METHOD AND DEVICE FOR SECURELY PROTECTING AN OFFICIAL DOCUMENT AND OFFICIAL DOCUMENT SO PROTECTED

摘要

The invention relates to a method for the secure protection of a surface portion of an official document bearing inscriptions, in which: - a protective device is chosen in which the transparent security film (16) comprises at least one semi-printed image -transparent comprising at least one transparent binder and at least one thermochromic pigment, - said semi-transparent printed image makes appear in a first non-activated state, at least at a first temperature, at least one semi-transparent visible pattern so as to allow the display of the inscriptions through this image, said pattern not being visible in a second activated, at least a second temperature different from the first temperature. The invention also relates to such a device for the secure protection of a surface portion of an official document and an official document comprising such a device.