04451521 is referenced by 86 patents and cites 6 patents.

Security paper with luminescing authenticity characteristics which after excitation with invisible light emit exclusively invisible light of different wavelengths as authenticity signal. The luminophores can be included in the printing ink used or they can be added to the paper material in the manufacture of the paper material. A corresponding test apparatus makes it possible to check the authenticity of the security paper in the presence of customers but unnoticed by them; thereby the invisibility of the test signal and the authenticity signal are taken advantage of and the test device is hidden behind a plate non-transmissive for visible light which however is transmissive for the test signal and for the authenticity signal.

Title
Security paper with authenticity features in the form of substances luminescing only in the invisible region of the optical spectrum and process for testing the same
Application Number
6/314842
Publication Number
4451521
Application Date
October 23, 1981
Publication Date
May 29, 1984
Inventor
Gerhard Stenzel
Munich
DE
Wittich Kaule
Gauting
DE
Agent
Schwartz Jeffery Schwaab Mack Blumenthal & Koch
Assignee
Gao Gesellschaft fur Automation und Organisation mbH
DE
IPC
B32B
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