| 摘要 |
<p>PURPOSE:To facilitate the long term usage in a high temperature and high humidity environment by a method wherein the output signal of a detection amplifier whose amplification factor is changed by the resistance change of a specific humidity sensor is rectified by a rectifier and the output signal of the rectifier is converted by logarithmic conversion to output a signal changed proportionally to the change of a relative humidity. CONSTITUTION:Carbon powder is dispersed in a quartz glass to form a porous element and the porous element is placed in an environment to be measured as a humidity sensor 3. The humidity sensor 3 is used as the feedback resistance or the input resistance of an inversion amplifier to constitute a detection amplifier 2 whose amplification factor is changed by the electric resistance of the humidity sensor 3. Therefore, if a signal with a certain amplitude and a certain frequency is given to the input of the detection amplifier 2 from an oscillator 1 and the output signal of the detection amplifier 2 is rectified and converted by logarithmic conversion, an output signal changed proportionally to the humidity change of the environment to be measured can be obtained. With this constitution, even if the temperature sensor is used in a high temperature and high humidity environment for a long term, stable characteristics can be obtained.</p> |
