Principle of proximity sensor Capacitive proximity sensor is composed of high-frequency oscillator and amplifier. The detection surface of the sensor and the outside world form a capacitor, which participates in the operation of the oscillation loop and is initially in an oscillation state. When the object approaches the detection surface of the sensor, the capacitance of the loop changes, which makes the high-frequency oscillator oscillate. Oscillation and stop oscillation are converted into electrical signals, which are converted into binary switching signals by amplifiers. Working principle of high-frequency oscillation proximity sensor The metal sensor consists of high-frequency oscillation, detection, amplification, trigger and output circuits. The detection surface of the oscillator sensor generates an alternating electromagnetic field. When a metal object approaches the detection surface of the sensor, the eddy current generated in the metal absorbs the energy of the oscillator, so that the oscillation is weakened and stopped. The oscillator oscillates and stops oscillating, converts it into an electrical signal, shapes and amplifies it, converts it into a binary switching signal, and outputs it after power amplification.

The working principle of universal proximity sensor varies with the metal type of the target, and the detection distance varies with the metal type of the target. Working principle of all metal sensors All metal sensors basically belong to high-frequency oscillation type. Like the ordinary type, it also has an oscillation circuit, in which the energy loss caused by the induced current flowing in the target affects the oscillation frequency. When the target is close to the sensor, the oscillation frequency will increase regardless of the metal type of the target. The sensor detects this change and outputs a detection signal. Working principle of non-ferrous metal sensor: Non-ferrous metal sensor basically belongs to high frequency oscillation type. It has an oscillation circuit, in which the energy loss caused by the flow of induced current in the target affects the change of oscillation frequency. When nonferrous metal objects such as aluminum or copper are close to the sensor, the oscillation frequency increases; When iron and other ferrous metal objects are close to the sensor, the oscillation frequency will decrease. When the oscillation frequency is higher than the reference frequency, the sensor outputs a signal.