Shield for radio frequency ID tag or contactless smart card

• US 20080055093A1
• Filed: 08/30/2007
• Published: 03/06/2008
• Est. Priority Date: 08/30/2006
• Status: Active Grant

• Current Assignee: Exponent Incorporated
• Original Assignee: Exponent Incorporated
• Inventors: McGoran, Brad Alexander, Du, Yanqing, Shkolnikov, Yakov Pytor
• Granted Patent: US 7,936,274 B2
• Time in Patent Office: Days
• US Class Current: 340/572.8
• CPC Class Codes: G06K 19/07327 Passive means, e.g. Faraday cages Faraday-type protection of electric circuits in general H05K9/00
• CPC Class Codes: G06K 19/07345 by activating or deactivating at least a part of the circuit on the record carrier, e.g. ON/OFF switches
• CPC Class Codes: H04K 2203/20 for contactless carriers, e.g. RFID carriers record carriers with integrated circuit chips including means for preventing undesired reading or writing from or to record carriers by hindering electromagnetic reading or writing G06K19/07318; arrangements for sensing record carriers including arrangements for protecting the interrogation against piracy attacks G06K7/10257
• CPC Class Codes: H04K 3/86 related to preventing deceptive jamming or unauthorized interrogation or access, e.g. WLAN access or RFID reading record carriers with integrated circuit chips including means for preventing undesired reading or writing from or to record carriers by hindering electromagnetic reading or writing G06K19/07318; arrangements for sensing record carriers including arrangements for protecting the interrogation against piracy attacks G06K7/10257

Abstract

We have found that to effectively shield inductively coupled RFID systems, the shield does not have to be present on all the sides of the device. It is also not required that one side be covered completely. In fact, a shield of any shape that allows a current to flow in a closed loop may be enough to shield the RFID. The only requirement is that the back electromagnetic field (EMF) from the shield induces sufficient flux to cancel all or part of the magnetic flux coming from the reader. It is possible for the shield to work even if the induced flux is small: the shift in the self-inductance of the RFID or contactless card coil due to the presence of the material in the shield can be enough to cause a shift in a resonant frequency of the circuit and thus in the power delivered to the chip. The current invention is a shield that does not completely cover a smartcard or RFID tag and/or has a hole or void within the shield. The advantage of this invention is that it will allow optical and mechanical access to the surface and the body of the smartcard or RFID tag and/or to parts of the smartcard/RFID coil. It also leads to significant cost savings since less shielding material is used.

Claims

1. A means for shielding at least one contactless smartcard or RFID tag from communicating with a remote transceiver comprising a material that:

allows an electric current to flow in a closed loop, and can induce sufficient flux to cancel at least part of the magnetic flux from said remote transceiver, wherein said material has an opening, void or interruption and said material need not substantially surround said smartcard or RFID tag.

2. The means for shielding of claim one wherein said material is a planar or curved sheet that contains a conductive material.

3. The means for shielding of claim one wherein said material is shaped to allow visual access to the surface or the contents of said contactless smartcard or RFID tag.

4. The means for shielding of claim one wherein said material is shaped to allow tactile access to the surface or the contents of said contactless smartcard or RFID tag.

5. The means for shielding of claim one wherein said opening, void or interruption can be used to prevent said electric current from flowing in said closed loop.

6. The means for shielding of claim five wherein said opening, void or interruption can be opened or closed mechanically.

7. The means for shielding of claim five wherein said opening, void or interruption can be opened or closed optically.

8. The means for shielding of claim five wherein said opening, void or interruption can be opened or closed via electrical means.

9. The means for shielding of claim one wherein said opening, void or interruption is bridged by an electrical circuit that allows said current to flow from one portion of said material to another portion of said material or through the entire material with or without user intervention.

10. The means for shielding of claim one wherein said opening, void or interruption is bridged by an electrical circuit that with or without user intervention allows said current to flow in the shield.

11. The means for shielding of claim one, two, three, four, five, six, seven, eight, nine or ten wherein said smartcard or said RFID tag can be held in position and prevented from sliding into a position that reduces the effectiveness of the shielding means.

12. A means of optically controlling the readability of a contact or contactless smartcard or RFID tag whereby said smartcard is only readable when the optical control is activated.

13. A device for shielding at least one contactless smartcard or RFID tag from communication with a remote transceiver comprising:

a material that allows an electric current to flow in a closed loop and can induce sufficient flux to cancel at least part of the magnetic flux from said remote transceiver wherein said material has an opening, void or interruption and need not substantially surround said smartcard or RFID tag,

and means to physically position said material relative to said contactless smartcard or RFID tag such that said material can induce sufficient flux to cancel at least part of the magnetic flux from said remote transceiver.

14. The device of claim thirteen wherein said material is a planar or curved sheet that contains a conductive material.

15. The device of claim thirteen wherein said material is shaped to allow visual access to the surface or the contents of said contactless smartcard or RFID tag.

16. The device of claim thirteen wherein said material is shaped to allow tactile access to the surface or the contents of said contactless smartcard or RFID tag.

17. The device of claim thirteen wherein said opening, void or interruption can be used to prevent said electric current from flowing in said closed loop.

18. The device of claim seventeen wherein said opening, void or interruption can be opened or closed mechanically.

19. The device of claim seventeen wherein said opening, void or interruption can be opened or closed via electrical means.

20. The device of claim seventeen wherein said opening, void or interruption is bridged by an electrical circuit that allows said current to flow from one portion of said material to another portion of said material or through the entire said material with or without user intervention.

21. The device of claim seventeen wherein said opening, void or interruption is bridged by an electrical circuit that with or without user intervention allows said current to flow.

22. The device for shielding of claim thirteen wherein said smartcard or said RFID tag can be held in position and prevented from sliding into a position that reduces the effectiveness of the shielding device.

23. A device, with or without an associated shielding device, for optically controlling the readability of a contact or contactless smartcard or RFID tag whereby said smartcard is only readable when the optical control is activated.

24. The device of claim one or thirteen wherein the user intervention via mechanical motion or force moves, deflects, or deforms the shield away from the card to allow the smartcard to be read.