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:
May. 07, 2002
Filed:
Mar. 02, 1999
Applicant:
Inventors:
Assignee:
Kabushiki Kaisha Ohara, Kanagawa-ken, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
B32B 1/706 ; C03C 3/085 ; G11B 5/84 ;
U.S. Cl.
CPC ...
B32B 1/706 ; C03C 3/085 ; G11B 5/84 ;
Abstract
There is provided a glass-ceramic substrate for an information storage medium usable in an information storage device of the ramp loading system. The glass ceramic substrate has a Young's modulus (GPa)/specific gravity of or over and includes 5.3 to 8 weight percent (expressed on an oxide basis) of Al O . The glass ceramic substrate has, as its predominant crystal phases, lithium disilicate (Li O.2SiO ) and &agr;-quartz (&agr;-SiO ), has a coefficient of thermal expansion within a range from 65×10 /° C. to 130×10 /° C. within a temperature range from −50° C. to +70° C. and has a surface roughness (Ra) (arithmetic mean roughness) of 9 Å or below.