On the morning of September 16, 2020, Bonn Instruments and several hospital instrument and equipment departments organized outpatient, emergency, medical, nursing, pre examination triage and other departments to hold an accuracy demonstration meeting for infrared thermometers. Through video lectures, training, and on-site discussions with engineers from Bonn Instruments Company, the following evaluation report was finally formed:

1、 Body temperature

Body temperature refers to the temperature inside the body, which can be divided into deep temperature and surface temperature. It is one of the important indicators reflecting the health status of the human body, and its accuracy directly affects the diagnosis, treatment, and care of diseases. Due to the difficulty in testing deep body temperature, temperatures in the armpits, forehead, palms, mouth, rectum, and other areas are commonly used in clinical practice to represent body temperature. The commonly used tools for temperature measurement in clinical practice include mercury thermometers, ear thermometers, non-contact infrared thermometers, etc. Body temperature is not fixed and can fluctuate normally with factors such as age, day and night, gender, and emotions. Abnormal body temperature: Fever is caused by the action of pyrogens on the thermoregulatory center or dysfunction of the thermoregulatory center, resulting in body temperature exceeding the normal range.

Classification of fever severity (based on oral temperature): Low fever: 37.3-38.0; Moderate heat: 38.139.0; High fever: 39.1-41.0; Ultra high heat: above 41.0.

IIThe principle of infrared thermometer

The infrared thermometer consists of an optical system, a photodetector, a signal amplifier, signal processing, display output, and other components. The optical system collects the infrared radiation energy of the target within its field of view, and the size of the field of view is determined by the optical components and position of the thermometer. Infrared energy is focused on the photodetector and converted into corresponding electrical signals. The signal is converted into the temperature value of the measured target after being amplified and processed by the signal processing circuit according to the algorithm and target emissivity correction inside the instrument. In addition, when using an infrared thermometer for temperature measurement, the environmental conditions of the target and the thermometer, such as temperature, atmosphere, pollution, and interference, should also be considered for their impact on performance indicators and correction methods. Infrared thermometer measures the surface temperature of a target object by receiving the energy emitted, reflected, and conducted by it. The detection components inside the infrared thermometer transmit the collected energy information to the microprocessor for processing, and then convert it into temperature readings for display.

IIIAt present, temperature measuring devices on the market are divided into two categories:

1The measurement accuracy of contact thermometers is higher than that of non-contact thermometers

2The accuracy ranking of non-contact thermometers is: infrared ear thermometer>infrared screening instrument red>external forehead thermometer

3The order of non-contact thermometers in terms of accuracy, speed, and practicality is: infrared screening instrument>infrared ear thermometer>infrared forehead thermometer

4、 National standard for infrared rapid screening instrument for human surface temperature

This standard specifies the classification, requirements, test methods, inspection rules, markings, and user manuals for infrared rapid screening devices for human surface temperature. This standard is applicable to the design, production, and inspection of infrared rapid screening devices for human surface temperature (hereinafter referred to as screening devices).

2 Normative References: The clauses in the following documents become clauses of this standard by reference. Any referenced document with a specified date shall not be subject to any subsequent revisions (excluding errata) or revisions to this standard. However, parties to agreements based on this standard are encouraged to explore the possibility of using new versions of these documents. Any referenced document without a date shall apply to the new version of this standard. GB/T191-2008 Packaging, storage and transportation pictorial markings (ISO780:1997, MOD)

GB/T2423.51995 Environmental testing for electrical and electronic products Part 2: Test methods Test Ea and guidelines: Impact (idt IEC60068-2:27:1987)

GB/T2423.102008 Environmental testing for electrical and electronic products - Part 2: Test methods - Test Fc and guidelines: Alarm (sinusoidal) (IEC 60068-2-6:1995, IDT)

GB9706.1 2007 Medical Electrical Equipment Part 1: General Requirements for Safety (IEC 60601-1:1988, IDT) GB/T 9969 General Principles for Industrial Product Instructions GB/T16886.1-2001 Biological Evaluation of Medical Devices Part 1: Evaluation and Testing (idt ISO10993-1:1997) GB/T182682000 Electromagnetic Compatibility Requirements for Electrical Equipment for Measurement, Control and Laboratory Use (idt IEC61326-1:1997)

4. ReminderThe function screening device should have one or more of the following methods: light on, sound, screen indication, etc. The prompt temperature value of the screening device can be set by the operator (optional). The prompt volume of the screening device can be adjusted, and the prompt function can be turned off (optional).

5The thermal imaging screening device should also have the following functions: a) focusing function, the screening device can adjust the image to be clear for objects within the temperature measurement distance; b) Temperature display function for single or multiple points in thermal images; c) Indication and tracking function of high-temperature areas in thermal images; d) The screening device can automatically store thermal images when prompted (optional); e) Temperature field shielding function, which means the function of not measuring temperature in certain areas of the thermal image (optional); f) Freeze function for hot images (optional).

