High speed read/write AVI system

• US 5,374,930 A
• Filed: 11/12/1993
• Issued: 12/20/1994
• Est. Priority Date: 04/14/1993
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments Deutschland Gesellschaft Mit Beschrã¤Nkter Haftung (Texas Instruments, Inc.)
• Inventors: Schuermann, Josef H.
• Primary Examiner(s): Hellner, Mark
• Application Number:
  US08/150,935
• Time in Patent Office: 403 Days
• Field of Search: 342/42, 342/51
• US Class Current: 342/42
• CPC Class Codes: G01S 13/758 using a signal generator powered by the interrogation signal
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer

Abstract

A transponder (14) for communicating with an interrogator (12) has a high Q-factor resonant circuit (34) of frequency f₁ for receiving RF powering signals. The transponder also has a tuning circuit (56,58) which when in electrical communication with the resonant circuit (34) is operable to form a lower Q-factor resonant circuit (60) of frequency f₃ for receiving RF communications from the interrogator unit. The transponder also includes a demodulator (66) which is in electrical communication with said resonant circuit (34). Additionally, the transponder (14) also included a control circuit (40) which receives a demodulated data signal from the demodulator (66). The control circuit (40) is further connected to the tuning circuit (56,58) and is operable to connect the tuning circuit (56,58) to the high Q-factor resonant circuit (34) in order to form the lower Q-factor resonant circuit (60). Control circuit (40) also converts the RF powering signals to a DC current for storing energy. The energy is stored in an energy storage device such as a storage capacitor (46). Other devices, methods and systems are disclosed.

Claims

1. A method of communicating between an interrogator and a transponder, the method comprising:

a) sending RF powering signals of frequency f₁ from said interrogator to said transponder;

b) receiving said RF powering signals in a resonant circuit of said transponder, said resonant circuit having a resonant frequency of approximately f₁ ;

c) controlling a tuning circuit in electrical communication with said resonant circuit to change the resonant frequency of said resonant circuit to approximately f₃ ;

d) sending RF communications from said interrogator, said RF communications having a carrier frequency of approximately f₃ ; and

e) receiving by said resonant circuit said RF communications.

2. The method of claim 1 wherein said resonant circuit initially has a high Q-factor.

3. The method of claim 2 wherein said tuning circuit is further operable to lower the Q-factor of said resonant circuit.

4. The method of claim 1 and further comprising the step of controlling said tuning circuit to return the resonant frequency of said resonant circuit to f₁.

5. The method of claim 1 and further comprising the step of writing data to a transponder memory.

6. The method of claim 1 and further comprising the step of sending responsive RF communications from said transponder to said interrogator.

7. The method of claim 6 and further comprising the step of modulating continued oscillations in said transponder resonant circuit with data provided to a modulator from a transponder memory.

8. The method of claim 1 wherein said tuning circuit comprises a damping resistor for lowering the Q-factor of said resonant circuit in combination with said tuning circuit.

9. The method of claim 1 wherein said RF communications are made by transmitting an FSK-modulated signal having a center frequency of approximately f₃.

10. The method of claim 10 and further comprising the step of demodulating said FSK-modulated signal in said interrogator.

11. A method of communicating between an interrogator and a transponder, the method comprising:

a) sending RF powering signals of frequency f₁ from said interrogator to said transponder;

b) receiving said RF powering signals in a resonant circuit of said transponder, said resonant circuit having a high Q-factor and a resonant frequency of approximately f₁ ;

c) electrically connecting a tuning circuit to said resonant circuit thereby changing the resonant frequency of said resonant circuit to approximately f₃ ;

d) sending RF communications from said interrogator, said RF communications having a carrier frequency of approximately f₃ ;

e) receiving by said resonant circuit said RF communications; and

f) sending responsive RF communications from said transponder to said interrogator in response to said RF communications.

12. The method of claim 11 wherein said tuning circuit is further operable to lower the Q-factor of said resonant circuit.

13. The method of claim 11 and further comprising the step of modulating continued oscillations in said transponder resonant circuit with data provided to a modulator from a transponder memory to form said responsive RF communications.

14. The method of claim 13 wherein said RF communications are made by transmitting an FSK-modulated signal having a center frequency of approximately f₃.

15. A method of communicating between an interrogator and a transponder, the method comprising:

a) sending RF powering signals of frequency, f₁, from an interrogator to a transponder;

b) storing the energy received in said powering signals in an energy storage device;

c) receiving by a high Q-factor resonant circuit of said transponder said RF powering signals, said transponder resonant circuit having a resonant frequency of approximately f₁ ;

d) connecting a tuning circuit to said resonant circuit, said tuning circuit operable to lower the Q-factor of said transponder resonant circuit and to change the frequency of said transponder resonant circuit to approximately f₃ ;

e) sending an FSK-modulated RF communication from said interrogator to said transponder, said FSK modulation having a center frequency of approximately f₃ ;

f) receiving in said transponder resonant circuit said FSK-modulated RF communication;

g) demodulating in said transponder said FSK-modulated RF communication;

h) responding by said transponder to said RF communication by sending an FSK-modulated RF response.

16. A high speed RFID system, the system comprising:

a) an interrogator for communicating with a transponder, said interrogator having

i) a programmable carrier wave generator capable of providing a carrier of a powering frequency, f₁, and of a communicating frequency, f₃, and

ii) a modulator for modulating data upon said carrier at said communicating frequency, f₃ ; and

b) a transponder for communicating with an interrogator, said transponder having

i) a high Q-factor resonant circuit having a resonant frequency of approximately said powering frequency, f₁,

ii) a tuning circuit which is operable to lower the Q-factor of said resonant circuit and to change the resonant frequency of said resonant circuit to approximately f₃,

iii) a control circuit which is in electrical communication with said high Q-factor resonant circuit and said tuning circuit and is operable to connect said tuning circuit to said high Q-factor resonant circuit in order to form said lower Q-factor resonant circuit, and

iv) an energy storage device for storing the energy received in said DC current from said control circuit.

17. The system of claim 16 wherein said transponder further comprises a modulator for modulating data upon a carrier signal oscillating in the resonant circuit of said transponder.

18. The system of claim 17 wherein said modulator modulates said data by frequency shift keying said carrier frequency, said frequency shift keying being centered about communicating frequency, f₃.

19. The system of claim 17 wherein powering frequency f₁ is also one of the frequency shift keying frequencies centered about communicating frequency, f₃.

20. The system of claim 17 wherein said programmable carrier wave generator comprises a carrier wave generator and a programmable divider whereby said powering and said communicating frequencies are generated by said programmable divider as submultiples of a reference carrier under direction from said modulator.