The Motion Sensor uses a pyroelectric infrared sensor to detect any moving object at front.When the infrared signal have rapidly changed, the sensor will return high to user, otherwise, return low.
 
Working Principle
The pyroelectric infrared sensor will keeping record the infrared signal inside target area. Human will emit the infrared light cause by the body temperature, when they pass thought the detection area, the signal received by sensor will have fluctuation which can determine the movement of object. Generally, the maximum range of the detection is 5 to 12 meters , create a spherical sector with 65 degree from normal line.