Transponders
AssigneeNational Research Development Corporation
InventorsBarry E. Jones, John A. Smith
Life of this patent
Estimating the term…
Abstract
A passive transponder, particularly for dental or medical applications, is described in which signals received by one or more receive resonant circuits are changed in frequency either up or down by a non-linear device coupled to one or more transmit resonant circuits. Each transmit resonant circuit includes a transducer whose impedance depends on a quantity whose value is to be transmitted and thus the frequency of signals received from the transponder depends on the value of the quantity.
Claims33
Information-transmission apparatus comprising:
- a transmitter for transmitting signals at a first frequency, and transponder apparatus including:
- a non-linear device having a non-linear impedance,
- a receive resonant circuit connected to the non-linear device for obtaining power from transmissions from the transmitter to vary the non-linear impedance of the said device and generate a non-sinusoidal waveform across the device when transmissions are received, the receive resonant circuit being at least broadly tuned to a frequency range in which the first frequency occurs,
- a transmit resonant circuit, resonant at a second frequency, connected to the non-linear device, and
- transducer means for varying the resonant frequency of the transmit resonant circuit;
- a receiver having a receiving circuit at least broadly tuned to a frequency range in which the second frequency occurs;
- and
- a frequency indicating circuit, coupled to the receiving circuit, for providing a signal indicative of the frequency of a signal received by the receiving circuit.
Transponder apparatus including:
- a non-linear device having a non-linear impedance;
- a receive resonant circuit, connected to the non-linear device, for obtaining power from transmissions by a transmitter to vary the non-linear impedance of the said device and generate a non-sinusoidal waveform across the device when transmissions are received, the receive resonant circuit being at least broadly tuned to a first frequency;
- a transmit resonant circuit, resonant at a second frequency, connected to the non-linear device to apply the non-sinusoidal waveform to the transmit resonant circuit to cause oscillations to occur therein;
- and
- transducer means for varying the resonant frequency of the transmit resonant circuit.
Information-transmission apparatus comprising:
- A. a transmitter for transmitting signals at a first frequency, and transponder apparatus including:
- a non-linear device having a non-linear impedance,
- a receive resonant circuit connected to the non-linear device for obtaining power from transmissions from the transmitter to vary the non-linear impedance of the said device and generate a non-sinusodial waveform having a plurality of harmonic frequencies across the device when transmissions are received, the receive resonant circuit being at least broadly tuned to a frequency range in which the first frequency occurs,
- a transmit resonant circuit, resonant at a second frequency, connected to the non-linear device for oscillation in response to a harmonic of said non-sinusoidal waveform having the resonant frequency of said transmit resonant circuit, and
- transducer means for varying the resonant frequency of the transmit resonant circuit;
- B. a receiver having a receiving circuit at least broadly tuned to a frequency range in which the second frequency occurs;
- and
- C. a frequency indicating circuit, coupled to the receiving circuit, for providing a signal indicative of the frequency of a signal received by the receiving circuit.
Dependencies are inferred from the claim text.