Optical card having light absorbing layer
US5272326A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 16, 1992 |
| Grant date | Dec 21, 1993 |
| Priority date | — |
| Expiry date | Nov 16, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0033
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A technique of optical card having high information recording density. In the optical cards, there are two types of optical cards having a read-only optical card and an additional recording optical card. Conventionally, separate readers for reproduction have been used due to difference in light reflectivity. In this invention, a light-absorbing layer (50) having light absorbing ability with respect to reading light (300) is arranged between a card side upon which the reading light is incident and a reflective surface of a pattern (21) of an optical data recording section (20), so that the optical cards have interchangeability therebetween in reading.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.