RFID transceiver sensitivity focusing system

• US 20080185540A1
• Filed: 02/06/2007
• Published: 08/07/2008
• Est. Priority Date: 02/06/2007
• Status: Active Grant

• Current Assignee: InCom Corporation
• Original Assignee: InCom Corporation
• Inventors: Turner, Florrie, Ahlers, Douglas
• Granted Patent: US 7,812,779 B2
• Time in Patent Office: Days
• US Class Current: 250/515.1
• CPC Class Codes: G01D 21/00 Measuring or testing not otherwise provided for
• CPC Class Codes: G06K 7/10079 the collision being resolved in the spatial domain, e.g. temporary shields for blindfolding the interrogator in specific directions

Abstract

Shielding of a particular material and geometry is interposed between a radio frequency identification (“RFID”) antenna transceiver and a zone to be monitored by the antenna. The shielding has an aperture therein that to some extent defines a degree of focusing of the radio frequency (“RF”) field associated with the antenna. RFID tags having appropriate RFID circuitry are only detected by the antenna when they pass within the focused RF field. The shielding is formed of a thin metalized plastic material, such as film used in forming anti-static material for storage of sensitive electronics. One particular formulation is primarily polyethylene film with an aluminum coating or layer thereon.

Claims

1. A system for focusing sensitivity of an RFID transceiver, the system comprising in combination:

an RFID transceiver antenna;

said RFID transceiver antenna adapted to be located proximate to but spaced from a monitoring zone;

said RFID transceiver antenna adapted to establish an RF field within the monitoring zone;

shielding interposed between said antenna and the monitoring zone;

an aperture formed in said shielding; and

said shielding formed at least partially of thin plastic anti-static film.

2. The system of claim 1 wherein said plastic film includes polyethylene.

3. The system of claim 2 wherein said plastic film includes a majority polyethylene.

4. The system of claim 3 wherein said plastic film includes aluminum therein.

5. The system of claim 4 wherein said plastic film includes between ten percent and thirty-five percent polyethylene terephthalate.

6. The system of claim 5 wherein said plastic film includes less than one percent aluminum.

7. The system of claim 6 wherein said plastic film is a laminate structure including a polyethylene layer and a polyethylene terephthalate layer and with an adhesive bonding said polyethylene layer to said polyethylene terephthalate layer.

8. The system of claim 1 wherein said thin plastic anti-static film is metalized plastic film.

9. The system of claim 8 wherein said metalized plastic film includes a majority polyethylene.

10. The system of claim 8 wherein said metalized plastic film includes polyethylene terephthalate.

11. The system of claim 8 wherein said metalized plastic film includes less than one percent metal.

12. The system of claim 1 wherein said shielding is located within an enclosure along with said antenna.

13. The system of claim 12 wherein said shielding is oriented substantially in a plane, with said plane substantially perpendicular to a line extending from said antenna to a center of said monitoring zone.

14. The system of claim 1 wherein said antenna includes a body with a lower surface oriented in a substantially horizontal plane, both said body of said antenna and said shielding oriented to overlie said monitoring zone.

15. The system of claim 14 wherein said shielding is located in a substantially horizontal plane.

16. The system of claim 14 wherein said shielding includes at least two separate sheets oriented parallel with each other and spaced from each other by a distance at least as great as a width of said aperture, said separate sheets oriented non-horizontally.

17. The system of claim 16 wherein said shielding includes four separate sheets with each of said sheets oriented within a separate vertical plane and with each of said four sheets surrounding a border of said aperture, and with each of said sheets located adjacent two other sheets.

18. A method for enhancing the reliability of an RFID tag presence monitoring system, the method including the steps of:

positioning an RFID transceiver antenna proximate to, but spaced from a zone to be monitored;

configuring the RFID transceiver to establish an electromagnetic field at the zone; and

locating shielding between the antenna and the zone, the shielding having an aperture therein.

19. The method of claim 18 including the further step of forming the shielding at least partially of thin anti-static film.

20. The method of claim 19 wherein said anti-static film is greater than fifty percent plastic.

21. The method of claim 20 wherein said anti-static film is greater than fifty percent polyethylene.

22. The method of claim 20 wherein said anti-static film is a laminate including at least two layers with one of said layers being a polyethylene layer and with the other of said at least two layers being a polyethylene terephthalate layer.

23. The method of claim 22 wherein said anti-static film includes aluminum therein.

24. The method of claim 19 wherein said anti-static film is formed at least partially of metalized plastic.

25. The method of claim 24 wherein said forming step includes the step of forming the anti-static film to be less than ten percent aluminum, greater than fifty percent polyethylene, and between five percent and fifty percent polyethylene terephthalate.

26. The method of claim 25 wherein said forming step includes the step of forming the anti-static film to be less than one percent aluminum, greater than fifty percent polyethylene and between ten percent and thirty-five percent polyethylene terephthalate.

27. The method of claim 18 including the further step of orienting the shielding to be substantially perpendicular to a line extending from the antenna to a center of the zone to be monitored.

28. The method of claim 27 including the further step of placing the aperture along the line extending from the antenna to the center of the zone to be monitored.

29. An RFID transceiver antenna featuring a focused RF field pattern, comprising in combination:

an antenna body;

shielding proximate to but spaced from said body;

an aperture in said shielding; and

said shielding formed at least partially of anti-static film.

30. The antenna of claim 29 wherein said shielding is formed of thin metalized plastic.

31. The antenna of claim 30 wherein said film is greater than fifty percent polyethylene.

32. The antenna of claim 30 wherein said film includes polyethylene terephthalate.

33. The antenna of claim 32 wherein said film includes both polyethylene and polyethylene terephthalate, with more polyethylene than polyethylene terephthalate.

34. The antenna of claim 33 wherein said film includes aluminum therein.

35. The antenna of claim 33 wherein said film is a laminate including at least two layers with a first layer formed primarily of polyethylene and a second layer formed primarily of polyethylene terephthalate.

36. An attendance monitoring method, including the steps of:

identifying at least one door into a room where attendance is to be tracked;

having attendees wear an RFID badge including an RFID circuit therein;

placing an RFID transceiver antenna adjacent the door and inside the room;

configuring the RFID transceiver antenna to generate an electromagnetic field within a monitoring zone inside the door;

interposing shielding between the antenna and the monitoring zone, the shielding having an aperture therein;

detecting the presence of particular attendees by sensing the particular RFID badges of particular attendees as they enter the room through the door; and

substantially avoiding sensing of RFID badges located outside of the door.

37. The method of claim 36 wherein said interposing shielding step includes the step of forming the shielding to be formed at least partially of anti-static film.

38. The method of claim 37 wherein said anti-static film includes metalized plastic.

39. The method of claim 37 wherein said anti-static film includes both polyethylene and polyethylene terephthalate.