Security ink system

Abstract

A security system, such as a banknote, comprises: i) a substrate, ii) a first ink, which is applied on at least a part of at least one surface of the substrate, wherein the first ink includes at least one IR luminescent dye and/or at least one IR luminescent pigment, and iii) a second non-luminescent ink, which is applied on at least a part of at least one surface of the substrate onto which the first ink is/are applied, wherein the second ink includes at least one non-luminescent IR absorbing pigment and/or a least one non-luminescent IR absorbing dye, wherein the first ink and the second ink at least partially overlap on the at least one surface of the substrate, wherein the second ink is applied in the overlapping area onto the first ink, and wherein the emission spectrum of the first ink and the absorption spectrum of the second ink at least partially overlap.

Dependencies are inferred from the claim text.