| 摘要 |
PROBLEM TO BE SOLVED: To provide a gas detector capable of properly detecting gas from as early a period as possible even during a period until the electrical characteristics of a gas sensor element after starting becomes stable, and an automatic ventilation system for a vehicle using the same. SOLUTION: The gas detector 10 and the automatic ventilation system 100 for the vehicle subject the output of a sensor resistance value converter circuit 14 to A/D conversion to obtain a sensor output value S(n) and a base value B(n) is calculated according to the formula: B(n)=B(n-1)+k S(n)-B(n-1)}. Further, during an initial period after starting, the previous base value B(n-1) is corrected according to the formula: B(n-1)=B(n-1)+L(Na) and the base value B(n) is subsequently calculated and, further, a difference value D(n)=S(n)-B(n) is calculated. If the difference value D(n) becomes larger than a first threshold value Tu, a concentration high signal is generated to close a flap 34.
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