US5017907A
Expired / Lapsed
US
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Double pulse magnetic markers
Assignee: Pitney Bowes Inc
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Filing: 1990-01-16
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Granted: 1991-05-21
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Expires: 2010-01-16
Abstract
Abstract A ferromagnetic marker for an electronic surveillance system is magnetically biased so that the magnetic fields of two different regions thereof extend in different direction, e.g. in opposite directions.
Inventors
- 👤 Robert A. Cordery
- 👤 William L. Kilmartin
- 👤 Claude Zeller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 14:44
CPC Classifications
G; G08; G08B; G08B13/00; G08B13/22; G08B13/24; G08B13/2402; G08B13/2405; G08B13/2408; G01; G01V; G01V15/00; G08B13/2428; G08B13/2437; G08B13/2442
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
120 words
In a marker for an electronic surveillance system, employing an alternating magnetic surveillance field including a strip of high permeability ferromagnetic material and means for applying a magnetic bias to said strip, the improvement wherein said strip has first and second regions spaced in the longitudinal direction thereof, said biasing means comprising first and second magnets for applying magnetic biases that are directed in first and second different directions in said first and second regions, and first and second magnets extending parallel to said strip adjacent said first and second regions, respectively, and being oppositely magnetized with respect to the longitudinal direction of said strip, whereby the marker produces a double pulse near each zero crossing of the surveillance field.
Claim 2
Dependent Claim
120 words
In a marker for an electronic surveillance system, employing an alternating magnetic surveillance field including a strip of high permeability ferromagnetic material and means for applying a magnetic bias to said strip, the improvement wherein said strip has first and second regions spaced in the longitudinal direction thereof, said biasing means comprising first and second magnets for applying magnetic biases that are directed in first and second different directions in said first and second regions, and first and second magnets extending parallel to said strip adjacent said first and second regions, respectively, and being oppositely magnetized with respect to the longitudinal direction of said strip, whereby the marker produces a double pulse near each zero crossing of the surveillance field.
Claim 3
Dependent Claim
18 words
The market of claim 1 wherein said first and second magnets are strip-shaped and are longitudinally spaced apart.
Claim 4
Dependent Claim
37 words
The marker of claim 1 wherein said means for biasing comprises a magnet oriented substantially perpendicular to said strip, generally centrally longitudinally thereof, and having a first pole closer to said strip than the other pole thereof.
Claim 5
Dependent Claim
31 words
The marker of claim 1 wherein said material comprises first and second parallel strips of ferromagnetic material, said first and second regions being located in said first and second strips, respectively.
Claim 6
Dependent Claim
71 words
The marker of claim 4 wherein said first and second strips are transversely spaced apart, and said biasing means comprises a first magnet extending between the first and second strips at a first adjacent position thereof, and a second magnet extending between the first and second strips at a second adjacent position thereof, said second magnet being poled opposite to said first magnet, with respect to said first and second strips.
Claim 7
Dependent Claim
47 words
A marker for an electronic surveillance system employing an alternating magnetic surveillance field comprising first and second bodies of ferromagnetic material, and means for magnetically biasing said bodies in different respective directions, whereby the marker produces a double pulse near each zero crossing of the surveillance field.
Claim 8
Dependent Claim
47 words
A marker for an electronic surveillance system employing an alternating magnetic surveillance field comprising first and second bodies of ferromagnetic material, and means for magnetically biasing said bodies in different respective directions, whereby the marker produces a double pulse near each zero crossing of the surveillance field.
Claim 9
Dependent Claim
22 words
The marker of claim 6 wherein said biasing means comprises means for biasing said first and second bodies in opposite respective directions.
Claim 10
Dependent Claim
12 words
The marker of claim 7 wherein said ferromagnetic material is fiber shaped.
Claim 11
Dependent Claim
110 words
In an electronic surveillance system including a magnetic field generator for producing an alternating magnetic surveillance field, a magnetic field detector and a marker adapted to pass in the field of said generator to influence the signals detected by said detector, the improvement wherein said marker comprises a high permeability ferromagnetic material and means for applying a magnetic bias to said ferromagnetic material, said material having first and second regions, and said biasing means comprising means for applying magnetic biases that are directed in first and second different directions in said first and second regions, whereby the marker produces a double pulse near each zero crossing of the surveillance field.
Claim 12
Dependent Claim
110 words
In an electronic surveillance system including a magnetic field generator for producing an alternating magnetic surveillance field, a magnetic field detector and a marker adapted to pass in the field of said generator to influence the signals detected by said detector, the improvement wherein said marker comprises a high permeability ferromagnetic material and means for applying a magnetic bias to said ferromagnetic material, said material having first and second regions, and said biasing means comprising means for applying magnetic biases that are directed in first and second different directions in said first and second regions, whereby the marker produces a double pulse near each zero crossing of the surveillance field.
References Cited (Backward Citations)
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| 3.5 Years (Year 4) | 1994-05-20 | 1994-11-19 | 1995-05-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-05-20 | 1998-11-19 | 1999-05-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-05-20 | 2002-11-19 | 2003-05-21 | $7700.00 | Window Closed / Lapsed |