| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the problems, wherein control, for example, for determining the amount of increase/decrease in the concentration of CO2 by the difference between an initial value when measurement is started and a result detected for each specified time for reducing an error, is not guaranteed, while an absolute value cannot be detected easily by variations, or the like of a sensor in a conventional gas sensor circuit, and influence depending on a usage environment is large. <P>SOLUTION: The sensor circuit comprises: the sensor for selectively detecting gas, such as carbon dioxide; a conversion section for converting the sensor output to a stable level; an A/D converter for converting the output of the conversion section from analog to digital by inputting; and a microcomputer for performing various control, based on the A/D conversion result. When the sensor output becomes abnormal, control is shifted from that by the A/D conversion result of the microcomputer to time control. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
