Photochromic papers or films for noncopyable documents.

摘要

This invention, is related to a paper film for a document in which (the writing) disappears and reappears due to irradiation by a light source and which is made so that, when copying a book or document, at the time of placing it in the copy machine, due to irradiation by its light source, a light sensitive, or so called photochromic light sensitive ink, prints in the surface vicinity of the already printed letters, pictures, and images; or, this printed transparent film is caused to be positioned and affixed to the front face; or lastly, by means of constructing a paper or plastic film which has laminated on it a light blocking film, at the time of copying, a light sensitive surface which makes it difficult to read the already printed letters, pictures, images and such is caused to be formed and erased, and by means of interrupting the light for a fixed time by means of a dark place or a filter, this light sensitive surface is erased and deciphering can be done.