| 摘要 |
A security device has a lenticular device including an array of lenticular focusing elements; a corresponding array of image strips sets, the sets having substantially the same periodicity as, or an integral multiple of the periodicity of, the array of focusing elements. The strips are formed and the focusing elements located relative to the strips such that at each of a plurality of viewing angles, a respective one strip from each set is viewed in response to incident light falling on a respective focusing element. The strips are constructed such that the device presents a cyclically repeating sequence of images as the device is viewed at successive viewing angles, the image sequence including a change in form of an image between a first and second form and then a reversal of the sequence back to the first form, the combined image sequences presenting a contiguous variation in the image form. |
