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US 8,147,062 B2Granted
Progressive-power lens
AssigneeSeiko Epson Corporation
InventorsTadashi Kaga, Toshihide Shinohara
Life of this patent
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Abstract
An eye-side refractive surface 11 of a distance portion is concave and at least part of an eye-side refractive surface 3 of a near portion is a convex region 31 where one or both of principal meridians of the surface are convex. This provides a back surface progressive-power lens capable of solving disadvantages in terms of lens thickness, external appearance and the like in a back surface progressive-power lens in which the eye-side refractive surface is formed of a progressive-power surface.
Claims3
A progressive-power lens comprising:
- an object-side refractive surface;
- and
- an eye-side refractive surface, the eye-side refractive surface including:
- a distance portion having power to view relatively distant objects;
- a near portion having power to view relatively near objects;
- and
- an intermediate portion having power to continuously view intermediate objects between the distant and near objects,
- wherein the eye-side refractive surface of the distance portion is concave,
- wherein at least part of the eye-side refractive surface of the near portion is a convex region, and
- wherein the ratio of the surface area of the convex region within a circle having a radius of 25 mm from the geometrical center of the progressive-power lens to the surface area of the circle is less than or equal to 30%.
7 more elements
Dependencies are inferred from the claim text.