Security devices for security documents

摘要

The invention relates to improvements in security devices for security documents. A security device comprises at least one at least partially light transmitting spacer layer, on one side of which are formed first indicia. The first indicia comprise a plurality of repeating elements and are formed from a material which emits a coloured visible light when excited by a form of radiation. On an opposing side of the spacer layer is an absorbing material, which absorbs the said radiation but not visible light. The absorbing material is applied in a pattern comprising a plurality of repeating elements similar to the elements of the first indicia and having gaps between the elements.