An ultrasonic proximity sensor uses a piezoelectric transducer to send and detect sound waves. Transducer generates high frequency sound waves and evaluates the echo by the detector which is received back after reflecting off the target. Sensors calculate the time interval between sending the signal and receiving the echo to determine the distance to the target. When the target enters the operating range the output switches. The ultrasonic proximity switches are equipped with temperature sensors and a compensation circuit, in order to be able to compensate for changes in operating distance caused by temperature fluctuations.

Diffuse Type : In this case the emitter and detector are put in the single package in such a way that their field of view crosses. Here the emitter continuously emits the light. When the target comes within the operating range of the sensor the light from the emitter is reflected off the target and detected by the detector.

No physical contact with the object to be detected, therefore, no friction and wear