What is a Proximity Sensor?

A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact. Proximity sensors are widely used in car and home alarms, car parking sensors, large motors and turbines; however I bet you heard about proximity sensors in smartphone specifications. Almost all modern touchscreen equipped smartphones have proximity sensor. The proximity sensor’s main function in motors and turbines is to measure the variation in distance between a shaft and its support bearing. In alarms and parking systems the sensor’s role is obvious. Do you wonder what does the proximity do in a smartphone? The primary function of a proximity sensor in a phone is to disable accidental touch events. The sensor is located on the top part, next to the speaker. The most common scenario being- The ear coming in contact with the screen and generating touch events, while on a call. It could cause funny or even unpleasant situations.

There are various technologies for proximity sensing:

Electrical (Inductive, Capacitive)

Optical. (IR, Laser)

Magnetic.

Sonar

Optical sensors are cheap and reliable. These can detect bodies in the vicinity of the device up to 5cm. This is perfect for use on smart-phones.

These are typically “active” proximity-sensors that have a light-source embedded in the module itself. This is usually an LED that emits light in the Infrared (non-visible) spectrum.

An object in the near vicinity of the proximity-sensor reflects a good amount IR light back to the sensor. By measuring the reflected IR light the sensor determines the distance. The distance value is measured in centimeters, however some proximity sensors only support a “close” or “far” measurement.

Check the following proximity sensor related Android apps below:

Sensor music player

Play music with the help of various sensors

ScreenWakeUp

Lock and unlock the screen with proximity sensor

Z-Device Test

AndroSensor

Check sensors and system information