Patent ID: 8713990

Claim:
A gas sensor, comprising: a normal detection element pair which has a first detection element whose temperature is raised and whose resistor value is changed by contact with a detected gas and a first compensation element which is inactive to the detected gas, and outputs a first signal corresponding to a concentration of the detected gas based on a difference between the resistor value of the first detection element and a resistor value of the first compensation element; a reference detection element pair which has a second detection element whose temperature is raised and whose resistor value is changed by contact with the detected gas and a second compensation element which is inactive to the detected gas, and outputs a second signal which is used as a deterioration standard corresponding to the concentration of the detected gas based on a difference between a resistor value of the second detection element and a resistor value of the second compensation element at the time when deterioration of the normal detection element pair is determined; an element housing which has a detection chamber which houses both of the normal detection element pair and the reference detection element pair; a temperature sensor which is placed in the detection chamber and is used for detecting a temperature in the detection chamber; and a correction unit for correcting the first signal of the normal detection element pair and the second signal of the reference detection element pair based on the temperature in the detection chamber detected by the temperature sensor respectively, wherein a first arrangement direction of the first detection element and the first compensation element is parallel to a second arrangement direction of the second detection element and the second compensation element, the normal detection element pair and the reference detection element pair are placed in a direction which is perpendicular to the first arrangement direction and the second arrangement direction, a first sequential order of the first detection element and the first compensation element is reverse to a second sequential order of the second detection element and the second compensation element, the first detection element, the first compensation element, the second detection element, and the second compensation element are placed at apexes of a virtual square, and the temperature sensor is placed at an intersection point of diagonal lines of a virtual square where the first detection element, the first compensation element, the second detection element, and the second compensation element are placed at four apexes of the virtual square.