Proximity Sensor - definition

A proximity sensor is a type of electronic device which can detect the presence of an object nearby or in front of it. Proximity sensor is one of the most used and a must sensor for smartphones. There are several types of proximity sensors such as Capacitive, Inductive, Ultrasonic, and Optical proximity sensors. Based on the target object the type of proximity is used. i.e.: To detect the presence of a metal object inductive proximity sensors have to be used, or optical proximity sensors can be used to detect any wooden or plastic or other similar types of material or object.
Application: In a smartphone when we receive a call and place the device near our ear the display of the device gets turned off automatically, this occurs because of the proximity sensor installed on the top front side of that device. It is also used in other electronic devices such as digital measuring scales, PDA, tablets, computing devices, gaming consoles.