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US4857891A
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Random-filament, multi-directionally responsive marker for use in electronic article surveillance systems
Assignee: 3M Co
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Filing: 1988-04-29
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Granted: 1989-08-15
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Expires: 2008-04-29
Abstract
Abstract A magnetic marker for use with electronic article surveillance (EAS) systems in which a two-directional response is obtained. The marker comprises a substantially two-dimensional, sheet-like substrate having multiple metallic filaments randomly dispersed in or adhered thereto, so as to be substantially parallel to the plane thereof. The filaments are selected of low coercive force, high permeability material, and the random orientation results in certain filaments intersecting with the being magnetically coupled to other filaments to thereby collect and concentrate lines of flux associated with an applied field of an EAS system into filaments parallel to the field.
Inventors
- 👤 Eugene C. Heltemes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:25
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
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
85 words
A marker for use in an electronic article surveillance system of the type in which an alternating magnetic field in an interrogation zone produces remotely detectable magnetization changes in the marker, wherein the marker comprises a substantially two-dimensional, sheet-like substrate and multiple metallic filaments randomly dispersed in or adhered thereto so as to be substantially parallel to the plane thereof, said filaments being selected of a high permeability, low coercive force, magnetic material, with said filaments thereby randomly intersecting each other to magnetically couple therewith.
Claim 2
Dependent Claim
85 words
A marker for use in an electronic article surveillance system of the type in which an alternating magnetic field in an interrogation zone produces remotely detectable magnetization changes in the marker, wherein the marker comprises a substantially two-dimensional, sheet-like substrate and multiple metallic filaments randomly dispersed in or adhered thereto so as to be substantially parallel to the plane thereof, said filaments being selected of a high permeability, low coercive force, magnetic material, with said filaments thereby randomly intersecting each other to magnetically couple therewith.
Claim 3
Dependent Claim
16 words
A marker according to claim 1, wherein all of said filaments are substantially the same dimension.
Claim 4
Dependent Claim
16 words
A marker according to claim 1, wherein all of said filaments are substantially the same composition.
Claim 5
Dependent Claim
43 words
A marker according to claim 1, further comprising at least one section of permanently magnetizable material positioned adjacent to a portion of said multiple filaments, and magnetically coupled thereto such that when so magnetized the detectable response resulting from the marker is altered.
References Cited (Backward Citations)
FR763681A
Cited
US3747086A
Cited
US3790945A
Cited
US3665449A
Cited
US4075618A
Cited
US4710754A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-08-14 | 1993-02-13 | 1993-08-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-08-14 | 1997-02-13 | 1997-08-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-08-14 | 2001-02-13 | 2001-08-15 | $7700.00 | Window Closed / Lapsed |