Pregrooved optical-disk
US4481620A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 22, 1982 |
| Grant date | Nov 6, 1984 |
| Priority date | — |
| Expiry date | Feb 22, 2002 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/25417
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical-disk according to an embodiment of the invention is disclosed. The optical-disk has a transparent substrate which has a surface in which a tracking groove is formed and which is made of a polymethyl methacrylate having a refractive index n.sub.1 of about 1.49, a transparent layer of polystyrene which is formed on the transparent substrate and which has a refractive index n.sub.2 of about 1.59, and a recording layer which is formed on the transparent layer of polystyrene and which is made of a substance which is melted by a pulse laser beam for recording, which becomes incident thereon through the transparent substrate and the transparent layer of polystyrene.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.