| 摘要 |
PROBLEM TO BE SOLVED: To realize an effective preventive method for the sensitivity drop of a gas sensor, by executing a short-time heating-up treatment. SOLUTION: The optimization of the temperature of a sensor at a time when a heating-up treatment is not executed is investigated by an accelerated experiment. For example, the sensitivity of the sensor with reference to the ordinary air (containing about 360 ppm of carbon dioxe) is set at 0 mV, a ΔEMF as the sensitivity of the sensor with reference to the air which contains 2000 ppm of carbon dioxde is detected, and a heating-up treatment (at 520 deg.C) is executed to the sensor for two minutes at intervals of ten minutes. At this time, the influence of the number of times of the heating-up treatment on an output is investigated at a time when an initial ΔEMF is set at 0 mV, and the ordinary temperature of the sensor is set at about 340 deg.C. As a result, even when the heating-up treatment for two minutes at 520 deg.C is executed 2000 times, it is found that the ΔEMF keeps an initial performance. In this manner, thanks to the effect of the periodical short-time heating-up treatment, it is found that the ΔEMF can be stabilized for a long period. |
