US4727668A
Expired / Lapsed
US
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Coded surveillance marker with improved biasing
Assignee: Sensormatic Electronics Corp
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Filing: 1985-09-03
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Granted: 1988-03-01
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Expires: 2005-09-03
Abstract
Abstract A surveillance marker is provided for utilization in antipilferage and anticounterfeiting systems. The marker includes a housing formed of barium ferrite impregnated plastic. Advantageously, the barium ferrite impregnated plastic housing provides a quasi-solenoidal dc magnetic bias field for activating one or more stacked ferromagnetic ribbons contained within the housing to produce an identifiable signal in response to an applied ac magnetic interrogation field.
Inventors
- 👤 Philip M. Anderson
- 👤 Ronald K. Reich
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 19:23
CPC Classifications
G; G08; G08B; G08B13/00; G08B13/22; G08B13/24; G08B13/2402; G08B13/2405; G08B13/2408; G08B13/2411; G08B13/2428; G08B13/2434; G08B13/2437; G08B13/2442; G08B13/2448
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
80 words
A surveillance marker for utilization in antipilferage, anticounterfeiting and like systems, comprising: ferromagnetic signal producing means comprising at least one strip of magnetostrictive ferromagnetic material; and combined housing and biasing means for said signal producing means formed of plastic impregnated with ferrimagnetic or ferromagnetic powder of relatively high coercivity; said high coercivity powder providing a quasi-solenoidal dc magnetic bias field for activating said ferromagnetic signal producing means to produce an identifiable singal in response to an applied magnetic interrogation field.
Claim 2
Dependent Claim
80 words
A surveillance marker for utilization in antipilferage, anticounterfeiting and like systems, comprising: ferromagnetic signal producing means comprising at least one strip of magnetostrictive ferromagnetic material; and combined housing and biasing means for said signal producing means formed of plastic impregnated with ferrimagnetic or ferromagnetic powder of relatively high coercivity; said high coercivity powder providing a quasi-solenoidal dc magnetic bias field for activating said ferromagnetic signal producing means to produce an identifiable singal in response to an applied magnetic interrogation field.
Claim 3
Dependent Claim
14 words
The surveillance marker recited in claim 1, wherein said strip has an amorphous structure.
Claim 4
Dependent Claim
18 words
The surveillance marker recited in claim 1, wherein said ferrimagnetic powder of relatively high coercivity is barium ferrite.
Claim 5
Dependent Claim
21 words
The surveillance marker recited in claim 3, wherein said combined housing and biasing means is from 7%-25% barium ferrite by volume.
Claim 6
Dependent Claim
21 words
The surveillance marker recited in claim 3, wherein said combined housing and biasing means is approximately 15%-21% barium ferrite by volume.
Claim 7
Dependent Claim
25 words
The surveillance marker recited in claim 3, wherein said combined housing and biasing means is approximately 17% barium ferrite and 83% ABS plastic by volume.
Claim 8
Dependent Claim
22 words
The surveillance marker recited in claim 1, wherein said ferromagnetic signal producing means is multiple magnetostrictive strips of ferromagnetic material stacked together.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-03-01 | 1991-08-31 | 1992-03-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-03-01 | 1995-08-31 | 1996-03-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-03-01 | 1999-08-31 | 2000-03-01 | $7700.00 | Window Closed / Lapsed |