Frequency selective surface aids to the operation of RFID products

• US 20080150691A1
• Filed: 12/20/2006
• Published: 06/26/2008
• Est. Priority Date: 12/20/2006
• Status: Active Grant

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Duron, Mark, Knadle, Richard T.
• Granted Patent: US 7,884,718 B2
• Time in Patent Office: Days
• US Class Current: 340/10.1
• CPC Class Codes: G06K 17/0029 the arrangement being specially adapted for wireless interrogation of grouped or bundled articles tagged with wireless record carriers
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10346 the antenna being of the far field type, e.g. HF types or dipoles
• CPC Class Codes: G06K 7/10435 the interrogation device being positioned close to a conveyor belt or the like on which moving record carriers are passing conveying in accordance with bodily destination marks, see B65G47/46, sorting of objects carrying identity markings, see B07C5/34
• CPC Class Codes: H01Q 1/2208 associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems methods or arrangements for sensing record carriers, e.g. for reading patterns G06K7/00; record carrier for use with machines and with at least a part designed to carry digital markings G06K19/00
• CPC Class Codes: H01Q 15/0013 said selective devices working as frequency-selective reflecting surfaces, e.g. FSS, dichroic plates, surfaces being partly transmissive and reflective

Abstract

The present invention is directed to systems that use frequency selective surfaces (FSS) to aid in the operation of radio frequency identification (RFID) devices and products. In one embodiment, a system for interrogating radio frequency identification (RFID) tags includes a conveyor belt and an RFID reader. The conveyor belt has a first surface and a second surface. The first surface is configured to receive an item to which an RFID tag is affixed and the second surface is configured to slide on a metal slide plate. The RFID reader is configured to transmit instructions embodied in a radio frequency (RF) signal to the RFID tag, wherein the metal slide plate is positioned between the RFID reader and the RFID tag and comprises a frequency selective surface that is substantially transparent to the RF signal.

Claims

1. A system for interrogating radio frequency identification (RFID) tags, comprising:

a conveyor belt having a first surface and a second surface, wherein the first surface is configured to receive an item to which an RFID tag is affixed and the second surface is configured to slide on a metal slide plate; and

an RFID reader configured to transmit instructions embodied in a radio frequency (RF) signal to the RFID tag;

wherein the metal slide plate is positioned between the RFID reader and the RFID tag and comprises a frequency selective surface that is substantially transparent to the RF signal.

2. The system of claim 1, wherein a structure of the frequency selective surface comprises at least one of a dipole, a tripole, an end-loaded tripole, a cross pattern, a square spiral, and a loop.

15. The system of claim 11, wherein a structure of the at least one frequency selective surface comprises at least one of a dipole, a tripole, an end-loaded tripole, a cross pattern, a square spiral, and a loop.

3. A system for interrogating radio frequency identification (RFID) tags, comprising:

an RFID reader configured to transmit instructions embodied in a radio frequency (RF) signal to at least one RFID tag; and

a metal container in which the at least one RFID tag is disposed, the metal container comprising at least one frequency selective surface configurable to cause at least a portion of the metal container to be substantially transparent to the RF signal.

4. The system of claim 3, wherein the metal container comprises a first frequency selective surface and a second frequency selective surface, such that the at least a portion of the metal container is substantially transparent to the RF signal when the first frequency selective surface is in a first position relative to the second frequency selective surface.

5. The system of claim 4, wherein the at least a portion of the metal container is substantially non-transparent to the RF signal when the first frequency selective surface is in a second position relative to the second frequency selective surface.

6. The system of claim 5, further comprising:

a key configured to lock and unlock the first frequency selective surface in the second position relative to the second frequency selective surface.

7. The system of claim 6, wherein the key comprises one of a mechanical key, a hydraulic key, or an electronic key.

8. The system of claim 6, wherein the metal container comprises a shipping container.

9. The system of claim 3, wherein a structure of the at least one frequency selective surface comprises at least one of a dipole, a tripole, an end-loaded tripole, a cross pattern, a square spiral, and a loop.

10. The system of claim 3, wherein the metal container comprises one of a bailer and a shopping cart.

11. A system for interrogating a radio frequency identification (RFID) tag, comprising:

an RFID reader configured to transmit instructions embodied in a radio frequency (RF) signal to the RFID tag; and

at least one frequency selective surface configured to increase a power flux density of the RF signal enroute to the RFID tag.

