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:
Apr. 15, 2003
Filed:
Jul. 12, 2002
Applicant:
Inventors:
Junji Kurachi, Osaka, JP;
Akihiro Koyama, Osaka, JP;
Nobuyuki Yamamoto, Osaka, JP;
Yasuhiro Saito, Osaka, JP;
Kazuishi Mitani, Osaka, JP;
Koichi Ataka, Osaka, JP;
Yoshihiro Matsuno, Osaka, JP;
Assignee:
Nippon Sheet Glass Co., Ltd., Osaka, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G11B 5/82 ; C03C 1/700 ; C03C 3/076 ;
U.S. Cl.
CPC ...
G11B 5/82 ; C03C 1/700 ; C03C 3/076 ;
Abstract
A glass substrate for an information recording medium has an acid resistance represented by an etching rate of at most 45 nm/min. upon contact with a hydrofluoric acid having a temperature of 50° C. and a concentration of 0.1 weight %. The glass substrate has a recording surface having an average surface roughness Ra smaller than 0.3 nm.