Directional curtain infrared detectors generally use two-way pulse counting operation mode, that is, alarm from direction A to direction B, and direction B to direction A do not alarm. With the ability to identify intrusion direction, the user enters the guard zone from the inside to the outside and will not trigger an alarm. Returning within a certain period of time will not cause an alarm. Only an illegal intruder will trigger an alarm when intruding from the outside, which greatly facilitates the user in the defense. The vigilance within the area does not trigger the alarm system at the same time.