JPS54136347A - Spectacle lens - Google Patents

Abstract

PURPOSE: To give a continuous and comfortable field of view from far to near vision to the person whose crystalline lens has decreased in control power by so forming the lens that the group of intersecting lines that the plane rectangular to the main meridian assumes becomes smaller in curvature on the lower side and larger on the upper side.

CONSTITUTION: The lens is divided to a far vision part F, progressive focus part P and near vision part N along the main meridian MM' and the circular intersecting line composed of the face crossing the line MM' at a right angle and refractive face exists at the point A. The circular intersecting lines are at the top end of the region P or above this to enable a wide field of view to be obtained from the point P up to the region N. The curvature of the group of intersecting lines perpendicular to the line MM' in the region P and region N becomes smaller as it goes further from the line MM', thus enabling the astigmatism and distortion aberrations around the lens to be minimized. In the region F, the curvature of the group of intersecting lines becomes larger as it goes further from the line MM' and therefore the balance of the distortion aberrations of the entire part of entire part of the lens may be improved.

COPYRIGHT: (C)1979,JPO&Japio