Copying preventing device

Abstract

Abstract PURPOSE:To prevent copying of confidential documents, drawings, etc. by forming a discoloring layer which discolors through chemical change, etc. when rays more than required illuminance necessary for copying are radiated on the writing surface of required writing paper. CONSTITUTION:A discoloring layer 3 which discolors from transparence to black color through, e.g., chemical change, etc. in proportion to the rays radiated when the rays of more than required illuminance necessary for copying with an electronic copying machine or the like is formed on the writing surface 2 of necessary writing paper 2 such as document or drawing. This coloring layer 3 may be a variable color sheet disposed with high-sensitivity silver compound or may use chemicals provided with such chemical properties. It is possible to cover the material through lamination or the like if it is of sheet form or to beforehand coat on the paper surface if it is liquid-form chemical. In this way, copying of confidential documents or drawings may be prevented.

Inventors

• 👤 Yoshihiro Yonahara

Bibliographic Details