Identification card bearing latent image perceptible in the presence of background light
US4420174A · kind A · utility
5Cited by
7References
12Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Dec 14, 1981 |
| Grant date | Dec 13, 1983 |
| Priority date | — |
| Expiry date | Dec 14, 2001 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB42D25/47
- WIPO fieldOther consumer goods
- WIPO sectorOther fields
Abstract
A latent image identification card has a translucent base with a multiplicity of engraved scores extending through a generally opaque top layer into the base layer whereby a "negative" image appears when the background light is below a determinable value and a latent, "positive" image appears when the background light passing through the translucent base is above the determinable value.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.