6performance

（1）The temperature display range of the screening device should not be narrower than 28.0 ℃ to 42.0 ℃ in any display mode.

（2）Under the specified working environment conditions, when the blackbody temperature is between 33 ℃ and 37 ℃, the laboratory error of the screening instrument should not exceed 0.4 ℃ Under the specified working environment conditions, when the blackbody temperature is below 33 ℃ or above 37 ℃, the laboratory error of the screening instrument shall not exceed 0.6 ℃

(3) ReminderThe response time of the prompt from the response time screening device should not exceed 2 seconds.

（4）The temperature consistency of the thermal imaging screening device should not exceed ± 0.2 ℃.

7Climate and environmental adaptability

（1）Under the following environmental conditions, the screening device should operate normally, and its laboratory error should comply with

（2）The regulations. The ambient temperature ranges from 16 ℃ to 32 ℃; Relative humidity: The upper limit should not be less than 85%.

（3）After 7 days of storage or transportation in an environment with a temperature of -20 ℃ to 50 ℃ and a relative humidity of up to 90% without condensation, the laboratory error of the screening instrument should comply with the provisions of 5. (2).

5、 National Calibration Specification for Infrared Thermometers for Measuring Human Body Temperature

Evaluation of Uncertainty in Calibration of Infrared Thermometers

The infrared thermometer used to measure human body temperature is calibrated using a standard blackbody radiation source to calibrate its readings in calibration mode.

1. Blackbody radiation source

The blackbody radiation source used for calibrating infrared thermometers consists of an isothermal cavity with a certain opening, known wall temperature, and high emissivity of the inner surface layer. The radiation characteristics of a blackbody cavity depend on the enclosure of the cavity, the uniformity of the cavity wall temperature, and the radiation characteristics of the inner surface material. Due to the large field of view of some infrared thermometer probes (for example, some infrared ear thermometer probes have a field of view close to a hemisphere), the blackbody cavity should ensure that its temperature non-uniformity and effective emissivity characteristics meet the calibration requirements within the field of view of the infrared thermometer. Common blackbody cavities with uniform temperature include:

（1）A thin-walled cavity placed in a thermostatic water bath with uniform temperature;

（2）Heat pipe cavity

(3) Other well designed thermal cavities. Due to the good uniformity of temperature space in the water tank and the convenience of measurement, the water tank scheme is widely used in room temperature blackbody radiation sources. When the effective emissivity of the blackbody cavity is close to 1, the blackbody radiation temperature can be measured using platinum resistance thermometers or mercury thermometers to approximate the temperature of the cavity wall or the temperature in the area close to the cavity wall temperature. Platinum resistors can be measured using standard platinum resistance thermometers or other precision platinum resistors that meet measurement uncertainty requirements. The radiation temperature of a blackbody radiation source should be traced back to the ITS1990 temperature reference.

2The mathematical model for evaluating the uncertainty of infrared thermometer calibration is as follows: Δ is the correction value of the displayed value of the infrared thermometer; , is the indication in the calibration mode of the infrared thermometer; Lm is the blackbody radiation temperature. The main factors contributing to the uncertainty of infrared thermometer calibration are:

(1) The uncertainty of radiation temperature calibration for a blackbody radiation source at the temperature controlled by a contact thermometer. ② The instability of radiation temperature during the calibration period. ③ The influence of environmental temperature differences on reproducing temperature control: When using the same electrical measuring instrument to measure the wall temperature of a blackbody cavity in the calibration experiments of infrared thermometers and blackbody radiation sources, the impact of environmental temperature differences on reproducing temperature control is considered; When using different electrical measuring instruments in the calibration experiment with blackbody radiation sources, the accuracy of the contact thermometer electrical measuring instrument affects the reproduction of temperature control. ④ Temperature control stability. ⑤ The non-uniformity of blackbody cavity radiation temperature: The comprehensive influence of cavity wall temperature and effective emissivity non-uniformity of 8JF11072003 blackbody radiation source in different infrared thermometer field of view regions.

(2) Uncertainty introduced by infrared thermometers ① repeatability of indication. ② Resolution.

The specific steps for uncertainty assessment can be found in the National Metrology Technical Specification JF10591999 "Evaluation and Representation of Measurement Uncertainty".

