Infrared geminate transistor emission-type device and method for detecting opening and closing states of door

The invention discloses an infrared geminate transistor emission-type device and method for detecting the opening and closing states of a door. The device comprises one first infrared receiving and transmitting module, one second infrared receiving and transmitting module, and one reflection module. The first and second infrared receiving and transmitting modules are installed on one door frame, and can transmit infrared signals downwards and receive reflected signals. The reflection module is installed on a door leaf below the door frame. When the door leaf is closed, the second infrared receiving and transmitting module is located exactly above the reflection module. The device can effectively detect the opening and closing states of the door through two pairs of infrared receiving and transmitting devices, also can detect a shielding object below the door, is remarkable in effect, is safe and reliable, is lower in price, is more convenient for fault inspection, and saves the manpower and material resources