Apparatus and method for communicating with an rfid transponder

Abstract

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 electro-magnetic 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.

That which is claimed: 
     
         1 . An apparatus comprising:
 a media conveyance configured to transport a series of discrete media through a transponder operating region, at least some of the media including a transponder; and   a near field coupler configured to generate a near field effect having an ultra-high frequency (UHF) to couple with the transponder for data transfer.   
     
     
         2 . The apparatus of  claim 1 , wherein the near field effect includes one or more frequencies between about 902 MHz and 928 MHz. 
     
     
         3 . The apparatus of  claim 1 , wherein:
 the near field coupler includes a plurality of lines electrically interconnected in parallel, and a spaced away ground plane; and   the near field coupler is formed as traces on a printed circuit board.   
     
     
         4 . The apparatus of  claim 3 , wherein at least one of the plurality of lines has a zig-zag configuration. 
     
     
         5 . The apparatus of  claim 1 , wherein the near field coupler has a characteristic impedance and the near field coupler is terminated by a terminating resistor having a different characteristic impedance. 
     
     
         6 . The apparatus of  claim 1 , wherein the transponder is a UHF radio frequency identification (RFID) transponder. 
     
     
         7 . The apparatus of  claim 1 , wherein the near field coupler is configured to operate as a one half wavelength unmatched transmission line. 
     
     
         8 . The apparatus of  claim 1 , wherein the media conveyance is further configured to feed a web of spaced transponders through the transponder operating region, and wherein the near field coupler is configured to communicate with a transponder located in the transponder operating region but not concurrently communicate with another transponder located outside of the transponder operating region. 
     
     
         9 . The apparatus of  claim 1 , wherein the media conveyance is configured to move the media forward, in response to at least losing communication with the transponder, to restore communication with the transponder while the transponder is in the transponder operating region. 
     
     
         10 . The apparatus of  claim 1 , wherein the near field coupler is configured such that the plurality of lines and the ground plane are disposed on opposite sides of a printed circuit board. 
     
     
         11 . A method comprising:
 transporting, via a media conveyance, a series of discrete media through a transponder operating region, at least some of the media including a transponder; and   generating a near field effect having an ultra-high frequency (UHF) via a near field coupler to couple with the transponder for data transfer.   
     
     
         12 . The method of  claim 11 , wherein generating the near field effect having an ultra-high frequency (UHF) via the near field coupler includes generating the near field effect having one or more frequencies between about 902 MHz and 928 MHz. 
     
     
         13 . The method of  claim 11 , wherein:
 the near field coupler includes a plurality of lines electrically interconnected in parallel, and a spaced away ground plane; and   the near field coupler is formed as traces on a printed circuit board.   
     
     
         14 . The method of  claim 11 , wherein the near field coupler has a characteristic impedance and is terminated by a terminating resistor having a different characteristic impedance. 
     
     
         15 . The method of  claim 11 , wherein the near field coupler includes a plurality of lines and at least one of the plurality of lines has a zig-zag configuration. 
     
     
         16 . The method of  claim 11 , wherein the transponder is a UHF radio frequency identification (RFID) transponder. 
     
     
         17 . The method of  claim 11 , wherein the near field coupler is configured to operate as a one half wavelength unmatched transmission line. 
     
     
         18 . The method of  claim 11 , wherein:
 transporting the series of discrete media through the transponder operating region includes feeding a web of spaced transponders through the transponder operating region, and   generating the near field effect includes generating the near field effect to communicate with the transponder while the transponder is located in the transponder operating region and not concurrently communicate with another transponder located outside of the transponder operating region.   
     
     
         19 . The method of  claim 11 , wherein transporting the series of discrete media through the transponder operating region includes moving the series of discrete media forward, in response to at least losing communication with the transponder, to restore communication with the transponder while the transponder is in the transponder operating region. 
     
     
         20 . The method of  claim 11 , wherein the near field coupler includes a plurality of lines and a ground plane configured such that the plurality of lines and the ground plane are disposed on opposite sides of a printed circuit board.