Patent US6317027B1 successfully refreshed from Google Patents.
US6317027B1
Expired / Lapsed
US
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Auto-tunning scanning proximity reader
Assignee: Soundcraft Inc
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Filing: 1999-01-12
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Granted: 2001-11-13
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Expires: 2019-01-12
Abstract
Abstract A proximity reader for a radio frequency identification (RFID) system is programmed for determining and storing optimum antenna impedance values to achieve peak antenna resonance at each of multiple operating frequencies. Antenna resonance is peaked at power up and periodically during operation to compensate for environmental detuning influences. The reader scans the multiple frequencies to more effectively search for off-frequency identification tags.
Inventors
- 👤 Randy Watkins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 20:39
CPC Classifications
G; G06; G06K; G06K7/00; G06K7/10; G06K7/10009; G06K7/10316; G06K7/10336; G06K7/0008; H; H03; H03J; H03J2200/00; H03J2200/10
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
205 words
A proximity reader for a radio frequency identification system wherein identification tags have transponder circuits powered by a radio frequency transmission of the reader at a resonant frequency of the tags for inducing a coded response, the reader having frequency generator means for generating a center frequency and a plurality of discrete side frequencies spaced from each other and from said center frequency, an antenna circuit connected for radiating each of said center frequency and said side frequencies in a sequence to interrogate transponder tags, and a microprocessor connected to said antenna circuit for receiving and decoding transponder tag information communicated by loading down a radiofrequency field radiated by said antenna circuit at any single one of said center and side frequencies, antenna resonance tuning means including a selectable impedance in said antenna circuit and tuner program means operative in step with said sequence for selecting discrete values of said impedance corresponding to each of said center frequency and said discrete side frequencies to substantially optimize the reactance of said antenna circuit for maximum radiated signal at each of said center frequency and side frequencies thereby to maximize operative range of the transmitter and for storing said values for reference by said tuner program means.
Claim 2
Dependent Claim
205 words
A proximity reader for a radio frequency identification system wherein identification tags have transponder circuits powered by a radio frequency transmission of the reader at a resonant frequency of the tags for inducing a coded response, the reader having frequency generator means for generating a center frequency and a plurality of discrete side frequencies spaced from each other and from said center frequency, an antenna circuit connected for radiating each of said center frequency and said side frequencies in a sequence to interrogate transponder tags, and a microprocessor connected to said antenna circuit for receiving and decoding transponder tag information communicated by loading down a radiofrequency field radiated by said antenna circuit at any single one of said center and side frequencies, antenna resonance tuning means including a selectable impedance in said antenna circuit and tuner program means operative in step with said sequence for selecting discrete values of said impedance corresponding to each of said center frequency and said discrete side frequencies to substantially optimize the reactance of said antenna circuit for maximum radiated signal at each of said center frequency and side frequencies thereby to maximize operative range of the transmitter and for storing said values for reference by said tuner program means.
Claim 3
Dependent Claim
33 words
The reader of claim 1 wherein said selectable impedance is a plurality of capacitances addressable by said microprocessor, and said impedance values are stored as a table of addresses representative of said capacitances.
Claim 4
Dependent Claim
11 words
The reader of claim 2 wherein said capacitances are binarily weighed.
Claim 5
Dependent Claim
30 words
The reader of claim 1 wherein said tuner program means are executed upon initial power-up of the reader to compensate for environmental impact on the resonance of the antenna circuit.
Claim 6
Dependent Claim
47 words
The reader of claim 4 wherein said tuner program means are executed at periodic intervals during operation of the reader so that the antenna circuit reactance is retuned to compensate for changes in environmental impact on the resonance of the antenna circuit during operation of the reader.
Claim 7
Dependent Claim
39 words
The reader of claim 1 further comprising scanning program means operative for executing a scanning sequence including sequentially switching said frequency generator through each of said side and center frequencies thereby to improve interrogation range of off-frequency transponder tags.
Claim 8
Dependent Claim
41 words
The reader of claim 6 wherein said scanning program means are further operative for interrupting said scanning sequence upon detection by said microprocessor of a response from a transponder tag and for resuming said scanning sequence upon completion of said response.
Claim 9
Dependent Claim
95 words
The reader of claim 1 wherein said antenna resonance tuning means comprises a peak detector circuit connected for measuring a radiofrequency voltage across said antenna circuit and providing a peak detector output to said microprocessor, and said microprocessor is operative for modifying an output frequency of said generator to obtain a peak resonance of the antenna circuit, and said tuner program means is operative for selecting a value of said impedance effective for bringing said output frequency to a desired frequency such that the reactance of said antenna circuit is optimized at said desired frequency.
Claim 10
Dependent Claim
33 words
The reader of claim 8 wherein said microprocessor and said tuner program means are operative for measuring said output frequency and for storing a value of said impedance associated with said desired frequency.
Claim 11
Dependent Claim
38 words
The reader of claim 9 wherein said desired frequency includes a plurality of spaced apart discrete frequencies, and said tuner program means is operative for storing a table of impedance values corresponding to said plurality of discrete frequencies.
Claim 12
Dependent Claim
18 words
The reader of claim 10 wherein said plurality of frequencies comprises said center frequency and said side frequencies.
Claim 13
Dependent Claim
26 words
The reader of claim 8 wherein said frequency generator is exterior to said microprocessor and includes said peak detector circuit on a common integrated circuit device.
