Support such as telephone card with concealed confidential information incorporates security substance rendered opaque by radiation

摘要

A support (1), such as a telephone card or game card, with hidden confidential information (2) revealed by removal of a scratch-off layer (3), incorporates a security substance (4), e.g. photochromic, which is rendered opaque when exposed to radiation at a predetermined intensity and wavelength, preventing the confidential information from being read illicitly by means of a powerful e.g. halogen light. A support (1), such as a telephone card or game card, with hidden confidential information (2) revealed by removal of a scratch-off layer (3), incorporates a security substance (4), e.g. photochromic, which is rendered opaque when exposed to radiation at a predetermined intensity and wavelength, preventing the confidential information from being read illicitly by means of a powerful e.g. halogen light. The security substance can be located over or under the confidential information or in the support, and can contain a photochrome substance of the chromene family dispersed in a polymer matrix.