherent beams are caused to be incident at different positions of a diffraction grating mounted on a rotary object, different beams diffracted from the diffraction grating are caused to overlap and form interference fringes, the fringes are detected by a light receiving detector to detect a rotational state of the rotary object, and the parallelism a of the rotary object satisfies the following inequality: