Transponder arrangement

• US 5,053,774 A
• Filed: 02/13/1991
• Issued: 10/01/1991
• Est. Priority Date: 07/31/1987
• Status: Expired due to Term

• Current Assignee: Texas Instruments Deutschland Gesellschaft Mit Beschrã¤Nkter Haftung (Texas Instruments, Inc.)
• Original Assignee: Texas Instruments Deutschland Gesellschaft Mit Beschrã¤Nkter Haftung (Texas Instruments, Inc.)
• Inventors: Schuermann, Josef H., Heinecke, Guenter, Kremer, Rudolf
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US07/655,182
• Time in Patent Office: 230 Days
• Field of Search: 342/42, 342/44, 342/51, 340/572, 340/825.54, 307/219.1
• US Class Current: 340/10.34
• CPC Class Codes: A01K 11/006 Automatic identification systems for animals, e.g. electronic devices, transponders for animals identification systems for access to feeding pens A01K1/0209; ear tags with electronic identification means A01K11/004
• CPC Class Codes: B60C 23/0408 transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
• CPC Class Codes: B60C 23/041 Means for supplying power to the signal- transmitting means on the wheel
• CPC Class Codes: B60C 23/0413 Wireless charging of active radio frequency circuits
• CPC Class Codes: B60C 23/0433 Radio signals
• CPC Class Codes: G01S 13/758 using a signal generator powered by the interrogation signal
• CPC Class Codes: G01S 13/78 discriminating between different kinds of targets, e.g. IFF-radar, i.e. identification of friend or foe G01S13/75, G01S13/79 take precedence
• CPC Class Codes: G01V 15/00 Tags attached to, or associated with, an object, in order to enable detection of the object record carriers for use with machines having a detectable tag or marker G06K19/00
• 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
• CPC Class Codes: G06K 7/10039 interrogator driven, i.e. synchronous
• CPC Class Codes: G07C 9/28 the pass enabling tracking or indicating presence
• CPC Class Codes: G08B 13/2454 Checking of authorisation of a person accessing tagged items in an EAS system

Abstract

A transponder arrangement is described comprising an interrogation unit (10) which sends an RF interrogation pulse to at least one responder unit (12). The responder unit (12) then transmits back data stored therein in the form of a modulated RF carrier to the interrogation unit (10). In the responder unit (12) is an energy accumulator (136) which stores the energy contained in the RF interrogation pulse. The responder unit (12) further contains means (142, 148) which in dependence upon the termination of the reception of the RF interrogation pulse and the presence of a predetermined energy amount in the energy accumulator (126) initiate the excitation of an RF carrier wave generator (130, 132, 134) operating with the frequency contained in the RF interrogation pulse. Further means (158, 192) are provided which from the output signal of the RF carrier wave generator (130, 132, 134) generate a control signal which is utilized to maintain the RF carrier wave and to modulate the RF carrier to be sent back with the stored data.

Claims

1. A transponder system comprising:

an interrogation unit for communicating with cooperating responder units comprising;

a microprocessor,

a transmitter for transmission of at least one RF interrogation signal of a first frequency having a duration predetermined by the microprocessor, and

a receiver for receiving signal information at the termination of the interrogation signal; and

a responder unit located in spaced relation with respect to said interrogation unit for receiving on a resonant circuit said at least one interrogation signal transmitted form the transmitter of said interrogation unit and returning data as signal information on said resonant circuit to the receiver of said interrogation unit in response to the reception of said at least one interrogation signal, said responder unit comprising;

an energy accumulator for storing the energy contained in said at least one interrogation signal as received by said responder unit,

a carrier wave generator operable for providing a FSK modulated carrier wave having at least two frequencies, one of said two frequencies being said first frequency contained in said at least one interrogation signal and a second frequency selectively shifted from said first frequency,

circuitry operably connected to the output of said carrier wave generator for producing control signals for maintaining and modulating the carrier wave,

circuitry for transmitting the FSK modulated carrier wave and data from said responder unit back to the receiver of said interrogation unit as signal information, and

circuitry for initiating operation of said carrier wave generator in response to the detected power level of the RF interrogation signal decreasing and the presence of a predetermined energy amount stored in said energy accumulator.

2. A transponder system as set forth in claim 1, wherein said circuitry for initiating operation of said carrier wave generator comprises;

an RF threshold detector,

a DC voltage threshold detector, and

a triggering circuit to which said RF threshold detector and said DC voltage threshold detector are connected for generating a start signal for initiating said operation of said carrier wave generator whenever the level of the interrogation signal received by the responder unit means drops below a predetermined value and a DC voltage of predetermined value is present at the output of said energy accumulator.

3. A transponder system as set forth in claim 2, wherein said carrier wave generator includes a parallel resonant circuit for receiving the interrogation pulse, said parallel resonant circuit having a coil and a capacitor and being responsive to the start signal initiating the flow of a direct current through the coil of said parallel resonant circuit to provide the carrier wave for a predetermined duration.

