RF tagging system and RF tags and method

RF tagging system comprising:

• a tag having thereon a plurality of passive resonant circuits, each of said passive resonant circuits resonant at a different resonant frequency selected from a predetermined plurality of known resonant frequencies;
• means for detecting said plurality of passive resonant circuits on said tag, when said tag is in a detection zone, and then providing a corresponding code signal, out of a plurality of possible code signals, indicative of which of said resonant frequencies for said passive resonant circuits were detected in said detection zone;
• wherein said detection means comprises means for producing a plurality of different oscillator signals, one at each of said plurality of known resonant frequencies, means for radiating each of said different frequency oscillator signals in said detection zone, and means for providing said one code signal by measuring signals indicative of absorption of radiated energy at each one of said known resonant frequencies in said detection zone by said passive resonant circuits on said tag, said absorption occurring during said radiation of each of said different frequency oscillator signals,
• wherein said measured signals are provided when said tag is in said detection zone and said radiated signals are provided with a first phase shift, and said measured signals are also provided when said tag is in said detection zone and said radiated signals are provided with a second and different phase shift, detection of whether one of said resonant circuits in said detection zone is resonant at one of said plurality of known resonant frequencies being dependent on absorption of radiant energy which occurs when said signals are radiated with any of said first and second phase shifts.

RF tagging system comprising:

• a tag having thereon a plurality of passive resonant circuits, each of said passive resonant circuits resonant at a different resonant frequency selected from a predetermined plurality of known resonant frequencies;
• means for detecting said plurality of passive resonant circuits on said tag, when said tag is in a detection zone, and then providing a corresponding code signal, out of a plurality of possible code signals, indicative of which of said resonant frequencies for said passive resonant circuits were detected in said detection zone;
• wherein said detection means comprises means for producing a plurality of different oscillator signals, one at each one of said plurality of known resonant frequencies, means for radiating each of said different frequency oscillator signals in said detection zone, and means for providing said one code signal by measuring signals indicative of absorption of radiated energy at each one of said known resonant frequencies in said detection zone by said passive resonant circuits on said tag, said absorption occurring during said radiation of each of said different frequency oscillator signals,
• wherein said measured signals are provided when said tag is in said detection zone and said radiated signals are provided with a first polarization, and said measured signals are also provided when said tag is in said detection zone and said radiated signals are provided with a second and different polarization, detection of whether one of said resonant circuits in said detection zone is resonant at one of said plurality of known resonant frequencies being dependent on absorption of radiant energy which occurs when said signals are radiated with any of said first and second polarizations.

RF tagging system comprising:

• a tag having thereon a plurality of passive resonant circuits, each of said passive resonant circuits resonant at a different resonant frequency selected from a predetermined plurality of known resonant frequencies;
• means for detecting said plurality of passive resonant circuits on said tag, when said tag is in a detection zone, and then providing a corresponding code signal, out of plurality of possible code signals, indicative of which of said resonant frequencies for said passive resonant circuits were detected in said detection zone;
• wherein said detection means comprises means for producing a plurality of different oscillator signals, one at each of said plurality of known resonant frequencies, means for radiating each of said different frequency oscillator signals in said detection zone, and means for providing said one code signal by measuring signals indicative of absorption of radiated energy at each one of said known resonant frequencies in said detection zone by said passive resonant circuits on said tag, said absorption occurring during said radiation of each of said different frequency oscillator signals,
• wherein said measured signals are provided when said tag is in said detection zone and said radiated signals are provided with a first phase shift and a first polarization, and said measured signals are also provided when said tag is in said detection zone and said radiated signals are provided with a second and different phase shift and a second and different polarization, detection of whether one of said resonant circuits in said detection zone is resonant at one of said plurality of known resonant frequencies being dependent on absorption of radiant energy which occurs when said signals are radiated with any of said first and second phase shifts and polarizations.

