| 摘要 |
PROBLEM TO BE SOLVED: To reduce an influence due to a change in the concentration of oxygen in a gas to be measured and to increase measuring accuracy by a method wherein a composite oxide semiconductor is used for a gas detecting part at a sensor element and the concentration of oxygen inside a measuring chamber is controlled. SOLUTION: A measuring chamber 5 which is formed of an enclosure 1 houses a sensor element which is composed of a gas detecting part 7 and of a measuring electrode 9, and a composite oxide semiconductor whose selectivity in a detection is excellent is used for the gas detecting part 7. A gas to be measured is diffused inside the measuring chamber 5 via a diffusion-limiting hole 3 which is formed at the enclosure 1, and the composition of the gas to be measured is reflected directly. A standard-oxygen-concentration-gas chamber 19 which is adjacent to the measuring chamber 5 maintains the concentration of oxygen inside the chamber at a constant concentration, and an influence due to a change in the concentration of oxygen outside the measuring chamber is reduced. The inside of the enclosure 1 is provided with an oxygen pump as an oxygen-ion conductive solid electrode 13 with electrodes 14, and the oxygen pump conducts oxygen in an ion state between the measuring chamber 5 and the standard-oxygen-concentration-gas chamber 19. Thereby, the concentration of the oxygen inside the measuring chamber 5 is maintained to be constant, and the measuring accuracy of a measuring apparatus is enhanced. |
