US4654641A
Expired / Lapsed
US
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Frequency divider with single resonant circuit and use thereof as a transponder in a presence detection system
Assignee: Sensormatic Electronics Corp
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Filing: 1985-09-13
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Granted: 1987-03-31
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Expires: 2005-09-13
Abstract
Abstract A batteryless, portable, frequency divider, consisting of a single resonant circuit including a nonlinear inductor having a core made of amorphous magnetic material; and a capacitance connected in series with the inductor to define a resonant circuit that detects electromagnetic radiation at a first predetermined frequency and responds to said detection by transmitting electromagnetic radiation at a second frequency that is a subharmonic of the first frequency. The resonant circuit may further include a second inductor connected in series with the nonlinear inductor and the capacitance to define the resonant circuit. The core of the nonlinear inductor includes an elongated thin flat ribbon of low coercivity amorphous magnetic material. It has been observed that the resonant circuit exhibits a bifurcated frequency-division characteristic in relation to the amplitude of the detected electromagnetic radiation at the first predetermined frequency, whereby additional frequency divisions occur as the amplitude is increased. This bifurcation characteristic is utilized in a presence detection system that uses a tag containing the frequency divider. The system transmits electromagnetic radiation at the first frequency into a surveillance zone and detects multiple subharmonic frequencies to detect the presence of the tag in the surveillance zone.
Inventors
- 👤 Lucian G. Ferguson
- 👤 Lincoln H. Charlot, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 13:56
CPC Classifications
G; G06; G06K; G06K7/00; G06K7/10; G06K7/10009; G06K7/10118; G06K7/10128; G01; G01S; G01S13/00; G01S13/74; G01S13/75; G01S13/751; G01S13/753; G08; G08B; G08B13/00; G08B13/22; G08B13/24; G08B13/2402; G08B13/2428; G08B13/2431; G08B13/2437; G08B13/2442
Claims Analysis
Total Claims: 46
Claim 1
Independent Claim
67 words
A batteryless, portable, frequency divider, consisting of a single resonant circuit comprising a nonlinear inductor having a core made of amorphous magnetic material; and a capacitance connected in series with the inductor to define a resonant circuit that detects electromagnetic radiation at a first predetermined frequency and responds to said detection by transmitting electromagnetic radiation at a second frequency that is a sub-harmonic of the first frequency.
Claim 2
Dependent Claim
67 words
A batteryless, portable, frequency divider, consisting of a single resonant circuit comprising a nonlinear inductor having a core made of amorphous magnetic material; and a capacitance connected in series with the inductor to define a resonant circuit that detects electromagnetic radiation at a first predetermined frequency and responds to said detection by transmitting electromagnetic radiation at a second frequency that is a sub-harmonic of the first frequency.
Claim 3
Dependent Claim
51 words
A frequency divider according to claim 1, wherein the resonant circuit further comprises a second inductor connected in series with the nonlinear inductor and the capacitance to define the resonant circuit and having a coil that is positioned so that the second inductor is not mutually coupled to the nonlinear inductor.
Claim 4
Dependent Claim
22 words
A frequency divider according to claim 2, wherein the coil of the second inductor is wound around the perimeter of the circuit.
Claim 5
Dependent Claim
22 words
A frequency divider according to claim 3, wherein the resonant circuit consists of said nonlinear inductor, said capacitance and said second inductor.
Claim 6
Dependent Claim
22 words
A frequency divider according to claim 2, wherein the resonant circuit consists of said nonlinear inductor, said capacitance and said second inductor.
Claim 7
Dependent Claim
19 words
A frequency divider according to claim 1, wherein the resonant circuit consists of said nonlinear inductor and said capacitance.
Claim 8
Dependent Claim
25 words
A frequency divider according to claim 1, wherein the core of the nonlinear inductor comprises an elongated thin flat ribbon of low-coercivity amorphous magnetic material.
Claim 9
Dependent Claim
33 words
A frequency divider according to claim 7, wherein the ratio of the length of the ribbon to the square root of the cross-sectional area of the ribbon is at least one-hundred-fifty to one.
