Authentication of documents and valuable articles by using moire intensity profiles
US6819775B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 11, 2001 |
| Grant date | Nov 16, 2004 |
| Priority date | — |
| Expiry date | Oct 30, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG07D7/207
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
This invention discloses new methods, security devices and apparatuses for authenticating documents and valuable articles which may be applied to any support, including transparent synthetic materials and traditional opaque materials such as paper. The invention relates to moire intensity profiles which occur in the superposition of periodic or aperiodic geometrically transformed structures. By using a specially designed basic screen and master screen, where at least the basic screen is comprised in the document, a moire intensity profile of a chosen shape becomes visible in their superposition, thereby allowing the authentication of the document. If a microlens structure is used as a master screen, the document comprising the basic screen may be printed on an opaque reflective support, thereby enabling the visualization of the moire intensity profile by reflection. Automatic document authentication is supported by an apparatus comprising a master screen, an image acquisition means such as a camera and a comparing processor whose task is to compare the acquired moire intensity profile with a reference image. Depending on the match, the document handling device connected to the comp…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.