In the proximity switch, there is a component that has the ability to "perceive" the object approaching it, that is, the displacement sensor. It can use the sensitivity of the displacement sensor to the approaching object to achieve the purpose of controlling the switch on or off. The object moves from the switch to the switch and the switch. The distance sensed by the displacement sensor after approaching a certain distance is called the detection distance. Sometimes the detected objects approach the switch at a certain time interval and then leave one after another, which is repeated continuously, and the response ability of different proximity switches to the detected object is also different, which is called the response frequency.