The working principle of dust sensor is based on the principle of light scattering. Particles and molecules will produce light scattering phenomenon under the illumination of light, and at the same time, it can also absorb part of the energy of the light.When a parallel monochromatic light incident on the measured particle field, it will be affected by the scattering and absorption around the particle, and the light intensity will be attenuated.
In this way, the relative attenuation rate of incident light passing through the concentration field to be measured can be obtained.The relative attenuation rate can basically reflect the relative concentration of dust in the field to be measured.The relative intensity of the electric signal can be measured by measuring the intensity of the electric signal.
The dust sensor is designed to sense dust particles in the air. Infrared light-emitting diodes and photo transistors are installed diagonally inside the sensor. Their optical axes intersect. When the airflow with dust passes through the intersection area of optical axes, the dust reflects infrared light, and the reflected light intensity is proportional to the dust concentration.
Phototransistor can detect the reflected light of dust in the air. Even very fine particles such as smoke and fog can be detected. Infrared light emitting diode emits light and produces reflected light when meeting dust. The receiving sensor detects the light intensity of reflected light and outputs the signal. According to the output signal light intensity, the dust concentration is judged. Two different pulse width modulation are outputThe signal distinguishes the concentration of different dust particles.
The external air enters the sensor darkroom through the labyrinth inlet under the suction of the exhaust fan.When the floating dust in the air is irradiated by the parallel light emitted by the laser generator in the dark room, the scattered light intensity of the dust is proportional to the mass concentration. The scattered light is converted into photocurrent by the photoelectric converter, and converted into the photoelectric pulse number which is positively proportional to the scattered light intensity through the photocurrent integral circuit of the main control board.
The relative mass concentration of dust can be measured by calculating the pulse number, and the dust mass concentration in the air can be directly displayed on the digital display screen by calibrating the preset K value on the setting keyboard.