3. Example of uncertainty evaluation for calibration of infrared ear thermometer

According to this specification, an infrared ear thermometer with an effective emissivity greater than 0.999 and a display resolution of 0.1 ℃ is calibrated at 37 ℃ using a blackbody radiation source. The ambient temperature is 22 ℃, and the measured temperature of the blackbody radiation source is directly read from the temperature controller. A. 3.1 Evaluation of standard uncertainty a) Calibration uncertainty u of blackbody radiation source; taken from the blackbody radiation source calibration certificate. Extended uncertainty U=0.04 ℃, k=2。 U=0.02 ℃. b) The uncertainty u introduced by the long-term instability of radiation temperature during the calibration period. The difference in radiation temperature between the last two calibration certificates of the blackbody radiation source is 0.02 ℃. According to the uniform distribution evaluation, u=(0.02/3) ℃. c) The impact of environmental temperature differences on reproducing temperature control; the calibration environment temperature for blackbody radiation source is 20 ℃, and the calibration environment temperature for infrared thermometer is 22 ℃. Both infrared thermometer calibration and blackbody radiation source calibration experiments use a blackbody radiation source temperature controller to measure the temperature reading and determine the reproduced cavity wall temperature. The temperature measurement indication of the temperature controller is not more than 0.03 ℃/10 ℃ affected by changes in ambient temperature. Therefore, when the ambient temperature difference is 2 ℃, the temperature measurement indication of the temperature controller does not change by more than 0.006 ℃. Evaluate according to uniform distribution,; =(0.006/③) ℃. d) The influence of short-term stability of temperature control on the stability of blackbody radiation source temperature control is 0.01 ℃/10min, evaluated according to uniform distribution, u4=(0.01/③) ℃. e) The influence of non-uniformity of blackbody cavity radiation temperature is evaluated as follows: the non-uniformity of blackbody cavity radiation temperature is 0.02 ℃. According to the uniform distribution, us=(0.02/3) ℃. f) The infrared thermometer measures repeatability u. The large difference between four measurements in the repeatability experiment is 0.1 ℃, and the standard deviation of the average value u is 0.1/C/4=0.024 ℃. When the number of measurements is 4, the range coefficient C is 2.06. g) The influence of infrared thermometer resolution u, evaluated according to uniform distribution, ug=(0.1/2/3) ℃. A. 3.2 The components above the composite standard uncertainty are independent of each other, and the composite standard uncertainty u for calculating the correction value is u2=0.048 ℃

The standard uncertainty of the blackbody radiation temperature, which is 0.03 ℃, is obtained by synthesizing the first five items.

VIWhy do some thermometers fail to measure accurately

Excluding quality reasons, non-contact thermometers have relatively high environmental requirements and are used indoors in a windless environment. If the temperature suddenly changes, deviations are likely to occur. On the other hand, the working environment of infrared thermometers is generally between 16 ℃ and 35 ℃. Nowadays, it is autumn and many places are outdoors. Using an forehead thermometer for temperature monitoring is also prone to deviation.

7Instructions for using an infrared thermometer:

(One)）Usage environment1. Temperature: 10-40 degrees Celsius. 2. Measure temperature difference+-0.2 degrees Celsius. Measure continuously three times, with the maximum value as the standard. 3. Insufficient battery will affect the measurement effect, so it is necessary to replace the battery in a timely manner.（2） Measurement location1. Measure the forehead when meeting environmental requirements, and keep the thermometer 3-5 centimeters away from the measurement site. 2. Low measurement: Upon entering the room from outside, the forehead is very cold and the temperature may not be measured or displayed as low (around 35 degrees Celsius). Suggest rolling up the cuffs and measuring the wrist, or opening the collar and measuring the neck. The measurement result will be close to the true body temperature. 3. High measurement: ① After drinking alcohol, the surrounding blood vessels dilate, and the body temperature is ≥ 37 ° CThe degree. ② When sweating, use a tissue to dry the sweat before measuring, otherwise the temperature measurement will be too high.（3） Precautions1. The body of the infrared thermometer is sensitive to cold, and measurements below 10 degrees Celsius may be inaccurate. 2. Infrared radiationContinuous use of thermometers can affect measurement accuracy. It is recommended to prepare several thermometers for alternating use. 3. Infrared thermometers are only used for initial screening. For those who have objections to body temperature, it is recommended to use a thermometer for further measurement and calibration.(Four)）The advantages of the column type infrared selector are its multi probe mode, good speed, high pass rate, long measurement distance, and non-contact measurement.

8Solution for thermometers

1. Improving environmental temperature: It is recommended to establish a stable temperature measurement environment at the temperature measurement inlet and outlet to maintain the ambient temperatureReduce the impact of wind speed (less than 1.5m/s) between 16 ℃ and 35 ℃.

2Skin temperature changes: It is recommended to measure the neck or wrist as much as possible.

3Use more accurate temperature measurement equipment: Due to the limitations of handheld temperature guns in terms of power supply and usage, it is recommended to use a vertical infrared screening device.

4Calibration method: Due to frequent use, the accuracy of the thermometer decreases and should be calibrated irregularly.

Copyright: Beijing Bonn Instrument Measurement and Control Technology Co., Ltd

The utility evaluation report of the infrared thermometer is legally copyrighted by "Bonn Instrument" and may not be reproduced, excerpted or used in any other way without authorization from our company. Those who have been authorized by our company to use the work should use it within the scope of authorization and indicate "Source:Beijing Bonn Instrument Measurement and Control Technology Co., Ltd”. Those who violate the above statement will be held legally responsible by our company.