Claim 10
Dependent Claim
19 words
A frequency divider according to claim 8, wherein the resonant circuit consists of said nonlinear inductor and said capacitance.
Claim 11
Dependent Claim
19 words
A frequency divider according to claim 7, wherein the resonant circuit consists of said nonlinear inductor and said capacitance.
Claim 12
Dependent Claim
45 words
A frequency divider according to claim 7, wherein the resonant circuit consists of said nonlinear inductor, said capacitance and a second inductor connected in series therewith and having coil that is positioned so that the second inductor is not mutually coupled to the nonlinear inductor.
Claim 13
Dependent Claim
33 words
A frequency divider according to claim 11, wherein the ratio of the length of the ribbon to the square root of the cross-sectional area of the ribbon is at least one-hundred-fifty to one.
Claim 14
Dependent Claim
22 words
A frequency divider according to claim 12, wherein the coil of the second inductor is wound around the perimeter of the circuit.
Claim 15
Dependent Claim
170 words
A presence detection system, comprising means for transmitting an electromagnetic radiation signal of a first predetermined frequency into a surveillance zone; a tag for attachment to an article to be detected within the surveillance zone, comprising a batteryless, portable, frequency divider consisting of a single resonant circuit comprising a nonlinear inductor having a coil wound around a core made of amorphous magnetic material; and a capacitance connected in series with the inductor to define a resonant circuit that detects electromagnetic radiation at the first predetermined frequency and responds to said detection by transmitting electromagnetic radiation at a second frequency that is a sub-harmonic of the first frequency; means for providing an external magnetic bias field within the surveillance zone that is equivalent in strength to the magnetic field generated by the saturation current in the coil wound around the core of the nonlinear inductor in response to the detected electromagnetic radiation at the first predetermined frequency; and means for detecting electromagnetic radiation at the second frequency in the surveillance zone.
Claim 16
Dependent Claim
170 words
A presence detection system, comprising means for transmitting an electromagnetic radiation signal of a first predetermined frequency into a surveillance zone; a tag for attachment to an article to be detected within the surveillance zone, comprising a batteryless, portable, frequency divider consisting of a single resonant circuit comprising a nonlinear inductor having a coil wound around a core made of amorphous magnetic material; and a capacitance connected in series with the inductor to define a resonant circuit that detects electromagnetic radiation at the first predetermined frequency and responds to said detection by transmitting electromagnetic radiation at a second frequency that is a sub-harmonic of the first frequency; means for providing an external magnetic bias field within the surveillance zone that is equivalent in strength to the magnetic field generated by the saturation current in the coil wound around the core of the nonlinear inductor in response to the detected electromagnetic radiation at the first predetermined frequency; and means for detecting electromagnetic radiation at the second frequency in the surveillance zone.
Claim 17
Dependent Claim
19 words
A system according to claim 14, wherein the means for providing the external bias field includes a permanent magnet.
Claim 18
Dependent Claim
94 words
A system according to claim 14, wherein the resonant circuit has a frequency-division characteristic with respect to the amplitude of the electromagnetic radiation at the first frequency such that when the amplitude exceeds a predetermined threshold, the resonant circuit transmits multiple sub-harmonics of the first frequency; wherein the transmitting means is adapted for transmitting electromagnetic radiation that exceeds said predetermined amplitude threshold within the surveillance zone; and wherein the detecting means are adapted for detecting said multiple sub-harmonics in the surveillance zone to thereby detect the presence of the tag within the surveillance zone.
Claim 19
Dependent Claim
116 words
A presence detection system, comprising means for transmitting an electromagnetic radiation signal of a first predetermined frequency into a surveillance zone; a tag for attachment to an article to be detected within the surveillance zone, comprising a batteryless, portable, frequency divider consisting of a resonant circuit comprising a nonlinear inductor having a core made of amorphous magnetic material; and a capacitance connected in series with the inductor to define a resonant circuit that detects electromagnetic radiation at the first predetermined frequency and responds to said detection by transmitting electromagnetic radiation at a second frequency that is a sub-harmonic of the first frequency; and means for detecting electromagnetic radiation at the second frequency in the surveillance zone.
