JPS54118851A - Spectacle lens - Google Patents

Abstract

PURPOSE: To obtain a comfortable field of view continuously from far vision to near vision by forming a far vision part, an intermediate part where curvature progressively changes and a near vision part along the main meridian provided in the nearly central longitudinal direction.

CONSTITUTION: The main meridian MM' provided in the nearly central longitudinal direction is made umbilical over the entire line and is segmented to a far vision sight correcting portion F, an intermediate sight correcting portion P where curvature changes progressively and a near vision sight correcting protion N, these being respectively continuously connected at the boundaries. Then, the circular intersecting line that the face crossing at a right angle to the main meridian MM' and the refractive face assume comes to the intermediate port of the intermediate sight correcting portion P, thus enabling the field of view of good total balance from the far vision sight correcting portion F to the intermediate and near vision sight correcting parts P, N. In addition, the curvatures of the intersecting line group perpendicular to the main meridian MM' in the intermediate and near vision sight correcting portions P, N become smaller as they go away from the main meridian MM' and said curvatures become larger as they go away from the main meridian MM' in the upper part of the intermediate sight correcting protion P and the far vision sight correcting part F, thus the astigmatisms and distortion aberrations in the entire part of the lens are reduced.

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