Method of rendering objects uncopyable by photocopy processes
US4118122A · kind A · utility
20Cited by
3References
6Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Feb 7, 1977 |
| Grant date | Oct 3, 1978 |
| Priority date | — |
| Expiry date | Feb 7, 1997 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S283/902
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Techniques to render documents and like objects uncopyable by photocopy means. Illumination spectral composition, object background color, and photoreceptor sensitivity are appropriately combined such that the photoreceptor perceives no object contrast. The result may be either a blackout or a whiteout of the object information.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.