RFID sensor device based on pulse-processing

• US 8,018,323 B2
• Filed: 01/27/2007
• Issued: 09/13/2011
• Est. Priority Date: 01/30/2006
• Status: Active Grant

• Current Assignee: Baohua Qi
• Original Assignee: Baohua Qi
• Inventors: Qi, Baohua
• Primary Examiner(s): Lee; Benjamin C
• Assistant Examiner(s): PHAM, QUANG
• Application Number:
  US11/699,232
• Publication Number:
  US 20070182549A1
• Time in Patent Office: 1,690 Days
• Field of Search: 340/539.26, 340/572.1, 340/539.1
• US Class Current: 340/10.4
• CPC Class Codes: H04Q 9/00 Arrangements in telecontrol or telemetry systems for selectively calling a substation from a main station, in which substation desired apparatus is selected for applying a control signal thereto or for obtaining measured values therefrom

Abstract

A radio frequency identification device having sensing elements incorporated in the clock generators of its tags, which generate a leading code and an identification code. In the interrogator, the leading code is detected and its pulse width is measured for calculating sensing values and the baud rate in receiving the identification code. No analog to digital converter is needed in digitizing sensing values and only discrete signals exist in sensing signal generation and communication. The tag device is insensitive to variations in its power supply voltage obtained from a continuous wave RF carrier.

Claims

1. A radio frequency identification tag device, comprising:

a clock generator having at least one sensing element incorporated for generating a clock signal with frequency changing with sensing values obtained from said at least one sensing element;

a logic circuit that generates a mixed code sequence by serially connecting a serial ID code to a leading code having at least one sensing pulse, the baud rate of said serial ID code and the width of said at least one sensing pulse change with the frequency of said clock signal generated by said clock generator;

a radio frequency tuned circuit; and

a circuit for loading and unloading said radio frequency tuned circuit with said mixed code sequence.

2. The radio frequency identification tag device according to claim 1, wherein said clock generator is an RC generator.

3. The radio frequency identification tag device according to claim 2, wherein said RC generator includes a resistive sensor.

4. The radio frequency identification tag device according to claim 2, wherein said RC generator includes a capacitive sensor.

5. The radio frequency identification tag device according to claim 1, wherein said clock generator is an LC generator.

6. The radio frequency identification tag device according to claim 5, wherein said LC generator includes an inductive sensor.

7. The radio frequency identification tag device according to claim 5, wherein said LC generator includes a capacitive sensor.

8. The radio frequency identification tag device according to claim 1, wherein said logic circuit includes a memory array.

9. The radio frequency identification tag device according to claim 8, wherein said serial ID code is generated using data stored in said memory array.

10. The radio frequency identification tag device according to claim 1, wherein said ID code includes information about said at least one sensing element in said clock generator.

11. A radio frequency interrogator device, comprising a circuit that detects a mixed code sequence generated by a radio frequency identification tag device, said mixed code sequence is generated by serially connecting a serial ID code to a leading code having at least one sensing pulse, and the baud rate of said serial ID code and the width of said at least one sensing pulse change with the frequency of a clock signal generated by a clock generator, wherein said clock generator has at least one sensing element incorporated for generating said clock signal with frequency changing with sensing values obtained from said at least one sensing element;

a pulse processing unit for measuring the width of said at least one sensing pulse in said leading code;

a communication unit that obtains said ID code with the baud rate calculated using the pulse width measured by said pulse processing unit; and

a sensing value processing unit that calculates sensing values using said ID code obtained with said communication unit and the pulse width measured by said processing unit.

12. The radio frequency interrogator device according to claim 11, wherein said pulse processing unit includes a counter.

13. The radio frequency interrogator device according to claim 11, further comprising a microcontroller.

14. The radio frequency interrogator device according to claim 13, wherein said pulse processing unit includes a routine in said microcontroller.

15. The radio frequency interrogator device according to claim 13, wherein said sensing value processing unit includes a routine in said microcontroller.

16. A system for identifying and reading a sensor value, comprising:

at least one radio frequency identification tag device including a clock generator having at least one sensing element incorporated for generating a clock signal with frequency changing with sensing values obtained from said at least one sensing element, a logic circuit that generates a mixed code sequence which includes by serially connecting a serial ID code to a leading code having at least one sensing pulse, and the baud rate of said serial ID code and the width of said at least one sensing pulse change with the frequency of said clock signal generated by said clock generator, a radio frequency tuned circuit, and a circuit for loading and unloading said radio frequency tuned circuit with said mixed code sequence;

a radio frequency interrogator device having a circuit that detects said mixed code sequence generated by said at least one radio frequency identification tag device, a pulse processing unit for measuring the width of said sensing pulse in said leading code, a communication unit that obtains said ID code with the baud rate calculated using the pulse width measured by said pulse processing unit, and a sensing value processing unit that calculates sensing values based on said ID code obtained with said communication unit and the pulse width measured by said pulse processing unit.