Marking
US4992347A · kind A · utility
30Cited by
1References
13Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jan 11, 1990 |
| Grant date | Feb 12, 1991 |
| Priority date | — |
| Expiry date | Jan 11, 2010 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S430/163
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A marking comprises a layer, preferably of film-forming material, which contains a photochromic compound. The photochromic compound is capable of changing color when exposed to uv light, but can be converted to a permanently non-photochromic compound, preferably by overexposure to uv light. An image is formed in the layer by converting the photochromic compound to a permanently non-photochromic compound in one or more selected areas. When the layer is subsequently viewed under uv light a colorless image of non-photochromic compound can be seen on a background of colored photochromic compound.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.