Information recording medium having a glass substrate
US5008176A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 28, 1988 |
| Grant date | Apr 16, 1991 |
| Priority date | — |
| Expiry date | Sep 28, 2008 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/2457
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An information recording disk for recording an information signal along a track defined by a depression on the disk as a change of physical property of a recording material deposited on the track comprises a disk-shaped glass substrate made of a glass and carries a groove corresponding to the track. The groove has a surface roughness substantially smaller as compared to the surface roughness caused at a bottom surface of a groove on a silica glass substrate when both the disk-shaped glass substrate and silica glass substrate are dry-etched under same conditions. The disk-shaped glass substrate comprises SiO.sub.2 component and one or both of Al.sub.2 O.sub.3 and BaO components with substantially no alkali components. Further, a recording layer comprised of the recording material which changes in physical property responsive to a projected energy beam is deposited on the substrate such that the depression is formed in correspondence with the track.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.