Methods and apparatus for switching a transponder to an active state, and asset management systems employing same

• US 7,876,225 B2
• Filed: 02/23/2007
• Issued: 01/25/2011
• Est. Priority Date: 02/23/2006
• Status: Active Grant

• Current Assignee: University of Pittsburgh of The Commonwealth System of Higher Education
• Original Assignee: University of Pittsburgh of The Commonwealth System of Higher Education
• Inventors: Hawrylak, Peter J., Marx, Frank, Mickle, Marlin H., Cain, James T., Hoare, Raymond R., Jones, Alex K.
• Primary Examiner(s): Nguyen; Tai T
• Application Number:
  US11/678,296
• Publication Number:
  US 20070205873A1
• Time in Patent Office: 1,432 Days
• Field of Search: 340/572.4, 340/572.7, 340/572.8, 340/539.22, 340/870.01, 340/10.5, 235/385, 235/492, 343/850, 343/860, 343/795
• US Class Current: 340/572.4
• CPC Class Codes: G06K 19/0707 the arrangement being capable of collecting energy from external energy sources, e.g. thermocouples, vibration, electromagnetic radiation G06K19/0702 takes precedence
• CPC Class Codes: G06K 19/0712 the arrangement being capable of triggering distinct operating modes or functions dependent on the strength of an energy or interrogation field in the proximity of the record carrier active means for hindering electromagnetic reading or writing G06K19/07336
• CPC Class Codes: G06K 19/0713 the arrangement including a power charge pump
• 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

Abstract

A transponder that may be used as an RFID tag includes a passive circuit to eliminate the need for an “always on” active RF receiving element to anticipate a wake-up signal for the balance of the transponder electronics. This solution allows the entire active transponder to have all circuit elements in a sleep (standby) state, thus drastically extending battery life or other charge storage device life. Also, a wake-up solution that reduces total energy consumption of an active transponder system by allowing all non-addressed transponders to remain in a sleep (standby) state, thereby reducing total system or collection energy. Also, the transponder and wake-up solution are employed in an asset tracking system.

Claims

1. A transponder apparatus, comprising:

an electronic device, said electronic device being switchable between an inactive, sleep state and an active state;

a power source in electronic communication with said electronic device, said power source providing power to said electronic device;

a switch having an antenna for receiving at least one RF signal, said switch converting said at least one RF signal into at least one DC signal; and

a filtering circuit in electronic communication with said switch, wherein said at least one DC signal is provided to said filtering circuit, wherein responsive to receiving said at least one DC signal said filtering circuit analyzes said at least one DC signal and determines whether said at least one DC signal has a predetermined format, wherein said predetermined format comprises a predetermined number of bursts, each of said bursts having a predetermined duration, and wherein said filtering circuit provides a wake-up signal to said electronic device to cause said electronic device to move from said inactive, sleep state to said active state only if it is determined that said at least one DC signal has said predetermined format.

2. The transponder apparatus according to claim 1, wherein said switch includes a rectifying circuit for converting said at least one RF signal into said at least one DC signal.

3. The transponder apparatus according to claim 2, wherein said rectifying circuit is a charge pump.

4. The transponder apparatus according to claim 3, wherein said switch further includes a matching network electrically connected to said antenna and wherein said charge pump is electrically connected to an output of said matching network.

5. The transponder apparatus according to claim 1, wherein said power source is a battery.

6. The transponder apparatus according to claim 1, wherein said electronic device is a processing unit.

7. The transponder apparatus according to claim 6, further comprising an RF transmitter in electronic communication with said processing unit.

8. The transponder apparatus according to claim 1, wherein said antenna is tuned to a particular frequency or range of frequencies, and wherein said at least one RF signal has a frequency that is substantially equal to said particular frequency or is within said range of frequencies.

9. The transponder apparatus according to claim 6, further comprising an RF receiver in electronic communication with said processing unit.

