METHODS AND APPARATUS FOR SWITCHING A TRANSPONDER TO AN ACTIVE STATE, AND ASSET MANAGEMENT SYSTEMS EMPLOYING SAME

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.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description given below, serve to explain the principles of the invention. As shown throughout the drawings, like reference numerals designate like or corresponding parts.

FIG. 1 is a block diagram of an active RF transponder according to one embodiment of the present invention;

FIG. 2 is a schematic diagram of a burst switch according to an aspect of the present invention;

FIG. 3 is a block diagram of an RF transponder according to an alternative embodiment of the present invention;

FIG. 4 is a schematic illustration of a code that may be required to awaken the transponder 50 shown in FIG. 3;

FIG. 5 is a block diagram of an RF transponder according to a further alternative embodiment of the present invention;

FIG. 6 is a block diagram of an alternative RF transponder that is similar to the RF transponder shown in FIG. 1 but that further includes an RF receiver;

FIG. 7 is a block diagram of an alternative RF transponder that is similar to the RF transponder shown in FIG. 3 but that further includes an RF receiver;

FIG. 8 is a block diagram of an RFID system according to an aspect of the present invention;

FIG. 9 is a block diagram of an asset management system according to a further aspect of the present invention; and

FIG. 10 is a block diagram of an interface device forming a part of the asset management system shown in FIG. 9.

Claims

1. A transponder apparatus, comprising: an electronic device, said electronic device being capable of being in 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; anda 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;wherein said at least one DC signal causes said electronic device to move from said inactive, sleep state to said active state.

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 DC signal is provided to said electronic device to directly cause said electronic device to move from said inactive, sleep state to said active state.

11. The transponder apparatus according to claim 1, further comprising a filtering circuit in electronic communication with said switch, wherein said at least one DC signal is provided to said filtering circuit, 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 said at least one DC signal has a predetermined format.

12. The transponder apparatus according to claim 11, 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.

13. The transponder apparatus according to claim 11, wherein said predetermined format comprises a predetermined number of bursts, each of said bursts having a predetermined duration.

14. The transponder apparatus according to claim 1, further comprising a filtering circuit in electronic communication with said switch, wherein said at least one DC signal is provided to said filtering circuit, 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 said at least one RF signal has a predetermined format.

15. The transponder apparatus according to claim 11, 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.

16. The transponder apparatus according to claim 1, further comprising one or more additional switches, each of said additional switches having an additional antenna for receiving at least one additional RF signal, said additional switch converting said at least one additional RF signal into at least one additional DC signal, wherein said at least one RF signal and each of said at least one additional RF signals have different frequencies, and wherein a logical combination of said at least one DC signal and one or more of said at least one additional DC signals causes said electronic device to move from said inactive, sleep state to said active state.

17. The transponder apparatus according to claim 1, further comprising one or more additional switches, each of said additional switches having an additional antenna for receiving at least one additional RF signal, said additional switch converting said at least one additional RF signal into at least one additional DC signal, wherein said at least one RF signal and each of said at least one additional RF signals have different frequencies, and wherein said electronic device is caused to move from said inactive, sleep state to said active state only if said at least one DC signal and said at least one additional DC signals are created in a particular sequence.

18. The transponder apparatus according to claim 1, further comprising one or more additional switches, each of said additional switches having an additional antenna for receiving at least one additional RF signal, said additional switch converting said at least one additional RF signal into at least one additional DC signal, wherein said at least one RF signal and each of said at least one additional RF signals have different frequencies, and wherein said electronic device is caused to move from said inactive, sleep state to said active state only if said at least one RF signal and each of said at least one additional RF signals are received in a particular sequence.

19. 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.

20. The transponder apparatus according to claim 16, wherein said transponder apparatus is an RFID tag and wherein said at least one RF signal and each of said at least one additional RF signals are transmitted by an RFID reader device.

21. 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.

