Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Ophthalmic lenses or blanks
Patent
1989-02-23
1990-07-31
Lowe, James
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Ophthalmic lenses or blanks
264 17, 264 18, 350413, G02B 310, B29D 1100
Patent
active
049445847
ABSTRACT:
A plastic multifocal point spherical lens comprising a unitary structure of (A) a first synthetic resin layer having a fixed refractive index, (B) a second synthetic resin layer having a substantially fixed refractive index different from the refractive index of the first synthetic resin layer, and (C) a third synthetic resin layer existing between the first synthetic resin layer and the second synthetic resin layer and having a refractive index gradient varying continuously from the refractive index of the first synthetic resin layer to that of the second synthetic resin layer, part of the second synthetic resin layer and part of the third synthetic resin layer together being recessed into the first synthetic resin layer, and the second synthetic resin layer being thicker at the recessed part than the rest. The lens is prepared by (1) partially polymerizing a first monomer to form a partially polymerized molded mass, (2) applying a second monomer to substantially the entire surface of the partially polymerized molded mass, and (3) after part of the second monomer has diffused into the partially polymerized molded mass, subjecting the entire monomers to polymerization reaction and substantially completing the polymerization.
REFERENCES:
patent: 3485556 (1969-12-01), Naujokas
patent: 4208362 (1980-06-01), Deichert et al.
patent: 4701288 (1987-10-01), Cook et al.
Maeda Koichi
Tago Yasuyoshi
Takigawa Akio
Yoshida Motoaki
Lowe James
Nippon Sheet Glass Co. Ltd.
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