Magnetic marker and reading and identifying apparatus therefor

Abstract

A magnetic marker has a plurality of thin strips or wires of saturatable magnetic material having square .phi.-H characteristics and coercive forces different from each other. Amorphous magnetic material may be used. When the marker is subjected to magnetization reversal by an external magnetic field, variations of magnetic flux corresponding to a plurality of magnetization reversals can be chronologically detected as a voltage pulse train by detecting coils. By processing this voltage pulse train, a pattern can be made, recognized, so that the magnetic marker effectively identifies the kind of article to which it is attached. A magnetic marker reading and identifying apparatus has a plurality of exciting coils for producing a rotating magnetic field, with the axis of at least one of the exciting coils being orthogonal to the axis of at least one other exciting coil. The rotating a.c. magnetic field can be applied to the magnetic marker while the marker passes across the magnetic field irrespective of the position and direction of the marker, with no deviation in the pulse voltage due to leakage flux from the magnetic marker, thereby permitting reliable detection of the pulse train so that the kind and quantity of articles can be identified with high accuracy.

Dependencies are inferred from the claim text.