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:
May. 12, 1992
Filed:
Apr. 08, 1991
Renshi Sawada, Sayama, JP;
Hidenao Tanaka, Tokyo, JP;
Osamu Ohguchi, Kawasaki, JP;
Junichi Shimada, Iruma, JP;
Nippon Telegraph & Telephone Corporation, Tokyo, JP;
Abstract
An encoder includes a semiconductor laser capable of emitting two coherent light beams from two end faces thereof, respectively. The end faces of the semiconductor laser are arranged such that the coherent light beams intersect each other. The two coherent light beams emitted from the end faces of the semiconductor laser are incident on a scale having a plurality of gratings. The two coherent light beams are diffracted by the gratings, resulting in two diffracted light beams. The two diffracted light beams interfere with each other, and the intensity of the resultant interference light beam is detected by a detector. In response to this detection, the detector produces a signal corresponding to the intensity change which is proportional to the relative moving distance between the detector and the scale.