| 摘要 |
<p>This invention discloses new methods, security devices and apparatuses for authenticating documetns and valuable articles which may be applied to any support, including transparent synthetic materiasl and traditional opaque materials such as paper. The invention relates to moire intensity profiles which occure in the superposition of periodic or aperiodic geometrically transformed structures. By using 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, wtherby allosing th eauthenticiation of the document. If a microlens structure is used as a maseter 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, and image acquisition means such as a camera and a comparing processor whose task is to compare the acquiredmore intensity prfile with a reference reference image. Depending on the match, the docuemtn handling device connected to the comparing processore accepts or rejects teh document. An important advantage of the present invetnion is that is can be incorporated into the standard document printing process, so that it offers high security at the same cost as standard state of the art document production.</p> |
