How Proximity Sensor works

A proximity sensor is a type of sensor which detects the presence of nearby objects called target without any physical contact. There are different types of proximity sensors such as inductive proximity sensor, capacitive proximity sensor, ultrasonic proximity sensor, photoelectric proximity sensor. Depending on the type of technology used proximity sensor emits an electromagnetic or electrostatic field, or a beam of electromagnetic radiation (infrared, for instance), and looks for changes in the field or return signal when target comes closer to the face of sensor.

There are different kinds of proximity sensors. They are

• Capacitive proximity sensor
• Inductive proximity sensor
• Photoelectric proximity sensor
• Ultrasonic proximity sensor
  

The advantages of the non contact proximity sensors are:

• No physical contact required with the target to be detected, therefore, no moving parts so no friction and wear out.
• Fast switching characteristics
• Unlimited number of switching cycles since there is no mechanical contact
• Can work in harsh conditions
• Any type of target material can be detected.

A proximity sensor is used in many applications such as in mobile phones and for level sensing. In Iphone proximity sensor is used to deactivate the touch screen when the phone comes near to the face.

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