Patent ID: 6598793
Filing Date: 2003-07-29
Classification: G06K,G07D,G07F

Abstract:
A method for checking the authenticity of a security article, said security article containing a plurality of randomly dispersed magnetic metal fibers, said method comprising the following steps:(a) generating an alternating field of one or more fundamental frequencies with an amplitude being greater than the saturation field of the magnetic metal fibers of the security article; (b) subjecting the security article to be detected to said field; (c) detecting a detection signal emanating from said security article to be detected; and (d) examining the detection signal for the presence of any particular harmonics of said fundamental frequency or said fundamental frequencies or of any linear combination of said fundamental frequencies and of said harmonics, said particular harmonics or said linear combination being indicative of the presence of the plurality of randomly dispersed magnetic metal fibers.