Device for transmitting signals via induction between a transponder circuit and an interrogation circuit
An inductive signal transmission device including a transponder circuit ( 1 ) having at least one first coil, and an interrogation circuit ( 3 ) having at least one second coil ( 4 ). The transponder circuit is placed on an object ( 5 ) capable of rotating about at least one rotational axis ( 9 ) passing through the object. The interrogation circuit is placed on a structure, which can be stationary, to which the object is connected. A coupling coil ( 2 ), provided with at least one turn describing a ring, is mounted on the structure or the object coaxially to the rotational axis of the object. This coupling coil acts as the inductive coupling interface between the first coil and the second coil such that the inductive signal transmission is independent of the rotation of the object. The transponder circuit is of the passive type and includes at least one sensor for measuring a physical parameter. The device can be used in the automobile industry by placing the transponder circuit ( 1 ) and the coupling coil ( 2 ) on the wheel of a vehicle ( 5 ) and the interrogation circuit ( 3 ) on the chassis or body of the vehicle.
1. A device for transmitting inductive signals, the device including a transponder circuit having at least one first coil, said transponder circuit being placed on an object, which is a vehicle wheel, capable of rotating about at least one rotational central axis passing through the object, and an interrogation circuit having at least one second coil, said interrogation circuit being placed on a structure to which the object is connected, said structure being a part of the body or chassis of said vehicle, wherein an annular coupling coil, provided with at least one closed loop turn, is mounted on a tire of the vehicle wheel coaxially to the rotational vehicle wheel axis of the vehicle wheel, said annular coupling coil acting as an inductive coupling interface between the first coil and the second coil in order to have a transmission of signals independent of the rotation of the vehicle wheel.
2. The device according to claim 1 , wherein the dimension of the annular coupling coil is greater than the dimension of the first coil of the transponder circuit, and wherein the first coil seen in the axial direction from the annular coupling coil is inside the loop of the annular coupling coil.
3. The device according to claim 1 , wherein the plane or axis of the turns of the first coil is arranged parallel to the plane or axis of the turns of the second coil, and to the plane and axis of the turn of the annular coupling coil.
4. The device according to claim 1 , wherein the transponder of the transponder circuit is passive, and wherein the interrogation circuit transmits inductive signals at a determined resonance frequency such that the transponder circuit extracts the energy necessary to operate from the received inductive signals.
5. The device according to claim 4 , wherein data is transmitted by the inductive signals by amplitude modulation from the interrogation circuit to the transponder circuit, and from the transponder circuit to the interrogation circuit, low frequency inductive signals transmitted between the two circuits having an identical carrier frequency.
6. The device according to claim 1 , wherein the transponder circuit includes at least one sensor for measuring a physical parameter, and wherein the transponder circuit transmits inductive signals for data relating to the measurements carried out by said sensor.
7. The device according to claim 6 , wherein the transponder circuit includes a pressure measurement sensor and/or a temperature measurement sensor.
8. The device according to claim 6 , wherein the transponder circuit includes a logic part connected to at least one measurement sensor and to a resonant unit, which includes, mounted in parallel, the first coil, a capacitor and a resistive load in series with a switch, and wherein the logic part controls the switch so as to modulate the amplitude of the inductive signals to be transmitted as a function of the measurements carried out by the sensor or sensors.
9. A device for transmitting inductive signals, the device including a transponder circuit having at least one first coil, said transponder circuit being placed on an object capable of rotating about at least one rotational axis passing through the object, and an interrogation circuit having at least one second coil, said interrogation circuit being placed on a structure to which the object is connected, wherein a coupling coil, provided with at least one closed loop turn, is mounted on the structure or on the object coaxially to the rotational axis of the object, said coupling coil acting as an inductive coupling interface between the first coil and the second coil,
wherein the transponder circuit includes at least one sensor for measuring a physical parameter,
wherein the transponder circuit transmits inductive signals for data relating to the measurements carried out by said sensor,
wherein the transponder circuit includes a logic part connected to at least one measurement sensor and to a resonant unit, which includes, mounted in parallel, the first coil, a capacitor and a resistive load in series with a switch,
wherein the logic part controls the switch so as to modulate the amplitude of the inductive signals to be transmitted as a function of the measurements carried out by the sensor or sensors, and
wherein the logic part and the sensor or sensors are made in the same semi-conductor substrate.