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Linear Motion Read Range Test System for BiStatix® Tags on a High-Speed Printing Web Disclosure Number: IPCOM000005573D
Original Publication Date: 2001-Oct-16
Included in the Prior Art Database: 2001-Oct-16
Document File: 5 page(s) / 420K

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James G. Quaderer: AUTHOR


Linear Motion Read Range Test System for BiStatix® Tags on a High-Speed Printing Web

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Linear Motion Read Range Test System for BiStatix® Tags on a High-Speed Printing Web

By James G. Quaderer

                    Conventional RFID cards inductively couple to readers via embedded resonant copper coils within the tags.  BiStatix® systems, on the other hand, capacitively couple to readers via capacitive coupling to achieve similar performance.  BiStatix®  card antennas are composed of extremely low cost conductive ink as opposed to expensive and bulky copper coils.


Figure 1


Figure 1 shows the construction of a typical BiStatix® tag 1.  The interposer 103 contains an RFID integrated circuit which couples to antenna electrodes 101 and 102.  BiStatix® electrodes 101 and 102 are usually composed of conductive ink.

Printed materials, including BiStatix®cards, are commonly manufactured on long continuous strips of paper called webs.  It is common for webs to move at speeds above 200 feet per minute in modern printing facilities.  Completed BiStatix® cards on the web must be tested at rates of 200 feet per minute to maintain efficient printing operations.  Conventional methods of testing inductive cards, which would require that the web be indexed (started and stopped for each individual card) over an RF test head, would be cumbersome and far less economical than a continuously moving-web test process.

                    Stationary linear electrode arrays require an insignificant amount maintenance.  Present read range methods require that either singulated cards be moved toward a stationary reader for a read range measurement or a reader be moved toward a stationary card under test for the same measurement.  This requires additional mechanical means that are prone to breakdown and/or maintenance.  In the case of BiStatix®, the amplitude of the electric field coupling is not varied by moving either the card or the reader but by keeping the distance between card and reader constant and moving the card past reader electrodes of varying amplitude until the card is successfully read.

When many cards are in close proximity on a web, it is possible to direct communications from each card to a specific readers to enable high-speed testing.  When many small, stationary electrodes are used to couple to only one card, the electrode design need not be changed whenever the card is redesigned – simply the number of electrodes associated with that card design may need to be changed.  When the card moves across a linear array of small electrodes, some of the electrodes in the array may be switched in and out to couple to that specific card.  When many cards are placed in close proximity on a high-speed web, multiple groups of small electrodes may be switched in and out to couple to a plurality of cards simultaneously.  The clock rate of the linear electrode array switches may be strobed by a switch or an opto-sensor which senses the cards as they move on the web so that as the speed of the web changes unexpectedly, the linear electrode switch rate may synchronized automatically.

Figure 2


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