Radio frequency identification transponder

• US 20030112128A1
• Filed: 11/05/2002
• Published: 06/19/2003
• Est. Priority Date: 02/28/2000
• Status: Active Grant

• Current Assignee: SATO Holdings Corporation
• Original Assignee: Magellan Technology Pty. Ltd (SATO Holdings Corporation)
• Inventors: Stanton, Michael John, Littlechild, Stuart Colin
• Granted Patent: US 7,248,145 B2
• Time in Patent Office: Days
• US Class Current: 340/10.52
• 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 7/10029 the collision being resolved in the time domain, e.g. using binary tree search or RFID responses allocated to a random time slot
• CPC Class Codes: G06K 7/10435 the interrogation device being positioned close to a conveyor belt or the like on which moving record carriers are passing conveying in accordance with bodily destination marks, see B65G47/46, sorting of objects carrying identity markings, see B07C5/34

Abstract

A radio frequency identification transponder including a power supply and a dynamic memory array which stores data. When power from the power supply ceases the data in the dynamic memory array is validly maintained for a predetermined period of time. The dynamic memory array is responsive to an interrogating signal for selectively updating the data. Further claimed is a radio frequency identification transponder wherein a signal processor extracts an identifier from the interrogation signal and is responsive to the identifier and the stored data to determine whether some or all of the identifier is stored in the dynamic memory array. Further claimed is a system wherein a transmitter provides a plurality of temporally spaced interrogating signals which are received by a receiver which incorporates a signal processor that is able to determine the order in which transponders were first in receipt of the interrogating signal. Further claimed is a baggage handling system wherein a transmitter provides a plurality of temporally spaced interrogating signals into an interrogating space through which a conveyor sequentially progresses baggage, a receiver receives transponder response signals which include baggage identity data, a signal processor then extracts the identity data and determines the order in which the baggage has progressed through the interrogating space.

Claims

1. A radio-frequency identification (“

RFID”

) transponder for use in an RFID system, the transponder including;

a dynamic memory array for storing first data; and

a power supply for powering circuitry associated with the RFID transponder, including the dynamic memory array;

wherein the transponder is configured such that, when power ceases to be provided to the dynamic memory array by the power supply, the data in the dynamic memory array is validly maintained therein for a predetermined time period; and

wherein the memory is responsive to an interrogating signal from the system for selectively updating the first data.

2. A transponder according to claim 1 wherein the RFID system provides an interrogating signal having an identifier and the transponder includes a receiver for receiving the signal.

3. A transponder according to claim 2 including a signal processor that is responsive to:

a) the receiver for extracting the identifier from the signal; and

b) the identifier and the first data for determining whether the identifier is stored in the memory array.

4. A transponder according to claim 1 wherein the power supply is configured to provide power by converting an externally applied electromagnetic excitation field into electrical power.

5. A transponder according to claim 1 wherein the first predetermined time period is determined by discharging of the dynamic memory array through stray leakage paths within the dynamic memory array.

6. A transponder according to claim 1 and including timer means for providing a validity flag in response to an interrogating signal, the flag being “

valid”

if the interrogating signal is received within a second time period and “

invalid”

if the interrogating signal is received after the second time period, the transponder being configured such that the data in the dynamic memory array is maintained in a readable state until at least the expiration of the second time period.

7. A transponder according to claim 6 wherein the timer means includes a capacitive cell for storing a charge generated by current from the power supply, the timer means being configured such that, once power from the power supply ceases to be supplied, the charge in the capacitive cell discharges at a predetermined rate.

8. A transponder according to claim 6 wherein the status of the validity flag is based on a voltage generated at a predetermined point in the timer means, the voltage decaying as the capacitive cell discharges.

9. A transponder according to claim 6 wherein the voltage is the output voltage of the capacitive cell as it discharges through a load.

10. A transponder according to claim 9 wherein the capacitive cell is a memory cell.

11. A transponder according to claim 10 wherein the memory cell forms part of the dynamic memory array.

12. An RFID system including a transponder according to claim 1 and a transponder interrogator for providing an interrogation field and reading data from the transponder.

13. A system according to claim 12 wherein the interrogator is configured to sequentially switch an orientation of the interrogation field, and the second time period is selected to exceed the time that the interrogation field is off during switching of its orientation.

