US5012224A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Audible tag for magnetic electronic article surveillance systems
Assignee: Sensormatic Electronics Corp
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Filing: 1990-08-03
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Granted: 1991-04-30
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Expires: 2010-08-03
Abstract
Abstract A tag for use in a magnetic article surveillance system employs an antenna means responsive to a transmitted magnetic signal and a piezoelectric means responsive to the antenna means for generating an audible acoustic signal. Embodiments are provided responding to unmodulated, amplitude modulated, and frequency modulated magnetic signals.
Inventors
- 👤 Frank Drucker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 23:22
CPC Classifications
G; G08; G08B; G08B13/00; G08B13/22; G08B13/24; G08B13/2402; G08B13/2405; G08B13/2422; G08B13/2428; G08B13/2431
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
32 words
A tag for use in a magnetic article surveillance system comprising: antenna means responsive to a magnetic field; and piezoelectric means responsive to said antenna means for generating an audible acoustic signal.
Claim 2
Dependent Claim
32 words
A tag for use in a magnetic article surveillance system comprising: antenna means responsive to a magnetic field; and piezoelectric means responsive to said antenna means for generating an audible acoustic signal.
Claim 3
Dependent Claim
50 words
A tag in accordance with claim 1 wherein: said piezoelectric means has an acoustic resonant frequency; said antenna means and said piezoelectric means are connected to form a circuit which is responsive to signals at said acoustic resonant frequency; and said audible acoustic signal is at said acoustic resonant frequency.
Claim 4
Dependent Claim
17 words
A tag in accordance with claim 2 wherein: said magnetic field is at said acoustic resonant frequency.
Claim 5
Dependent Claim
61 words
A tag in accordance with claim 2 wherein: said magnetic field is at a higher frequency than said acoustic resonant frequency and is modulated at said acoustic resonant frequency; and said tag further includes demodulator means for demodulating the signal developed by said antenna means in response to said magnetic field and for coupling said demodulated signal to said piezoelectric means.
Claim 6
Dependent Claim
63 words
A tag in accordance with claim 4 wherein: said magnetic field is amplitude modulated at said acoustic resonant frequency; said piezoelectric means comprises a piezoelectric crystal; and said demodulator means comprises: a resistor connected across said crystal; and a rectifier having a first end connected to one end of said resistor and a second end connected to one end of said antenna means.
Claim 7
Dependent Claim
15 words
A tag in accordance with claim 5 wherein: said rectifier means comprises a Schotky diode.
Claim 8
Dependent Claim
81 words
A tag in accordance with claim 4 wherein: said magnetic field is frequency modulated at said acoustic resonant frequency said magnetic field is frequency modulated at said acoustic resonant frequency; said piezoelectric means comprises a piezoelectric crystal; and said demodulator means comprises: a resistor connected across said crystal; a capacitor connected across said antenna means; and a rectifier having a first end connected to one end of said resistor and a second end connected to one end of said antenna means.
Claim 9
Dependent Claim
20 words
A tag in accordance with claim 1 wherein: said piezoelectric means comprises a piezoelectric crystal connected across said antenna means.
Claim 10
Dependent Claim
37 words
An electronic article surveillance system comprising: means for transmitting a magnetic field; and a tag comprising: antenna means responsive to said magnetic field; and piezoelectric means responsive to said antenna means for generating an audible acoustic signal.
Claim 11
Dependent Claim
37 words
An electronic article surveillance system comprising: means for transmitting a magnetic field; and a tag comprising: antenna means responsive to said magnetic field; and piezoelectric means responsive to said antenna means for generating an audible acoustic signal.
Claim 12
Dependent Claim
50 words
A system in accordance with claim 9 wherein: said piezoelectric means has an acoustic resonant frequency; said antenna means and said piezoelectric means are connected to form a circuit which is responsive to signals at said acoustic resonant frequency; and said audible acoustic signal is at said acoustic resonant frequency.
Claim 13
Dependent Claim
18 words
A system in accordance with claim 10 wherein: said magnetic field is transmitted at said acoustic resonant frequency.
Claim 14
Dependent Claim
62 words
A system in accordance with claim 10 wherein: said magnetic field is transmitted at a higher frequency than said acoustic resonant frequency and is modulated at said acoustic resonant frequency; and said tag further includes demodulator means for demodulating the signal developed by said antenna means in response to said magnetic field and for coupling said demodulated signal to said piezoelectric means.
Claim 15
Dependent Claim
20 words
A system in accordance with claim 9 further comprising: receiver means for receiving said audible signal and generating an alarm.
Claim 16
Dependent Claim
49 words
A system in accordance with claim 9 further comprising: means for transmitting a further magnetic field, said tag being responsive to said further magnetic field and causing a perturbation to said further magnetic field; and antenna and receiver means for receiving and detecting said perturbation and generating an alarm.
Claim 17
Dependent Claim
36 words
A system in accordance with claim 9 wherein: said tag causes a perturbation to said magnetic field; and said system further comprises antenna and receiver means for receiving and detecting said perturbation and generating an alarm.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-04-29 | 1994-10-29 | 1995-04-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-04-29 | 1998-10-29 | 1999-04-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-04-29 | 2002-10-29 | 2003-04-30 | $7700.00 | Window Closed / Lapsed |