RFID tag battery charging method

• US 10,236,554 B2
• Filed: 01/08/2016
• Issued: 03/19/2019
• Est. Priority Date: 01/08/2016
• Status: Active Grant

• Current Assignee: Intermec (Honeywell International Inc.)
• Original Assignee: Intermec (Honeywell International Inc.)
• Inventors: Ackley, H. Sprague, Nikitin, Pavel
• Primary Examiner(s): Dunn, Drew A
• Assistant Examiner(s): Robbins, Jerry D
• Application Number:
  US14/991,218
• Publication Number:
  US 20170201003A1
• Time in Patent Office: 1,166 Days
• Field of Search: 320107
• CPC Class Codes: G06K 19/0704 the battery being rechargeable, e.g. solar batteries
• CPC Class Codes: G06K 19/0709 the source being an interrogation field
• CPC Class Codes: G06K 19/071 the source being a field other than an interrogation field, e.g. WLAN, cellular phone network
• CPC Class Codes: H01Q 1/2225 used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence
• CPC Class Codes: H04B 5/77 for interrogation

Abstract

A trickle-charged RFID device includes a main antenna receiving wireless interrogator signals from one or more RFID readers, a power harvester connected with the main antenna to obtain power from the wireless interrogator signals, and an intermediate storage device connected to the power harvester to collect trickle flows of unused power harvested from wireless interrogator signals received by the RFID device that lack an inquiry for the device. The RFID device further includes a primary storage device, into which the intermediate storage device discharges its collection of trickle flows of unused power when the collection reaches a predetermined threshold level, which recharges power lost from the main storage device. The intermediate storage device can include one or more capacitors including super-capacitors, and the main storage device can include a rechargeable battery, such that the effective life of the main storage device is extended from the collected trickle flows.

Claims

1. A trickle-charged Radio Frequency Identification (RFID) device comprising:

a first main antenna element configured to receive a first plurality of wireless interrogator signals from one or more RFID readers;

a first power harvester electrically connected with the first main antenna element and configured to obtain power from each of the first plurality of wireless interrogator signals;

an intermediate storage device electrically connected to the first power harvester via a first circuit and configured to collect a plurality of trickle flows of obtained power from the first power harvester for the portion of the first plurality of wireless interrogator signals, the first circuit being configured to divert the plurality of trickle flows to the intermediate storage;

a primary storage device connected with the intermediate storage device via a second circuit, the second circuit configured to drain a collected store of the plurality of trickle flows from the intermediate storage when the collected store reaches a predetermined discharge level;

a control unit configured to direct the plurality of trickle flows obtained from the portion of the first plurality of wireless interrogator signals to the intermediate storage; and

a plurality of switches comprising a first switch and a second switch, wherein the control unit is further configured to close the first switch, upon receipt of the first plurality of wireless interrogator signals lacking a tag inquiry, in order to direct the obtained power to the intermediate storage device until the predetermined discharge level of the collected store has been met in the intermediate storage device, and close the second switch when the predetermined discharge level of the collected store has been reached in order to transfer the power from the intermediate storage device to the primary storage device.

2. The trickle-charged RFID device of claim 1, wherein the primary storage device comprises a rechargeable battery and the intermediate storage device comprises one or more capacitors.

3. The trickle-charged RFID device of claim 2, wherein the one or more capacitors comprise one or more super-capacitors.

4. The trickle-charged RFID device of claim 2, wherein the second circuit comprises one or more diodes configured to drain automatically the collected store of the trickle flows when the predetermined discharge level is met and to provide a recharge burst formed from the collected store to the rechargeable battery.

5. The trickle-charged RFID device of claim 4, wherein the one or more diodes are further configured to stop the draining of the collected store to the rechargeable battery when a predetermined low level for the collected store is reached.

6. The trickle-charged RFID device of claim 1, further comprising a main switch configured to switch from a first position connecting the intermediate storage to the first power harvester for providing a trickle charge to the intermediate storage and at least a second position connecting the primary storage to a passive antenna element to provide stored power to the passive antenna element while in an active mode.

7. The trickle-charged RFID device of claim 6, wherein the control unit is further configured to perform actions comprising:

determine if the first plurality of wireless interrogator signals received includes a tag inquiry for the RFID device to enter an active mode;

if yes, then switch the main switch from a first position connecting the intermediate storage to the first power harvester to a second position connecting the main storage to the passive antenna element while the passive antenna element is in the active mode, and then switch the main switch back to the first position to allow trickle flows of obtained power to charge the intermediate storage; and

if no, then maintain the main circuit in the first position.

8. The trickle-charged RFID device of claim 7, further comprising a second main antenna connected to a second power harvester, the second power harvester connected to the intermediate storage via a third circuit, the second power harvester being configured to obtain power from each of a plurality of unmodulated wireless signals received at the RFID device.

9. The trickle-charged RFID device of claim 8, further comprising a third main antenna connected to a third power harvester, the third power harvester connected to the intermediate storage via a fourth circuit, the third power harvester being configured to obtain power from each of a second plurality of modulated, interrogator wireless signals received at the RFID device.

10. The trickle-charged RFID device of claim 1, further comprising:

a second main antenna element configured to receive a second plurality of wireless interrogator signals; and

a second power harvester electrically connected with the second main antenna element and configured to obtain power from each of the second plurality of wireless interrogator signals, wherein the intermediate storage device is electrically connected to the second power harvester via a second circuit and configured to collect a plurality of second trickle flows of obtained power from the second power harvester, the second circuit being configured to divert the plurality of second trickle flows to the intermediate storage.

