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:
Sep. 02, 1986
Filed:
Dec. 22, 1981
Seiko Epson Corporation, Tokyo, JP;
Abstract
A synthetic resin lens having a refractive index of at least 1.55 and an antireflection coating thereon is provided. The antireflection coating includes at least a hard coat layer formed of a dielectric substance having a refractive index n.sub.h disposed on the lens having a refractive index n.sub.s (n.sub.s .noteq.n.sub.h) and at least one antireflection layer of a dielectric or metallic material disposed between the lens and the hard coat layer. The antireflection layer has a refractive index n in the range represented by the formula: ##EQU1## and an optical film thickness of 4 (where denotes a wavelength in the range between about 450 nm to 650 nm) or two or more plies optically equivalent to a single layer of the antireflection material. The synthetic resin lens may be prepared by radical polmerization of a mixed monomer solution of styrene, 2,2-bis[3,5-dibromo-4-(2-methacryloloxyethoxy)phenyl]propane, and ultraviolet absorber and a light stabilizer. Such synthetic resin lenses generally have a refractive index of about 1.6 and a surface hardening layer usually SiO.sub.2 has a refractive index of about 1.46. It is desirable to provide an antireflection layer having a refractive index of about 1.52 which may be provided by a first layer of silicon dioxide and another layer of an oxide selected from the group of oxides of ZrO.sub.2, HfO.sub.2, Ti.sub.2 O.sub.3 TiO.sub.2, Ta.sub.2 O.sub.5, Si.sub.3 N.sub.4, Yb.sub.2 O.sub.3, Y.sub.2 O.sub.3 or Al.sub.2 O.sub.3. An outer antireflection layer is then disposed on the outer surface of the surface hardening layer.