Magnetic markers
First Claim
1. An electronic article surveillance tag wherein a magnetic material on the tag is divided into distinct zones such that the zones and their relative positions represent information or a code which is readable magnetically by passing the tag through a magnetic field which comprises a relatively small region of zero magnetic field (a magnetic null) contiguous with regions where the magnetic field is sufficient to saturate said magnetic material, the tag being moved through the magnetic field and its magnetic response being detected as it traverses the magnetic null.
2 Assignments
0 Petitions
Accused Products
Abstract
An improved EAS tag is disclosed. The tag is characterised in that the or one of the magnetic materials on the tag is divided into distinct zones such that the zones and their relative positions can represent information or a code which is readable magnetically by passing the tag through a magnetic field which comprises a relatively small region of zero magnetic field (a magnetic null) contiguous with regions where the magnetic field is sufficient to saturate said magnetic material, the tag being moved through the magnetic field and its magnetic response being detected as it traverses the magnetic null.
48 Citations
11 Claims
- 1. An electronic article surveillance tag wherein a magnetic material on the tag is divided into distinct zones such that the zones and their relative positions represent information or a code which is readable magnetically by passing the tag through a magnetic field which comprises a relatively small region of zero magnetic field (a magnetic null) contiguous with regions where the magnetic field is sufficient to saturate said magnetic material, the tag being moved through the magnetic field and its magnetic response being detected as it traverses the magnetic null.
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8. A magnetic information system comprising:
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(a) a device further comprising distinct magnetic zones; (b) a steady magnetic field comprising a magnetic null region, and a saturating field region closely adjacent thereto; (c) a time-varying magnetic field superimposed on the steady magnetic field and being substantially spatially uniform over the magnetic null region; and (d) an interrogation device including a detector of induced magnetic fields produced by one of the magnetic zones passing through the magnetic null region; whereby a motion of the tag through the magnetic null region produces a series of induced magnetic fields corresponding to an arrangement of the distinct magnetic zones on the tag along a direction of relative motion between the tag and the magnetic null region. - View Dependent Claims (9, 10, 11)
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Specification