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US 5,510,860 AGranted
Progressive multifocal lens
AssigneeNikon Corporation
InventorsYasunori Ueno, Toshiaki Umeda, Fumio Takahashi
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AssigneeNikon Corporation
InventorsYasunori Ueno, Toshiaki Umeda, Fumio Takahashi
Estimating the term…
A progressive multifocal lens of the present invention has, along a principal meridional curve, a farsight portion having a refracting power corresponding to a distant view, a nearsight portion having a refracting power corresponding to a near view, and an intermediate portion, located between the farsight and nearsight portions, for continuously connecting the refracting powers of the farsight and nearsight portions, wherein a refracting surface has a shape such that the angle .theta. formed by normal lines of the refracting surface at respective points on each of vertical crossing curves of the lens refracting surface and a principal meridional curve is changed gently and monotonously away from the principal meridional curve along the respective vertical crossing curves in a direction perpendicular to the principal meridional curve.
A progressive multifocal lens comprising, along a principal meridional curve, a farsight portion having a refracting power corresponding to a distant view, a nearsight portion having a refracting power corresponding to a near view, and an intermediate portion, located between said farsight and nearsight portions, for continuously connecting said refracting powers of the farsight and nearsight portions, and wherein a lens refracting surface has a shape such that the angle .theta. formed by normal lines of said refracting surface at respective points on each of vertical crossing curves of said lens refracting surface and a principal meridional curve is changed gently and monotonously away from said principal meridional curve along said vertical crossing curves.
Dependencies are inferred from the claim text.