US4992776A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Antipilferage tags and their use
Assignee: Meto International GmbH
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Filing: 1989-04-10
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Granted: 1991-02-12
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Expires: 2009-04-10
Abstract
Abstract A housing contains a pick-up coil for detecting an external magnetic field; a power supply; a tone generator; and an electric circuit powered by said power supply and arranged to activate said tone generator in response to an output from said magnetic field pick-up including a piezoelectric material surrounded about its circumference by a thin layer of magnetostrictive material. Since the electrical output of the piezoelectric material is dependent on the stress imparted to it by the magnetostrictive material, and since the dimensional change in the magnetostrictive material is proportional to the magnetic field in the environment in which the magnetostrictive material is located, the electrical output of the piezoelectric material provides a measure of magnetic field strength.
Inventors
- 👤 Michael D. Crossfield
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 23:00
CPC Classifications
G; G08; G08B; G08B13/00; G08B13/22; G08B13/24; G08B13/2402; G08B13/2428; G08B13/2431; G08B13/2437; G08B13/2442
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
78 words
A magnetic antipilferage tag which comprises a housing containing means for detecting an external magnetic field; a power supply; a tone generator; and an electric circuit powered by said power supply and arranged to activate said tone generator in response to an output from said magnetic field detector means, wherein said means for detecting an external magnetic field includes at least one pick-up having a piezoelectric material surrounded about its circumference by a thin layer of magnetostrictive material.
Claim 2
Dependent Claim
78 words
A magnetic antipilferage tag which comprises a housing containing means for detecting an external magnetic field; a power supply; a tone generator; and an electric circuit powered by said power supply and arranged to activate said tone generator in response to an output from said magnetic field detector means, wherein said means for detecting an external magnetic field includes at least one pick-up having a piezoelectric material surrounded about its circumference by a thin layer of magnetostrictive material.
Claim 3
Dependent Claim
16 words
A tag as claimed in claim 1, wherein said tone generator is a piezoelectric tone generator.
Claim 4
Dependent Claim
21 words
A tag as claimed in claim 1, wherein a resonant acoustic enclosure for said tone generator is provided in the housing.
Claim 5
Dependent Claim
17 words
A tag as claimed in claim 1, wherein said electric circuit is a low-power CMOS integrated circuit.
Claim 6
Dependent Claim
40 words
A tag as claimed in claim 1, which further comprises attachment means whereby the tag can be attached to an article of merchandise, and which serves to activate the tone operator in the event of unauthorized removal of the tag.
Claim 7
Dependent Claim
31 words
An antipilferage system comprising a tag as claimed in claim 1, and an interrogating gate comprising a coil of electrically conductive material and an alternating current generator connected to said coil.
Claim 8
Dependent Claim
65 words
An active magnetic antipilferage tag attachable to a piece of merchandise which comprises a housing containing three pick-up coils disposed in mutual orthogonal directions for detecting an external magnetic field; a power supply; a tone generator, and an electric circuit powered by said power supply and arranged to activate said tone generator in response to an output from one or more of said pick-up coils.
Claim 9
Dependent Claim
65 words
An active magnetic antipilferage tag attachable to a piece of merchandise which comprises a housing containing three pick-up coils disposed in mutual orthogonal directions for detecting an external magnetic field; a power supply; a tone generator, and an electric circuit powered by said power supply and arranged to activate said tone generator in response to an output from one or more of said pick-up coils.
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) | 1994-02-11 | 1994-08-13 | 1995-02-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-02-11 | 1998-08-13 | 1999-02-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-02-11 | 2002-08-13 | 2003-02-12 | $7700.00 | Window Closed / Lapsed |