| 摘要 |
PURPOSE:To detect inflammable gas and carbon monoxide at the same time and to shorten the detection time by providing a detecting device with an inflammable gas detecting means, an auxiliary detecting means, a temperature varying means, and a carbon monoxide detecting means. CONSTITUTION:The heating temperature of a gas sensor 2 which uses a metal oxide semiconductor which varies in resistance value according to gas is varied periodically between a high-temperature range and a low-temperature range. Then, the inflammable gas detecting means composed of a comparing circuit 24, a D-FF 26, and an LED 28 detects the inflammable gas from the output of the sensor in the high-temperature range. The auxiliary detecting means composed of a converter 30 and a D-FF 32, on the other hand, serves as the temperature varying means, and detects carbon monoxide with the output of the sensor 2 in the low-frequency range preliminarily to vary the heating temperature into the intermediate temperature between the high-temperature range and low-temperature range. The carbon monoxide detecting means consisting of a converter 34, amplifiers 36 and 38, a D-FF 40, and an LED 42 compensates the output of the sensor 2 in the low-temperature range with the intermediate temperature to detect carbon monoxide selectively.
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