22. The transponder apparatus according to claim 11, wherein said switch does not require power from said power source or another power source within or connected to said transponder apparatus.

23. The transponder apparatus according to claim 22, wherein said filtering circuit receives power from said power source.

24. 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; andproviding a wake-up signal to said electronic device in response to receipt of said at least one RF signal, said wake-up signal causing said electronic device to move from said inactive, sleep state to said active state.

25. The method according to claim 24, wherein said wake-up signal is said at least one DC signal.

26. The method according to claim 24, 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.

27. The method according to claim 24, further comprising determining whether said at least one DC signal has a predetermined format, wherein said providing step comprises providing said 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.

28. The method according to claim 27, 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.

29. The method according to claim 28, wherein said predetermined format comprises a predetermined number of bursts, each of said bursts having a predetermined duration.

30. The method according to claim 24, further comprising determining whether said at least one RF signal has a predetermined format, wherein said providing step comprises providing said 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.

31. The method according to claim 30, 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.

32. The method according to claim 24, further comprising receiving at least one additional RF signal and converting said at least one additional RF signal into at least one additional DC signal without requiring the consumption of power from said power source or another power source within or connected to said transponder apparatus, wherein said at least one RF signal and each of said at least one additional RF signals have different frequencies, and wherein said providing step comprises providing said wake-up signal to said electronic device to cause said electronic device to move from said inactive, sleep state to said active state only in response to a logical combination of said at least one DC signal and one or more of said at least one additional DC signals.

33. The method according to claim 24, further comprising receiving at least one additional RF signal and converting said at least one additional RF signal into at least one additional DC signal without requiring the consumption of power from said power source or another power source within or connected to said transponder apparatus, wherein said at least one RF signal and each of said at least one additional RF signals have different frequencies, and wherein said providing step comprises providing said 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 said at least one DC signal and said at least one additional DC signals are created in a particular sequence

34. The method according to claim 24, further comprising receiving at least one additional RF signal and converting said at least one additional RF signal into at least one additional DC signal without requiring the consumption of power from said power source or another power source within or connected to said transponder apparatus, wherein said at least one RF signal and each of said at least one additional RF signals have different frequencies, and wherein said providing step comprises providing said 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 said at least one RF signal and each of said at least one additional RF signals are received in a particular sequence.

35. The method according to claim 24, 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.

36. The method according to claim 32, wherein said transponder apparatus is an RFID tag and wherein receiving steps comprise receiving said at least one RF signal and each of said at least one additional RF signals from an RFID reader device.

37. The method according to claim 24, wherein said power source is a battery.

38. The method according to claim 24, wherein said electronic device is a processing unit.

39. The method according to claim 24, 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.

40. A system for tracking a plurality of assets, comprising: a central computer system, said central computer system maintaining a plurality of records relating to said assets; anda plurality of transponders, each of said transponders being associated with a respective one of said assets and storing an identifier identifying the particular asset with which the transponder is associated, wherein each of said transponders comprises: an electronic device, said electronic device being capable of being in 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; anda switch having an antenna for receiving at least one RF signal, said at least one RF signal being generated at the direction of said central computer system, said switch converting said at least one RF signal into at least one DC signal;wherein said at least one DC signal causes said electronic device to move from said inactive, sleep state to said active state, wherein when said electronic device is in said active state the transponder generates and transmits a response signal including the identifier identifying the particular asset with which the transponder is associated, and wherein said response signal is used to update a particular one of the record maintained by the central computer system relating to the asset identified by the identifier in the response signal.

41. The system according to claim 40, wherein the switch in each of the transponders does not require power from the power source of the transponder or another power source within or connected to the transponder.