12. The system of claim 11, wherein the at least one frequency selective surface is also configured to at least one of focus or re-direct the RF signal enroute to the RFID tag.

13. The system of claim 11, wherein the at least one frequency selective surface is also configured to de-focus the RF signal enroute to the RFID tag.

14. The system of claim 11, wherein the at least one frequency selective surface is also configured to modify a polarization of the RF signal enroute to the RFID tag.

16. A system for interrogating radio frequency identification (RFID) tags, comprising:

an RFID reader configured to transmit instructions embodied in a radio frequency (RF) signal to at least one RFID tag; and

a metal radome that houses the RFID reader and that comprises at least one frequency selective surface configured to cause at least a portion of the metal radome to be substantially transparent to the RF signal.

17. The system of claim 16, wherein a structure of the at least one frequency selective surface comprises at least one of a dipole, a tripole, an end-loaded tripole, a cross pattern, a square spiral, and a loop.

18. A system for interrogating radio frequency identification (RFID) tags, comprising:

an RFID reader configured to transmit instructions embodied in a radio frequency (RF) signal to at least one RFID tag; and

a metal radome that houses the RFID reader and that comprises at least one frequency selective surface configured to controllably affect the RF signal.

19. The system of claim 18, wherein the at least one frequency selective surface is configured to at least one of focus or deflect the RF signal.

20. The system of claim 18, wherein the at least one frequency selective surface is configured to at least one of de-focus or deflect the RF signal.

21. The system of claim 18, wherein a structure of the at least one frequency selective surface comprises at least one of a dipole, a tripole, an end-loaded tripole, a cross pattern, a square spiral, and a loop.

22. A method for interrogating radio frequency identification (RFID) tags, comprising:

transmitting a radio frequency (RF) signal configured to be received by an RFID tag; and

interacting the RF signal with a frequency selective surface (FSS) enroute to the RFID tag;

wherein the interacted RF signal is received by the RFID tag.

23. The method of claim 22, wherein interacting the RF signal with a FSS enroute to the RFID tag comprises:

transmitting the RF signal through the FSS, wherein the FSS is substantially transparent to the RF signal.

24. The method of claim 22, wherein interacting the RF signal with a FSS enroute to the RFID tag comprises:

focusing the RF signal with the FSS enroute to the RFID tag.

25. The method of claim 22, wherein interacting the RF signal with a FSS enroute to the RFID tag comprises:

re-directing the RF signal with the FSS enroute to the RFID tag.

26. The method of claim 22, wherein interacting the RF signal with a FSS enroute to the RFID tag comprises:

modifying a polarization of the RF signal with the FSS enroute to the RFID tag.

27. A system for interrogating radio frequency identification (RFID) tags, comprising:

means for transmitting a radio frequency (RF) signal configured to be received by an RFID tag; and

means for interacting the RF signal with a frequency selective surface (FSS) enroute to the RFID tag;

wherein the interacted RF signal is received by the RFID tag.

28. A system for interrogating radio frequency identification (RFID) tags, comprising:

an RFID reader comprising a plurality of antennas that each transmit a circularly polarized radio frequency (RF) signal configured to be received by an RFID tag; and

a plurality of frequency selective surfaces (FSS) that each convert a corresponding one of the circularly polarized RF signals into a substantially linearly polarized RF signal enroute to the RFID tag;

wherein the RFID tag receives the substantially linearly polarized RF signals, and wherein a first linearly polarized RF signal is linearly polarized along a first axis and a second linearly polarized RF signal is linearly polarized along a second axis perpendicular to the first axis.

29. A method for interrogating radio frequency identification (RFID) tags, comprising:

transmitting a first circularly polarized radio frequency (RF) signal and a second circularly polarized RF signal that are each configured to be received by an RFID tag; and

converting the first and second circularly polarized RF signals into corresponding first and second linearly polarized RF signals enroute to the RFID tag using corresponding first and second frequency selective surface (FSS) lenses;

wherein the first and second linearly polarized RF signals are received at the RFID tag, and wherein the first linearly polarized RF signal is linearly polarized along a first axis and the second linearly polarized RF signal is linearly polarized along a second axis that is perpendicular to the first axis.

30. The method of claim 29, wherein the first RF signal and the second RF signal are polarized in the same sense.

31. The method of claim 29, wherein the first RF signal is circularly polarized in a first sense and the second RF signal is circularly polarized in a second sense.