There are two automatic door sensor commonly used: microwave radar sensor and infrared sensors.
The microwave radar sensor is reaction for the displacement of the object , so that the reaction speed is fast, suitable for normal place that people walking speed is normal, which is characterized that staff near the door do not want to go out, the radar will no longer respond, automatic doors will be closed, So this can protect the automatic door operator.
The infrared sensor is respond to the existence of objects, whether move or not, as long as the object in the infrared sensor scan range, it will respond to outgoing contact signal. So the automatic door will keep opening. The disadvantage is the infrared sensor response is slow, suitable for people with slow access to the place. In addition, if the automatic door to accept the contact signal time is too long, the controller will think that there is some problem from the signal input system. And if the automatic sliding door to keep open time is too long, this will damage the electrical components.