Security printed document to prevent unauthorized copying
First Claim
1. A method for inhibiting the photo-reproduction of an image appearing on a surface of sheet material comprising the steps of,covering the surface of the sheet material with a reflective coating forming a mirrored surface,printing the mirrored surface with a random geometric light absorbing pattern forming randomly spaced apertures on the mirrored surface,superimposing an image on the light absorbing pattern, anddiffracting light generated during the photo-reproduction and cast upon the mirrored surface by the randomly spaced apertures creating an interference pattern and preventing the image from being legibly reproduced.
2 Assignments
0 Petitions
Accused Products
Abstract
A paper substrate is laminated with a metalized layer forming a mirrored surface. A partially transparent black diffraction grating is applied by stochastic screening to the mirrored surface. The diffraction grating forms a frequency modulated pattern from selected geometric shapes. Information, such as alphanumeric indicia or graphics, is printed on the stochastic screen to thus form a reflective diffraction device which is printable in a conventional manner while inhibiting reproduction of the printed information by conventional techniques, including black and white and color photo-reproduction and facsimile machines. The partially transparent black stochastic screen forms a diffraction grating on the metalized layer so that when illuminated from the light source of either a specular or diffuse illumination-type photocopier, random interference patterns of light occur at the interface of the metalized surface and the stochastic screen. The diffracted light is not readable by a photocopier drum with the result that the indicia is not legibly reproduced. Thus, the indicia printed on the security document is protected from counterfeiting and unauthorized copying.
201 Citations
8 Claims
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1. A method for inhibiting the photo-reproduction of an image appearing on a surface of sheet material comprising the steps of,
covering the surface of the sheet material with a reflective coating forming a mirrored surface, printing the mirrored surface with a random geometric light absorbing pattern forming randomly spaced apertures on the mirrored surface, superimposing an image on the light absorbing pattern, and diffracting light generated during the photo-reproduction and cast upon the mirrored surface by the randomly spaced apertures creating an interference pattern and preventing the image from being legibly reproduced.
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6. A method for making a security document to prevent the photo-reproduction of information printed on the document comprising the steps of,
applying a reflective coating to a surface of a substrate to form a mirrored surface thereon, partially covering the mirrored surface with a light absorbing pattern having a random geometric configuration forming spaced apertures on the mirrored surface, printing indicia on the light absorbing pattern, and diffracting light cast from photo-reproduction at the interface between the light absorbing screen and the mirrored surface in a random interference pattern extending over the entire substrate to render the indicia illegible in the photo-reproduction.
Specification