Proximity identification system with power aided identifier

• US 4,656,472 A
• Filed: 01/23/1985
• Issued: 04/07/1987
• Est. Priority Date: 01/23/1985
• Status: Expired due to Fees

• Current Assignee: Charles A. Walton
• Original Assignee: Charles A. Walton
• Inventors: Walton, Charles A.
• Primary Examiner(s): Weldon, Ulysses
• Assistant Examiner(s): Smith, Ralph E.
• Application Number:
  US06/693,992
• Time in Patent Office: 804 Days
• Field of Search: 340/825.06, 340/825.10, 340/825.34, 340/825.69, 340/825.72, 340/825.54, 340/825.70, 340/539, 340/572, 340/573, 340/825.3, 340/825.64, 343/6.5 R-6.8 LC, 455/41, 455/70, 455/71, 361/172, 235/439-444, 235/380, 368/205
• US Class Current: 340/10.4
• 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: G07C 9/28 the pass enabling tracking or indicating presence

Abstract

An electronic identification and recognition system which has a battery powered identifier. The reader section radiates stimulus to the identifier section. A battery is switched on and power a clock and memory which in turn vary the reactance of the identifier antenna circuit. The change in reactance affects the phase angle of the voltage within the reader antenna. The phase angle changes are detected and recorded by the reader section such that the internal code of the identifier section is determined.

Claims

1. An electronic recognition and identification system comprising:

a reader section including an oscillator, a reader antenna connected to said oscillator for radiating electromagnetic power responsive to said oscillator, and a detection means connected to said reader antenna and to said oscillator for detecting changes in a vector phase angle of a voltage across said reader antenna relative to the oscillator signal and for delivering output signals responsive to said changes in vector phase angle; and

an identifier section having an identifier antenna for receiving power from said reader antenna by mutual coupling, a reactance modulation circuit connected to said identifier antenna, a data register means for providing an advance and sequence of data joined to said reactance modulation circuit, such that a vector phase angle of a current of said modulation circuit varies responsive to said sequence of data, a battery for powering said data register means, a diode connected intermediate said identifier antenna and said battery such that the battery is recharged when the identifier section is in close proximity to the reader section, and means for switching on power from said battery when the identifier section is in close proximity to the reader section and for switching off power from said battery when the identifier section is distant from the reader section.

2. The system of claim 1 wherein,

the reader section further includes an amplifier intermediate said oscillator and said reader antenna for amplifying the signal from said oscillator, and an impedance intermediate said amplifier and said reader antenna.

3. The system of claim 1 wherein,

the reader section further includes an amplifier connected to the output of said detection means for amplifying the signal from said detection means.

4. The system of claim 1 wherein,

the data register comprises a clock and a memory circuit.

5. The system of claim 1 wherein,

the identifier section further includes a fixed capacitor connected parallel with said identifier antenna to tune said indentifier antenna to predetermined frequencies.

6. The system of claim 1 wherein,

said reactance modulation circuit is comprised of a varactor means and an impedence connected across said identifier antenna for varying the phase angle of the current passing through said identifier antenna in accordance with the sequence of data from said data register means.

7. The system of claim 6 wherein,

a resistor is connected intermediate said varactor means and said data register means.

8. The system of claim 1 wherein,

said means for switching on and off power from said battery is comprised of a power supply transistor connected to said identifier antenna such that a control voltage of said power supply transistor controls the flow of power from said battery to said data register means.

9. The system of claim 8 wherein,

the identifier section further includes rectifying means and filtering means intermediate said identifier antenna and said power supply transistor.

10. The system of claim 1 wherein,

the reader section further includes a tuning capacitor connected parallel with said reader antenna to tune said reader antenna to predetermined frequencies.

11. The system of claim 1 wherein,

said reader and identifier antennas are loop antennas, such that power is radiated by mutual coupling from said reader antenna to said identifier antenna, and said identifier antenna radiates changes in vector phase angle to the reader antenna by mutual coupling.

12. The system of claim 1 wherein,

the identifier section further includes a solar cell connected parallel to said battery.

13. An electronic recognition and identification system comprising:

a reader section including an oscilltor, a reader antenna connected to said oscillator for radiating electromagnetic power responsive to said oscillator, and a detection means connected to said reader antenna and to said oscillator for detecting changes in an amplitude of a voltage across said reader antenna relative to the oscillator signal and for delivering output signals responsive to said changes in amplitude; and

an identifier section having an identifier antenna for receiving power from said reader antenna by mutual coupling, a reactance modulation circuit connected to said identifier antenna, a data register means for providing an advance and sequence of data joined to said reactance modulation circuit, such that an amplitude of a voltage of said modulation circuit varies responsive to said sequence of data, a battery for powering said data register means, a diode connected intermediate said identifier antenna and said battery such that the battery is recharged when the identifier section is in close proximity to the reader section, and a means for switching on power from said battery when the identifier section is in close proximity to the reader section and for switching off power from said battery when the identifier section is distant from the reader section.

14. The system of claim 13 wherein,

the reader section further includes an amplifier intermediate said oscillator and said reader antenna for amplifying the signal from said oscillator, and an impedance intermediate said amplifier and said reader antenna.

15. The system of claim 13 wherein,

the reader section further includes an amplifier connected to the output of said detection means for amplifying the signal from said detection means.

16. The system of claim 13 wherein,

the data register means comprises a clock and a memory circuit.

17. The system of claim 13 wherein,

the identifier section further includes a fixed capacitor connected parallel with said identifier antenna to tune said identifier antenna to predetermined frequencies.

18. The system of claim 13 wherein,

said reactance modulation circuit is comprised of a varactor means and an impedance connected across said identifier antenna for varying the amplitude of the voltage in said identifier antenna in accordance with the sequence of data from said data register means.

19. The system of claim 18 wherein,

a resistor is connected intermediate said varactor means and said data register means.

20. The system of claim 14 wherein,

said means for switching on and off power from said battery is comprised of a power supply transistor connected to said identifier antenna such that a control voltage of said power supply transistor controls the flow of power from said battery to said data register means.

21. The system of claim 20 wherein,

the identifier section further includes rectifying means and filtering means intermediate said identifier antenna and said power supply transistor.

22. The system of claim 13 wherein,

the reader section further includes a tuning capacitor connected parallel with said reader antenna to tune said reader antenna to predetermined frequencies.

23. The system of claim 13 wherein,

said reader and identifier antennas are loop antennas, such that power is radiated by mutual coupling from said reader atenna to said identifier antenna, and said identifier antenna radiates changes in voltage amplitude to the reader antenna by mutual coupling.

24. The system of claim 13 wherein,

the identifier section further includes a solar cell connected parallel to said battery.