NFC card for handheld device

• US 8,811,894 B2
• Filed: 09/14/2011
• Issued: 08/19/2014
• Est. Priority Date: 09/21/2010
• Status: Active Grant

• Current Assignee: Verimatrix Incorporated (Verimatrix SA)
• Original Assignee: Inside Secure SA
• Inventors: CORDIER, Nicolas
• Primary Examiner(s): Wendell, Andrew
• Assistant Examiner(s): Soltanzadeh, Maryam
• Application Number:
  US13/232,346
• Publication Number:
  US 20120071088A1
• Time in Patent Office: 1,070 Days
• Field of Search: 455/41.1, 455/41.2
• US Class Current: 455/41.1
• CPC Class Codes: G06K 19/07769 the further communication means being a galvanic interface, e.g. hybrid or mixed smart cards having a contact and a non-contact interface
• CPC Class Codes: G06K 19/07771 the record carrier comprising means for minimising adverse effects on the data communication capability of the record carrier, e.g. minimising Eddy currents induced in a proximate metal or otherwise electromagnetically interfering object

Abstract

An NFC card includes an antenna circuit including an antenna coil having at least one magnetic axis, and at least one integrated circuit linked to the antenna circuit. The magnetic axis of the antenna coil is substantially parallel to at least one side of the card, and the card further includes at least one electrically conductive screen extending near the antenna coil, which does not cross the magnetic axis. The card does not include any magnetically permeable material between the at least one conductive screen and the antenna coil. Embodiments of the invention are applicable in particular to SIM-NFC card and SD-NFC cards.

Claims

1. An NFC card comprising:

an antenna circuit comprising an antenna coil having at least one magnetic axis,

at least one integrated circuit linked to the antenna circuit, and

at least one electrically conductive screen extending near the antenna coil, which does not cross the magnetic axis

wherein the magnetic axis of the antenna coil is substantially parallel to at least one side of the card, and the card does not include any magnetically permeable material between the at least one conductive screen and the antenna coil.

2. The NFC card according to claim 1, wherein the antenna circuit has a tuning frequency which has been set in the presence of the at least one electrically conductive screen, and does not detune when a metallic element is placed near the electrically conductive screen.

3. The NFC card according to claim 1, further comprising contact pads arranged on a first side of the card.

4. The NFC card according to claim 3, wherein the conductive screen extends on or near the first side of the card.

5. The NFC card according to claim 3, wherein the conductive screen extends on or near a second side of the card.

6. The NFC card according to claim 1, wherein the at least one electrically conductive screen comprises a first conductive screen extending on one side of the antenna coil without crossing its magnetic axis, and a second conductive screen extending on another side of the antenna coil without crossing its magnetic axis.

7. The NFC card according to claim 1, wherein the antenna coil is wound around a magnetically permeable core.

8. The NFC card according to claim 1, in which the integrated circuit is configured to implement an active load modulation method comprising emitting bursts of magnetic field by way of the antenna coil when data are to be sent, in order to compensate the negative effect of the at least one screen on the maximum communication distance offered by the card for the sending of data by load modulation.

9. The NFC card according to claim 1, wherein the antenna coil comprises at least two coils in series, the coils having non-parallel magnetic axes, to enhance the sensing of a counter magnetic field generated by eddy currents when the card is arranged near a printed circuit board in the presence of an external magnetic field.

10. The NFC card according to claim 1, wherein the at least one conductive screen comprises at least one slot to reduce the effect of eddy currents circulating in the conductive screen in the presence of an external magnetic field.

11. The NFC card according to claim 1, wherein the at least one conductive screen is split into at least two sub-screens to reduce the effect of eddy currents circulating in the conductive screen in the presence of an external magnetic field.

12. A method for tuning an antenna coil of an NFC card, the method comprising:

providing a card according to claim 1, and

setting a tuning frequency of the antenna circuit in the presence of the at least one electrically conductive screen.

13. A method for performing a contactless communication between an NFC card and an NFC external device (ED), the method comprising:

providing an NFC card comprising;

an antenna circuit comprising an antenna coil having at least one magnetic axis,

at least one integrated circuit linked to the antenna circuit, and

at least one electrically conductive screen extending near the antenna coil, which does not cross the magnetic axis,

wherein the magnetic axis of the antenna coil is substantially parallel to at least one side of the card, and the card does not include any magnetically permeable material between the at least one conductive screen and the antenna coil,

setting a tuning frequency of the antenna circuit of the card in the presence of the at least one electrically conductive screen,

emitting a first oscillating magnetic field with the external device,

placing the card near the edges of a printed circuit board, and

using the conductive screen to protect the tuning frequency of the antenna circuit against the detuning effect of the printed circuit board, to increase the maximum communication distance between the card and the external device.

14. The method according to claim 13, further comprising sensing, with the antenna coil of the NFC card, a counter magnetic field generated by eddy currents in the printed circuit board, to increase the maximum communication distance between the card and the external device.

15. The method according to claim 13, further comprising emitting bursts of a second oscillating magnetic field (FLD2) with the antenna coil of the NFC card, while the external device (ED) emits the first oscillating magnetic field (FLD1), to transfer data (DTx)from the card to the external device.