Security documents

Details Security documents Security documents

1988-02-04

1989-12-05

Yost, Frank T.

Printed matter

Having revealable concealed information, fraud preventer or...

Utilizing electromagnetic radiation

283 92, 3501622, 356374, B42D 1500, B42D 1502, G02B 318, G01B 1114

Patent

active

048848280

ABSTRACT:
A security document has security printing formed as a moire pattern of two superimposed sets of generally parallel lines. In each line set the line spacing varies progressively along the length of the lines so that each line set has one or more areas in which the line frequency is low and individual lines can be seen with the naked eye, and one or more further areas of high line frequency in which individual lines can only be readily distinguished by using magnification. Futhermore, the thickness of each line varies progressively between relatively large and relatively small values corresponding respectively to the areas of low and high line frequency, the ration of line spacing to line thickness being approximately constant so that the color or tonal density of the security printing is approximately uniform. For additional security the individual line sets are printed in inks of which the colors can be differentiated by the naked eye but not by a reproducing machine used for counterfeiting. One or both of the line sets may additionally or alternatively be printed in an ink having an anti-fraud characteristic such, for example, as water-fugitivity, solvent-sensitivity or UV fluroescence.

REFERENCES:
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patent: 3886083 (1974-08-01), Laxer
patent: 4066280 (1978-01-01), La Capria
patent: 4168088 (1979-09-01), Somlyody
patent: 4442170 (1984-04-01), Kaule et al.
patent: 4525858 (1985-06-01), Cline et al.
patent: 4582346 (1986-04-01), Caprio et al.
patent: 4588212 (1986-05-01), Castagnoli
patent: 4627642 (1986-12-01), Peronneau et al.
patent: 4661983 (1987-04-01), Knop

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