14. A method of using a radio-frequency identification (“

RFID”

) transponder in an RFID system, the method including the steps of;

storing data in a dynamic memory array included within the transponder; and

powering circuitry associated with the RFID transponder, including the dynamic memory array, with a power supply;

validly maintaining the data in the dynamic memory array for a predetermined time period after power ceases to be provided to the dynamic memory array by the power supply; and

being responsive to an interrogating signal from the system for selectively updating the first data.

15. A method according to claim 14 including the additional step of the RFID system providing an interrogating signal having an identifier, wherein the transponder includes a receiver for receiving the signal.

16. A method according to claim 15 wherein the transponder includes a signal processor that is responsive to:

a) The receiver for extracting the identifier from the signal; and

b) The identifier and the first data for determining whether the identifier is stored in the memory array.

17. A radio-frequency identification (“

RFID”

) transponder for use with an RFID interrogator that provides a plurality of temporally spaced interrogating signals, wherein the signals include respective identifiers and the transponder includes;

a receiver for receiving the interrogating signals from the interrogator;

a memory array for storing first data; and

a signal processor being responsive to the receiver for extracting the identifier from the signal and being responsive to the identifier and the first data for determining whether some or all of the identifier is stored in the memory array.

18. A transponder according to claim 17 wherein some or all of the identifier is stored in the memory array and that the data stored updates some or all of the first data.

19. A transponder according to claim 17 wherein the signal processor determines that the identifier is stored in the memory array if the identifier is different to the first data.

20. A transponder according to claim 17 wherein the signal processor determines that the identifier is stored in the memory array if a predetermined portion of the identifier is different to the first data.

21. A transponder according to claim 17 wherein the identifier includes data that is selected from one or more of the following types:

second data indicative of the interrogator; and

third data that is not constant for the respective signals.

22. A transponder according to claim 21 wherein the third data is indicative of the timing of the respective signal.

23. A transponder according to claim 21 wherein the third data is a pseudo random number or character string.

24. A transponder according to claim 21 wherein the second data includes a reference number for the interrogator that is the same for all the signals provided by the interrogator.

25. A transponder according to claim 24 wherein the third data includes a date stamp that varies with the passage of time.

26. A transponder according to claim 21 wherein the signal processor determines that the second data is stored in the memory array if the second data is different to the first data.

27. A transponder according to claim 21 wherein the signal processor determines that the third data is stored in the memory array if the second data is different to the first data.

28. A transponder according to claim 27 wherein the signal processor determines that the second data is also stored in the memory array if the second data is different to the first data.

29. A transponder according to claim 21 wherein the signal processor determines that the identifier is stored in the memory array if the third data is sufficiently different to some or all of the first data.

30. A transponder according to claim 29 wherein the third data includes a date stamp that is indicative of the time of the respective signal, and that date stamp is compared with the first data to determine whether sufficient time has elapsed since the last store of the third data in the memory array.

31. A transponder according to claim 21 wherein the transponder includes a transmitter for transmitting a reply signal to the interrogator in response to an interrogating signal, wherein the reply signal includes:

fourth data indicative of the transponder; and

fifth data derived from the first data.

32. A transponder according to claim 31 wherein the fifth data includes either or both of the second data or the third data.

33. A transponder according to claim 31 wherein the fifth data includes the second data.

34. A transponder according to claim 33 wherein the fifth data includes the third data.

35. A transponder according to claim 31 wherein the fifth data includes the second data and the third data.

36. A transponder according to claim 31 wherein the fourth data is a coded string for allowing discrimination between other transponders used with the interrogator.

37. A method of using a radio-frequency identification (“

RFID”

) transponder with an RFID interrogator that provides a plurality of temporally spaced interrogating signals, wherein the signals include respective identifiers and the method includes the steps of;

receiving the interrogating signals from the interrogator with a receiver;

storing first data in a memory array; and

being responsive to the receiver for extracting the identifier from the signal and being responsive to the identifier and the first data for determining whether some or all of the identifier is stored in the memory array.

38. A radio-frequency identification (“

RFID”

) interrogator for interrogating a plurality of RFID transponders, the interrogator including;

a transmitter for providing a plurality of temporally spaced interrogating signals, wherein the signals include respective identifiers;

a receiver for receiving response signals from the respective transponders, the response signals including respective identity data that is derived from one or more of the interrogator signals; and

a signal processor being responsive to the receiver for extracting the identity data from the response signals to determine the order in which the transponders were first in receipt of an interrogating signal.

