Infrared dust sensors
Infrared LEDs are light-emitting diodes whose emission wavelengths are in the infrared range. The common wavelengths are generally around 850nm to 940nm. They are widely used in medical, security, communication, remote control and sensing fields. Since the emitting wavelength of infrared LED is outside the visible spectrum, with the receiver of a specific spectrum, the influence of ambient light on the received signal can be greatly reduced. Thanks to the continuous maturity of infrared LED technology in recent years, infrared LEDs have the characteristics of long service life, high emission efficiency, good monochromaticity and good directionality, which makes infrared LEDs widely used in the sensor field, especially in the dust sensor industry.
Laser dust sensors
Compared with ordinary visible light, lasers have the characteristics of good coherence, good directionality, good monochromaticity, and high-power density. For example, the light generated by the laser light source is like a chorus, and everyone's voice is in one tone and the rhythm is neat; the light generated by the ordinary visible light source is like the noise in the teahouse, which is out of order. As a result, the laser light can be focused into a very concentrated parallel beam with a small spread angle and high-power density over long distances. Common lasers are generally divided into three categories, that is, solid lasers, gas lasers and semiconductor lasers (commonly known as laser LEDs). In the field of instrument-level laser particle counters, (helium-neon) gas lasers are generally used as light sources.
The difference between laser dust sensors and infrared dust sensors
The principle
The structure and circuit of PM2.5 dust sensors are relatively simple. The light source is an infrared LED light source, and the air inlet and outlet are mainly heated by resistance to obtain hot air flow, and a high level is output when particles pass through. The output signal is only for PWM models. The structure and circuit of the laser PM2.5 sensor are relatively complex. The light source is a laser diode. The sampled air is pushed by a fan or blower, and a complex designed air duct is used for detection. When the fine particles in the air enter the area where the laser beam is located, the laser light will be scattered; the scattered light is radiated at an angle of 360. Place the photodetector in an appropriate position so that it only receives scattered light. A current signal is generated due to the photoelectric effect of the photodetector. The concentration value of fine particles can be obtained after being amplified and processed by the circuit. The output signal is generally serial output.
Prices and costs
The infrared dust sensor has been used in the industry for many years, and the market price is about a few dozen RMB. The price of the laser dust sensor is about 200 RMB. The cost gap between the two is mainly due to the addition of mechanisms such as laser generators and fans, which requires complex circuit structures and high technology.
Measurement accuracy
The infrared dust sensor can only detect particles above 1 micron, and the measurement accuracy is insufficient. Because the particle signal scattered by the infrared LED light is weak, it only responds to large particles larger than 1 micron, and only the heating resistor is used to drive the sampling airflow; the sampling is not many, and the data calculation is completely handed over to the host computer. Laser sensors can detect particles larger than 0.3 microns. Because of its high-performance CPU, a large amount of data is collected by fans or blowers, and analyzed by professional particle counting algorithms; in summary, it has more advantages than infrared dust sensors in terms of sampling numbers, data source, and algorithm.
Applications
The infrared sensor is mainly used for industrial and mining dust due to insufficient precision. The detection object is a large particle and dust with high concentration. The detection level is mg/m3, which cannot accurately measure the concentration of PM2.5. The laser sensor is mainly used in the field of PM2.5 detection, quantifying the quality of PM2.5 with precision. It can be embedded into a household vehicle or hand-held air detectors and air purifiers. In addition, laser sensors are also used in IoT data collection, environmental quality detection and other fields.
Development trends
Before the laser sensor entered the civilian field, a large number of infrared sensors were used in air purifiers. However, with the development of the air purification industry, the cost of laser sensors is gradually decreasing, and end users put forward higher and higher requirements for accurate air quality measurement. The use of laser sensors to accurately quantify the quality of PM2.5 is a recognized trend in the industry. Some air purifiers have used laser sensors. It all depends on the needs of customers, such as requirements for costs, accuracy, signal output, applications, and the relevant particles to be tested.
