Patent ID: 8603310

Claim:
A gas-concentration/humidity detection apparatus including a gas sensor connected thereto and detecting concentration of a specific component of a subject gas and humidity of air introduced into the gas sensor as the subject gas, wherein the gas sensor comprises: an oxygen concentration detection cell which includes a first solid electrolyte body and a pair of first electrodes formed on the first solid electrolyte body, one of the first electrodes being disposed within a detection chamber into which the subject gas is introduced, and the other first electrode being exposed to an oxygen concentration atmosphere serving as a reference; and an oxygen pump cell which includes a second solid electrolyte body and a pair of second electrodes formed on the second solid electrolyte body, one of the second electrodes being disposed within the detection chamber, and which pumps out oxygen contained in the subject gas introduced into the detection chamber or pumps oxygen into the detection chamber in accordance with current flowing between the pair of second electrodes, the gas-concentration/humidity detection apparatus being characterized by comprising: current control means for detecting a voltage produced between the pair of first electrodes due to a difference between an oxygen concentration within the detection chamber and the oxygen concentration atmosphere that serves as a reference and for controlling the current flowing between the pair of second electrodes such that the voltage produced between the pair of first electrodes becomes equal to a control target voltage; atmosphere determination means for determining whether or not the subject gas is air; voltage setting means for setting the control target voltage to a first voltage and for setting the control target voltage to a second voltage greater than the first voltage when the atmosphere determination means determines that the subject gas is air; first current detection means for detecting a first current which flows between the pair of second electrodes in a state in which the first voltage is produced between the pair of first electrodes; second current detection means for detecting a second current which flows between the pair of second electrodes in a state in which the second voltage is produced between the pair of first electrodes; and humidity detection means for detecting humidity of the subject gas on the basis of the first current detected by the first current detection means when the atmosphere determination means determines that the subject gas is air, and the second current detected by the second current detection means after the first voltage is changed to the second voltage by the voltage setting means.