1. There is a high-frequency transmitter in the human body proximity sensor, which causes the coil to emit a high-frequency magnetic field.

2. The proximity of the measured object to the high-frequency magnetic field will cause eddy currents on the surface of the tested object, and the eddy currents will cause magnetic fields in the opposite direction.

3. The transmitter is offset by the influence of the magnetic field caused by the eddy current and stops vibrating.

4. The control output is turned on/off by the presence or absence of vibration.