US Patent No: 6,535,108
Number of patents in Portfolio can not be more than 2000
Modulation of the resonant frequency of a circuit using an energy field
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Mar 18, 2003
Issued date -
Aug 18, 1998
filing date -
09/136,157
serial no -
In Force
status
Importance
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Abstract
A transponder has a resonant RLC circuit with one or more electromagnetic energy storage components that vary in response to an externally applied modulating energy field. In addition to the externally modulating energy field, a base station transmits a carrier signal with a frequency essentially the same as the quiescent resonant frequency of the RLC circuit. As the component(s) vary, the resonant frequency of the RLC circuit changes, modulating the carrier signal with the external modulating energy field. Effects of the modulation are detected by the base station. Information (e.g., the presence of a tag) is obtained by receiving and demodulating the modulated signal at the base station. One or more of the circuit elements (e.g. different preferred embodiments of one or more capacitors, inductors, and resistors) can be varied (e.g. mechanically) to modulate the carrier signal. This allows the resonant circuit to modulate the carrier signal with multiple modulation frequencies to encode multiple bits of information on the carrier.
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First Claim
Related Publications
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International Classification(s)
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Cited Art
| Patent Info | (Count) | # Cites | Year |
|---|---|---|---|
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| 5,538,803 Multibit tag using Barkhausen effect | 33 | 1994 | |
| 5,552,778 Multibit bimorph magnetic tags using acoustic or magnetic interrogation for identification of an object coupled thereto | 36 | 1994 | |
| 5,554,974 Encodable tag with radio frequency readout | 70 | 1994 | |
| 5,563,583 Multibit magnetic radio frequency tag using micromechanics | 39 | 1994 | |
| 5,565,847 Magnetic tag using acoustic or magnetic interrogation | 45 | 1994 | |
| 5,812,065 Modulation of the resonant frequency of a circuit using an energy field | 87 | 1995 | |
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| 4,835,524 Deactivatable security tag | 51 | 1987 | |
| 5,081,445 Method for tagging articles used in conjunction with an electronic article surveillance system, and tags or labels useful in connection therewith | 60 | 1991 | |
| 5,218,189 Binary encoded multiple frequency RF indentification tag | 123 | 1991 | |
| 5,276,431 Security tag for use with article having inherent capacitance | 100 | 1992 | |
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| 5,204,681 Radio frequency automatic identification system | 40 | 1991 | |
| 5,581,257 Radio frequency automatic identification system | 91 | 1994 | |
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| 5,381,137 RF tagging system and RF tags and method | 121 | 1992 | |
| 5,446,447 RF tagging system including RF tags with variable frequency resonant circuits | 202 | 1994 | |
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| 4,341,189 Knock detecting apparatus for combustion engines | 14 | 1979 | |
| 4,465,047 Knock detecting apparatus for combustion engines | 9 | 1982 | |
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| 4,940,966 Article detection and/or recognition using magnetic devices | 76 | 1989 | |
| 5,420,569 Remotely readable data storage devices and apparatus | 23 | 1993 | |
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| 5,111,186 LC-type electronic article surveillance tag with voltage dependent capacitor | 32 | 1990 | |
| 5,257,009 Reradiating EAS tag with voltage dependent capacitance to provide tag activation and deactivation | 24 | 1991 | |
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| 5,235,326 Multi-mode identification system | 183 | 1991 | |
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| 5,559,507 Signal transmission and tag reading circuit for an inductive reader | 38 | 1993 | |
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| 4,999,609 Antipilferage tags having an acoustic resonator chamber | 9 | 1989 | |
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| 5,055,786 Barber-pole magnetoresistive magnetic field sensor | 18 | 1990 | |
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| 5,341,118 Multilayer magnetic structure wherein the magnitude of the structure magnetoresistance is a function of nonmagnetic layer thickness | 47 | 1993 | |
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| 4,338,554 Automatic gain control apparatus for a motor servo system | 5 | 1980 | |
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| 4,447,781 Magnetoresistive transducer apparatus | 8 | 1981 | |
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| 4,510,490 Coded surveillance system having magnetomechanical marker | 109 | 1982 | |
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| 4,476,454 New magnetoresistive materials | 15 | 1983 | |
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| 5,450,492 Transponder system with variable frequency transmission | 101 | 1992 | |
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| 4,745,401 RF reactivatable marker for electronic article surveillance system | 112 | 1985 | |
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| 5,001,458 Method of remote sensing of objects | 22 | 1989 | |
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| 5,038,130 System for sensing changes in a magnetic field | 20 | 1990 | |
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| 4,647,917 Article control system having coded magnetomechanical marker | 37 | 1984 | |
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| 5,166,612 Micromechanical sensor employing a SQUID to detect movement | 12 | 1990 | |
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| 5,550,536 Circuit frequency following technique transponder resonant | 109 | 1994 | |
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| 5,001,933 Micromechanical vibration sensor | 37 | 1989 | |
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| 5,420,596 Quarter-wave gap-coupled tunable strip antenna | 42 | 1993 | |
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| 4,940,996 Drop-on-demand printhead | 44 | 1989 | |
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| 4,388,524 Electronic identification and recognition system with code changeable reactance | 114 | 1981 | |
Patent Citation Ranking
Maintenance Fees
| Fee | Large entity fee | small entity fee | micro entity fee | due date |
|---|---|---|---|---|
| 11.5 Year Payment | $7400.00 | $3700.00 | $1850.00 | Sep 18, 2014 |
| Fee | Large entity fee | small entity fee | micro entity fee |
|---|---|---|---|
| Surcharge - 11.5 year - Late payment within 6 months | $160.00 | $80.00 | $40.00 |
| Surcharge after expiration - Late payment is unavoidable | $700.00 | $350.00 | $175.00 |
| Surcharge after expiration - Late payment is unintentional | $1,640.00 | $820.00 | $410.00 |