SECURITY DOCUMENTS AND TESTING THEIR AUTHENTICITY,申请号GB19820030240-传众专利搜索

SECURITY DOCUMENTS AND TESTING THEIR AUTHENTICITY

申请公布号：GB2108428(A)

申请号：GB19820030240

申请日期：1982.10.22

申请公布日期：1983.05.18

申请人：

* LGZ LANDIS AND GYR ZUG AG

发明人：GREGOR * ANTES

分类号：G06K19/10;B42D25/328;G01N21/89;G01N21/892;G06K7/00;G06K19/06;G06K19/16;G07D7/00;G07D7/06;G07D7/12;G07D7/20;G07F7/08

主分类号：G06K19/10

摘要：In a security blank which includes a substrate which has two major surfaces, a thermoplastic layer which has a predetermined refraction index and is suitable for embossing thereon a machine-readable authenticity feature in the form of an optical microstructure, and a transparent layer which has a prearranged refraction index for covering and protecting the microstructure, and wherein the prearranged refraction index has a value different from the predetermined refraction index, and the microstructure generates a characteristic diffraction effect from light incident thereonto, the improvement includes a surface of the substrate facing the thermoplastic layer, which has within a region of the microstructure diffuse reflection characteristics of a predetermined magnitude, and wherein the thermoplastic layer is transparent, and wherein the difference between the refraction indexes is sufficiently small, and the magnitude of the diffuse reflection characteristics is sufficiently large, so that the characteristic diffraction effect of the microstructure is not normally detectable by the eye of an observer.