Diffractive security element comprising a half-tone picture
US7719733B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 2, 2004 |
| Grant date | May 18, 2010 |
| Priority date | — |
| Expiry date | Sep 18, 2027 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB42D25/29
- WIPO fieldOther consumer goods
- WIPO sectorOther fields
Abstract
A diffractive security element has a half-tone image comprising diffractive structures in a reflection layer, which are embedded in a layer composite between a transparent embossing layer and a protective lacquer layer. The half-tone image is divided into image elements of at least one dimension less than 1 mm, wherein the surface of each image element is divided up into a background field and an image element pattern. The proportion of the image element pattern to the surface of the image element determines the surface brightness of the half-tone image at the location of the image element. The background field has a first diffractive structure from which the image element pattern differs by its light-modifying effect. Pattern strips of a width of up to 0.3 mm additionally extend over the surface of the half-tone image. The pattern strips occupy a small proportion of the surface of the background fields and/or the image element patterns and produce coloured strips on the half-tone image.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.