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. 20, 2004
Filed:
Oct. 11, 2001
Tetsuro Yoshii, Osaka, JP;
Jun Yamaguchi, Osaka, JP;
Nippon Sheet Glass Co., Ltd., Osaka, JP;
Abstract
A compositional range for a mother glass composition for graded index lenses which has a desired refractive index and is less apt to be devitrified and to develop cracks upon ion exchange was obtained by incorporating at least a given amount of one or more ingredients which are selected from oxides of metal elements ranging from yttrium, atomic number 39, to tantalum, atomic number 73, and which are less apt to cause glass coloration into a glass based on SiO —TiO —Li O—Na O and containing no lead oxide. In particular, a compositional range in which a large angular aperture is obtained and devitrification is less apt to occur was obtained by incorporating Ta O and ZrO in a specific proportion and in specific amounts.