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. 08, 2008
Filed:
Jun. 13, 2003
Hideki Kawai, Nishinomiya, JP;
Toshiharu Mori, Settsu, JP;
Hideki Kawai, Nishinomiya, JP;
Toshiharu Mori, Settsu, JP;
Minolta Co., Ltd., Osaka, JP;
Abstract
A glass substrate for use as the substrate of an information recording medium such as a magnetic disk, magneto-optical disk, DVD, or MD or of an optical communication device, and a glass composition for making such a glass substrate, contains the following glass ingredients: 45 to 75% by weight of SiO; 1 to 20% by weight of AlO; 0 to 15% by weight, zero inclusive, of BO; SiO+AlO+BOaccounting for 65 to 90% by weight; a total of 7 to 20% by weight of RO compounds, where R=Li, Na, and K; and a total of 0 to 12% by weight, zero inclusive, of R'O compounds, where R′=Mg, Ca, Sr, Ba, and Zn. Moreover, the following conditions are fulfilled: BO=0% by weight, or AlO/BO≧1.0; and (SiO+AlO+BO)/(the total of RO compounds+the total of RO compounds)≧3.