Update: 2019-08-21 17:16 Source: LUFTMY
With the improvement of people's living standard and the improvement of people's health awareness, air quality monitoring and air purification products are attracting more and more public attention. Then what kind of dust sensor should be used in air purifier? Starting from user experience and creating value, this paper briefly talks about it.
In the current dust particle PM2.5 detection field, infrared dust sensor and laser dust sensor are mainly used. What are the differences and questions between the two?
The structure and circuit of infrared dust sensor are relatively simple. Its light source is infrared LED light source. The air inlet and outlet are mainly heated by resistance to obtain hot air flow. The particles pass through, i.e. output high level. The output signal is only PWM type.
The structure and circuit of laser sensor are relatively complex. The light source is a laser diode. Sampled air is driven by fans or blowers and tested through complex designed ducts. When the fine particles in the air enter the region where the laser beam is located, the laser will scatter, and then the current signal will be generated by the photoelectric effect of the photodetector. After amplification and treatment by the circuit, the concentration of fine particles can be obtained.
Infrared dust sensor can only detect more than 1um particles, and the measurement accuracy is insufficient. Because the particle signal of infrared LED light scattering is weak, it only responds to large particles larger than 1um, and only uses heating resistance to drive the sampling airflow, so the sampling number is small.
Laser dust sensor can detect particles above 0.3um. Because of its own high-performance CPU, fan or blower is used to collect a large amount of data, which is analyzed by professional particle counting algorithm. In summary, it has more advantages than infrared dust sensor in sampling number, data source and algorithm.
Infrared dust sensor in the industry has been mature for many years, the market price is about 35-50 yuan, laser dust sensor in the market price of 90-180 yuan. The cost gap between the two is mainly due to the increase of laser generator and fan and other institutions in the material cost of the latter, which requires complex circuit structure and has a high technical threshold.
Due to the inadequate accuracy, the infrared principle sensor is mainly used for industrial and mining dust. The detection object is large particle size and high concentration dust. The detection level is mg/m3, so the concentration of PM2.5 can not be accurately measured. Laser principle sensors are mainly used in the field of PM2.5 detection to quantify PM2.5 quality with accuracy. It can be embedded in household (car-mounted, hand-held) air detector and air purifier. In addition, laser principle sensors are also used in data acquisition, environmental quality detection and other fields of the Internet of Things.
Infrared dust sensors were widely used in air purifiers before laser dust sensors entered the civil field. However, with the development of air purifier industry and the batch production of laser dust sensor in some large factories, the cost of laser dust sensor is gradually decreasing, and the requirement of terminal customers for accurate measurement of air quality is becoming higher and higher. The use of laser principle sensors and precise quantification of PM2.5 quality has been recognized as a trend in the industry.