Magnetic marker and reading and identifying apparatus therefor
First Claim
1. A magnetic marker adapted to be applied on an object to be detected passing through an a.c. magnetic field, comprising:
- a plurality of long and narrow magnetic fine wires which are disposed in a longitudinal direction, said magnetic fine wires being produced by drawing amorphous magnetic material and by heat treating the drawn amorphous magnetic material under tension, each of said magnetic fine wires having a layered stress structure which includes an outer surface layer in which compressive stress exists and a core in which tensile stress exists, said outer surface layer being concentric to said core, said magnetic fine wires having square magnetic hysteresis characteristics and magnetic flux jumping characteristics and also at least having magnetic coercive forces which are different from each other, said magnetic fine wires being arranged in a direction orthogonal to the longitudinal direction thereof at predetermined intervals.
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Accused Products
Abstract
A magnetic marker has a plurality of thin strips or wires of saturatable magnetic material having square φ-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.
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Citations
16 Claims
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1. A magnetic marker adapted to be applied on an object to be detected passing through an a.c. magnetic field, comprising:
- a plurality of long and narrow magnetic fine wires which are disposed in a longitudinal direction, said magnetic fine wires being produced by drawing amorphous magnetic material and by heat treating the drawn amorphous magnetic material under tension, each of said magnetic fine wires having a layered stress structure which includes an outer surface layer in which compressive stress exists and a core in which tensile stress exists, said outer surface layer being concentric to said core, said magnetic fine wires having square magnetic hysteresis characteristics and magnetic flux jumping characteristics and also at least having magnetic coercive forces which are different from each other, said magnetic fine wires being arranged in a direction orthogonal to the longitudinal direction thereof at predetermined intervals.
- View Dependent Claims (2, 3, 4, 5)
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6. A magnetic marker adapted to be applied on an object to be detected passing through an a.c. magnetic field, comprising:
- at least one fine wire made of amorphous magnetic material, the at least fine wire having magnetic properties and a layered stress structure which are produced by drawing the amorphous magnetic material and by heat treating the drawn amorphous magnetic material under tension, the layered stress structure of the at least one fine wire including an outer surface layer in which compressive stress exists and a core in which tensile stress exists.
- View Dependent Claims (7, 8, 9, 10)
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11. A method for making a magnetic marker for use on an object that is to be passed through an a.c. magnetic field, comprising the steps of:
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(a) making a fine wire by drawing amorphous magnetic material; (b) heat treating the fine wire under tension; and (c) mounting a segment of the fine wire on a substrate. - View Dependent Claims (12, 13, 14, 15, 16)
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Specification