| 摘要 |
A security device (1) for verifying an authenticity of a security document (100) comprises an at least partially transparent substrate (2) with a first surface (3) and a second surface (4). A first pattern (10) is arranged on the first surface (3). A second pattern (20) is arranged on said second surface (4). The first (10) and the second (20) pattern each comprise a plurality of pixels with at least three different gray levels visible from a macroscopic perspective. The first (10) and second (20) pattern cover only gray levels in a range between 20% black and 80% black, in particular between 35% black and 65% black. The first pattern (10) is inverted with respect to the second pattern (20). As an effect a transmission-mode-viewer (PI) sees a homogeneous image, if the first and the second pattern are superposed, because the first and the second pattern are indiscernible, cancel each other out in the transmission viewing mode. Information disappears. However, in a reflection viewing mode (P2, P3), information contained in the first or in the second pattern can be discerned since the first and the second pattern do not cancel each other out. |
