US5580664A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dual status thin-film eas marker having multiple magnetic layers
Assignee: 3M Co
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Filing: 1995-01-04
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Granted: 1996-12-03
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Expires: 2015-01-04
Abstract
Abstract A dual status marker for use with a magnetic-type EAS system has a signal-producing layer including at least one magnetic thin-film of high permeability and low coercive force such as permalloy, and a signal-blocking layer including at least one remanently magnetizable thin-film such as an Fe-Cr alloy. The remanently magnetizable thin-film or thin-films should have a total thickness at least equal to, and preferably at least twice, the total thickness of the magnetic thin-film or thin-films of high permeability. By doing so, the marker is more reliably deactivated when the signal-blocking layer is magnetized. For even greater assurance of deactivation, the signal-blocking layer should include more than one remanently magnetizable thin-film, thus giving it a squarer B-H loop and greater assurance against false alarms.
Inventors
- 👤 Ching-Long Tsai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 18:03
CPC Classifications
G; G08; G08B; G08B13/00; G08B13/22; G08B13/24; G08B13/2402; G08B13/2405; G08B13/2408; G08B13/2411; G08B13/2428; G08B13/2437; G08B13/2442; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/12; Y10T428/12465; Y10T428/12493; Y10T428/12535; Y10T428/31504; Y10T428/31678
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
146 words
A dual status marker for use with a magnetic electronic article surveillance system, which system produces in an interrogation zone alternating magnetic fields having average peak intensities of less than 20 Oersteds, the dual status marker comprising: a signal-producing layer having a differential permeability above 5000 and a coercive force less than the average peak intensities encountered in the interrogation zone, such that upon exposure to the alternating magnetic fields, the magnetization state of the signal-producing layer is periodically reversed thus producing an alarm signal; and a signal-blocking layer in substantial contact with the signal-producing layer, the signal-blocking layer comprised of a plurality of remanently magnetizable deposition film layer, the signal blocking layer further having a coercivity above 25 Oe and providing magnetic flux such that the signal-producing layer is prevented from producing the alarm signal in the interrogation zone when the signal-blocking layer is magnetized.
Claim 2
Dependent Claim
146 words
A dual status marker for use with a magnetic electronic article surveillance system, which system produces in an interrogation zone alternating magnetic fields having average peak intensities of less than 20 Oersteds, the dual status marker comprising: a signal-producing layer having a differential permeability above 5000 and a coercive force less than the average peak intensities encountered in the interrogation zone, such that upon exposure to the alternating magnetic fields, the magnetization state of the signal-producing layer is periodically reversed thus producing an alarm signal; and a signal-blocking layer in substantial contact with the signal-producing layer, the signal-blocking layer comprised of a plurality of remanently magnetizable deposition film layer, the signal blocking layer further having a coercivity above 25 Oe and providing magnetic flux such that the signal-producing layer is prevented from producing the alarm signal in the interrogation zone when the signal-blocking layer is magnetized.
Claim 3
Dependent Claim
31 words
A dual status marker as defined in claim 1 wherein said plurality of remanently magnetizable deposition films comprises an Fe-Cr alloy having a Cr content up to about 20 atomic percent.
Claim 4
Dependent Claim
28 words
A dual status marker as defined in claim 2 wherein the Cr content of said plurality of remanently magnetizable deposition films is from 1 to 15 atomic %.
Claim 5
Dependent Claim
33 words
A dual status marker as defined in claim 1 wherein said plurality of remanently magnetizable deposition films has a total thickness from 2 to 5 times the total thickness of the signal-producing layer.
Claim 6
Dependent Claim
27 words
A dual status marker as defined in claim 1 wherein the total thickness of the plurality of remanently magnetizable deposition films is from 0.8 to 1.2 μm.
Claim 7
Dependent Claim
17 words
A dual status marker as defined in claim 1 wherein the remanently magnetizable deposition films are discontinuous.
Claim 8
Dependent Claim
92 words
A control element which affords dual status to a marker having a signal-producing layer that produces an alarm signal when the marker is passed through an interrogation zone of a magnetic electronic article surveillance system, the control element comprising: a plurality of remanently magnetizable deposition film layer having a coercivity above 25 Oe and providing magnetic flux such that, when placed in substantial contact with the signal-producing layer, the signal-producing layer is prevented from producing the alarm signal in the interrogation zone when the plurality of remanently magnetizable deposition films are magnetized.
Claim 9
Dependent Claim
92 words
A control element which affords dual status to a marker having a signal-producing layer that produces an alarm signal when the marker is passed through an interrogation zone of a magnetic electronic article surveillance system, the control element comprising: a plurality of remanently magnetizable deposition film layer having a coercivity above 25 Oe and providing magnetic flux such that, when placed in substantial contact with the signal-producing layer, the signal-producing layer is prevented from producing the alarm signal in the interrogation zone when the plurality of remanently magnetizable deposition films are magnetized.
Claim 10
Dependent Claim
25 words
A marker-deactivating product as defined in claim 7 wherein said plurality of remanently magnetizable thin-films have a total thickness of from 0.8 to 1.2 μm.
Claim 11
Dependent Claim
26 words
A dual status marker as defined in claim 1 wherein the signal-blocking layer further comprises alternating layers of remanently magnetizable deposition films and non-magnetic deposition films.
Claim 12
Dependent Claim
28 words
A dual status marker as defined in claim 9 wherein discontinuities of the at least one remanently magnetizable deposition film are segments of substantially uniform size and shape.
Claim 13
Dependent Claim
25 words
A dual status marker as defined in claim 10 wherein each of the segments has an area of from 1 to 100 mm 2 .
Claim 14
Dependent Claim
23 words
A dual status marker as defined in claim 1 further including a substrate adapted to support the signal-producing layer and the signal-blocking layer.
Claim 15
Dependent Claim
16 words
A dual status marker as defined in claim 12 wherein the substrate is a flexible web.
Claim 16
Dependent Claim
22 words
A dual status marker as defined in claim 12 wherein the substrate comprises an article that is to be protected against theft.
Claim 17
Dependent Claim
23 words
A dual status marker as defined in claim 1 wherein the marker has an area of from 2 to 10 cm 2 .
Claim 18
Dependent Claim
24 words
A dual status marker as defined in claim 12 wherein each of the nonmagnetic deposition films is no greater than 20 nm in thickness.
References Cited (Backward Citations)
US3765007A
Cited
USRE32427E
Cited
US4539558A
Cited
US4682154A
Cited
US4710754A
Cited
US4746908A
Cited
EP0295028B1
Cited
US4960651A
Cited
WO1990007784A1
Cited
US5015993A
Cited
US5010320A
Cited
EP0448114A1
Cited
EP0459722A1
Cited
US5083112A
Cited
US5405702A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-12-03 | 2000-06-03 | 2000-12-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-12-03 | 2004-06-03 | 2004-12-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-12-03 | 2008-06-03 | 2008-12-03 | $7700.00 | Window Closed / Lapsed |