US3755803A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electronic surveillance system
Assignee: Unisearch Ltd
•
Filing: 1970-03-31
•
Granted: 1973-08-28
•
Expires: 1990-03-31
Abstract
Abstract An electronic surveillance system in which a passive label attached to an article under surveillance is interrogated by means of a transmitted signal in a first form of energy, the label using the energy of that signal to return a signal to a receiver which gives an indication of the presence of the label if a reply signal has predetermined characteristics. In order to enable the receiver to distinguish the reply signal from the original transmitted signal the label is constructed to produce the reply signal in a form of energy different from that of the original transmitted signal. It is preferred that the first form of energy is accoustic energy and the second form of energy is electromagnetic energy.
Inventors
- 👤 P Cole
- 👤 R Vaughn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 06:39
CPC Classifications
G; G08; G08B; G08B13/00; G08B13/22; G08B13/24; G08B13/2402; G08B13/2405; G08B13/2422; G06; G06K; G06K19/00; G06K19/06; G06K19/067; G06K19/0672; G06K7/00; G06K7/0008; G06K7/02; G06K7/08; G06K7/082; G06K7/083; G06K7/086; G06K7/10; G06K7/10009; G08B13/2428; G08B13/2437; G08B13/2465; G08B13/2468; G08B13/2471
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
137 words
An electronic surveillance system, comprising transmitter means for transmitting signals having a first form of energy, a passive label for attachment to an article to be placed under surveillance, signal answering means mounted on said label for receiving the signals from said transmitting means and producing signals having a second form of energy and corresponding to the received signals, receiver means responsive to the signals transmitted by said signal answering means for receiving and processing the signals of the second form of energy, control means for defining a surveillance volume, said control means including modulator means coupled to said transmitter means and rendering said receiver means unresponsive to signals from said answering means when the phase of the signals from said answering means relative to the phase of signals from said transmitter means exceeds a given value.
Claim 2
Dependent Claim
137 words
An electronic surveillance system, comprising transmitter means for transmitting signals having a first form of energy, a passive label for attachment to an article to be placed under surveillance, signal answering means mounted on said label for receiving the signals from said transmitting means and producing signals having a second form of energy and corresponding to the received signals, receiver means responsive to the signals transmitted by said signal answering means for receiving and processing the signals of the second form of energy, control means for defining a surveillance volume, said control means including modulator means coupled to said transmitter means and rendering said receiver means unresponsive to signals from said answering means when the phase of the signals from said answering means relative to the phase of signals from said transmitter means exceeds a given value.
Claim 3
Dependent Claim
51 words
A system as in claim 1, wherein said modulator means constrains said transmitter means to produce a series of regular pulses and gate said receiver means synchronously so as to switch on said receiver means at a predetermined time after the commencement of each transmitter pulse and for a predetermined period.
Claim 4
Dependent Claim
19 words
A system as in claim 1, wherein one of said transmitter means and said answering means transmit acoustical energy.
Claim 5
Dependent Claim
13 words
A system as in claim 1, wherein said transmitter means transmits acoustical energy.
Claim 6
Dependent Claim
13 words
A system as in claim 1, wherein said answering means transmits acoustical energy.
Claim 7
Dependent Claim
13 words
A system as in claim 4, wherein said answering means transmits electromagnetic energy.
Claim 8
Dependent Claim
13 words
A system as in claim 5, wherein said transmitter means transmits electromagnetic energy.
Claim 9
Dependent Claim
78 words
A system as in claim 1, wherein said answering means includes second receiver means on said label for receiving the signals of the first form of energy, transducer means on said label coupled to said receiver means for responding to the signals on said second receiver means for forming signals of the second form of energy, and second transmitter means on said label responsive to said transducer means for transmitting the signals of the second form of energy.
Claim 10
Dependent Claim
17 words
A system as in claim 1, wherein said answering means includes an electroacoustic resonator on said label.
Claim 11
Dependent Claim
11 words
A system as in claim 9, wherein said resonator is piezoelectric.
Claim 12
Dependent Claim
11 words
A system as in claim 9, wherein said resonator is magnetostrictive.
Claim 13
Dependent Claim
17 words
An apparatus as in claim 10, wherein said answering means includes an antenna connected to said resonator.
Claim 14
Dependent Claim
56 words
A system as in claim 1, wherein said label includes a plastic card having a cutout, said answering means including a piezoelectric resonator adapted to vibrate in a flexural mode, said resonator including electrodes attached to the surface of said piezoelectric resonator, and an antenna formed on the surface of the card connected to said electrodes.
Claim 15
Dependent Claim
25 words
A system as in claim 13, wherein said label includes covering means sandwiching the plastic card between them for protecting the resonator and said antenna.
References Cited (Backward Citations)
US2774060A
Cited
US2899546A
Cited
US3031643A
Cited
US3293595A
Cited
GB1085704A
Cited
US3399405A
Cited
US3500373A
Cited
US3389391A
Cited
US3432852A
Cited
US3577136A
Cited
US3631442A
Cited
US3493955A
Cited
US3521280A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-08-27 | 1977-02-26 | 1977-08-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-27 | 1981-02-26 | 1981-08-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-27 | 1985-02-26 | 1985-08-28 | $7700.00 | Window Closed / Lapsed |