11. The trickle-charged RFID device of claim 1, wherein the plurality of switches are configured to permit a periodic flow of trickle charges into the intermediate storage device while preventing the intermediate storage device from discharging into the primary storage device until the predetermined discharge level of the collected store has been met in the intermediate storage device.

12. The trickle-charged RFID device of claim 11, wherein the first switch is disposed between the first power harvester and the intermediate storage device, and the second switch that is disposed between the intermediate storage device and the primary storage device.

13. A method for extending a useful life of a main power storage device of a RFID device, the method comprising:

receiving a wireless interrogator signal from a RFID reader;

determining if the wireless interrogator signal includes a tag inquiry for the RFID device requiring it to enter an active mode in response to the wireless interrogator signal;

if the wireless interrogator signal includes the tag inquiry, perform steps comprising;

switching a main switch from a first position connecting an intermediate storage device to a power harvester, to a second position connecting the main storage device for providing stored power out of the main storage device for use while in the active mode;

decoding the received tag inquiry;

backscattering data from the received tag inquiry; and

switching the main switch back to the first position including disconnecting the main storage device from the main circuit and connecting the intermediate storage device to the power harvester; and

providing a plurality of trickle charges obtained from a portion of a first plurality of interrogator signals received that lack a tag inquiry to the intermediate storage device to trickle charge the intermediate storage device; and

if the wireless interrogator signal lacks the tag inquiry, perform steps comprising;

obtaining power from the wireless interrogator signal;

close a first switch, upon receipt of the wireless interrogator signal lacking a tag inquiry, in order to direct the obtained power to the intermediate storage device until a predetermined discharge level of the collected store has been met in the intermediate storage device, thereby diverting a plurality of trickle flows of the obtained power to the intermediate storage;

collecting the plurality of trickle flows; and

close a second switch when the predetermined discharge level of the collected store has been reached in order to transfer the power from the intermediate storage device to the primary storage device, thereby draining the collected plurality of trickle flows from the intermediate storage to the main storage device when the collected store reaches the predetermined discharge level.

14. The method of claim 13, further comprising:

monitoring a charge level of the intermediate storage device; and

if the charge level of the intermediate storage device reaches a predetermined threshold discharge level, discharging stored power in the intermediate storage device to the main storage device to recharge the main storage device.

15. The method of claim 14, further comprising:

receiving a second plurality of interrogator wireless signals; and

providing a plurality of trickle charges obtained from the second plurality of interrogator wireless signals to the intermediate storage device to trickle charge the intermediate storage device.

16. The method of claim 15, wherein:

the second plurality of interrogator wireless signals includes a first type of wireless signals and a second type of wireless signals;

the intermediate storage includes a first type intermediate storage, a second type intermediate storage and an overall intermediate storage;

receiving the second plurality of interrogator wireless signals includes receiving the first type of wireless signals and the second type of wireless signals; and

providing the plurality of trickle charges from the second plurality of interrogator wireless signals to the intermediate storage includes providing the trickle charges from the first type of wireless signals to the first type intermediate storage and providing the trickle charges from the second type of wireless signals to the second type intermediate storage.

17. The method of claim 16, further comprising:

monitoring a first type charge level of the first type intermediate storage device;

monitoring a second type charge level of the second type intermediate storage device;

if the charge level of the first type intermediate storage device reaches a first type predetermined threshold discharge level, discharging stored power in the first type intermediate storage device to the overall intermediate storage device; and

if the charge level of the second type intermediate storage device reaches a second type predetermined threshold discharge level, discharging stored power in the second type intermediate storage device to the overall intermediate storage device.

18. The method of claim 17, further comprising:

monitoring an overall charge level of the overall intermediate storage device;

if the charge level of the overall intermediate storage device reaches an overall predetermined threshold discharge level, discharging stored power in the overall intermediate storage device to the main storage device to recharge the main storage device.

19. The method of claim 18, wherein monitoring an overall charge level includes dynamically adjusting charge/discharge parameters.

20. A method for extending a useful life of a RFID device comprising a power harvester, a primary energy storage device and an intermediate storage device, the method comprising:

receiving a wireless interrogator signal from a RFID reader into the power harvester, a portion of the wireless interrogator signal lacking a tag inquiry for the RFID device;

connecting the power harvester to the intermediate storage device;

closing a first switch, when the wireless interrogator signal lacks a tag inquiry, in order to direct one or more trickle charges obtained from one or more interrogator signals received at the power harvester to trickle charge the intermediate storage device until a predetermined discharge level has been met in the intermediate storage device, and when the intermediate storage device reaches a predetermined charge level, close a second switch in order to transfer power of the one or more trickle charges from the intermediate storage device to the primary energy storage device.

21. The method of claim 20, further comprising:

determining if the received wireless interrogator signal includes a tag inquiry for the RFID device requiring it to enter an active mode in response to the wireless interrogator signal;

if yes, perform steps comprising;

switching a main switch from a first position connecting the intermediate storage device to the power harvester, to a second position connecting the primary energy storage device for providing stored power out of the primary energy storage device for use while in the active mode;

decoding the received tag inquiry;

backscattering data from the received tag inquiry; and

switching the main switch back to the first position including disconnecting the primary energy storage device from the main circuit and connecting the intermediate storage device to the power harvester.

22. The method of claim 20, further comprising:

receiving a second plurality of interrogator wireless signals; and

providing a plurality of trickle charges obtained from the second plurality of interrogator wireless signals to the intermediate storage device to trickle charge the intermediate storage device.