Apparatus and method for communicating with an RFID transponder
View Patent ↗A system having a UHF RFID transceiver is adapted to communicate exclusively with a single electro-magnetically coupled transponder located in a predetermined confined transponder operating region. The system includes a near field coupling device comprising a plurality of lines connected in parallel with an unmatched load. The near field coupling device may be formed, for example on a printed circuit board with a plurality of electrically interconnected traces and a ground plane. The system establishes, at predetermined transceiver power levels, a mutual electromagnetic coupling which is selective exclusively for a single transponder located in a defined transponder operating region. Also included are methods for selective communication with the transponder in an apparatus such as a printer-encoder.
1. A system for communicating with a transponder on a carrier substrate in a printer, the system comprising:
a feed path extending through the printer such that the printer is configured to receive the carrier substrate along the feed path;
a transceiver configured to be energized to communicate with the transponder; and
a controller in communication with the transceiver and configured to selectively energize the transceiver to a first power level to write data to the transponder within a write region and to a second power level to read data from the transponder within a read region, wherein the second power level is different from the first power level, wherein the read region is substantially the same as the write region, and wherein the first power level and the second power level are at least substantially independent of a signal's frequency produced when the transceiver is energized.
2. A system according to claim 1 , wherein the second power level is less than the first power level.
3. A system according to claim 2 , wherein the first power level is less than three times the second power level.
4. A system according to claim 1 , wherein the controller is configured to compare the data read from the transponder to the data written to the transponder and thereby determine a defective characteristic of the transponder.
5. A system according to claim 1 , wherein the controller is configured to energize the transponder to write to and read from a spatial region of substantially equal area.
6. A system according to claim 1 , further comprising a memory configured to store values characteristic of a plurality of read power levels and write power levels, each power level being associated with a characteristic of at least one of the transponder and the carrier substrate, and wherein the controller is configured to selectively energize the transceiver at one of the read and write power levels stored in the memory according to a characteristic of at least one of the transponder and the carrier substrate.
7. A system according to claim 1 , wherein said controller is configured to:
determine a plurality of read success rates and a plurality of write success rates for a plurality of power levels and for a plurality of distances between the transceiver and the transponder, and
select a select distance, the first power level, and the second power level,
wherein the first power level is associated with a relatively high write success rate at a first limited range of distances including the select distance and the second power level is associated with a relatively high read success rate at a second limited range of distances including the select distance.
8. A system according to claim 1 , wherein said controller is configured to selectively energize the transceiver to the first power level to write to the transponder independent of writing to other transponders on the carrier substrate and to selectively energize the transceiver to a second power level to read from the transponder independent of reading from other transponders on the carrier substrate.
9. A system according to claim 1 , wherein said controller is configured to selectively energize the transceiver to the first power level to write to the transponder before selectively energizing the transceiver to the second power level to read from the transponder.
10. A system according to claim 1 , wherein said controller is configured to selectively energize the transceiver to the first power level to write to the transponder after selectively energizing the transceiver to the second power level to read from the transponder.
11. A system according to claim 1 , wherein said controller is configured to selectively energize the transceiver to the first power level to write to the transponder independent of writing to other transponders on the carrier substrate and to the second power level to read from the transponder independent of reading from other transponders on the carrier substrate.
12. A system according to claim 1 , wherein said controller is configured to selectively energize the transceiver to the first power level to write to the transponder and to selectively energize the transceiver to a third power level to write to the transponder, wherein the third power level is different than the first power level.
13. A system according to claim 1 , wherein said controller is configured to selectively energize the transceiver to the second power level to read from the transponder and to selectively energize the transceiver to a third power level to read from the transponder, wherein the third power level is different than the first power level.