An electronic sensor used for measuring the infrared light radiation emitted from objects in its field of view is called as a PIR sensor or Pyroelectric sensor. Every object that has a temperature above absolute zero emit heat energy in the form of radiation radiating at infrared wavelengths which is invisible to the human eye, but can be detected by special purpose electronic devices such as PIR motion detectors.
PIR sensor itself is split into two halves, which are sensitive to IR and whenever object comes in the field of view of the sensor, then positive differential change will be produced between two halves with the interception of the first half of the PIR sensor. Similarly, if the object leaves the field of view, then negative differential change will be produced. PIR or Passive Infrared sensor is named as passive because it doesn’t emit any energy or radiation for detecting the radiation. There are different types of sensors used for detecting the motion and these PIR sensors are classified based on angle (wide area) over which they can detect motion of the objects like 110degrees, 180degrees and 360degress angles.
Automatic Door Opening System is a typical application of PIR sensors which is intended for automatic door closing and opening operations based on body movement near the door. PIR-sensor-based-automatic-door- opening system circuit mainly consists of a PIR sensor, an 8051 micrcontroller, a driver IC, a door motor.
If a body movement is present near the door, then infrared radiation emitted from the body will cause the sensor to produce sensing signal which is fed to microcontroller. The door motor is then controlled and operated by the microcontroller through driver IC. Thus, if anybody comes near to door, then a command will be sent by microcontroller for opening door and a time delay is set for closing door automatically. This project is intended for operating doors of shopping malls, theatres and hotels.