PURPOSE: To obtain the information only on the fibers consisting of magnetic materials and to obviate forgery and alteration by detecting fibers consisting of nonmagnetic materials as well together with the fibers consisting of the magnetic materials at the time of irradiating the information recording medium with X-rays and detecting the coexisting positions, postures and shapes of the fibers coexisting therein.
CONSTITUTION: The region is scanned by using a magnetic head and magnetic flux densities are changed in the positions where the magnetic fibers 3 exist. The changes thereof vary with the distances of the fibers 3 from the scanning plane of a base material 2 and the postures thereof. Electrical analog signals are thereby obtd. and the reading of the information recorded on the information recording medium 1 is possible. A person needs to exactly know the positions and postures of the materials 3 in order to make forgery and alteration in this constitution. Seeing-through the inside by irradiation with X-rays is used as the means thereof and the nonmagnetic fibers 4 are also made to coexist in addition to the materials 3 in order to prevent such forgery or alteration. The fresh detection signals are generated in correspondence to the fiber 4 which are ought not to be detected in such a manner, by which the forgery or alteration is surely prevented.
ITO NORIYUKI
MURATA KAHEI