Claim 20
Dependent Claim
116 words
A presence detection system, comprising means for transmitting an electromagnetic radiation signal of a first predetermined frequency into a surveillance zone; a tag for attachment to an article to be detected within the surveillance zone, comprising a batteryless, portable, frequency divider consisting of a resonant circuit comprising a nonlinear inductor having a core made of amorphous magnetic material; and a capacitance connected in series with the inductor to define a resonant circuit that detects electromagnetic radiation at the first predetermined frequency and responds to said detection by transmitting electromagnetic radiation at a second frequency that is a sub-harmonic of the first frequency; and means for detecting electromagnetic radiation at the second frequency in the surveillance zone.
Claim 21
Dependent Claim
50 words
A system according to claim 17, wherein the resonant circuit further comprises a second inductor connected in series with the nonlinear inductor and the capacitance to define the resonant circuit and having a coil that is positioned so that the second inductor is not mutually coupled to the nonlinear inductor.
Claim 22
Dependent Claim
21 words
A system according to claim 18, wherein the resonant circuit consists of said nonlinear inductor, said capacitance and said second inductor.
Claim 23
Dependent Claim
24 words
A system according to claim 19, wherein the core of the nonlinear inductor comprises an elongated thin flat ribbon of low-coercivity amorphous magnetic material.
Claim 24
Dependent Claim
18 words
A system according to claim 17, wherein the resonant circuit consists of said nonlinear inductor and said capacitance.
Claim 25
Dependent Claim
24 words
A system according to claim 21, wherein the core of the nonlinear inductor comprises an elongated thin flat ribbon of low-coercivity amorphous magnetic material.
Claim 26
Dependent Claim
94 words
A system according to claim 17, wherein the resonant circuit has a frequency-division characteristic with respect to the amplitude of the electromagnetic radiation at the first frequency such that when the amplitude exceeds a predetermined threshold, the resonant circuit transmits multiple sub-harmonics of the first frequency; wherein the transmitting means is adapted for transmitting electromagnetic radiation that exceeds said predetermined amplitude threshold within the surveillance zone; and wherein the detecting means are adapted for detecting said multiple sub-harmonics in the surveillance zone to thereby detect the presence of the tag within the surveillance zone.
Claim 27
Dependent Claim
91 words
A batteryless, portable, frequency divider, consisting of an elongated thin flat ribbon of low coercivity magnetoelastic amorphous magnetic material that has been annealed in a magnetic field that is transverse to the length of the ribbon and in the the plane of the ribbon, which has a characteristic electromagnetic resonant frequency "f", and which detects electromagnetic radiation having a given frequency nf, wherein "n" is an even integer, and responds to the detection of said radiation by transmitting electromagnetic radiation at a subharmonic of the given frequency of the detected radiation.
Claim 28
Dependent Claim
91 words
A batteryless, portable, frequency divider, consisting of an elongated thin flat ribbon of low coercivity magnetoelastic amorphous magnetic material that has been annealed in a magnetic field that is transverse to the length of the ribbon and in the the plane of the ribbon, which has a characteristic electromagnetic resonant frequency "f", and which detects electromagnetic radiation having a given frequency nf, wherein "n" is an even integer, and responds to the detection of said radiation by transmitting electromagnetic radiation at a subharmonic of the given frequency of the detected radiation.
Claim 29
Dependent Claim
13 words
A frequency divider according to claim 24, wherein the subharmonic is one-half nf.
Claim 30
Dependent Claim
52 words
A frequency divider according to claim 24, wherein the material is selected from a group consisting of Fe 67 Co 18 B 14 Si 1 , Fe 81 B 13 .5 Si 3 .5 C 2 , Fe 82 B 12 Si 6 , and Fe 78 B 13 Si 9 .
