ANTI-COUNTERFEITING LABEL FOR DETECTING CORK ALTERATIONS
A near field magnetically coupled contactless device, comprises a foldable substrate in the form of a tape; an antenna circuit tuned to a nominal frequency, including an antenna and a capacitor connected to the antenna; a sacrificial impedance connected to the antenna circuit to contribute to the tuning of the antenna circuit to the nominal frequency; and a sacrificial structure comprising a conductive track connecting the sacrificial impedance to the antenna circuit, configured in meanders occupying a region of interest of the substrate such that a piercing of the region of interest severs the conductive track.
1 . A contactless device comprising:
a foldable substrate in the form of a tape;
an antenna circuit tuned to a nominal frequency, including an antenna and a capacitor connected to the antenna;
a sacrificial impedance connected to the antenna circuit to contribute to the tuning of the antenna circuit to the nominal frequency; and
a sacrificial structure comprising a conductive track connecting the sacrificial impedance to the antenna circuit, configured in meanders occupying a region of interest of the substrate such that a piercing of the region of interest severs the conductive track.
2 . The device of claim 1 , wherein the sacrificial impedance is connected in parallel with the antenna.
3 . The device of claim 1 , wherein the antenna encircles the region of interest.
4 . The device of claim 1 , comprising a control microcircuit connected to be powered by the antenna circuit, and including information transmission functions and cryptographic functions; wherein the antenna circuit tuning parameters are selected so that a suppression of the sacrificial impedance lowers the supply power received by the microcircuit to a level insufficient for supplying the cryptographic functions, yet sufficient for supplying the transmission functions.
5 . The device of claim 1 , comprising a conductive track for connecting the sacrificial impedance to the antenna circuit, configured to cross areas of preferential rupture of the tape.
6 . A container comprising:
a cork; and
a contactless device according to claim 5 adhesively secured over the container and the cork so that the region of interest of the substrate is in correspondence with the cork.
7 . The container of claim 6 in the form of a bottle comprising a cap enveloping the cork, the neck of the bottle, and the tape, the cap including, in the vicinity of the cork, a material permeable to magnetic field.