42. The system according to claim 40, further comprising: a network, said central computer system being in electronic communication with said network;a plurality of wireless access points, each of said wireless access points being in electronic communication with said network; anda plurality of interface devices, each of said interface devices being adapted to (i) wirelessly communicate with at least one of said wireless access points, (ii) receive the response signal transmitted by a particular one or more of said transponders, and (iii) generate and transmit to the at least one of said wireless access points at least one second response signal that includes each identifier that was included in each response signal received by the interface device;wherein each at least one second response signal is transmitted to said central computer system through said network, and wherein said central computer system uses the at least one second response signal received from one or more of said interface devices to update one or more of said records.

43. The system according to claim 42, wherein said network and said wireless access points implement a wireless network according to the IEEE 802.11 set of standards.

44. The system according to claim 40, further comprising a wired network in electronic communication with said central computer system, said transponders being adapted to communicate with said central computer system through said wired network.

45. The system according to claim 40, further comprising: a network, said central computer system being in electronic communication with said network; anda plurality of interface devices, each of said interface devices being adapted to (i) communicate with said network, (ii) receive the response signal transmitted by a particular one or more of said transponders, and (iii) generate and transmit to said network at least one second response signal that includes at least each identifier that was included in each response signal received by the interface device;wherein each at least one second response signal is transmitted to said central computer system through said network, and wherein said central computer system uses the at least one second response signal received from one or more of said interface devices to update one or more of said records.

46. The system according to claim 42, wherein said assets are located within an environment, wherein each of said interface devices is associated with a particular location within said environment, wherein each of said second response signals includes an identification of the interface device from which it was transmitted, and wherein said central computer system uses the identification included in each second response signal to update in said records a location of one or more of said assets.

47. The system according to claim 46, wherein said environment is one or more buildings.

48. The system according to claim 47, wherein said one or more buildings includes a hospital.

49. The system according to claim 45, wherein said assets are located within an environment, wherein each of said interface devices is associated with a particular location within said environment, wherein each of said second response signals includes an identification of the interface device from which it was transmitted, and wherein said central computer system uses the identification included in each second response signal to update in said records a location of one or more of said assets.

50. The system according to claim 49, wherein said environment is one or more buildings.

51. The system according to claim 50, wherein said one or more buildings includes a hospital.

52. The system according to claim 40, wherein the switch in each of the transponders includes a rectifying circuit for converting the at least one RF signal received by the switch into the at least one DC signal.

53. The system according to claim 52, wherein the rectifying circuit of the switch in each of the transponders is a charge pump.

54. The system according to claim 53, wherein the switch in each of the transponders further includes a matching network electrically connected to the antenna of the switch and wherein the charge pump of the switch is electrically connected to an output of the matching network.

55. The system according to claim 40, wherein the power source in each of the transponders is a battery.

56. The system according to claim 40, wherein the electronic device in each of the transponders is a processing unit.

57. The system according to claim 40, wherein the antenna in each of the transponders is tuned to a particular frequency or range of frequencies, and wherein the at least one RF signal generated at the direction of said central computer system and received by the antenna in each of the transponders has a frequency that is substantially equal to said particular frequency or is within said range of frequencies.

58. The system according to claim 40, wherein each of the transponders further comprises a filtering circuit in electronic communication with the switch of the transponder, wherein the at least one DC signal from the switch is provided to the filtering circuit, and wherein the filtering circuit will provide a wake-up signal to the electronic device of the transponder to cause the electronic device to move from the inactive, sleep state to the active state only if the at least one RF signal generated at the direction of said central computer system and received by the antenna in the transponder has a predetermined format.

59. The system according to claim 58, wherein the predetermined format for each of the transponders comprises a predetermined number of RF bursts, each of said RF bursts having a predetermined duration.

60. The system according to claim 40, wherein the at least one DC signal of the switch in each of the transponders is provided to the electronic device of the transponder to directly cause the electronic device to move from said inactive, sleep state to said active state.

61. The system according to claim 40, wherein each of the transponders further comprises a filtering circuit in electronic communication with the switch of the transponder, wherein the at least one DC signal from the switch is provided to the filtering circuit, and wherein the filtering circuit provides a wake-up signal to the electronic device of the transponder to cause the electronic device to move from the inactive, sleep state to the active state only if the at least one DC signal has a predetermined format.

