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:
Dec. 04, 1990
Filed:
Mar. 14, 1990
Tetsuharu Nishimura, Kawasaki, JP;
Koh Ishizuka, Urawa, JP;
Masaaki Tsukiji, Tokyo, JP;
Satoshi Ishii, Tokyo, JP;
Yoichi Kubota, Kawasaki, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
A rotary encoder for detecting a rotation status of a rotary scale having a diffraction grating formed along a rotational direction comprises a directing device for directing a radiation beam to a first position on the rotary scale and directing a plurality of diffracted beams generated at the first position to a second position different from the first position. The direction device is constructed such that the plurality of diffracted beams gave a common light path between the first position and the second position. The encoder also includes a forming device for forming an interference beam from a plurality of rediffracted beams generated at the second position, and a convertor for converting the interference beam to a signal to produce the signal representing the rotation status.