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. 18, 1990
Filed:
Jun. 13, 1989
Hiromu Mukai, Osaka, JP;
Etsuko Nakai, Osaka, JP;
Minolta Camera Kabushiki Kaisha, Osaka, JP;
Abstract
A finder optical system comprises a first reflecting surface disposed at an image side of an objective lens to reflect light flux passing through the objective lens obliquely upward on the exit pupil side, a roof surface consisting of two reflecting surfaces orthogonally intersecting each other which is disposed obliquely upward on the exit pupil side of the first reflecting surface to perform right-left inversion of the light flux reflected by the first reflecting surface and to reflect the light flux obliquely downward on the exit pupil side, and a second reflecting surface disposed obliquely downward on the exit pupil side of the roof surface to perform an up-down inversion of the light flux reflected obliquely downward on the exit pupil side by the roof surface and reflect the light flux toward an eyepiece, and wherein the finder optical system fulfills the following condition: 20.degree.<.theta.<40.degree. wherein, .theta. represents an angle made by the first reflecting surface and an optical axis of the objective lens. Thereby, an optical path length in an erecting system can be shortened, and the finder optical system itself becomes long in the direction of the objective lens, and therefore a finder image without eclipse can be obtained at high magnification.