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Title: Article surveillance magnetic marker having an hysteresis loop with large Barkhausen discontinuities

Abstract

A marker for an electronic article surveillance system is disclosed comprising a body of magnetic material with retained stress and having a magnetic hysteresis loop with a large Barkhausen discontinuity such that, upon exposure of the marker to an external magnetic field whose field strength in the direction opposing the instantaneous magnetic polarization of the marker exceeds a predetermined threshold value, there results a regenerative reversal of the magnetic polarization of the marker. An electronic article surveillance system and a method utilizing the marker are also disclosed. Exciting the marker with a low frequency and low field strength, so long as the field strength exceeds the low threshold level for the marker, causes a regenerative reversal of magnetic polarity generating a harmonically rich pulse that is readily detected and easily distinguished.

Inventors:
 [1]
  1. (Bradfordwoods, PA)
Issue Date:
Research Org.:
KMS FUSION INC
OSTI Identifier:
866229
Patent Number(s):
4660025
Assignee:
Sensormatic Electronics Corporation (Boca Raton, FL) OSTI
DOE Contract Number:  
AC08-82DP40152
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
article; surveillance; magnetic; marker; hysteresis; loop; barkhausen; discontinuities; electronic; disclosed; comprising; material; retained; stress; discontinuity; exposure; external; field; strength; direction; opposing; instantaneous; polarization; exceeds; predetermined; threshold; value; results; regenerative; reversal; method; utilizing; exciting; frequency; level; causes; polarity; generating; harmonically; rich; pulse; readily; detected; easily; distinguished; readily detected; threshold value; disclosed comprising; threshold level; predetermined threshold; magnetic field; field strength; magnetic material; method utilizing; external magnetic; article surveillance; magnetic polarity; hysteresis loop; /340/

Citation Formats

Humphrey, Floyd B. Article surveillance magnetic marker having an hysteresis loop with large Barkhausen discontinuities. United States: N. p., 1987. Web.
Humphrey, Floyd B. Article surveillance magnetic marker having an hysteresis loop with large Barkhausen discontinuities. United States.
Humphrey, Floyd B. Thu . "Article surveillance magnetic marker having an hysteresis loop with large Barkhausen discontinuities". United States. https://www.osti.gov/servlets/purl/866229.
@article{osti_866229,
title = {Article surveillance magnetic marker having an hysteresis loop with large Barkhausen discontinuities},
author = {Humphrey, Floyd B.},
abstractNote = {A marker for an electronic article surveillance system is disclosed comprising a body of magnetic material with retained stress and having a magnetic hysteresis loop with a large Barkhausen discontinuity such that, upon exposure of the marker to an external magnetic field whose field strength in the direction opposing the instantaneous magnetic polarization of the marker exceeds a predetermined threshold value, there results a regenerative reversal of the magnetic polarization of the marker. An electronic article surveillance system and a method utilizing the marker are also disclosed. Exciting the marker with a low frequency and low field strength, so long as the field strength exceeds the low threshold level for the marker, causes a regenerative reversal of magnetic polarity generating a harmonically rich pulse that is readily detected and easily distinguished.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1987},
month = {1}
}

Patent:

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