4. A transponder system as set forth in claim 3, wherein said circuitry for initiating operation comprises a first monostable flip-flop circuit responsive to the start signal generated by the triggering circuit and which provides an excitation pulse having a duration determining the duration of the current flow through the coil of said parallel resonant circuit.

5. A transponder system as set forth in claim 4, wherein said circuitry for producing the control signal is effective to produce said control signal in response to each occasion of a predetermined number of carrier waves provided by said carrier wave generator, said control signal initiating the application of a maintenance pulse of predetermined duration to said carrier wave generator.

6. A transponder system as set forth in claim 5, further including a second monostable flip-flop circuit responsive to said control signal for furnishing said maintenance pulse providing a direct current for the duration thereof flowing through the coil of said parallel resonant circuit.

7. A transponder system as set forth in claim 1, further including memory circuitry in which the data to be returned by said responder unit to said interrogation unit is stored,

a modulator device connected to said memory circuitry and to said carrier wave generator, and

said memory circuitry being responsive to said control signal for supplying the data stored therein to said modulator device for modulation of said carrier wave.

8. A transponder system as set forth in claim 7, further including a shift register connected between said memory circuitry and said modulator device,

divider circuit for receiving the control signal and generating therefrom a clock signal at a lower recurring frequency,

a counter operably connected to said memory circuitry for counting the clock pulses, derived from said carrier wave, applied to said memory circuitry,

said memory circuitry providing data to said modulator device via said shift register into which said memory circuitry introduces the data stored therein in timed sequency under control of the carrier wave clock signal, and

a counter incrementing in response to each of the carrier wave clock pulses applied to said memory circuitry and being responsive to a predetermined number of pulses indicative of the entry of all the data from said memory circuitry into said shift register to apply the clock signal generated by said divider circuit to said shift register instead of the clock signal derived from the carrier wave.

9. A transponder system as set forth in claim 8, wherein said shift register is provided with a feedback line from its output to its input to enable the data supplied thereto to be circulated therewithin as long as clock signals are applied thereto, and said shift register being effective to provide the data contained therein from its output to said modulator device as long as said carrier wave generator provides carrier waves.

10. A transponder system as set forth in claim 9, wherein said modulator device is so constructed to vary the frequency of the carrier wave in dependence upon the data supplied to it from said memory circuitry.

11. A transponder system as set forth in claim 10, wherein said modulator device comprises a capacitor, and

switching circuitry connected to said capacitor and being disposed in closed or open positions depending upon whether the data is operatively connected or disconnected with respect to said carrier wave generator.

12. A transponder system as set forth in claim 7, wherein said memory circuitry is a programmable read-only-memory.

13. A transponder system as set forth in claim 7, wherein said memory circuitry is a random access memory.

14. A transponder system as set forth in claim 13, wherein said responder unit further includes a data processor operably connected to said random access memory for generating the data to be sent back to said interrogation unit and entering said data in said random access memory.

15. A transponder system as set forth in claim 14, further including sensor circuitry sensitive to predetermined physical parameters in the environmental area of said responder unit and operably connected to said data processor, said data processor being responsive to output signals from said sensor circuitry in generating the data to be entered into said random access memory.

16. A transponder system as set forth in claim 14, wherein at least one interrogation signal transmitted by the transmitter of said interrogation unit is modulated to include a specific address of one or more of a plurality of said responder unit to enable only selected responder unit having an address corresponding to the address included in said interrogation signal to react to the reception of said interrogation signal with the return of a modulated carrier wave having data provided therein to said interrogation unit,

said responder unit further including demodulator circuit for receiving said at least one interrogation signal from said interrogation unit and determining the address provided therein;

said data processor enabling said responder unit to send back the store data to said interrogation unit in response to a comparison between the address as determined by said demodulator circuit with the address stored in said responder unit establishing identity of the compared addresses.

17. A transponder system as set forth in claim 1, wherein the transmitter of said interrogation unit after transmitting a first interrogation signal is effective to transmit a further interrogation signal with higher transmission power after a predetermined time interval from the transmission of said first interrogation signal.

18. A transponder as set forth in claim 1, wherein the receiver of said interrogation unit includes a random access memory for receiving data sent back by said responder unit.

19. A transponder system as set forth in claim 18, wherein said interrogation unit further includes circuitry operably connected to said random access memory included in the receiver thereof for enabling transmission of data contained in said random access memory to a central data processing unit.

20. A transponder system as set forth in claim 1, wherein said responder unit further includes circuitry for sending the stored data in the form of said FSK modulated carrier a multiplicity of times in response to a single interrogation signal.

21. A transponder system as set forth in claim 7, wherein the data stored in said memory circuitry uniquely identifies each transponder.