Touch and approach detection with capacitative sensors

A sensor device for detection of an approach of an object in a observation area supervised by the sensor device, comprising:

• a server circuit with an LC-oscillating circuit with a signal transducer circuit operable to generate an electric field;
• a first electrode device coupled with the LC-oscillating circuit, wherein a capacitance of the first electrode device is a component of an oscillator circuit capacitance and wherein the electric field generated by the LC-oscillating circuit via the first electrode device is adapted to be radiated into the observation area;
• and an evaluating device;
• wherein the approach of an object in the observation area of the first electrode device causes a change of the capacitive environment of the first electrode device, which is detectable by the evaluating device,
• further comprising at least one client circuit with a second electrode device, comprising at least one first electrode and at least one second electrode;
• and a modulation device coupled with the second electrode device;
• wherein the electric field radiated by the first electrode device of the server circuit is couplable at the first electrode of the second electrode device, the coupled electric field being modulatable via the modulation device wherein the modulated signal is fed back to the server circuit via the first electrode device of the server circuit and the signal fed back being detectable and evaluatable by the evaluating device.