| 摘要 |
<P>PROBLEM TO BE SOLVED: To raise stability and reliability of a magnetic detection device by preventing a detection error, damage of a medium, etc. due to adhesion of iron powder in circumference environment in a conventional magnetic detection device which identifies the medium by detecting magnetic fields H1 and H2 generated by remnant magnetism with which a magnetic ink is charged by impressing a polarization magnetic field produced on a medium in a prestage of a carrier path of the medium which is printed with a magnetic ink and carried to a relative movement direction Y through a magnetic detection element 16 in a poststage on the carrier path. <P>SOLUTION: A permanent magnet which forms a magnetizing magnetic field is changed to an electromagnet 120 for magnetization, and the permanent magnet used for a conventional magnetic detection device is changed into an electromagnet 128 for bias in order to provide a biased magnetic field Hb to a magnetic detection element 16. Only when a medium arrival on a carrier path is detected by a means (not shown in the figure) to detect the arrival of a medium, the electromagnets 120, 128 are energized. Even if the iron powder is adhered to a magnetic pole face of the electromagnet 120 for polarization, it can be removed when the medium 10 is not passing. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
