DOCUMENT AGAINST COUNTERFEIT PROTECTION METHOD Russian patent published in 2007 - IPC B42D15/10 

FIELD: polygraphy, possibly manufacture of printed products such as credit cards, identification documents and other valuable papers protected against counterfeit.

SUBSTANCE: method for protecting document against counterfeit comprises steps of making opening in protected document; forming on films two holographic identification marks and joining said films coaxially one to other by their sides having no marks; then securing holographic identification marks to inner side of transparent envelope coaxially to opening of protected document and laminating it. Contour of said opening and boundary lines of holographic identification marks are formed according to relations representing current coordinates of point on edge of opening (Xo, Yo) and current coordinates of point on boundary line of holographic identification mark (Xm, Ym). Holographic identification marks are rotated one relative to other and relative to vertical axis of opening by angles determined by amplitude-frequency characteristics of functions Xo, Yo, Xm, Ym.

EFFECT: improved protection degree of document due to using set of amplitude-frequency characteristics and their combinations known only to maker of protected document.

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