| 摘要 |
PROBLEM TO BE SOLVED: To make carbon monoxide detectable easily and accurately in a wide concentration range from a low concentration area to a high concentration area by changing the temperature of a sensor element by a sensor element temperature changing means according to the concentration of measured object gas. SOLUTION: An output port 1301 of an MPU 13 controls a heater power source 12 to switch high-low of the temperature of a solid electrolyte type sensor element 11. With power source closed, the MPU 13 outputs a signal L0 from the output port 1301 to the heater power source 12 and substitutes the output of the sensor element 11 held at a low temperature (400 deg.C, for instance) for a variable (x) from an input port 13i. When this variable X-value is 2V or more, that is, a measured object has high concentration, the signal L0 is outputted again to the heater power source 12 to hold the sensor element 11 at a high temperature (500 deg.C, for instance). When the variable x-value substituted by the output of the sensor element 11 at the time of high temperature is 1.3 V or more, concentration is high, and the variable x-value is made X by amplification to obtain gas concentration (y) by a high concentration time analytical curve, while gas concentration (y) is obtained by a low concentration time analytical curve at the time of low concentration with the x-value less than 2 V and outputted from an output port 1302 to an LCD 14. |
