Optical information recording and reproducing disc employing a film having thermally changeable optical characteristics
US4852076A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 16, 1987 |
| Grant date | Jul 25, 1989 |
| Priority date | — |
| Expiry date | Jun 16, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B27/32
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical information recording and reproducing disc information has a substrate in the surface of which are formed signal recording grooves and cue signal recording pits. A light-absorbing thin film is formed on the surface of the substrate, the optical characteristics of the light-absorbing film being changeable thermally through irradiation by a light beam. The pitches of the grooves and pits, as well as the widths of the grooves and pits, are determined to meet specific conditions in relation to the diameter of the laser beam which is used for recording and reproduction of the signals. In addition, the depths of the grooves and pits are determined suitably in relation to the wavelength of the laser beam. With this arrangement, it is possible to attain a high quality of reproduction of information from the disc.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.