Security device
US6822769B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 26, 2001 |
| Grant date | Nov 23, 2004 |
| Priority date | — |
| Expiry date | Nov 26, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03H2230/10
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A security device includes a holographic optically variable effect generating structure having at least two discrete section. The sections that generate in response to white light illumination an optically variable image having at least two defined graphical elements located at or near an image plane either on or adjacent to the plane of the device. In response to coherent illumination, the sections generate at least two discrete covert images, in the form of indicia, whose image planes are located at a distance away from the real place of the device. The covert images are reconstructed at different angles to a normal to a substrate supporting the device such that the covert images are spatially separated on their image plane, the covert images being non-visible under white light illumnination.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.