| 摘要 |
PURPOSE:To obtain a small-size, inexpensive device capable of detecting the kind and density of the number of specific kinds of gas by comparing a spectrum calculated by using one or plural semiconductor gas detecting elements with a stored spectrum. CONSTITUTION:A digital control signal (n) from a microprocessor 82 is converted by a D/A converter 83 into v(n), which is supplied to a heater 85 through a voltage follower 84 to obtain the temperature T(n) of a gas detecting element 81. Then, the variation in conductivity of the element 81 by gas detection is converted into the drop of a measurement voltage VS across a series resistance 86 and this is amplified by an operational amplifier 87 to obtain an analog voltage vs, which is converted by an A/D converter 88 into a digital signal v*(n) and stored in the microprocessor 82. Then, measurement data sequence V*(n) is normalized to obtain a detection spectrum V(n). Then the spectrum V(n) is compared with the previously stored spectrum P(n) for standard gas to indentify the kind of gas and the gas density is obtained from measurement data V*(n) corresponding to the identified kind of gas. |
