In front of many office building automatic door, you can enter the door automatically. When people near it, the door will automatically open and close automatically. It was amazing how did it know someone was going in? What is the power to open the door? In fact, the earliest automatic doors in 3000 before there, but much more complex than it is now.
Modern automatic door operation has three main ways:
① pedal type:
Under the pedal there is a pressure switch.
② light beam type:
A light beam emitting device and a photoelectric sensing device are provided in the vicinity of the door
③ button way:
Press the button similar to the switch to open the door.