| 摘要 |
PURPOSE:To discriminate whether the dewed water is dew or frost and to measure the dew point accurately, by varying the cooling electric current and detecting the variation of the reflected light when the temp. is <=0 deg.C when the increase or decrease of the dewed quantity attains to the equilibrium state. CONSTITUTION:If the output of a DA converter 21 is increased, the cooling current I flows and an electron cooler 5 cools a mirror surface 4, and if the temp. of the surface 4 attains to the dew point of the gas to be measured in a darkbox 1, the dewing occurs at the surface 4. Thereby, the quantity of the reflected light light attaining to a photodetecting element 10 is decreased, the output signal is sent out from a comparator circuit 15, and the current I is decreased. If the increasing or decreasing of the dewed quantity attains to the equilibrium state, a microcomputer 20 stops the increase of the output of the converter 21, and measure the temp. of a temp. measuring device 7 to display the dew point. At this time, if the measured temp. is <=0 deg.C, the current I varies during the short prescribed time, and if the output of the circuit 15 scarcely varies at the time, the dewed water is discriminated as the frost and the necessity for correction is displayed by an emission diode 24. |
