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:
Sep. 10, 2019
Filed:
Jun. 30, 2017
Canon Kabushiki Kaisha, Tokyo, JP;
Masakazu Kodaira, Utsunomiya, JP;
CANON KABUSHIKI KAISHA, Tokyo, JP;
Abstract
A wide attachment which is detachably attached to an object side of a lens apparatus and in which a focal length of the lens apparatus is shifted to a short focal length side. The wide attachment is formed of a single meniscus lens having a negative refractive power. The lens has an aspherical surface. The following conditional expressions are satisfied: −5.2<−(r+r)/(r−r)<−1.3, and 1.50<nd<1.53, where rrepresents a curvature radius of a surface on an object side of the lens, rrepresents a curvature radius of a surface on an image side of the lens, and nd represents a refractive index of a material constituting the lens with respect to d-line, wherein a curvature radius of the aspherical surface is defined as a curvature radius of a spherical surface passing through a lens vertex and a maximum effective diameter of the aspherical surface.