| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a gas concentration detector suppressing an increase in cost while improving the precision of a voltage applied to a pump cell and increasing a response speed for setting the concentration of oxygen of a gas to be measured to a required concentration of oxygen. <P>SOLUTION: The gas concentration detector 1 has the pump cell 2A, a sensor cell, and a monitor cell. A pump cell output circuit 4 has: a switching element 41 for receiving the pulse width modulation signal from a control microcomputer 7 to perform switching; a first operational amplifier OP1 for smoothing the pulse voltage converted to a predetermined voltage value by the switching element 41: and a second operational amplifier OP2 connected to the output terminal of the first operational amplifier OP1 to apply a voltage to the electrode of the pump cell 2A. An operational amplifier small in input bias current is used as the first operational amplifier OP1, and an operational amplifier large in output current is used as the second operational amplifier OP2. <P>COPYRIGHT: (C)2009,JPO&INPIT |
