Induction

On a signal printed circuit board, there is one sinusoidal and one cosinusoidal conductor loop (sin(x), cos(x) – transmit loop) along the measurement path x. Each of these is supplied with an alternating voltage (u∙sin(ωt), u∙cos(ωt)) that is phase-shifted by 90° in time. This results in alternating magnetic fields perpendicular to the circuit board, whose strength H(ωt) along the measurement path x also follows a sinusoidal or cosinusoidal pattern. Thus, a signal is generated whose phase shift, relative to the transmission signal, is directly proportional to the path x.

The Position marker, which is designed as a resonant circuit, serves as the summing element for the two transmission signals. It hovers above the signal circuit board. Its resonance frequency is tuned to the transmission frequency of the two input signals. It is excited by them (TX) and, in turn, transmits its magnetic field back to the circuit board (RX).

The rectangular receiving coil, which is also integrated into the signal circuit board, picks up this signal and transmits it to the evaluation electronics. There, the received signal is compared with one of the two transmitted signals. The evaluation electronics process the resulting phase information into a linear analog voltage signal that corresponds to the distance traveled.

In addition to its inherent resistance to magnetic interference, this technology offers very high dynamic range (up to >10 kHz) for position detection, as well as the fact that in processes where metal chips are generated, these are not Position marker to Position marker and cannot accumulate on them. These characteristics make it an ideal alternative or complement to magnetostriction.