RFID TAG WITH REDUCED DETUNING CHARACTERISTICS

• US 20080231458A1
• Filed: 03/21/2008
• Published: 09/25/2008
• Est. Priority Date: 03/23/2007
• Status: Active Grant

• Current Assignee: Zebra Technologies Corporation
• Original Assignee: ZIH Corp. (Zebra Technologies Corporation)
• Inventors: FEIN, MICHAEL
• Granted Patent: US 7,999,683 B2
• Time in Patent Office: Days
• US Class Current: 340/572.7
• 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: H01Q 1/2225 used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal
• CPC Class Codes: H01Q 9/0421 with a shorting wall or a shorting pin at one end of the element H01Q9/0414 takes precedence
• CPC Class Codes: H01Q 9/26 with folded element or elements, the folded parts being spaced apart a small fraction of operating wavelength resonant loop antennas H01Q7/00
• CPC Class Codes: H01Q 9/285 Planar dipole H01Q9/065 takes precedence; patch antenna H01Q9/0407

Abstract

An RFID tag and an RFID access card configured to reduce detuning effects from a typical RFID environment. The present invention provides an RFID tag that is specifically configured to reduce the detuning effects caused by initiating communication between an RFID tag and an RFID tag reader in the presence of materials such as metal, liquid, and the human body. In one embodiment, the present invention provides an RFID tag comprising an electronic circuit portion attached to a main antenna body portion, the main antenna body portion having two opposite side portions, which are substantially symmetrical with respect to one another, wherein each side portion extends outwardly to form a generally side-oriented v-shape.

Claims

1. An RFID tag for use in an RFID card, the RFID tag comprising:

an electronic circuit attached to a main antenna body, the main antenna body defining a center through which an imaginary pair of first and second perpendicular axes intersect and comprising two opposite side portions, wherein each side portion is substantially symmetrical with respect to itself about the second imaginary axis, and wherein each side portion extends outwardly from the first imaginary axis along the second imaginary axis to form a generally side-oriented v-shape, wherein the main antenna body further comprises an elongate first slot that extends from the center of the main antenna body, substantially along the second imaginary axis, and a second slot substantially perpendicular to and intersecting the first slot proximate the center of the main antenna body.

2. The RFID tag of claim 1, wherein the side portions are substantially symmetrical with respect to one another about the first imaginary axis, and wherein the upper and lower angled edges extend from the first imaginary axis at a substantially constant angle α

.

3. The RFID tag of claim 2, wherein the angle α

is in the range of about 10°

to about 85°

.

4. The RFID tag of claim 3, wherein the angle α

is in the range of about 40°

to about 85°

.

5. The RFID tag of claim 1, wherein the electronic circuit is attached proximate the intersection of the first and second slots.

6. The RFID tag of claim 1 wherein each side portion further defines upper and lower angled edges and upper and lower side edges, and wherein the upper and lower side edges are separated by a notch substantially located along the second imaginary axis, and wherein the notch has a side oriented v-shape defined by an upper notch edge and a lower notch edge, wherein the upper notch edge is substantially parallel to the upper angled edge and the lower notch edge is substantially parallel to the lower angled edge.

7. The RFID tag of claim 1, wherein the elongate first slot defines a slot half-length, and wherein the slot half-length is in the range of about 5 mm to about 25 mm.

8. The RFID tag of claim 7, wherein the slot half-length is in the range of about 15 mm to about 25 mm.

9. The RFID tag of claim 1, wherein the elongate first slot defines a slot height, and wherein the slot height is in the range of about 0.5 to about 5 mm.

10. The RFID tag of claim 9, wherein the slot height is approximately 1 mm.

11. The RFID tag of claim 1, wherein the RFID tag operates in the UHF range.

12. The RFID tag of claim 1, further including a back plate comprised of a metal material located on one side of the RFID tag and configured to shield the RFID tag.

13. An RFID access card, the RFID access card comprising:

a card substrate; and

an RFID tag attached to the card substrate, the RFID tag comprising an electronic circuit attached to a main antenna body, the main antenna body defining a center through which an imaginary pair of first and second perpendicular axes intersect and comprising two opposite side portions, wherein each side portion is substantially symmetrical with respect to itself about the second imaginary axis, and wherein each side portion extends outwardly from the first imaginary axis along the second imaginary axis to form a generally side-oriented v-shape, defined by upper and lower angled edges and upper and lower side edges, and wherein the main antenna body further comprises an elongate first slot that extends from the center of the main antenna body, substantially along the second imaginary axis, and a second slot substantially perpendicular to and intersecting the first slot proximate the center of the main antenna body.

14. The RFID access card of claim 13, wherein the side portions are substantially symmetrical with respect to one another about the first imaginary axis, and wherein the upper and lower angled edges extend from the first imaginary axis at a substantially constant angle α

.

15. The RFID access card of claim 14, wherein the angle α

is in the range of about 10°

to about 85°

.

16. The RFID access card of claim 15, wherein the angle α

is in the range of about 40°

to about 85°

.

17. The RFID access card of claim 13, wherein the electronic circuit is attached proximate the intersection of the first and second slots.

18. The RFID access card of claim 13, wherein the upper and lower side edges are separated by a notch substantially located along the second imaginary axis, the notch having a side oriented v-shape defined by an upper notch edge and a lower notch edge, wherein the upper notch edge is substantially parallel to the upper angled edge and the lower notch edge is substantially parallel to the lower angled edge.

19. The RFID access card of claim 13, wherein the elongate first slot defines a slot half-length, and wherein the slot half-length is in the range of about 5 mm to about 30 mm.

20. The RFID access card of claim 19, wherein the slot half-length is in the range of about 15 mm to about 25 mm.

21. The RFID access card of claim 13, wherein the elongate first slot defines a slot height, and wherein the slot height is in the range of about 0.5 to about 5 mm.

22. The RFID access card of claim 21, wherein the slot height is approximately 1 mm.

23. The RFID access card of claim 13, wherein the RFID tag operates in the UHF range.

24. The RFID access card of claim 13, further including a back plate located on one side of the RFID tag and configured to shield the RFID tag.

25. An RFID tag for use in an RFID card, the RFID tag comprising:

an electronic circuit attached to a main antenna body, the main antenna body defining a center through which an imaginary pair of first and second perpendicular axes intersect and comprising two opposite side portions, wherein each side portion is substantially symmetrical with respect to itself about the first imaginary axis, and wherein each side portion extends outwardly from the center along the second imaginary axis to form a shape having a relatively large surface area, and wherein the main antenna body further comprises an elongate first slot that extends from the center of the main antenna body, substantially along the second imaginary axis, and a second slot substantially perpendicular to and intersecting the first slot proximate the center of the main antenna body.

26. The RFID tag of claim 25, further including a back plate comprised of a metal material located on one side of the RFID tag and configured to shield the RFID tag.

27. The RFID tag of claim 26, further including a dielectric layer between the back plate and the main antenna body, wherein a thickness of the dielectric layer is in the range of about 0.5 mm to about 3 mm and a dielectric constant of the dielectric layer is in the range of about 1 to about 10.

28. The RFID tag of claim 25, wherein each side portion of the main antenna body extends outwardly from the first imaginary axis along the second imaginary axis to form a generally side-oriented v-shape, wherein the opposite side portions further comprise convex upper edges, each defining respective vertex points.