MAGNETIC PARTICLES, SHEET WHICH CONTAINS SUCH PARTICLES, PROTECTION DOCUMENT, AND METHOD FOR DETECTING SUCH PARTICLES

摘要

PROBLEM TO BE SOLVED: To prevent a document from being copied and easily identify a document as a genuine protection document so as to contribute to the authentication of the document.

SOLUTION: (a) One or more electromagnetic source signals of specific base frequencies are emitted to a sheet so that existing certain magnetic extension particles may be in the nonlinear part of a B-H curve to the one cycles, at least the one parts, of the electromagnetic source signals. Then, (b) the electromagnetic source signals emitted from the sheet are detected, and (c) detection signals are examined to the existence of specific high harmonic waves of the base frequencies or the existence of optional linear combinations of the base frequencies with the high harmonic waves, and the specific high harmonic waves are indicative of the existence of the magnetic particles.

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