RF tagging system comprising:

• a tag having thereon a plurality of passive resonant circuits, each of said passive resonant circuits resonant at a different resonant frequency selected from a predetermined plurality of resonant frequencies:
• means for detecting said plurality of passive resonant circuits on said tag, when said tag is in a detection zone, and then providing a corresponding code signal, out of a plurality of possible code signals, indicative of which of said resonant frequencies for said passive resonant circuits were detected in said detection zone;
• wherein said detection means comprises means for producing a plurality of different oscillator signals, one at each of said plurality of known resonant frequencies, means for radiating each of said different frequency oscillator signals in said detection zone, and means for providing said one code signal by measuring signals indicative of absorption of radiated energy at each one of said known resonant frequencies in said detection zone by said passive resonant circuits on said tag, said absorption occurring during said radiation of each of said different frequency oscillator signals,
• wherein said code signal providing means includes means for measuring both voltage and current of each of said different frequency oscillator signals so as to measure energy and wherein said measured energy of said different frequency oscillator signals is measured when said tag is inside and outside said detection zone, said code signal providing means including means for comparing said measured voltage and current signals when said tag is inside said detection zone with said measured voltage and current signals measured when said tag is outside of said detection zone to indicate the presence of resonant circuits on said tag at any of said predetermined plurality of known frequencies.

RF tagging system comprising:

• a tag having thereon a plurality of passive resonant circuits, each of said circuits resonant at a resonant frequency selected from a predetermined plurality of known resonant frequencies;
• and
• means for detecting said plurality of passive resonant circuits on said tag, when said tag is in a detection zone, and then providing a corresponding code signal, out of a plurality of possible code signals, indicative of which of said resonant frequencies for said passive resonant circuits were detected as being in said detection zone;
• wherein each of said plurality of resonant circuits on said tag comprises a first metalization area determining an inductance and a second metalization area determining a capacitance for said resonant circuit, said second metalization area defining a capacitor plate having a plurality of planar capacitive metalization projections each connected to one another by a thin conductor runner, whereby step adjustment of the resonant frequency of the resonant circuit is readily achieved by removing one or more of said conductor runners either during initial manufacture or subsequently.

RF tagging system comprising:

• a tag having thereon a plurality of passive resonant circuits, each of said passive resonant circuits resonant at a resonant frequency selected from a predetermined plurality of known resonant frequencies;
• means for detecting said plurality of passive resonant circuits on said tag, when said tag is in a detection zone, and then providing a corresponding code signal, out of a plurality of possible code signals, indicative of which of said resonant frequencies for said passive resonant circuits were detected in said detection zone;
• wherein said detection means comprises means for producing a plurality of different oscillator signals at each one of said plurality of known resonant frequencies, means for radiating each of said different frequency oscillator signals in said detection zone, and means for providing said one code signal by measuring signals indicative of absorption of radiated energy at each one of said known resonant frequencies in said detection zone by said passive resonant circuits on said tag, said absorption occurring during said radiation of each of said different frequency oscillator signals,
• wherein said detection means includes means for sensing an object having any number of said resonant circuits, including zero, approaching said detection zone, and wherein said code signal providing means includes means for storing a no load reference value of said measured signals in response to determining the approach of an object to said detection zone by said object approaching sensing means and utilizing said stored signals for comparison with said measured signals measured in response to detecting positioning of said object in said detection zone.

RF tagging system comprising:

• a tag having thereon a plurality of passive resonant circuits, each of said passive resonant circuits resonant at a different resonant frequency selected from a predetermined plurality of known resonant frequencies;
• means for detecting said plurality of passive resonant circuits on said tag, when said tag is in a detection zone, and then providing a corresponding code signal, out of a plurality of possible code signals, indicative of which of said resonant frequencies for said passive resonant circuits were detected in said detection zone;
• wherein said detection means comprises means for radiating RF energy at at least each of said predetermined plurality of known resonant frequencies in said detection zone, and means for providing said one code signal by measuring signals indicative of absorption of said radiated energy at each one of said known resonant frequencies in said detection zone by said passive resonant circuits on said tag,
• wherein said measured signals are provided when said tag is in said detection zone and said radiated energy is provided with a first phase shift, and said measured signals are also provided when said tag is in said detection zone and said radiated energy is provided with a second and different phase shift, detection of whether one of said resonant circuits in said detection zone is resonant at one of said plurality of known resonant frequencies being dependent on absorption of radiant energy which occurs when said RF energy is radiated with any of said first and second phase shifts.

