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Diffractive safety element

  • US 6,801,346 B2
  • Filed: 11/06/2003
  • Issued: 10/05/2004
  • Est. Priority Date: 06/08/2001
  • Status: Expired due to Fees
First Claim
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1. A security element comprising a reflecting, optically variable surface pattern which is embedded in a layer composite of plastic material and which can be visually recognized from predetermined observation directions, formed from a mosaic of surface elements with optically active structures, whereina part of the surface pattern is divided in accordance with a regular matrix into cells of equal size, wherein each cell is occupied by a single elementary surface or a group of identical surface portions, the elementary surfaces and the surface portions contain an optically active structure which is independent of the mosaic of the surface pattern, provided in the matrix are at least five cells per mm, the diameter of the elementary surfaces is less than 0.2 mm and a largest dimension of the surface portions is less than 0.04 mm, wherein the elementary surface or the group of the surface portions occupies an equal surface area proportion in the range of between 40% and 70% of the cell, and the arrangement of the elementary surfaces and the surface portions in the matrix forms an item of concealed information which is not perceptible to the naked eye, being in the form of graphic or alphanumeric characters which however are reproduced in a color photocopy with a color or gray value contrast which can be recognized with the naked eye and which is produced upon copying as an artifact.

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