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:
-
- Bradfordwoods, PA
- Issue Date:
- Research Org.:
- KMS FUSION INC
- OSTI Identifier:
- 866229
- Patent Number(s):
- 4660025
- Assignee:
- Sensormatic Electronics Corporation (Boca Raton, FL)
- Patent Classifications (CPCs):
-
G - PHYSICS G08 - SIGNALLING G08B - SIGNALLING OR CALLING SYSTEMS
- 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 = {Thu Jan 01 00:00:00 EST 1987},
month = {Thu Jan 01 00:00:00 EST 1987}
}