US4864281A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ferromagnetic label for use in anti-theft surveillance system
Assignee: Sensormatic Electronics Corp
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Filing: 1988-12-12
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Granted: 1989-09-05
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Expires: 2008-12-12
Abstract
Abstract Permanently magnetized members (24, 26) of a surveillance system label (16) are disposed adjacent a ferromagnetic nonlinear element (30) for biasing the hysteresis loop of the nonlinear element (30) near the knee (40) of the magnetization curve. The nonlinear element (30) includes low permeability sections (32, 34) and a high permeability section (36). The high permeability section (36) of the nonlinear element (30) is disposed adjacent a radiating dipole (28) for radiating the summation frequency of a pair of frequencies impinging on the nonlinear element (30). A memory magnet (38) with a changeable magnetism is disposed adjacent the high reluctance section (36) of the nonlinear element (30). The magnetism of the memory magnet (38) can be changed to provide either an active or inactive status of the label (16).
Inventors
- 👤 Edward R. Fearon
- 👤 Robert E. Fearon
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 11:46
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: 7
Claim 1
Independent Claim
111 words
A ferromagnetic label for use in an anti-theft surveillance system, comprising: a first permanent magnet; a second permanent magnet being of a size smaller than said first permanent magnet, said second permanent magnet disposed adjacent said first magnet and being oppositely poled with respect to said first permanent magnet; an electromagnetic radiating dipole oriented orthogonal to said first and second permanent magnets; a nonlinear magnetic element responsive to frequencies in the superhigh frequency range and disposed adjacent said radiating dipole; and a third permanent magnet associated with said first and second magnets and said nonlinear magnetic element, said third permanent magnet for placing the label in an active or nonactive state.
Claim 2
Dependent Claim
111 words
A ferromagnetic label for use in an anti-theft surveillance system, comprising: a first permanent magnet; a second permanent magnet being of a size smaller than said first permanent magnet, said second permanent magnet disposed adjacent said first magnet and being oppositely poled with respect to said first permanent magnet; an electromagnetic radiating dipole oriented orthogonal to said first and second permanent magnets; a nonlinear magnetic element responsive to frequencies in the superhigh frequency range and disposed adjacent said radiating dipole; and a third permanent magnet associated with said first and second magnets and said nonlinear magnetic element, said third permanent magnet for placing the label in an active or nonactive state.
Claim 3
Dependent Claim
17 words
The ferromagnetic label of claim 1 wherein said first permanent magnet is less than one inch long.
Claim 4
Dependent Claim
22 words
The ferromagnetic label of claim 1 wherein said first and said second permanent magnets are constructed of ferromagnetic materials having identical properties.
Claim 5
Dependent Claim
22 words
The ferromagnetic label of claim 1 wherein said second permanent magnet is approximately one-half of the size of said first permanent magnet.
Claim 6
Dependent Claim
44 words
The ferromagnetic label of claim 1 wherein said first and said second permanent magnets include a magnetic field substantially higher than the magnetic field of the earth, thereby providing a magnetic field to said nonlinear element irrespective of the magnetic field of the earth.
Claim 7
Dependent Claim
34 words
The ferromagnetic label of claim 1 wherein said nonlinear element comprises: a first area of a low permeability; and a first and second area of higher permeability adjacent said first area of low permeability.
References Cited (Backward Citations)
US4682154A
Cited
US4799045A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-09-04 | 1993-03-06 | 1993-09-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-09-04 | 1997-03-06 | 1997-09-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-09-04 | 2001-03-06 | 2001-09-05 | $7700.00 | Window Closed / Lapsed |