Systems and methods for reading large populations of RFID tags
View Patent ↗Systems and methods are provided for better reading large populations of RFID tags. Such systems include an RFID reader and a plurality of RFID tags, each having an antenna and an associated RFID chip. Each chip includes an auto-tune circuit and is programmed to confirm the occurrence of a preselected condition. Upon such confirmation, the RFID chip modifies the functionality of the auto-tune circuit to reduce the effects of proximity coupling within the population. The preselected condition may be the tag being read by the RFID reader or the elapse of a preselected amount of time since a power-on-reset of the chip or some other event. The modification to the functionality of the auto-tune circuit may be the disabling of the auto-tune circuit or the changing of the impedance value of the chip or a decrease in the power supplied to the chip or some other modification.
1. An RFID tag comprising:
an antenna; and
an RFID chip having an internal flag such that the chip is electrically connected to the antenna, wherein the RFID chip includes an auto-tune circuit, to operate the RFID chip in a decreased power state such that the auto-tune is used to recover adequate power to the RFID chip;
and the flag is programmed to confirm the occurrence of a preselected condition and, upon confirming the occurrence of said preselected condition, modify the functionality of the auto-tune circuit.
2. The RFID tag of claim 1 , wherein said preselected condition is the RFID tag being read by an RFID reader.
3. The RFID tag of claim 2 , wherein the internal flag is programmed to move from a first state to a second state when the RFID tag has been read by the RFID reader.
4. The RFID tag of claim 1 , wherein
the preselected condition is the elapse of a preselected amount of time since a power-on-reset of the RFID chip, and
the RFID chip includes a timer programmed to determine the time elapsed since a power-on-reset of the RFID chip.
5. The RFID tag of claim 1 , wherein the RFID chip is programmed to disable the auto-tune circuit upon confirming the occurrence of the preselected condition.
6. The RFID tag of claim 1 , wherein the RFID chip is programmed to set the auto-tune circuit to a maximum value upon confirming the occurrence of the preselected condition.
7. The RFID tag of claim 1 , wherein the RFID chip is programmed to set the auto-tune circuit to a minimum value upon confirming the occurrence of the preselected condition.
8. The RFID tag of claim 1 , wherein the RFID chip is programmed to set the auto-tune circuit to a randomly chosen value upon confirming the occurrence of the preselected condition.
9. The RFID tag of claim 1 , wherein the RFID chip is programmed to cause the auto-tune circuit to supply the RFID chip with a decreased amount of power upon confirming the occurrence of the preselected condition.
10. The RFID tag of claim 9 , wherein the decreased amount of power comprises the minimum amount of power required to allow the RFID chip to operate.
11. An RFID-based method of reading a plurality of RFID tags, comprising:
providing a plurality of RFID tags each including an RFID chip having an internal flag and each chip comprising an auto-tune circuit, the auto-tune circuit operates the RFID chip in a decreased power state such that the auto-tune is used to recover adequate power to the RFID chip;
confirming the occurrence of a preselected condition for one of the RFID tags by the flag; and
upon confirming the occurrence of the preselected condition, the flag modifies the functionality of the auto-tune circuit of said one of the RFID tags.
12. The method of claim 11 , wherein said preselected condition is said one of the RFID tags being read by an RFID reader.
13. The method of claim 12 , wherein said confirming the occurrence of a preselected condition includes moving the internal flag of said one of the RFID tags from a first state to a second state when said one of the RFID tags has been read by the RFID reader.
14. The method of claim 11 , wherein the preselected condition is the elapse of a preselected amount of time since a power-on-reset of the RFID chip of said one of the RFID tags.
15. The method of claim 11 , wherein said modifying the functionality of the auto-tune circuit includes disabling the auto-tune circuit of said one of the RFID tags.
16. The method of claim 11 , wherein said modifying the functionality of the auto-tune circuit includes setting the auto-tune circuit of said one of the RFID tags to a maximum value.
17. The method of claim 11 , wherein said modifying the functionality of the auto-tune circuit includes setting the auto-tune circuit of said one of the RFID tags to a minimum value.
18. The method of claim 11 , wherein said modifying the functionality of the auto-tune circuit includes setting the auto-tune circuit of said one of the RFID tags to a randomly chosen value.
19. The method of claim 11 , wherein said modifying the functionality of the auto-tune circuit includes causing the auto-tune circuit of said one of the RFID tags to supply the RFID chip of said one of the RFID tags with a decreased amount of power.
20. The method of claim 19 , wherein the decreased amount of power comprises the minimum amount of power required to allow the RFID chip of said one of the RFID tags to operate.