JPS5484755A - Spectacle lens - Google Patents

Abstract

PURPOSE: To eliminate fluctuations of an image in the medium vision position, by providing a part, which is not an umbilical point, in the plane running along the principal meridian in the near-sightedness correcting position, and providing an umbilical point curve in the horizontal direction in the medium vision correcting position so as to remove astigmatism in the near-sighted vision.

CONSTITUTION: In the long-sightedness correcting position F of variable focal spectacle lens, the intersecting line group formed by the plane orthogonal to the principal meridian M-M' and the refracted plane is not circular, and the curvature decreases as going away from the principal meridian M-M'. The near-signtedness correcting position N is an aspherical face symmetrical with respect to the axis of non-rotation, and the curvature decreases as going away from the principal meridian M-M'. In the plane running along the principal meridian M-M', a part which is not an umbilical point is provided in at least one part. In the medium vision correcting position P, the intersecting line group Cn-Cn' formed by the plane Ln orthogonal to the principal meridian M-M' and the refracted plane also contains a curve which is not circular, and the plane running along a certain intersecting line Cn-Cn' is shaped in an umbilical point.

COPYRIGHT: (C)1979,JPO&Japio