RF tagging system comprising:

• a tag having thereon a plurality of passive resonant circuits, each of said passive resonant circuits resonant at a different resonant frequency selected from a predetermined plurality of known resonant frequencies;
• means for detecting said plurality of passive resonant circuits on said tag, when said tag is in a detection zone, and then providing a corresponding code signal, out of a plurality of possible code signals, indicative of which of said resonant frequencies for said passive resonant circuits were detected in said detection zone;
• wherein said detection means comprises means for radiating RF energy at at least each of said predetermined plurality of known resonant frequencies in said detection zone, and means for providing said one code signal by measuring signals indicative of absorption of said radiated energy at each one of said known resonant frequencies in said detection zone by said passive resonant circuits on said tag,
• wherein said measured signals are provided when said tag is in said detection zone and said radiated energy is provided with a first polarization, and said measured signals are also provided when said tag is in said detection zone and said radiated energy is provided with a second and different polarization, detection of whether one of said resonant circuits in said detection zone is resonant at one of said plurality of known resonant frequencies being dependent on absorption of radiant energy which occurs when said RF energy is radiated with any of said first and second polarizations.

RF tagging system comprising:

• a tag having thereon a plurality of passive resonant circuits, each of said passive resonant circuits resonant at a different resonant frequency selected from a predetermined plurality of known resonant frequencies;
• means for detecting said plurality of passive resonant circuits on said tag, when said tag is in a detection zone, and then providing a corresponding code signal, out of a plurality of possible code signals, indicative of which of said resonant frequencies for said passive resonant circuits were detected in said detection zone;
• wherein said detection means comprises means for radiating RF energy at at least each of said predetermined plurality of known resonant frequencies in said detection zone, and means for providing said one code signal by measuring signals indicative of absorption of radiated energy at each one of said known resonant frequencies in said detection zone by said passive resonant circuits on said tag,
• wherein said code signal providing means includes means for measuring both voltage and current at each of said predetermined plurality of known resonant frequencies and wherein said measured voltage and current signals are measured when said tag is inside and outside said detection zone, said code signal providing means including means for comparing said measured voltage and current signals when said tag is inside said detection zone with said measured voltage and current signals measured when said tag is outside of said detection zone to indicate the presence of resonant circuits on said tag at any of said predetermined plurality of known frequencies.

RF tagging system comprising:

• a tag having thereon a plurality of passive resonant circuits, each of said passive resonant circuits resonant at a resonant frequency selected from a predetermined plurality of known resonant frequencies;
• means for detecting said plurality of passive resonant circuits on said tag, when said tag is in a detection zone, and then providing a corresponding code signal, out of plurality of possible code signals, indicative of which of said resonant frequencies for said passive resonant circuits were detected in said detection zone;
• wherein said detection means comprises means for radiating RF energy at at least each of said predetermined plurality of known resonant frequencies in said detection zone, and means for providing said one code signal by measuring signals indicative of absorption of radiated energy at each one of said known resonant frequencies in said detection zone by said passive resonant circuits on said tag,
• wherein said detection means includes means for sensing an object having any number of said resonant circuits, including zero, approaching said detection zone, and wherein said code signal providing means includes means for storing a no load reference value of said measured signals in response to determining the approach of an object to said detection zone by said object approaching sensing means and utilizing said stored signals for comparison with said measured signals measured in response to detecting positioning of said object in said detection zone.