39. A transponder according to claim 38 wherein the interrogator is a TRP and the transponders are attached to respective articles that are being progressed through the TRP, wherein the signal processor is responsive to the determination of the order in which the transponders were first in receipt of an interrogating signal for determining the order in which the articles progress through the TRP.

40. A method of interrogating a plurality of radio-frequency identification (“

RFID”

) transponders with an RFID interrogator, the method including the steps of;

providing a plurality of temporally spaced interrogating signals to the transponders, wherein the signals include respective identifiers;

receiving response signals from the respective transponders with a receiver, the response signals including respective identity data that is derived from one or more of the interrogator signals; and

being responsive to the receiver for extracting the identity data from the response signals to determine the order in which the transponders were first in receipt of an interrogating signal.

41. A plurality of radio-frequency identification (“

RFID”

) transponders for use with an RFID interrogator that provides a plurality of temporally spaced interrogating signals that include respective identifiers, the transponders each including;

a receiver for receiving one or more of the interrogating signals;

a signal processor being responsive to the receiver for extracting the identifiers from the one or more signals; and

a transmitter being responsive to the identifiers for transmitting a response signal for allowing the interrogator to determine the order in which the transponders were first in receipt of an interrogating signal.

42. A plurality of transponders according to claim 41 wherein the identifier includes first data indicative of the time of the provision of the interrogating signal and the response signal includes data derived from the identifier and data unique to the respective transponder.

43. A plurality of transponders according to claim 42 wherein the identifier also includes second data unique to the interrogator and the response signal is derived from the first and the second data.

44. A plurality of transponders according to claim 41 wherein the transponders each include respective memory arrays for storing selected data.

45. A plurality of transponders according to claim 44 wherein each transponder includes a power supply for supplying power to the transponder, inclusive of the memory array.

46. A plurality of transponders according to claim 45 wherein each memory array validly maintains the selected data for a predetermined time period after power ceases to be provided to the power supply.

47. A plurality of transponders according to claim 41 wherein the memory array is comprised of dynamic memory.

48. A method of using a plurality of radio-frequency identification (“

RFID”

) transponders with an RFID interrogator that provides a plurality of temporally spaced interrogating signals that include respective identifiers, the method including the steps of;

the transponders receiving one or more of the interrogating signals with respective receivers;

being responsive to the respective receivers for extracting the identifiers from the one or more signals; and

transmitting respective response signals in response to the identifiers for allowing the interrogator to determine the order in which the transponders were first in receipt of an interrogating signal.

49. A baggage handling system for baggage that is tagged with respective radio-frequency identification (“

RFID”

) transponders, the system including;

an RFID interrogator that transmits a plurality of temporally spaced interrogating signals into an interrogating space, wherein the signals include respective identifiers;

a conveyer for sequentially progressing the baggage through the interrogating space;

a receiver for receiving response signals from the transponders, wherein the response signals include identity data that is derived from one or more of the interrogator signals; and

a signal processor being responsive to the receiver for extracting the identity data from the response signals and thereby determining the order in which the baggage is progressed through the interrogating space.

50. A system according to claim 49 including a plurality of spaced apart interrogators, wherein the identifiers include data indicative of the interrogator that transmitted the respective interrogating signal.

51. A method of handling baggage that is tagged with respective radio-frequency identification (“

RFID”

) transponders, the method including the steps of;

transmitting a plurality of temporally spaced interrogating signals into an interrogating space with an RFID interrogator, wherein the signals include respective identifiers;

sequentially progressing the baggage through the interrogating space;

receiving response signals from the transponders with a receiver, wherein the response signals include identity data that is derived from one or more of the interrogator signals; and

being responsive to the receiver for extracting the identity data from the response signals and thereby determining the order in which the baggage is progressed through the interrogating space.

52. A method according to claim 51 including the step of muting the transponder once it has been interrogated.

53. A method according to claim 52 including the step of muting the transponder only in respect of interrogation signals from the same interrogator.

54. A method according to claim 52 including the step of configuring the interrogator to selectively un-mute the interrogated transponder by providing in identifier that indicates to the transponder that it is another interrogator.