Radio frequency identification tag

• US 5,914,862 A
• Filed: 09/05/1997
• Issued: 06/22/1999
• Est. Priority Date: 05/19/1995
• Status: Expired due to Term

• Current Assignee: IPC Unipost SC
• Original Assignee: Kasten Chase Applied Research Limited
• Inventors: Paun, Mircea, Ferguson, Donald Harold
• Primary Examiner(s): Feild, Lynn D.
• Assistant Examiner(s): Vu, Phuong T.
• Application Number:
  US08/926,321
• Time in Patent Office: 655 Days
• Field of Search: 361/749, 361/782, 361/783, 361/814, 361/737, 343/895, 343/702, 343/700 MS, 235/491, 235/492, 235/487, 340/572, 340/825.54, 340/825.3
• US Class Current: 361/737
• CPC Class Codes: G06K 19/04 characterised by the shape
• CPC Class Codes: G06K 19/0702 the arrangement including a battery
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• 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 19/07758 arrangements for adhering the record carrier to further objects or living beings, functioning as an identification tag
• CPC Class Codes: G06K 19/07779 the inductive antenna being a coil
• CPC Class Codes: G06K 19/07781 the coil being fabricated in a winding process
• CPC Class Codes: G06K 19/07783 the coil being planar
• CPC Class Codes: G08G 1/017 identifying vehicles G08G1/015, G08G1/054 take precedence
• CPC Class Codes: H05K 1/16 incorporating printed electric components, e.g. printed resistor, capacitor, inductor
• CPC Class Codes: H05K 1/165 incorporating printed inductors
• CPC Class Codes: Y10T 29/435 Solid dielectric type
• CPC Class Codes: Y10T 29/49018 with other electrical component
• CPC Class Codes: Y10T 29/4902 Electromagnet, transformer or inductor
• CPC Class Codes: Y10T 29/49146 with encapsulating, e.g., potting, etc.

Abstract

A radio frequency identification tag with printed antenna coil integrated on a flexible substrate, and an integrated circuit area of the substrate adjacent the antenna coil for carrying circuit elements. The radio frequency identification tag is designed to be sufficiently robust to withstand the rigors of mail efficiency processing measurement applications.

Claims

1. A printed circuit adapted for RF identification and processing through sorting apparatus, the printed circuit comprising:

a) a single thin layer of flexible circuit board fabricated from epoxy glass laminate and having a cutout window in a first area;

b) an imbedded antenna coil printed on at least one side of the first area of said flexible circuit board around a perimeter of the cutout window;

c) an integrated circuit mounted on top of a second area of said flexible circuit board substrate laterally adjacent said imbedded antenna coil for carrying circuit elements;

d) electrical connection means extending laterally between the first area and the second area to connect electrically said antenna coil and said integrated circuit;

e) a layer of semi-rigid material encapsulating only said integrated circuit in the second area having a limited degree of flexibility which is less than a degree of flexibility of the substrate; and

f) a membrane laid over said layer of semi-rigid material, said flexible circuit board substrate with imbedded antenna coil and said electrical connection means, providing a slip surface over said circuit elements.

2. The printed circuit of claim 1, wherein said antenna coil comprises a first winding printed on one side of said substrate, and a second winding printed on an opposite side of said substrate, said first and second windings being connected together at one end through said substrate and to said electrical connection means at respective opposite ends thereof.

3. The printed circuit of claim 2 wherein said first and second windings are offset from each other to reduce parasitic capacitance therebetween.

4. The printed circuit of claim 1, wherein said electrical connection means comprises a plurality of electrically conducting traces deposited on said substrate.

5. The printed circuit of claim 1, further comprising gold plating applied to said antenna coil for increasing conductivity thereof.

6. The printed circuit of claim 1, further comprising a resistive coating deposited on said membrane for reducing electrostatic charge build-up and decreasing surface charge and discharge currents thereon.

7. The printed circuit board of claim 1, wherein said layer of semi-rigid material comprises UV adhesive.

8. The printed circuit board of claim 7, wherein the UV adhesive provides a limited degree of flexibility to prevent cracking and fracturing of the adhesive under stresses administered by automated postal equipment.

9. The printed circuit board of claim 1, wherein said integrated circuit area houses a plurality of electrical and electronic components in one portion thereof connected to a battery in another portion thereof.

