The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 31, 1990
Filed:
Feb. 23, 1989
Koichi Maeda, Nishinomiya, JP;
Akio Takigawa, Nishinomiya, JP;
Yasuyoshi Tago, Nishinomiya, JP;
Motoaki Yoshida, Kawanishi, JP;
Nippon Sheet Glass Co., Ltd., Osaka, JP;
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.