An IrOx film is formed as a first conductive oxide film on a PLZT film by a reactive sputtering method. The hydrocarbon adsorbent state determining apparatus determines the state of a hydrocarbon adsorbent disposed in an exhaust system of an internal combustion engine for adsorbing hydrocarbons and moisture within exhaust gases. The system automatically tracks the selected pixel objects in the preceding and succeeding video frames by determining range limits for various color variables of the selected pixel object to compensate for the effects in lighting changes and decompression effects. An upper limit is set on the current that is to be input to the TIA from the sensor, and respective values of the resistor and the capacitor are chosen, responsively to the characteristic duration of the pulses and the selected voltage, to prevent the current input to the TIA from exceeding the upper limit. The head restraint is movable in a direction generally perpendicular to the body of the patient.