Claim 31
Dependent Claim
162 words
A presence detection system, comprising means for transmitting an electromagnetic radiation signal of a first predetermined frequency nf into a surveillance zone; a tag for attachment to an article to be detected within the surveillance zone, comprising a batteryless, portable, frequency divider consisting of an elongated thin flat ribbon of low coercivity magnetoelastic amorphous magnetic material that has been annealed in a magnetic field that is transverse to the length of the ribbon and in the the plane of the ribbon, which has a characteristic electromagnetic resonant frequency "f", and which detects electromagnetic radiation having the frequency nf, wherein "n" is an even integer, and responds to the detection of said radiation by transmitting electromagnetic radiation at a sub-harmonic of the frequency of the detected radiation; means for providing an external magnetic bias field within the surveillance zone of sufficient strength to cause the ribbon to frequency divide; and means for detecting electromagnetic radiation at the subharmonic frequency in the surveillance zone.
Claim 32
Dependent Claim
162 words
A presence detection system, comprising means for transmitting an electromagnetic radiation signal of a first predetermined frequency nf into a surveillance zone; a tag for attachment to an article to be detected within the surveillance zone, comprising a batteryless, portable, frequency divider consisting of an elongated thin flat ribbon of low coercivity magnetoelastic amorphous magnetic material that has been annealed in a magnetic field that is transverse to the length of the ribbon and in the the plane of the ribbon, which has a characteristic electromagnetic resonant frequency "f", and which detects electromagnetic radiation having the frequency nf, wherein "n" is an even integer, and responds to the detection of said radiation by transmitting electromagnetic radiation at a sub-harmonic of the frequency of the detected radiation; means for providing an external magnetic bias field within the surveillance zone of sufficient strength to cause the ribbon to frequency divide; and means for detecting electromagnetic radiation at the subharmonic frequency in the surveillance zone.
Claim 33
Dependent Claim
12 words
A system according to claim 27, wherein the subharmonic is one-half nf.
Claim 34
Dependent Claim
51 words
A system according to claim 27, wherein the material is selected from a group consisting of Fe 67 Co 18 B 14 Si 1 , Fe 81 B 13 .5 Si 3 .5 C 2 , Fe 82 B 12 Si 6 , and Fe 78 B 13 Si 9 .
Claim 35
Dependent Claim
76 words
A batteryless, portable, frequency divider, consisting of an elongated thin flat ribbon of low coercivity magnetoelastic amorphous magnetic material that has been annealed in a magnetic field that is transverse to the length of the ribbon and in the the plane of the ribbon, and which detects electromagnetic radiation having a given frequency and responds to the detection of said radiation by transmitting electromagnetic radiation at a subharmonic of the given frequency of the detected radiation.
Claim 36
Dependent Claim
76 words
A batteryless, portable, frequency divider, consisting of an elongated thin flat ribbon of low coercivity magnetoelastic amorphous magnetic material that has been annealed in a magnetic field that is transverse to the length of the ribbon and in the the plane of the ribbon, and which detects electromagnetic radiation having a given frequency and responds to the detection of said radiation by transmitting electromagnetic radiation at a subharmonic of the given frequency of the detected radiation.
Claim 37
Dependent Claim
18 words
A frequency divider according to claim 30, wherein the subharmonic is one-half the frequency of the detected radiation.
Claim 38
Dependent Claim
51 words
A frequency divider according to claim 30, wherein the material is selected from a group consisting of Fe 67 Co 18 B 14 Si 1 , Fe 81 B 13:5 Si 3 .5 C 2 , Fe 82 B 12 Si 6 , and Fe 78 B 13 Si 9 .
