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:
Feb. 18, 1992
Filed:
Feb. 21, 1990
Applicant:
Inventor:
Nozomu Kitagishi, Tokyo, JP;
Assignee:
Canon Kabushiki Kaisha, Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G03B / ;
U.S. Cl.
CPC ...
354200 ; 359569 ;
Abstract
A focusing screen suited to be used in the camera, having three plane portions of different heights in each of small areas, wherein the plane portion A, the plane portion B and the plane portion C are arranged in the order from the lowest height, and letting the height of the plane portion B measured from the plane portion A be denoted by d.sub.B, the height of the plane portion C from the plane portion A by d.sub.C, and the area ratios of the plane portions A, B and C to the entire area by S.sub.A, S.sub.B and S.sub.C (where S.sub.A +S.sub.B +S.sub.C =1) respectively, the following conditions are satisfied