10. The transponder apparatus according to claim 1, wherein said at least one RF signal comprises a plurality of RF bursts, and wherein said at least one DC signal comprises a corresponding plurality of DC bursts.

11. The transponder apparatus according to claim 1, wherein said transponder apparatus is an RFID tag and wherein said at least one RF signal is transmitted by an RFID reader device.

12. The transponder apparatus according to claim 1, wherein said switch does not require power from said power source or another power source within or connected to said transponder apparatus.

13. The transponder apparatus according to claim 12, wherein said filtering circuit is electrically connected to said power source and receives power from said power source.

14. A transponder apparatus, comprising:

an electronic device, said electronic device being switchable between an inactive, sleep state and an active state;

a power source in electronic communication with said electronic device, said power source providing power to said electronic device;

a switch having an antenna for receiving at least one RF signal, said switch converting said at least one RF signal into at least one DC signal; and

a filtering circuit in electronic communication with said switch, wherein said at least one DC signal is provided to said filtering circuit, wherein responsive to receiving said at least one DC signal said filtering circuit analyzes said at least one DC signal and determines whether said at least one DC signal has a first predetermined format, wherein said at least one RF signal comprises a plurality of RF bursts, and wherein said predetermined format comprises a predetermined number of bursts, each of said bursts having a predetermined duration, and wherein said filtering circuit will provide a wake-up signal to said electronic device to cause said electronic device to move from said inactive, sleep state to said active state only if it is determined that said at least one DC signal has said first predetermined format, wherein said at least one DC signal will have said first predetermined format only if said at least one RF signal has a second predetermined format.

15. A method of moving an electronic device included in a transponder apparatus from an inactive, sleep state to an active state, wherein said electronic device consumes power from a power source of said transponder apparatus in said active state, comprising:

receiving at least one RF signal and converting said at least one RF signal into at least one DC signal without consuming power from said power source or another power source within or connected to said transponder apparatus;

analyzing said at least one DC signal and determining whether said at least one DC signal has a predetermined format wherein said predetermined format comprises a predetermined number of bursts, each of said bursts having a predetermined duration; and

providing a wake-up signal to said electronic device only if it is determined that said at least one DC signal has said predetermined format, said wake-up signal causing said electronic device to move from said inactive, sleep state to said active state.

16. The method according to claim 15, wherein said at least one RF signal has a frequency that is substantially equal to a particular frequency or is within a particular range of frequencies.

17. The method according to claim 15, wherein said at least one RF signal comprises a plurality of RF bursts, and wherein said at least one DC signal comprises a plurality of DC bursts, and wherein said determining step comprises determining whether said DC bursts have said predetermined format.

18. The method according to claim 15, wherein said transponder apparatus is an RFID tag and wherein said receiving step comprises receiving said at least one RF signal from an RFID reader device.

19. The method according to claim 15, wherein said power source is a battery.

20. The method according to claim 15, wherein said electronic device is a processing unit.

21. The method according to claim 15, wherein said transponder apparatus is an RFID tag, and wherein said receiving step includes receiving said at least one RF signal from an RFID reader device.

22. A method of moving an electronic device included in a transponder apparatus from an inactive, sleep state to an active state, wherein said electronic device consumes power from a power source of said transponder apparatus in said active state, comprising:

receiving at least one RF signal and converting said at least one RF signal into at least one DC signal without consuming power from said power source or another power source within or connected to said transponder apparatus;

analyzing said at least one DC signal and determining whether said at least one RF signal has a predetermined format based on said at least one DC signal wherein said at least one RF signal comprises a plurality of RF bursts, wherein said determining step comprises determining whether said RF bursts have said predetermined format, and wherein said predetermined format comprises a predetermined number of bursts, each of said bursts having a predetermined duration; and

providing a wake-up signal to said electronic device to cause said electronic device to move from said inactive, sleep state to said active state only if it is determined that said at least one RF signal has said predetermined format.