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. 22, 1978
Filed:
Sep. 08, 1976
Youichi Okuno, Yokohama, JP;
Takehiko Kiyohara, Zama, JP;
Tokuichi Tsunekawa, Yokohama, JP;
Teiji Hashimoto, Kawasaki, JP;
Canon Kabushiki Kaisha, Tokyo, JA;
Abstract
In a reflex camera having a penta prism positioned in the view-finder thereof, there is provided a glass member having a reflactive index equal to or larger than that of the penta prism and positioned in intimately contacting relation with the exit surface of said penta prism to utilize that portion of a view-finder image forming light beam which is directed to the exit surface of said penta prism after successive reflection from the two roof surfaces, the front reflection surface and again the roof surfaces of the penta prism such light beam portion would be otherwise subject to the total reflection from the exit surface in vain in measuring the light at a central portion of the view-finder image as well as at any portions outside thereof. In this way it being made possible to operate the camera selectively in a spot-metering mode or overall field of view light metering mode by the use of a single light value sensing means without causing the reduction of quality of the view-finder image.