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:
Aug. 27, 1991
Filed:
Apr. 26, 1989
Applicant:
Inventors:
Hirofumi Shibata, Asahikawa, JP;
Yasuaki Fukuda, Hadano, JP;
Assignee:
Canon Kabushiki Kaisha, Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G01B / ;
U.S. Cl.
CPC ...
356150 ; 356152 ; 356154 ;
Abstract
A mask structure and a mask positioning device, executes accurate and quick positioning of a mask having a generally ring-like shape. The mask structure includes a supporting frame of a generally ring-like shape, and at least one flat surface formed by a mirror surface is provided at a peripheral part of the supporting frame. Light is projected upon the flat surface and, on the basis of detection of reflected light therefrom, the mask can be positioned with respect to the rotational direction, the inclination and orthogonal coordinate position. The mask positioning device is adapted to execute such positioning accurately and quickly.