Glass-ceramic substrate for an information storage medium
US6383645B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 2, 1999 |
| Grant date | May 7, 2002 |
| Priority date | — |
| Expiry date | Mar 2, 2019 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S428/90
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
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 37 or over and includes 5.3 to 8 weight percent (expressed on an oxide basis) of Al2O3. The glass ceramic substrate has, as its predominant crystal phases, lithium disilicate (Li2O.2SiO2) and &agr;-quartz (&agr;-SiO2), has a coefficient of thermal expansion within a range from 65×10−7/° C. to 130×10−7/° 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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.