JPS54118850A - Spectacle lens - Google Patents

Abstract

PURPOSE: To obtain a comfortable field of view continuously from far vision to near vision by providing a far vision part, an intermediate part where curvature changes progressively and a near vision part along the umbilical main meridian.

CONSTITUTION: The main meridian MM' provided in the nearly central longitudinal direction is made umbilical over the entire line and is semgented to a far vision sight correcting portion F, an intermediate sight correcting portion P where curvature changes progressively and a near vision sight correcting portion N, which are 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 positions in the intermediate part of the intermediate sight correction 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 portion P, N to be obtained. In addition, the curvatures of the intersecting line group perpendicular to the main meridian MM' become smaller as they go away from the main meridian MM' in the lower part of the intermediate sight correcting portion P and the near vision sight correcting portion N, and since the main meridian MM' is umbilical, a comfortable field of view may be obtained along the main meridian MM'.

COPYRIGHT: (C)1979,JPO&Japio