MAGNETIC INK FOR JUDGING TRUTH OR FALSEHOOD, ARTICLE FOR JUDGING TRUTH OR FALSEHOOD USING SAME, METHOD FOR JUDGING TRUTH OR FALSEHOOD, AND APPARATUS THEREFOR

摘要

PROBLEM TO BE SOLVED: To obtain a magnetic ink which is excellent in sensitivity of reading and in durability and provides a high forgery prevention effect by incorporating a magnetic powder having specified coercive force and Curie temp. into the same. SOLUTION: The first magnetic powder having a coercive force of 100 Oe or lower, pref. 10-50 Oe, and a Curie temp. of -50 to 150 deg.C and pref. has a particle size of 1μm or lower is incorporated. If necessary, the second magnetic powder having a coercive force of 100 Oe or lower and a Curie temp. different from that of the first magnetic powder is also incorporated, Truth or falsehood is judged by basing on signals detected at the first Curie temp. or higher and at a temp. lower than the Curie temp. by using an article for judging truth or falsehood which uses an ink contg. the first magnetic powder. Truth or falsehood is judged by basing on signals detected at the first Curie temp, or lower, at a temp. between the first and the second Curie temp. and at the second Curie temp. or higher by using an ink contg. the first and the second magnetic powder.