Research On A New Type Method Of Non-Contact Normal Temperature Measurement

As an important way of temperature measurement, non-contact infrared measurement has many advantages, such as rapid reaction, wide measurement range and high sensitivity. Therefore, non-contact infrared temperature measurement is used in many fields. Infrared radiation method is usually adopted in non-contact measurement of running objects' temperature. But it is hard to measure temperature of running objects at room temperature by this method.Aiming at present status of non-contact infrared temperature measurement, this paper puts forward a new type method of non-contact normal temperature measurement. It is a non-contact measurement method for running object at room temperature using refrigeration parameter reference. The following is basic working principle of temperature measurement. After comparing the lower reference and measured temperature, relative temperature of measured workpiece is obtained, and then real temperature of objects is obtained after adding relative temperature to reference temperature of semiconductor refrigerator.Based on the principle of temperature measurement, this paper designs a new type system of non-contact normal temperature measurement. In this system, relative temperature signal (non-contact infrared signal) is transformed to sinusoidal voltage signal after received and modulated by autonomous sampling pyroelectric infrared detector. Meanwhile, reference temperature signal of semiconductor refrigerator is transformed to standard voltage signal by electric bridge circuit. Then the two transformed voltage signals is processed, compensated and displayed in single micro-computer system after they are amplified, filtered and shaped by circuit. In order to improve the measurement accuracy, software algorithm such as least square method and fuzzy PID control is adopted to compensate temperature.The simulation test indicates that measurement of detected temperature at normal temperature using this new type method can not only overcome low SNR (Signal Noise Ratio) problem caused by small measurement temperature difference, but also compensate measurement error caused by ambient temperature changes. And this method improves the measurement accuracy greatly.