| 摘要 |
PURPOSE:To detect an aimed gas (CH4) with high accuracy, by adding two series resistance and compensating resistance to a bridge circuit connected so that the outputs of both sensors may become differential by two kinds of gas sensors and two resistors. CONSTITUTION:Resistors pi5, pi6 are connected in parallel with the first gas sensor pi1 and a resistor pi2 which are connected in series and a compensating resistor pi0 is inserted between a connecting point (c) of the gas sensor pi1 and the resistor pi2 and a connecting point (b) of the resistors pi5, pi6. An output V is generated between a connecting point (a) of the second gas sensor pi3 with a resistor pi4 and the connecting point (b). Resistance values of the resistors pi5, pi6 are selected so as to satisfy the following equation pi5/pi6=pi1/pi2 (=pi3/pi4) in the air. When either CH4 or H2 is mixed in the air, electric potential of the connecting points c and b, is displaced but the variation rate of the connecting point (b) is lowered by the resistor pi0. Then, the sensor pi1 desired to cancell for one gas (H2) is made accorded with the sensor pi3 by selecting suitably the value of the resistor pi0, and the aimed gas (CH4) is detected with high accuracy. |
