Patent ID: 8333875
Filing Date: 2012-12-18
Classification: G01N

Abstract:
1. A sensor control device for controlling the operation of a sensor element made up of solid polymer electrolyte capable of detecting a concentration of a specific gas component contained in a target gas in a wide detection range, comprising: a current detection resistance for detecting a current flowing in the sensor element and generating a terminal voltage which corresponds to the detected current; an amplification circuit comprised of an operational amplifier, an input resistance and a feedback resistance, the input resistance and the feedback resistance being connected to the operational amplifier, a positive or negative input signal terminal of the operational amplifier inputting an element current signal as the detected terminal voltage at the current detection resistance, and the operational amplifier amplifying the element current signal on the basis of a ratio between the input resistance and the feedback resistance; an offset setting circuit for flowing an offset current in a connection node between the input resistance and the feedback resistance in the amplification circuit in order to offset an output signal of the operational amplifier on the basis of the offset current; and offset switching device for switching the offset determined by the offset setting circuit on the basis of the element current signal, which is continuously supplied from the sensor element, regarding the concentration of the specific gas component contained in the target gas; wherein the amplification circuit comprises a first resistance which is always at least part of the input resistance, and a third resistance which is always at least part of the feedback resistance, and a second resistance which is selected by the offset switching device to become part of either the input resistance or the feedback resistance, the input resistance and the feedback resistance being selected by an amplification factor switching device in order to determine the amplification factors of the amplification circuit.