62. The system according to claim 61, wherein the predetermined format for each of the transponders comprises a predetermined number of DC bursts, each of said DC bursts having a predetermined duration.

63. The system according to claim 62, wherein the predetermined format for each of the transponders is different.

64. The system according to claim 59, wherein the predetermined format for each of the transponders is different.

65. The system according to claim 40, wherein each of the transponders further comprises one or more additional switches, each of said additional switches of the transponder having an additional antenna for receiving at least one additional RF signal generated at the direction of said central computer system, said additional switch of the transponder converting said at least one additional RF signal into at least one additional DC signal, wherein said at least one RF signal received by the antenna of the switch of the transponder and each of said at least one additional RF signals received by the one or more additional switches of the transponder have different frequencies, and wherein a logical combination of the at least one DC signal and one or more of the at least one additional DC signals of the transponder causes said electronic device of the transponder to move from the inactive, sleep state to the active state.

66. The system according to claim 40, wherein each of the transponders further comprises one or more additional switches, each of said additional switches of the transponder having an additional antenna for receiving at least one additional RF signal generated at the direction of said central computer system, said additional switch of the transponder converting said at least one additional RF signal into at least one additional DC signal, wherein said at least one RF signal received by the antenna of the switch of the transponder and each of said at least one additional RF signals received by the one or more additional switches of the transponder have different frequencies, and wherein the electronic device of the transponder is caused to move from said inactive, sleep state to said active state only if the at least one DC signal and the at least one additional DC signals of the transponder are created in a particular sequence.

67. The system according to claim 40, wherein each of the transponders further comprises one or more additional switches, each of said additional switches of the transponder having an additional antenna for receiving at least one additional RF signal generated at the direction of said central computer system, said additional switch of the transponder converting said at least one additional RF signal into at least one additional DC signal, wherein said at least one RF signal received by the antenna of the switch of the transponder and each of said at least one additional RF signals received by the one or more additional switches of the transponder have different frequencies, and wherein the electronic device of the transponder is caused to move from said inactive, sleep state to said active state only if said at least one RF signal and each of said at least one additional RF signals are received by the transponder in a particular sequence.

68. The system according to claim 40, wherein each of said transponders has a code associated therewith, and wherein for each of said transponders in order for the at least one RF signal received by the transponder to be converted in at least one DC signal that will cause the electronic device of the transponder to move from the inactive, sleep state to the active state, the at least one RF signal received by the transponder must be formatted according to said code associated with the transponder.

69. The system according to claim 68, wherein said code associated with each of said transponders represents a predetermined number of RF bursts, each of said RF bursts having a predetermined duration.

70. The system according to claim 40, wherein for each of said transponders in order for the at least one RF signal received by the transponder to be converted in at least one DC signal that will cause the electronic device of the transponder to move from the inactive, sleep state to the active state, the at least one RF signal received by the transponder must be have a predetermined format associated with the transponder.

71. The system according to claim 70, wherein said predetermined format associated with each of said transponders comprises a predetermined number of RF bursts, each of said RF bursts having a predetermined duration.

72. The system according to claim 40, wherein each of one or more groups of selected ones of said transponders have a code associated therewith, and wherein for each of said groups of transponders in order for the at least one RF signal received by each transponder in the group to be converted in at least one DC signal that will cause the electronic device of the transponder in the group to move from the inactive, sleep state to the active state, the at least one RF signal received by the transponder in the group must be formatted according to said code associated with the group of transponders.

73. The system according to claim 72, wherein said code associated with each of said groups of transponders represents a predetermined number of RF bursts, each of said RF bursts having a predetermined duration.

