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 proximitysensor, 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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