In the recent outbreak of the new coronavirus, fever usually appears as the first symptom after infection, so measuring body temperature has become the main means of screening for suspected cases, especially in crowded places such as hospitals, subway stations, railway stations.
The most common temperature measurement tools currently on the market are divided into three categories:
The first type is a thermometer, which includes common mercury thermometers and electronic thermometers, mostly for home use;
The second type is a temperature measuring gun, which relies on the sensor to receive the human body's infrared to determine the body temperature and converts the body temperature of an adult through a formula. Generally, a single person's temperature measurement can be completed in 3-5 seconds;
The third category is the recently-observed infrared thermal camera temperature measurement. By converting the invisible infrared energy emitted by the human body into a visible thermal image, in simple terms, the temperature is changed from a numerical value to a temperature data. The efficiency of the image is one of its biggest advantages.
How does infrared camera temperature measurement achieve accurate human body temperature screening? Recently, Li, a domestic listed company focusing on thermal image research and development for 10 years, is a technical answer to FOTRIC application engineer Li.
First of all, Li takes the temperature measurement demand of a crowded railway station as an example, with a daily passenger flow of 100,000 passengers. Tens of thousands of people take 83 hours and 3.5 days, which is obviously unreasonable.
Of course, multiple entrances can be opened to disperse the passenger flow, but passengers still need to stay for 3-5 seconds to pass through. However, if an infrared thermal imaging thermometer is set, it can ensure that the flow of people passes at normal speed, and there is no need for close contact between people.
Then, how to measure the temperature of the infrared camera to achieve accurate screening of the human body temperature, Li of FOTRIC Foundation has analyzed from the following points:
I. Why the infrared camera temperature measurement is the most efficient temperature measurement method at present
The thermal imaging camera can perform temperature screening because it can convert the temperature into a visual image. The pixels in each thermal image are temperature points. The number of temperature points is related to the infrared pixels of the device itself, such as FOTRIC.
The infrared pixel of 692 is 384 * 288, that is, there are 110,000 temperature points in a thermal image, which is equivalent to measuring temperature with 110,000 temperature measuring guns at the same time, and the efficiency will be significantly improved.
Second, the temperature difference between the normal temperature and the abnormal temperature of the human body is very small, how to identify it through the thermal image screen
The higher the thermal sensitivity of the infrared camera, the stronger the ability to distinguish small temperature differences, and the more accurate the temperature measurement.
If the thermal sensitivity of an infrared camera is 0.03 degrees Celsius, then the thermal camera can distinguish the difference in temperature difference of 0.03 degrees Celsius. For the high accuracy requirement of body temperature screening, it can be well satisfied. Technical parameters such as thermal sensitivity need to be certified by the national metrology agency before they can be launched.
3. For such accurate temperature measurement requirements, is there any fluctuation in the temperature measurement data to affect the temperature measurement results?
If you study infrared thermal imaging technology in depth, you will know that there are two very important indicators to judge whether an infrared thermal imager is professional and reliable, that is, "temperature stability" and "temperature consistency".
For example, a FOTRIC thermal imager in the "China Electric Power Research Institute" test report shows that a 29.8-hour continuous temperature measurement is performed on a test target of 49.8 degrees Celsius.
The fluctuation of the test result is very small (the fluctuation value is between 0 degrees Celsius and 0.03 degrees Celsius), and when measuring the same black body target surface, the values of the 9 areas in the same frame are basically consistent, it can indicate that Consistency is to meet the requirements of accurate measurement.
Fourth, the infrared thermal imaging thermometer for body temperature screening, how to catch abnormal body temperature
If there is a person with abnormal temperature in the crowd, FOTRIC's automatic infrared body temperature screener will automatically sound a buzzer for audible alarm, and the over-temperature part in the screen will automatically display red.
In addition, the LWLIR temperature screening software will automatically capture a thermal image of a person who is over-temperature, which is convenient for later staff statistics and analysis.
As a non-contact temperature measurement tool, the infrared camera has matured in the daily inspection of the power industry, troubleshooting of factory equipment, quality control of the processing industry, safe production of steel and petrochemicals, and material research in biological research. application.
And its characteristics of non-contact, image-based temperature imaging, and efficient screening have been concerned by large-scale body temperature screening sites. At airports, railway stations, subway stations and other high-traffic transportation hubs, hospitals, large enterprises, institutions, and schools Such crowded social places have been widely used.