PURPOSE: To improve a security property by constituting a magnetic recording region of irreversible magnetic recording parts and reversible magnetic recording parts and forming the magnetic recording patterns of the irreversible parts as patterns varying with recording media.
CONSTITUTION: A magnetic coating material contg. high-coercive force Ba ferrite powder having about 30000e coercive force is printed on the ordinary reversible magnetic recording layer 2 having about 8000e coercive force in such a manner that the ordinarily used magnetic recording patterns are formed and this coating is magnetized in one direction by a permanent magnet, etc., by which the irreversible recording layer 3 is provided. Only the reversible layer 2 is recorded while the irreversible layer 3 is held intact when this card is subjected to writing by an ordinary magnetic writing device. The reversible layer 2 in the lower part of the irreversible layer 3 is magnetized in one direction when the magnetic field in one direction is impressed to the irreversible layer 3 prior to reading of magnetic signals and, therefore, the reading S/N of the printing patterns of the irreversible layer 3 is increased.
OIWA TSUNEMI
OSHIMA TOSHIO
INOSE FUMIYUKI