Infrared LEDs are light-emitting diodes whose emission wavelengths are in the infrared range. The common wavelengths are generally around 850nm to 940nm. They are widely used in medical, security, communication, remote control and sensing fields. Since the emitting wavelength of infrared LED is outside the visible spectrum, with the receiver of a specific spectrum, the influence of ambient light on the received signal can be greatly reduced. Thanks to the continuous maturity of infrared LED technology in recent years, infrared LEDs have the characteristics of long service life, high emission efficiency, good monochromaticity and good directionality, which makes infrared LEDs widely used in the sensor field, especially in the dust sensor industry.
Laser dust sensors
Compared with ordinary visible light, lasers have the characteristics of good coherence, good directionality, good monochromaticity, and high-power density. For example, the light generated by the laser light source is like a chorus, and everyone's voice is in one tone and the rhythm is neat; the light generated by the ordinary visible light source is like the noise in the teahouse, which is out of order. As a result, the laser light can be focused into a very concentrated parallel beam with a small spread angle and high-power density over long distances. Common lasers are generally divided into three categories, that is, solid lasers, gas lasers and semiconductor lasers (commonly known as laser LEDs). In the field of instrument-level laser particle counters, (helium-neon) gas lasers are generally used as light sources.
The difference between laser dust sensors and infrared dust sensors
The principle
The structure and circuit of PM2.5 dust sensors are relatively simple. The light source is an infrared LED light source, and the air inlet and outlet are mainly heated by resistance to obtain hot air flow, and a high level is output when particles pass through. The output signal is only for PWM models. The structure and circuit of the laser PM2.5 sensor are relatively complex. The light source is a laser diode. The sampled air is pushed by a fan or blower, and a complex designed air duct is used for detection. When the fine particles in the air enter the area where the laser beam is located, the laser light will be scattered; the scattered light is radiated at an angle of 360. Place the photodetector in an appropriate position so that it only receives scattered light. A current signal is generated due to the photoelectric effect of the photodetector. The concentration value of fine particles can be obtained after being amplified and processed by the circuit. The output signal is generally serial output.
Prices and costs
The infrared dust sensor has been used in the industry for many years, and the market price is about a few dozen RMB. The price of the laser dust sensor is about 200 RMB. The cost gap between the two is mainly due to the addition of mechanisms such as laser generators and fans, which requires complex circuit structures and high technology.
Measurement accuracy
The infrared dust sensor can only detect particles above 1 micron, and the measurement accuracy is insufficient. Because the particle signal scattered by the infrared LED light is weak, it only responds to large particles larger than 1 micron, and only the heating resistor is used to drive the sampling airflow; the sampling is not many, and the data calculation is completely handed over to the host computer. Laser sensors can detect particles larger than 0.3 microns. Because of its high-performance CPU, a large amount of data is collected by fans or blowers, and analyzed by professional particle counting algorithms; in summary, it has more advantages than infrared dust sensors in terms of sampling numbers, data source, and algorithm.
Applications
The infrared sensor is mainly used for industrial and mining dust due to insufficient precision. The detection object is a large particle and dust with high concentration. The detection level is mg/m3, which cannot accurately measure the concentration of PM2.5. The laser sensor is mainly used in the field of PM2.5 detection, quantifying the quality of PM2.5 with precision. It can be embedded into a household vehicle or hand-held air detectors and air purifiers. In addition, laser sensors are also used in IoT data collection, environmental quality detection and other fields.
Development trends
Before the laser sensor entered the civilian field, a large number of infrared sensors were used in air purifiers. However, with the development of the air purification industry, the cost of laser sensors is gradually decreasing, and end users put forward higher and higher requirements for accurate air quality measurement. The use of laser sensors to accurately quantify the quality of PM2.5 is a recognized trend in the industry. Some air purifiers have used laser sensors. It all depends on the needs of customers, such as requirements for costs, accuracy, signal output, applications, and the relevant particles to be tested.
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