Gas detector and its regulating method

把金属氧化物半导体气体传感器S连接到电阻梯形网络R上，输出电压根据LnR＝2-4VR1/Vc+LnR1，在温度变化的波形上的多个点上，进行对数变换。其中，R表示MOS的电阻值，VR1表示加至电阻梯形网络上的输出电压，Vc表示检测电压，R1表示电阻梯形网络的电阻值，Ln表示自然对数。把在多个浓度且在波形的多个点上，由MOS的电阻值的对数构成的基准信号存储到EEPROM中，对这些基准信号和所得到的对数进行比较，来检测气体。 A metal oxide semiconductor gas sensor S is connected to a ladder resistance R, and the output voltage is subjected to logarithmic transformation at plural points on a waveform of temperature change by where R indicating the resistance of the metal oxide semiconductor, V R1 the output voltage to the ladder resistance, Vc the detecting voltage, R1 the resistance of the ladder resistance, and Ln natural logarithm, respectively. Standard signals comprising logarithms of resistance values of the metal oxide semiconductor in plural concentrations and at plural points on the waveform are stored in the EEPROM, and these standard signals and logarithms obtained are compared with each other to detect the gas.