Design Of Infrared Ear Thermometer And The Evaluation Of The Uncertainty Of The Results Calibration

With the rapid development of science and technology, the technology of infrared temperature measurement has been widely applied in many field, such as health care, epidemic disease prevention and control, industrial inspection, aerospace and military fields, and gradually expanded to be used in other application areas. In this work, we present the design of infrared ear thermometer system and the evaluation of the uncertainty of the results calibration based to the principle of infrared temperature measurement.This paper begins with a theoretical analysis of the working principle of infrared temperature measurement technology. The theoretical basis, characteristics, application areas, and influencing factors of the infrared temperature measurement technology were elaborated in detail. Furthermore, we analyzed the characteristics of several measuring methods of human body temperature in medical care service and summarized the advantages of the infrared ear thermometer. Based on the working principle of the measurement technology of infrared temperature, this research designed a circuit of infrared ear thermometer, which is applicable for hospital and domestic usage. Specifically, this circuit includes a temperature sensor, an amplifier circuit, a filter circuit, a Micro Controller Unit(MCU), a display circuit, an alarm circuit, and a temperature compensation system et al. Additionally, this research paper systematically introduced the design of the performance parameters of the modules including the temperature sensor, the amplifier, the temperature compensation circuit, and the filter circuit. Furthermore, due to the small change rang of body temperature, a blackbody furnace with temperature display was used as the measured object to expand the measuring range of the ear thermometer. The results indicated that the accuracy of the measured temperature correlated with the object distance. In addition, this study provided an assess men t of the measurement uncertainty according to the analysis of several methods on the calibration of the blackbody furnace and the transmission; and the experimental calibrations on the submitted infrared ear thermometer in the daily work. The assessment includes the calculation and presentation of standard uncertainty, combined uncertainty, expanded uncertainty and degree of freedom. Finally, we proposed a method to reduce the error of measurement. This work shed lights on the approach of the improvement of infrared ear thermometer.