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:
Jun. 21, 2016
Filed:
Oct. 23, 2014
Ricoh Imaging Company, Ltd., Tokyo, JP;
Moriyasu Kanai, Saitama, JP;
RICOH IMAGING COMPANY, LTD., Tokyo, JP;
Abstract
A finder optical system includes an image inverter optical member and an eyepiece lens system. The eyepiece lens system includes a first lens element, a positive biconvex second lens element, and a meniscus third lens element having a concave surface on the eyepoint side, in that order from the object side. A diopter adjustment operation is performed by moving the second lens element along the optical axis. Conditions (1) and (2) are satisfied:−0.2<3<0.2  (1), and2.15<(3−1)/3<3.00  (2),wherein f designates the focal length of the entire the eyepiece lens system at a diopter of −1, f3 designates the focal length of the third lens element, L3n designates the refractive index at the d-line of the third lens element, and L3b designates the radius of curvature of the surface on the eyepoint side of the third lens element.