The classification of the proximity switch(2)

Hall proximity switch
Hall element is a kind of magnetic sensor. The switch made of Hall element is called Hall switch. When the magnetic object moves close to the hall switch, the hall element on the detection surface of the switch changes the internal circuit state of the switch due to the Hall effect, so as to identify the presence of nearby magnetic objects, and then control the on or off of the switch. The detection object of this proximity switch must be a magnetic object.

Photoelectric proximity switch
The switch made of photoelectric effect is called photoelectric switch. The light emitting device and the photoelectric device are installed in the same detection head in a certain direction. When a reflective surface (detected object) approaches, the photoelectric device will output the signal after receiving the reflected light, so as to "perceive" the approach of an object.

Other types of proximity switch
When the distance of the observer or system to the wave source changes, the frequency of the approaching wave will shift. This phenomenon is called Doppler effect. Sonar and radar are made using the principle of this effect. Ultrasonic proximity switch and microwave proximity switch can be made by using Doppler effect. When an object moves close, the reflected signal received by the proximity switch will produce Doppler frequency shift, which can identify whether there is an object approaching