RFID devices for enabling reading of non-line-of-sight items
Radio-frequency identification (RFID) apparatus and methodology enable a plurality of or all of the RFID tags in a stack of items such as cartons and boxes—including items that do not have a line of sight to a reader—to be read. An RFID system includes RFID tags and a transmission line. The RFID tags are mountable to items to be read and include an RFID circuit that generates tag energy when activated by activation energy from a reader. The transmission line carries activation energy from the reader and tag energy from the tags. The transmission line is positionable in operative or coupling proximately to a plurality of the tags when the plurality of the tags are mounted to items and when the items are stacked. Accordingly, when carrying activation energy from the reader, the transmission line couples with and thereby enables activation of the plurality of the tags. Further, when the plurality of the tags are activated and generating tag energy, the transmission line couples with and carries the tag energy from the plurality of the tags. The transmission line can be configured as an elongated adhesive tape-like structure that can be adhered across a plurality of RFID tags mounted to a plurality of items. The transmission line can also be disposed on an inter-item reading device that can be positioned between adjacent rows of stacked items.
1. A radio-frequency identification (RFID) system for use with a reader that transmits activation energy to read a stack of items, the system comprising:
a plurality of RFID tags each being respectively mountable to one of the items and including an RFID circuit for generating tag energy when activated; and
a transmission line for carrying activation energy from the reader and tag energy from the tags;
the transmission line being positionable in coupling proximity to a plurality of the tags when the plurality of the tags are mounted to items and when the items are stacked, such that:
when carrying activation energy, the transmission line couples with and thereby enables activation of the plurality of the tags; and
when the plurality of the tags are activated, the transmission line couples with and carries tag energy from the plurality of the tags.
2. The system of claim 1 wherein the transmission line is elongated such that when the items are stacked and the tags are spatially separated from each other, the transmission line is positionable in coupling proximity with a plurality of the tags.
3. The system of claim 1 wherein the transmission line is disposed on a piece of sheet material.
4. The system of claim 3 wherein the piece of sheet material is flexible.
5. The system of claim 4 wherein the piece of sheet material includes an adhesive on a surface thereof.
6. The system of claim 3 wherein the piece of sheet material includes a substantially inflexible board.
7. The system of claim 1 further comprising a stack antenna operatively coupled with the transmission line for receiving activation energy transmitted by the reader and for radiating tag energy carried by the transmission line.
8. The system of claim 7 wherein the stack antenna and the transmission line are mounted on a piece of sheet material.
9. The system of claim 7 further comprising an amplifier operatively disposed with the stack antenna and the transmission line.
10. The system of claim 7 wherein:
the stack antenna includes a receive section for receiving activation energy from the reader and a radiate section for radiating tag energy from the tags; and
the transmission line includes an activation conductor operatively coupled with the receive section of the stack antenna for carrying activation energy and a tag conductor operatively coupled with the radiate section of the stack antenna for carrying tag energy.
11. The system of claim 10 further comprising a pair of amplifiers operatively and respectively disposed the sections of the stack antenna and the conductors of the transmission line.
12. The system of claim 1 wherein each of the tags includes a substrate on which the RFID circuit is disposed.
13. The system of claim 12 wherein the substrate of each of the tags includes an adhesive layer.
14. A method of reading radio-frequency identification (RFID)-enabled items, the method comprising:
providing a load of a plurality of RFID-tagged items stacked together, each of the RFID-tagged items including:
a item; and
a RFID tag mounted to the item and including an RFID circuit with an antenna and a chip for generating tag energy when activated; and
providing a transmission line that is configured to carry activation energy from the reader and tag energy from the tags;
positioning the transmission line in operative proximately to at least a number of the RFID tags, such that:
when carrying activation energy, the transmission line couples with and thereby enables activation of the plurality of the tags; and
when the plurality of the tags are activated, the transmission line couples with and carries tag energy from the plurality of the tags.
15. The method of claim 14 further comprising transmitting activation energy to the load.
16. The method of claim 14 wherein the transmission line is disposed on a piece of sheet material, and wherein positioning the transmission line comprises:
positioning the piece of sheet material adjacent to a stack of the RFID-tagged items in the load.
17. The method of claim 14 wherein the transmission line is disposed on an elongated adhesive substrate, and wherein positioning the transmission line comprises:
adhering the substrate to a plurality of the RFID tags.
18. A method of reading a plurality radio-frequency identification (RFID) tags that are spatially separated from each other and that generate tag energy when activated by activation energy from a reader, the method comprising:
receiving activation energy from the reader;
activating the tags by carrying the activation energy on a transmission line that is positioned in coupling proximity with the tags; and
carrying tag energy from the activated tags on the transmission line.
19. The method of claim 18 further comprising amplifying the activating energy received from the reader.
20. The method of claim 18 further comprising amplifying the tag energy carried on the transmission line.