Photosensitive multi-resonator chipless RFID

• US 9,640,855 B1
• Filed: 12/22/2015
• Issued: 05/02/2017
• Est. Priority Date: 12/22/2015
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Gibson, George A., Larson, James R.
• Primary Examiner(s): Frech, Karl D
• Application Number:
  US14/979,354
• Time in Patent Office: 497 Days
• Field of Search: 235379, 235380, 235382, 235491
• CPC Class Codes: G06K 19/0672 with resonating marks
• CPC Class Codes: G06K 19/07743 External electrical contacts
• 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 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 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 21/28 Combinations of substantially independent non-interacting antenna units or systems multiple beam H01Q25/00

Abstract

A chipless RFID transponder is disclosed. The transponder comprises an antenna and a plurality of resonant structures that together define a spectral signature of the RFID transponder. Each of the resonant structures comprises conductive portions separated by interstitial regions. A photo-polymerizable filler is disposed in the interstitial regions of the resonant structures between the conductive portions. The photo-polymerizable filler is positioned so as to shift the spectral signature of the RFID when exposed to radiation.

Claims

1. A chipless RFID transponder, comprising:

an antenna and a plurality of resonant structures that together define a spectral signature of the RFID transponder, each of the resonant structures comprising conductive portions separated by interstitial regions; and

a photo-polymerizable filler disposed in the interstitial regions of the resonant structures between the conductive portions, the photo-polymerizable filler positioned so as to shift the spectral signature of the RFID transponder when exposed to radiation.

2. The chipless RFID transponder of claim 1, wherein the conductive portions of each resonant structure are formed from a continuous segment of electrically conductive material that is coplanar with the interstitial regions.

3. The chipless RFID transponder of claim 1, wherein the photo-polymerizable filler has a property of having a first conductivity prior to being exposed to radiation at a specified wavelength and a second conductivity that is lower than the first conductivity after being exposed to radiation at the specified wavelength.

4. The chipless RFID transponder of claim 3, wherein the photo-polymerizable filler is an electrical conductor prior to being exposed to radiation at the specified wavelength.

5. The chipless RFID transponder of claim 3, wherein the change in value of the second conductivity relative to the first conductivity is substantially linearly dependent on the intensity of the light to which the photo-polymerizable filler is exposed.

6. The chipless RFID transponder of claim 3, wherein the value of the second conductivity is substantially the same as the first conductivity unless the photo-polymerizable filler is exposed to radiation having a threshold intensity.

7. The chipless RFID transponder of claim 3, wherein the photo-polymerizable filler comprises a polymeric binder, an ethylenically unsaturated monomer, a 2-o-substituted hexaarylbiimidazole photopolymerization initiator, and a chain transfer agent.

8. The chipless RFID transponder of claim 3, wherein the photo-polymerizable filler comprises aliphatic Isocyanates.

9. The chipless RFID transponder of claim 1, wherein the photo-polymerizable filler has a property of exhibiting a permanent change in conductivity when exposed to radiation at a specified threshold wavelength.

10. The chipless RFID transponder of claim 1, further comprising at least one of an optical filter or a converter disposed over the plurality of resonant structures.

11. The chipless RFID transponder of claim 1, wherein the photo-polymerizable filler is disposed in a plurality of the resonant structures.

12. The chipless RFID transponder of claim 1, further comprising an adhesive backing on which the RFID transponder is disposed.

13. The chipless RFID transponder of claim 1, further comprising a security overlayer.

14. A method of tracking inventory, comprising:

placing a chipless RFID transponder on an article, the RFID transponder comprising,

an antenna and a plurality of resonant structures that together define a spectral signature of the RFID transponder, each of the resonant structures comprising conductive portions separated by interstitial regions; and

a photo-polymerizable filler disposed in the interstitial regions of the resonant structures between the conductive portions, the photo-polymerizable filler positioned so as to shift the spectral signature of the RFID transponder when exposed to radiation.

15. The method of claim 14, further comprising detecting a spectral response of the RFID transponder.

16. The method of claim 15, further comprising determining if the RFID transponder has been exposed to radiation based on the detected spectral response.

17. The method of claim 15, wherein the detecting comprises administering at least one interrogating pulse emitted by an interrogator, the at least one interrogating pulse comprising a spectral range.

18. The method of claim 15, wherein each of the plurality of resonant structures comprise a continuous segment of electrically connected material.