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:
Jan. 13, 1998
Filed:
Oct. 19, 1995
Francedilla.oise Ahsbahs, Saint-Maur-des-Fosses, FR;
Claude Pedrono, Briis Sous Forges, FR;
Essilor International, Charenton le Pont, FR;
Abstract
A progressive multifocal ophthalmic lens is provided having an aspherical surface with a mean sphere and a cylinder at every point. The aspherical surface has a distance vision portion, with a control point for distance vision, a near vision portion with a control point for near vision, and an intermediate vision portion between the near vision portion and the distance vision portion. A power addition value A is defined as a variation in mean sphere between the control point for distance vision and the control point for near vision portion. A base B is defined as a value of mean sphere at the control point for distance vision. A width of the near vision portion varies not only as a function of the power addition value A, but also as a function of the value B of the base. The invention thereby ensures the presence of a substantially constant object field for all values of the power addition and of the base.