10. The printed circuit board of claim 1, wherein the total weight of the printed circuit board does not exceed approximately 6.0 g.

11. The printed circuit board of claim 1, wherein the substrate has a core thickness of approximately 8 mils.

12. The printed circuit of claim 1, wherein a battery to power said printed circuit is provided adjacent said integrated circuit, said battery being connected to said imbedded antenna coil and said integrated circuit.

13. A printed lightweight circuit comprising:

a) a single body portion comprising a single rectangular thin layer of flexible circuit board having a cutout window in a first area of said circuit board;

b) an imbedded antenna coil embedded on the first area of said flexible circuit board comprising a first winding printed on one side of said circuit board and a second winding printed on an opposite side of said circuit board, said windings being offset from each other to reduce parasitic capacitance there between, wherein said antenna coil is printed around the perimeter of said hole in said substrate and first area of the circuit board;

c) an integrated circuit mounted on top of a second area of said flexible circuit board adjacent said imbedded antenna coil for carrying circuit elements;

d) electrical connection means between said antenna coil and said integrated circuit area, said electrical connection means comprising a plurality of electrically conducting traces deposited on said circuit board;

e) a layer of semi-rigid material encapsulating only said integrated circuit in the second area having a limited degree of flexibility which is less than a degree of flexibility of the circuit board;

f) a membrane laid over said layer of semi-rigid material, said flexible circuit board with imbedded antenna coil and said electrical connection means, for providing a slip surface on said circuit elements; and

g) a resistive coating deposited on said membrane for reducing electrostatic charge build-up and decreasing surface charge and discharge currents thereon.

14. A printed circuit adapted for radio frequency identification and arranged to be sufficiently durable and resilient for processing through sorting apparatus comprising rollers and belts, the printed circuit comprising:

a) single thin layer of flexible circuit board;

b) an imbedded antenna coil printed on at least one side of a first area of said flexible circuit board;

c) an integrated circuit mounted on top of a second area of said flexible circuit board and adjacent said imbedded antenna coil for carrying circuit elements;

d) electrical connection means between said antenna coil and said integrated circuit area; and

e) a layer of semi-rigid material encapsulating only said integrated circuit in the second area having a limited degree of flexibility which is less than a degree of flexibility of the circuit board; and

f) a polyester film membrane laid over said layer of semi-rigid material, said flexible circuit board with imbedded antenna coil and said electrical connection means, for providing a slip surface over said circuit elements.

15. The printed circuit of claim 14 in which the circuit board is fabricated from epoxy glass laminate and the semirigid material is formed of UV adhesive encapsulation material.

16. The printed circuit of claim 14 in which the first area of the flexible circuit board includes a cutout window in a central portion thereof and the embedded antenna coil is printed around a perimeter of the window.

17. A printed lightweight circuit adapted for radio frequency identification and arranged to be sufficiently durable and resilient for processing through sorting apparatus comprising rollers and belts, the printed circuit comprising:

a) a single rectangular thin layer of flexible circuit board having a cutout window in a first area of said circuit board;

b) an imbedded antenna coil embedded on a first area of said flexible circuit board comprising a first winding printed on one side of said circuit board and a second winding printed on an opposite side of said circuit board, said windings being offset from each other to reduce parasitic capacitance there between, wherein said antenna coil is printed around the perimeter of said cutout window;

c) an integrated circuit mounted on top of a second area of said flexible circuit board and adjacent said imbedded antenna coil for carrying circuit elements;

d) electrical connection means between said antenna coil and said integrated circuit area, said electrical connection means comprising a plurality of electrically conducting traces deposited on said substrate; and

e) a layer of semi-rigid material encapsulating only said integrated circuit in the second area having a limited degree of flexibility which is less than said degree of flexibility of the substrate; and

f) a membrane laid over said layer of semi-rigid material, said flexible circuit board with imbedded antenna coil and said electrical connection means, for providing a slip surface over said circuit elements.

18. The printed lightweight circuit of claim 17 additionally comprising

a resistive coating deposited on said membrane for reducing electrostatic charge build-up and decreasing surface charge and discharge currents thereon.

19. The printed circuit of claim 17 which the antenna has a gold plating applied thereto for increasing the conductivity thereof.

20. The printed circuit of claim 17 in which the circuit board is fabricated from epoxy glass laminates, the semirigid material is formed of UV adhesive encapsulation material;

and the membrane is formed by a thin polyester film material.