Optical recording medium, method of producing the same and method of producing the optical recording card
US5217844A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 8, 1989 |
| Grant date | Jun 8, 1993 |
| Priority date | — |
| Expiry date | Nov 8, 2009 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S430/165
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical recording medium includes a silver grain layer containing a large number of blackened fine silver grains and a coloring matter layer containing coloring matter on a base board and the coloring matter has an ability of absorbing near-infrared ray. When laser beam having a density of optical energy more than a boundary which represents a threshold with respect to the density of optical energy is radiated to the optical recording medium, a part of the latter is deformed to form a plurality of convexities which will be utilized as optical recording pit. The recording pits formed in this way are detected by presence or absence of reflection of radiated light whereby the content of optical recorded informations can be read. The optical recording pits are not deformed further irrespective of how long a reading light comprising laser beam having a density of energy less than the threshold is repeatedly radiated to the optical pits. Accordingly, any reduction of S/N ratio of a signal does not take place as time elapses.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.