RFID tags having improved read range

• US 7,375,639 B2
• Filed: 03/27/2006
• Issued: 05/20/2008
• Est. Priority Date: 03/29/2005
• Status: Expired due to Fees

• Current Assignee: Emerson & Cuming Microwave Products, Inc. (DuPont de Nemours, Inc.)
• Original Assignee: Emerson & Cuming Microwave Products, Inc. (DuPont de Nemours, Inc.)
• Inventors: Osward, Mary M., Carpenter, Michael P., Gibbs, David A., Dixon, Paul F.
• Primary Examiner(s): MULLEN, THOMAS J
• Application Number:
  US11/390,032
• Publication Number:
  US 20060220867A1
• Time in Patent Office: 785 Days
• Field of Search: 340/572.1, 340/572.8, 428/615, 428/620, 428/621, 235/492
• US Class Current: 340/572.8
• CPC Class Codes: G06K 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
• CPC Class Codes: G06K 19/07771 the record carrier comprising means for minimising adverse effects on the data communication capability of the record carrier, e.g. minimising Eddy currents induced in a proximate metal or otherwise electromagnetically interfering object
• CPC Class Codes: Y10T 428/12493 Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]

Abstract

The present invention provides a system and method for optimizing the performance of 13.56 MHz frequency RFID tags in conjunction with metal substrates. Briefly, a thickness exists for each type of RFID isolator material at which the performance of a 13.56 MHz RFID tag is optimal when used with metal. Varying from this optimal value, in either the positive or negative direction adversely affects read distance. A method of determining this optimal thickness is disclosed, as well as an RFID tag or a substrate being used in conjunction with a material of this thickness.

Claims

1. An identification system, adapted to transmit identifying information about an article via radio frequency, comprising:

an RFID tag, adapted to transmit said identifying information via radio frequency when energized;

said RFID tag and said article defining a space therebetween, and

said space comprising a layer having a thickness of less than 0.1 inches and wherein said layer comprises ferromagnetic material having a permeability less than 10.

2. The system of claim 1, wherein said identification system utilizes radio frequency at 13.56 MHz.

3. The system of claim 1, wherein said layer comprises ferromagnetic material having a permeability greater than 1.

4. The system of claim 3, wherein said material is selected from the group consisting of Nickel/Zinc Ferrite, Manganese/Zinc Ferrite, Carbonyl Iron, Carbonyl Iron+Magnetite, Iron Silicide and Iron/Nickel Alloy.

5. The system of claim 3, wherein the optimal thickness of said layer of said ferromagnetic material, in mils, is equal to 240 divided by the permeability of said material.

6. The system of claim 1, wherein said article comprises a cavity, and said layer and RFID tag are embedded in said cavity.

7. The system of claim 1, wherein said article comprises metal.

8. The system of claim 1, wherein said article comprises liquid.

9. The system of claim 1, wherein said space comprises a metal sheet.

10. The system of claim 1, wherein said space comprises a layer of organic material.

11. An identification system, adapted to transmit identifying information about an article via radio frequency, comprising:

an RFID tag, adapted to transmit said identifying information via radio frequency when energized;

said RFID tag and said article defining a space therebetween, and

said space comprising a layer comprising ferromagnetic material having a permeability greater than 1 and less than 10 and a thickness, wherein said thickness, in mils, multiplied by said permeability is between about 170 and 450.

12. The system of claim 11, wherein said ferromagnetic material is selected from the group consisting of Nickel/Zinc Ferrite, Manganese/Zinc Ferrite, Carbonyl Iron, Carbonyl Iron+Magnetite, Iron Silicide and Iron/Nickel Alloy.

13. The system of claim 11, wherein said article comprises a cavity, and said layer and RFID tag are embedded in said cavity.

14. The system of claim 11, wherein said identification system utilizes radio frequency at 13.56 MHz.

15. The system of claim 11, wherein said article comprises metal.

16. The system of claim 11, wherein said article comprises liquid.

17. The system of claim 11, wherein said space comprises a metal sheet.

18. The system of claim 11, wherein said space comprises a layer of organic material.

19. An identification system, adapted to transmit identifying information about an article via radio frequency, comprising:

a substrate comprising an antenna and a silicon chip mounted thereon, adapted to transmit said identifying information via radio frequency when energized;

said substrate and said article defining a space therebetween, and

said space comprising a layer having a thickness of less than 0.1 inches and wherein said layer comprises ferromagnetic material having a permeability less than 10.

20. The system of claim 19, wherein said identification system utilizes radio frequency at 13.56 MHz.

21. The system of claim 19, wherein said layer comprises ferromagnetic material having a permeability greater than 1.

22. The system of claim 21, wherein said material is selected from the group consisting of Nickel/Zinc Ferrite, Manganese/Zinc Ferrite, Carbonyl Iron, Carbonyl Iron+Magnetite, Iron Silicide and Iron/Nickel Alloy.

23. The system of claim 21, wherein the optimal thickness of said layer of said ferromagnetic material, in mils, is equal to 240 divided by the permeability of said material.

24. The system of claim 19, wherein said article comprises a cavity, and said layer and substrate are embedded in said cavity.

25. The system of claim 19, wherein said article comprises metal.

26. The system of claim 19, wherein said article comprises liquid.

27. The system of claim 19, wherein said space comprises a metal sheet.

28. The system of claim 19, wherein said space comprises a layer of organic material.

29. An identification system, adapted to transmit identifying information about an article via radio frequency, comprising:

a substrate comprising an antenna and a silicon chip mounted thereon, adapted to transmit said identifying information via radio frequency when energized;

said substrate and said article defining a space therebetween, and

said space comprising

a layer comprising ferromagnetic material having a permeability greater than 1 and less than 10 and a thickness, wherein said thickness, in mils,

multiplied by said permeability is between about 170 and 450.

30. The system of claim 29, wherein said identification system utilizes radio frequency at 13.56 MHz.

31. The system of claim 29, wherein said ferromagnetic material is selected from the group consisting of Nickel/Zinc Ferrite, Manganese/Zinc Ferrite, Carbonyl Iron, Carbonyl Iron+Magnetite, Iron Silicide and Iron/Nickel Alloy.

32. The system of claim 29, wherein said article comprises a cavity, and said layer and substrate are embedded in said cavity.

33. The system of claim 29, wherein said article comprises metal.

34. The system of claim 29, wherein said article comprises liquid.

35. The system of claim 29, wherein said space comprises a metal sheet.

36. The system of claim 29, wherein said space comprises a layer of organic material.