74. The system according to claim 40, wherein said transponders are grouped into one or more groups of selected ones of said transponders, and wherein for each of said groups of transponders in order for the at least one RF signal received by each transponder in the group to be converted in at least one DC signal that will cause the electronic device of the transponder in the group to move from the inactive, sleep state to the active state, the at least one RF signal received by the transponder in the group must be have a predetermined format associated with group.

75. The system according to claim 74, wherein said predetermined format associated with each of said groups of transponders comprises a predetermined number of RF bursts, each of said RF bursts having a predetermined duration.

76. The system according to claim 56, wherein each of said transponders includes an RF transmitter in electronic communication with the processing unit of the transponder.

77. The system according to claim 56, wherein each of said transponders includes an RF receiver in electronic communication with the processing unit of the transponder.

78. The system according to claim 40, wherein the at least one DC signal of each of said transponders is provided to the electronic device of the transponder to directly cause the electronic device to move from said inactive, sleep state to said active state.

79. The system according to claim 40, wherein each of said transponders is an RFID tag and wherein said at least one RF signals are generated by an RFID reader device.

80. A system for tracking a plurality of assets, comprising: a central computer system, said central computer system maintaining a plurality of records relating to said assets;a network, said central computer system being in electronic communication with said network; a plurality of interface devices, each of said interface devices being adapted to communicate with said network; anda plurality of transponders, each of said transponders being associated with a respective one of said assets and storing an identifier identifying the particular asset with which the transponder is associated, each of said transponders being adapted to receive from one of said interface devices at least one RF signal that is generated at the direction of said central computer system and in response thereto to generate and transmit a response signal including the identifier identifying the particular asset with which the transponder is associated;wherein each of said interface devices is adapted to (i) receive the response signal that is transmitted by each of a particular one or more of said transponders, and (ii) generate and transmit to said network at least one second response signal, said at least one second response signal including each identifier that was included in each response signal received by the interface device, wherein the at least one second response signal is transmitted to said central computer system through said network, and wherein said central computer system uses the at least one second response signal received from one or more of said interface devices to update one or more of said records.

81. The system according to claim 80, wherein the at least one second response signal is a plurality of second response signals, wherein each of said second response signals corresponds to a respective one of the response signals that was received by the interface device and includes the identifier that was included the corresponding one of the response signals.

82. The system according to claim 81, wherein said central computer system is adapted to cause the generation of the at least one RF signal particular to one or more of said transponders in a sequential fashion, and wherein corresponding response signals and second response signals are generated and transmitted in a corresponding sequential fashion.

83. The system according to claim 80, wherein one or more of said transponders is an active RFID tag.

84. The system according to claim 80, wherein one or more of said transponders is a passive RFID tag.

85. The system according to claim 80, further comprising a plurality of wireless access points, each of said wireless access points being in electronic communication with said network, wherein each of said interface devices is adapted to wirelessly communicate with at least one of said wireless access points.

86. The system according to claim 85, wherein said network and said wireless access points implement a wireless network according to the IEEE 802.11 set of standards.

87. The system according to claim 80, wherein said assets are located within an environment, wherein each of said interface devices is associated with a particular location within said environment, wherein each at least one second response signal includes an identification of the interface device from which it was transmitted, and wherein said central computer system uses the identification included in each second response signal to update in said records a location of one or more of said assets.

88. The system according to claim 87, wherein said environment is one or more buildings.

89. The system according to claim 88, wherein said one or more buildings includes a hospital.

90. The system according to claim 80, wherein for a group of selected ones of said transponders the at least one RF signal that is generated at the direction of said central computer system and that causes each of the transponders in the group to generate and transmit the response signal including the identifier identifying the particular asset with which the transponder is associated is common to the transponders in the group.

91. The system according to claim 80, wherein said interface devices are in wired electronic communication with said network.

92. The system according to claim 80, wherein said interface devices are in wireless electronic communication with said network.

93. The system according to claim 88, wherein each of said transponders is an RFID device and wherein said central computer system includes an RFID reader device.