DECISION METHOD OF TRUTH OR FALSEHOOD OF DOCUMENT

摘要

PROBLEM TO BE SOLVED: To provide a method by which the truth or falsehood of a document can be discriminated by using a material which is hardly copied by general forgers and has a limited source of supply. SOLUTION: An objective document 10 is printed by using ink containing a magnetic pigment having a Curie point lower than 130 deg.C. After printed parts 12, 14, and 16 are magnetized in an arbitrary magnetic pattern by applying a magnetic field, the parts 12, 14, and 16 are heated to a temperature of 130 deg.C by using a heat lamp 22. Then whether or not the magnetic pattern is destroyed or not by the heat in a temperature region higher than the Curie point is discriminated.