Postage stamp, has coloring layer applied over electrically conductive layer, where color of coloring layer changes upon heating, and electrically conductive layer applied such that layer forms graphic object

摘要

The stamp (1) has an electrically conductive layer (3), and a coloring layer (5) applied over the conductive layer, where the color of the coloring layer changes upon heating. The conductive layer includes an electrically conductive dye such as ferromagnetic dye or electrically conductive foil such as ferromagnetic foil. The electrically conductive layer is arranged in such a manner that the layer forms a graphic object. Independent claims are also included for the following: (1) a device for obliterating a postage stamp (2) a method for obliterating a postage stamp (3) a method for checking whether the stamp is obliterated (4) a method for checking the stamp to authenticity.