Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Ophthalmic lenses or blanks
Patent
1994-05-27
1996-06-04
Sugarman, Scott J.
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Ophthalmic lenses or blanks
G02C 706
Patent
active
055238076
ABSTRACT:
In a progressive multifocal lens of the present invention, the horizontal sectional shape of a refracting surface of the lower portion of a farsight portion defines a non-circular arc in which a horizontal section curvature is increased and then decreased away from an intersecting point with the principal meridional curve along a horizontal crossing curve, the horizontal sectional shape of a refracting surface of the upper portion of a nearsight portion defines a non-circular arc in which a horizontal section curvature is decreased and then made approximately constant away from an intersecting point with the meridional curve along a horizontal crossing curve, the gradient of the decrease of a horizontal section curvature is approximately constant from the upper portion of the nearsight portion to the lower portion thereof, the horizontal sectional shape of a refracting surface of the center of an intermediate portion in which a horizontal section curvature is decreased away from an intersecting point with the principal meridional curve along a horizontal crossing curve, and the gradient of the decrease of a horizontal section curvature is increased approaching the nearsight portion from the center of the intermediate portion.
REFERENCES:
patent: 5000559 (1991-03-01), Takahashi et al.
patent: 5048945 (1991-09-01), Ueno et al.
Guilino, G. H., "Design Philosophy for Progressive Addition Lenses", Applied Optics, vol. 32, No. 1, Jan. 1, 1993, pp. 111-117.
Takahashi Fumio
Ueno Yasunori
Umeda Toshiaki
Nikon Corporation
Sugarman Scott J.
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