| 摘要 |
PURPOSE:To easily detect temperature without being affected by a limit current value by finding the ratio of a limit current value which is limited corresponding to the oxygen concn. in gas to be measured and a limit current value which is limited corresponding to temperature. CONSTITUTION:When the oxygen sensor 1 is placed in the gas to be measured and a voltage is applied between an anode 12 and a cathode 13, the amount of diffusion of oxygen into an electrode part 13a is controlled corresponding to the oxygen concn. in the gas to be measured and a current value is also limited correspondingly to reach a diffusion control current value IL, thereby showing a 1st flat part F1. Then, when the applied voltage is raised, the current value increases with the moisture concn. in the gas to be measured, but when the diffusion amount of moisture is limited at a connection part 13b, the current value is also limited to reach a diffusion control current value IL2 corresponding to the moisture concn., thereby showing a 2nd flat part F2. The current ratio RI of those two currents IL1 and IL2 is constant when the humidity (moisture density) in the gas is constant. For the purpose, the relation between the current ratio RI and humidity is measured previously and the humidity corresponding to the current value RI can be detected. |
