| 摘要 |
<p>PURPOSE:To make the title sensor selectively sensitive only to humidity, by measuring the electrostatic capacity between a measuring electrode and a common electrode caused by a porous ceramic layer and that between a reference electrode and the common electrode caused by the ceramic layer to operate both measured values. CONSTITUTION:The moisture in air is adsorbed by a porous PTZ layer 2 corresponding to the humidity at that time. When the moisture is adsorbed, the surface resistance of the porous PTZ layer 2 is lowered and an effective electrode area increases while the distance between electrodes is reduced. As a result, the electrostatic capacity between a mesh electrode 4 and a common electrode 3 is changed (increased). Since this change depends on the adsorbed moisture, humidity can be measured from a change in electrostatic capacity. The dielectric constant of ceramics has large temp. dependence but the relation between a temp. change and output is preliminarily measured to be stored in an operation apparatus 10. Temp. is measured on the side of a reference electrode 5 and this measuring result is used in correction thereof to know accurate humidity.</p> |
