Photoelectric smoke alarm tube(IR LED Emitter & IR Receiver)

There is an optical labyrinth in the photoelectric smoke alarm, which is equipped with an infrared counter(means IR LED Emitter & IR Receiver or IR LED pair).

When there is no smoke, the infrared receiving tube cannot receive the infrared light emitted by the infrared transmitting tube. When the smoke enters the optical labyrinth, the receiving tube receives the infrared light through refraction and reflection, and the intelligent alarm circuit judges whether it exceeds the threshold value, and if it exceeds the threshold value, an alarm will be given.

IR LED pair can packaged by throiugh-hole LED type and SMD LED type. For smoke detector, people will use 940nm Through-Hole IR LED or 850nm Through-Hole IR LED with IR Receiver normally. You can also choose with High Power IR LED emitter with some other wavelength.

The photoelectric smoke detector can be divided into light reducing type and scattering type, which are described as follows:

(1) Dimming photoelectric smoke detector
The detection room of the detector is equipped with light-emitting devices and light receiving devices. Under normal circumstances, the light receiving device receives a certain amount of light emitted by the light emitting device; when there is smoke, the light emitted by the light emitting device is blocked by the smoke, which reduces the amount of light received by the light receiving device, reduces the photocurrent, and the detector sends an alarm signal.

(2) Scattered light photoelectric smoke detector

The detection room of the detector is also equipped with light-emitting devices and light receiving devices. Under normal circumstances, the receiving device can not receive the light emitted by the light-emitting device, so it does not produce the photoelectric current. In case of fire, when the smoke enters the detection room, the light emitted by the light-emitting device will be diffused due to the function of smoke particles. The diffused light is received by the light receiving device, which changes the impedance of the light receiving device and generates the photoelectric current, thus realizing the function of transforming the smoke signal into an electrical signal. The detector receives the signal and then judges whether it needs to send an alarm signal.