Development Of High Precision Temperature And Humidity Measurement Instrument

In order to obtain higher measurement accuracy and less uncertainty during the nano scale resolution measurement, the demands on the environment measurement and control, such as air pressure, humidity, temperature, vibration and so on, should be met, specially stricter for the temperature and humidity measurement and control in the ultra high precision nanometer measurement. There are all kinds of instruments for measuring temperature and humidity which can not meet the demand of the nano scale accuracy measurement in the domestic and foreign industry at the present day. So it is necessary to design a high precision measurement system of temperature and humidity. In the thesis the research on high precision temperature and humidity measurement is realized. The main content of the thesis is as follows:Firstly, a summary is presented about the present situation of the temperature and humidity measurement techniques as well as the development trend of the techniques on the future. Secondly, the plan was drawn up for selecting, using and setting the temperature and humidity sensors according to the practical measurement demands. In order to ameliorate the sensors character, I studied diversity schemes during the design, made abundant experiment on it. At last, I select the most optimal scheme to improve the instrument character. At the same time, the paper introduces some methods that can eliminate the error produced by lead resistance in the temperature measurement. Owing to its self-heat effect, a method of using pulse drive current is presented in this paper. Fourthly, according to the application demands, a hardware system of microcontroller was designed. It can realize data acquisition, timely displaying and storage of the value of the measured temperature, communication with an upper computer and so on. The corresponding software was designed. The authors analyze in details the non-linear characteristics of temperature measured platinum resistance and its linearization method, also the experimental results and the measuring errors are presented.Through the studies in the paper, especially the research of eliminating the error in temperature measurement can provide practical significance in the high precision measurement system.