Security Document

Abstract

Described is a security document with a transparent security element ( 12 ) which is arranged in a window or in a transparent region of the security document and has a structure layer, in which a first region ( 12 f ) of the structure layer has an asymmetrical diffractive relief structure, wherein the first region ( 12 f ) has an optical effect which is unexpectedly different in a front view and in a rear view of the security document.

1 . A security document comprising a carrier substrate and a transparent security element which is arranged in a window or in a transparent region of the carrier substrate and which has a transparent structure layer and a diffractive relief structure shaped into a first surface of the structure layer, wherein in a first region of the structure layer a first relief structure is shaped into the first surface of the structure layer, which is in the form of an asymmetrical diffractive relief structure with a period length of up to 20 μm and contains an item of alphanumeric and/or graphic information which is visible for a viewer on a front side and/or a rear side of the security element, wherein in respect of the first surface adjoining the structure layer are one or more layers which are in the form of reflective transparent layers or are in the form of transparent layers having a refractive index difference >0.2 in relation to the structure layer so that both the light incident on the front side of the security element and also the light incident on the rear side thereof is diffracted in a first region by the first relief structure and wherein the first relief structure is such that the first relief structure in incident light produces an optical effect which is different in the front view and in the rear view such that the information visible to the viewer on the front side and/or the rear side is not merely a laterally reversed representation of the respective item of information visible on the opposite side. 
   
   
       2 . A security document according to  claim 1 , wherein in a second region of the structure layer a second relief structure is shaped into the first surface of the structure layer, which is in the form of an asymmetrical diffractive structure and the configuration of which is formed substantially in mirror image relationship with the configuration of the first relief structure shaped in the first region, wherein the second relief structure in incident light has an optical effect which is different in the front view and in the rear view. 
   
   
       3 . A security document according to  claim 2 , wherein the first region and the second region of the structure layer form mutually interlocking rasters. 
   
   
       4 . A security document according to  claim 3 , wherein the first region and the second region of the structure layer form mutually interlocking linear rasters. 
   
   
       5 . A security document according to  claim 3 , wherein the raster width is <300 μm. 
   
   
       6 . A security document according to  claim 1 , wherein the first relief structure and/or second relief structure is in the form of a blaze grating. 
   
   
       7 . A security document according to  claim 6 , wherein the blaze grating is in the form of an achromatic blaze grating with a grating constant of 20 μm to 3 μm, and is of a profile depth of from 0.3 μm to 5 μm. 
   
   
       8 . A security document according to  claim 6 , wherein the blaze grating is a chromatic blaze grating with a grating constant of less than 2 μm. 
   
   
       9 . A security document according to  claim 1 , wherein the first surface of the structure layer is coated at least region-wise with a reflecting metallic layer. 
   
   
       10 . A security document according to  claim 9 , wherein the reflecting metallic layer is formed portion-wise from different materials, wherein the first region is coated with a first metallic layer and the second region is coated with a second metallic layer. 
   
   
       11 . A security document according to  claim 9 , wherein the metallic layer has opaque regions in a pattern form. 
   
   
       12 . A security document according to  claim 9 , wherein the metallic layer is formed at least region-wise of such a thickness that it is transparent in transillumination. 
   
   
       13 . A security document according to  claim 1 , wherein the first surface of the structure layer is coated at least region-wise with a dielectric HRI layer with a high refractive index, wherein the coated regions are of semi-transparent nature. 
   
   
       14 . A security document according to  claim 1 , wherein the first relief structure or the second relief structure is an asymmetrical diffractive relief structure which is formed starting from a reference point in at least two directions with changing spatial frequency or depth and to which a reflection layer is applied. 
   
   
       15 . A security document according to  claim 1 , wherein in a third region of the structure layer a third relief structure is shaped into the first surface of the structure layer, wherein in incident light the third relief structure produces an optical effect which is the same in a front view and a rear view. 
   
   
       16 . A security document according to  claim 14 , wherein the third relief structure is in the form of a symmetrical diffractive relief structure. 
   
   
       17 . A security document according to  claim 14 , wherein the third relief structure is in the form of a matt structure. 
   
   
       18 . A security document according to  claim 14 , wherein a thin layer system is arranged in the third region. 
   
   
       19 . A security document according to  claim 14 , wherein a liquid crystal layer is arranged in the third region. 
   
   
       20 . A security document according to  claim 1 , wherein the security element is a multi-layer film body with a transparent carrier layer. 
   
   
       21 . A security document according to  claim 1 , wherein the security element is a transfer layer of a transfer film. 
   
   
       22 . A security document according to  claim 1 , wherein the structure layer is an outer layer of the security document or a portion of an outer layer of the security document. 
   
   
       23 . A security document according to  claim 1 , wherein the structure layer is an inner layer of the security document or a portion of an inner layer of the security document.