Patent ID: 8578756

Claim:
A particulate matter detection sensor comprising a sensor element capable of detecting particulate matter of conductive characteristics contained in a target detection gas, the sensor element comprising: a substrate; a pair of detection electrodes formed on the substrate, the detection electrodes facing to each other; a temperature detection resistance formed in a conductive path between the pair of the detection electrodes, a temperature of the sensor element being detected on the basis of a resistance value of the temperature detection resistance; and a switching means making a first state and second state, in the first state no current flowing through the temperature detection resistance and a quantity of particulate matter accumulated in the sensor element being detected, and in the second state a current flowing through the temperature detection resistance and a temperature of the sensor element being detected during the second state, and a quantity of particulate matter accumulated between the detection electrodes being detected on the basis of a change of the resistance value between the detection electrodes caused by the accumulated particulate matters of conductive characteristics; wherein the switching means is comprised of a capacitor, the capacitor is connected in series to the temperature detection resistance formed in the conductive path, and the capacitor as the switching means receives one of a direct current signal and an alternating current signal supplied from an electric power source through the pair of the detection electrodes, and the capacitance as the switching means makes the first state when receiving the direct current signal which is supplied from the electric power source to the pair of the detection electrodes, and makes the second state when receiving the alternating current signal which it supplied from the electric power source to the pair of the detection electrodes.