Activation and indication of an RF field on a device including a chip
A device includes a main antenna suitable for capturing and transmitting an RF signal, at least one chip containing information and configured to transmit the information via the main antenna in response to an excitation of an external RF signal, and a mechanism for activating and deactivating the main antenna. The device further includes a detection circuit for detecting the presence of the external RF signal, and an indicator circuit, which is connected to the detection circuit so as to indicate the presence.
1. A device comprising:
a main antenna suitable for capturing and transmitting a radio frequency signal called RF signal,
at least one chip containing information and configured for transmitting this information via the main antenna in response to an excitation of an external RF signal, and
a mechanism for activating and deactivating the main antenna by selectively connecting and disconnecting an interrupted link between the main antenna and the at least one chip;
a detection circuit for detecting the presence of the external RF signal, and
an indicator circuit, connected to the detection circuit, so as to indicate said presence,
the activation and deactivation mechanism and the detection circuit are arranged so that the activation and deactivation mechanism only activates the main antenna on the double condition that the indicator circuit receives an activation instruction from a user and that the detection circuit reports the presence of the external RF signal to the indicator circuit.
2. The device according to claim 1 , wherein the detection circuit and the indicator circuit are connected to said main antenna.
3. The device according to claim 1 , wherein the detection circuit and the indicator circuit are connected to a secondary antenna independent of the main antenna.
4. The device according to claim 1 , wherein the detection circuit and the indicator circuit are powered by a cell whether flexible or not, rechargeable or not.
5. The device according to claim 1 , wherein the activation and deactivation mechanism is a mono-stable mechanism for which the stable state corresponds to a deactivation state of the main antenna, and the unstable state corresponds to the momentary activation of the main antenna in response to an instruction.
6. The device according to claim 1 , further including a clock system enabling a period of time to be defined for which the activation and deactivation mechanism maintains the main antenna into the activated state.
7. The device according to claim 1 , wherein the activation and deactivation mechanism includes a push button which activates the main antenna when the button is depressed.
8. The device according to claim 1 , wherein the activation and deactivation mechanism includes: a piezoelectric sensor which activates the main antenna when this piezoelectric sensor receives a predetermined wave, a temperature sensor, a light sensor, a movement sensor or a pressure sensor.
9. The device according to claim 1 , wherein the activation and deactivation mechanism includes a human-machine interface such as a keyboard enabling a pin code to be keyed so as to activate or deactivate the main antenna after processing the pin code.
10. The device according to claim 1 , wherein the activation and deactivation mechanism includes a human-machine interface such as an integrated biometric sensor enabling biometric data to be detected so as to activate or deactivate the main antenna after processing the biometric data.
11. The device according to claim 1 , wherein the activation and deactivation mechanism includes an on/off type bistable switch which activates or deactivates the main antenna depending on the switch position.
12. The device according to claim 1 , wherein the activation and deactivation mechanism includes a switch associated with an electronic component, the switch-electronic component assembly modifying the impedance of the main antenna so as to tune or detune the main antenna depending on the switch position.
13. The device according to claim 12 , wherein the electronic component includes at least one capacitor, at least one resistor or at least one inductor.
14. The device according to claim 1 , wherein the indicator circuit includes audio and/or visual indicators.
15. The device according to claim 1 , wherein the device includes a state displaying system, such as LEDs, to indicate the state wherein the device is when activated, this state being:
an RF transmission active state for a predetermined period of time,
a dialogue state with an RF reader, and
a non-dialogue state with the RF reader.
16. The device according to claim 1 , wherein the information comprises a random or dynamic RF signature.
17. The device according to claim 1 , wherein the device is under the format of a chip card, USB key or electronic tag.