Claim 14
Dependent Claim
40 words
The reader of claim 1 wherein said frequency generator is internal to said microprocessor and comprises a crystal controlled clock and a clock frequency divider controlled by said tuner program means for setting said center frequency and said side frequencies.
Claim 15
Dependent Claim
135 words
A proximity reader for a radio frequency identification system, the reader having frequency generator means for generating an output frequency, an antenna circuit connected for radiating a radiofrequency field at said output frequency for a time period sufficient to receive and decode a transponder tag coded response communicated by loading down said radiofrequency field at said output frequency, a microprocessor connected to said antenna circuit for receiving and decoding transponder tag information, scanner program means operative for sequentially switching said output frequency through a plurality of discrete frequencies spaced apart from each other and waiting for a predetermined listening time at each of said discrete frequencies sufficient to receive and verify a transponder tag response at said each of said discrete frequencies, thereby to improve interrogation of transponder tags built to relatively loose frequency tolerances.
Claim 16
Dependent Claim
135 words
A proximity reader for a radio frequency identification system, the reader having frequency generator means for generating an output frequency, an antenna circuit connected for radiating a radiofrequency field at said output frequency for a time period sufficient to receive and decode a transponder tag coded response communicated by loading down said radiofrequency field at said output frequency, a microprocessor connected to said antenna circuit for receiving and decoding transponder tag information, scanner program means operative for sequentially switching said output frequency through a plurality of discrete frequencies spaced apart from each other and waiting for a predetermined listening time at each of said discrete frequencies sufficient to receive and verify a transponder tag response at said each of said discrete frequencies, thereby to improve interrogation of transponder tags built to relatively loose frequency tolerances.
Claim 17
Dependent Claim
83 words
The proximity reader of claim 14 further comprising antenna resonance tuning means including a selectable impedance in said antenna circuit and tuner program means operative for selecting and storing values of said impedance at each of said plurality of frequencies, and means for connecting each selected impedance values to said antenna circuit at a corresponding one of said output frequencies thereby to substantially optimize the reactance of said antenna circuit and maximize operational range of the transmitter at each of said discrete frequencies.
Claim 18
Dependent Claim
141 words
A proximity reader for a radio frequency identification system, the reader having frequency generator means for generating a center frequency and a plurality of discrete side frequencies spaced from each other, an antenna circuit connected for radiating said center frequency and said side frequencies to interrogate transponder tags, and a microprocessor connected to said antenna circuit for receiving and decoding transponder tag information, an addressable variable tuning capacitance in said antenna circuit and tuner program means operative for addressing said tuning capacitance and electrically connected to said antenna for detecting a radio frequency signal amplitude in said antenna circuit at different capacitance values of said capacitance thereby to build a table of addresses representative of capacitance values yielding an optimum signal amplitude at each of said center frequency and discrete side frequencies, thereby to optimize the operative range of the reader.
Claim 19
Dependent Claim
141 words
A proximity reader for a radio frequency identification system, the reader having frequency generator means for generating a center frequency and a plurality of discrete side frequencies spaced from each other, an antenna circuit connected for radiating said center frequency and said side frequencies to interrogate transponder tags, and a microprocessor connected to said antenna circuit for receiving and decoding transponder tag information, an addressable variable tuning capacitance in said antenna circuit and tuner program means operative for addressing said tuning capacitance and electrically connected to said antenna for detecting a radio frequency signal amplitude in said antenna circuit at different capacitance values of said capacitance thereby to build a table of addresses representative of capacitance values yielding an optimum signal amplitude at each of said center frequency and discrete side frequencies, thereby to optimize the operative range of the reader.
Claim 20
Dependent Claim
95 words
The reader of claim 16 further comprising a peak detector circuit connected for measuring a radiofrequency voltage across said antenna circuit and providing a peak detector output to said microprocessor, and said microprocessor is operative for modifying an output frequency of said generator to obtain a peak resonance of the antenna circuit, and wherein said tuner program means is operative for selecting a value of said tuning capacitance effective for bringing said output frequency to one of the center and side frequencies such that the reactance of said antenna circuit is optimized at said frequencies.
Claim 21
Dependent Claim
53 words
The reader of claim 17 wherein said microprocessor and said tuner program means are operative for timing cycles of said output frequency thereby to measure the output frequency, and for storing a table of values of said tuning capacitance associated with an output frequency equal to each of the center and side frequencies.
Claim 22
Dependent Claim
39 words
The reader of claim 18 further comprising scanning program means operative for executing a scanning sequence comprising sequentially switching said frequency generator through each of said side and center frequencies thereby to improve interrogation range of off-frequency transponder tags.
References Cited (Backward Citations)
US3713148A
Cited
US4201960A
Cited
US4356477A
Cited
US4480178A
Cited
US5053774A
Cited
US5025492A
Cited
US5270717A
Cited
US5396251A
Cited
US5491484A
Cited
US5353011A
Cited
US5374930A
Cited
US5491715A
Cited
US5347280A
Cited
US5541604A
Cited
US5568512A
Cited
US5583819A
Cited
US5856809A
Cited
US5815355A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2004-11-12 | 2005-05-14 | 2005-11-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-11-12 | 2009-05-14 | 2009-11-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-11-12 | 2013-05-14 | 2013-11-13 | $7700.00 | Window Closed / Lapsed |