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. 13, 2001
Filed:
Dec. 02, 1999
Yoshimi Obara, Tokyo, JP;
Asahi Kogaku Kabushiki Kaisha, Tokyo, JP;
Abstract
A back-surface progressive power lens is provided having a negative dioptric power for distance vision, the value of a surface power Pf,of the progressive surface in the main meridional plane at a first point on the main meridian in a distance portion of the progressive power lens is less than the value of a surface power Pf,of the progressive surface in a plane perpendicular to the main meridional plane at the first point; and the value of a surface power Pn,of the progressive surface in the main meridional plane at a second point on the main meridian in a near portion of the progressive power lens is greater than the value of a surface power Pn,of the progressive surface in a plane perpendicular to the main meridional plane at the second point. The surface power P is defined by the following condition: P=(n−1)/r; wherein “n” represents the refractive index of the progressive power lens, and “r” represents the radius of curvature at one of the first point and the second point on the main meridian in the near portion and the distance portion, respectively.