Inductive sensors detect objects made of metal or electrically conductive objects that move into their measuring field without any contact. They provide the user with a binary signal that provides information about whether an object has been detected or not. Inductive sensors are also called proximity switches or position sensors.
Inductive sensors consist of three functional units: an oscillator, an evaluation unit and an output stage. As part of the oscillator, a coil has the task of using an oscillating circuit to generate an alternating magnetic field that emerges from the active surface of the inductive sensor. Eddy currents are generated in the metallic object approaching from the front, which draw energy from the oscillator. The amplitude and frequency of the oscillating circuit change and the output stage is switched via a Schmitt trigger or the amplitude is converted into a distance. If several coils are used, this increases the measuring accuracy of the inductive sensor.