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. 04, 1991
Filed:
Mar. 20, 1990
Applicant:
Inventors:
Tetsuharu Nishimura, Kawasaki, JP;
Koh Ishizuka, Urawa, JP;
Satoshi Ishii, Tokyo, JP;
Masaaki Tsukiji, Tokyo, JP;
Assignee:
Canon Kabushiki Kaisha, Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G01D / ;
U.S. Cl.
CPC ...
25023116 ; 2502 / ;
Abstract
An encoder of this invention radiates a light beam onto an optical scale, in which a reflection film is formed on a surface of a relief type diffraction grating formed on one surface of a light-transmission substrate, from a surface opposite to the formation surface of the diffraction grating, and detects a change in intensity of interference light caused by diffracted light produced by the diffraction grating, thereby measuring a displacement of the optical scale.