Claim 39
Dependent Claim
149 words
A presence detection system, comprising means for transmitting an electromagnetic radiation signal of a first predetermined frequency nf into a surveillance zone; a tag for attachment to an article to be detected within the surveillance zone, comprising a batteryless, portable, frequency divider consisting of an elongated thin flat ribbon of low coercivity magnetoelastic amorphous magnetic material that has been annealed in a magnetic field that is transverse to the length of the ribbon and in the the plane of the ribbon, and which which detects electromagnetic radiation having the first frequency and responds to the detection of said radiation by transmitting electromagnetic radiation at a sub-harmonic of the frequency of the detected radiation; means for providing an external magnetic bias field within the surveillance zone of sufficient strength to cause the ribbon to frequency divide; and means for detecting electromagnetic radiation at the subharmonic frequency in the surveillance zone.
Claim 40
Dependent Claim
149 words
A presence detection system, comprising means for transmitting an electromagnetic radiation signal of a first predetermined frequency nf into a surveillance zone; a tag for attachment to an article to be detected within the surveillance zone, comprising a batteryless, portable, frequency divider consisting of an elongated thin flat ribbon of low coercivity magnetoelastic amorphous magnetic material that has been annealed in a magnetic field that is transverse to the length of the ribbon and in the the plane of the ribbon, and which which detects electromagnetic radiation having the first frequency and responds to the detection of said radiation by transmitting electromagnetic radiation at a sub-harmonic of the frequency of the detected radiation; means for providing an external magnetic bias field within the surveillance zone of sufficient strength to cause the ribbon to frequency divide; and means for detecting electromagnetic radiation at the subharmonic frequency in the surveillance zone.
Claim 41
Dependent Claim
17 words
A system according to claim 33, wherein the subharmonic is one-half the frequency of the detected radiation.
Claim 42
Dependent Claim
51 words
A system according to claim 33, wherein the material is selected from a group consisting of Fe 67 Co 18 B 14 Si 1 , Fe 81 B 13 .5 Si 3 .5 C 2 , Fe 82 B 12 Si 6 , and Fe 78 B 13 Si 9 .
Claim 43
Dependent Claim
131 words
A coded tag for attachment to an article to be detected within a surveillance zone, comprising a plurality of a batteryless, portable, frequency dividers, each of which consists of an elongated thin flat ribbon of low coercivity magnetoelastic amorphous magnetic material that has been annealed in a magnetic field that is transverse to the length of the ribbon and in the the plane of the ribbon, which has a characteristic electromagnetic resonant frequency "f", and which detects electromagnetic radiation having the frequency nf, wherein "n" is an even integer, and responds to the detection of said radiation by transmitting electromagnetic radiation at a sub-harmonic of the frequency of the detected radiation; wherein the ribbons of the respective frequency dividers are of different lengths and thereby have different characteristic electromagnetic resonant frequencies.
Claim 44
Dependent Claim
131 words
A coded tag for attachment to an article to be detected within a surveillance zone, comprising a plurality of a batteryless, portable, frequency dividers, each of which consists of an elongated thin flat ribbon of low coercivity magnetoelastic amorphous magnetic material that has been annealed in a magnetic field that is transverse to the length of the ribbon and in the the plane of the ribbon, which has a characteristic electromagnetic resonant frequency "f", and which detects electromagnetic radiation having the frequency nf, wherein "n" is an even integer, and responds to the detection of said radiation by transmitting electromagnetic radiation at a sub-harmonic of the frequency of the detected radiation; wherein the ribbons of the respective frequency dividers are of different lengths and thereby have different characteristic electromagnetic resonant frequencies.
Claim 45
Dependent Claim
19 words
A tag according to claim 36, wherein the subharmonic is one-half nf for each of the respective frequency dividers.
Claim 46
Dependent Claim
51 words
A tag according to claim 36, wherein the material is selected from a group consisting of Fe 67 Co 18 B 14 Si 1 , Fe 81 B 13 .5 Si 3 .5 C 2 , Fe 82 B 12 Si 6 , and Fe 78 B 13 Si 9 .
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1990-03-30 | 1990-09-29 | 1991-03-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-03-30 | 1994-09-29 | 1995-03-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-03-30 | 1998-09-29 | 1999-03-31 | $7700.00 | Window Closed / Lapsed |