Particulate matter detection apparatus

A particulate matter detection apparatus that detects particulate matter contained in a gas to be measured, the particulate matter detection apparatus comprising:

• a sensor unit that includes a detecting unit in which a pair of electrodes that are separated from each other are arranged on a surface of a substrate that is exposed to the gas to be measured, and outputs a signal based on an amount of particulate matter that is electrostatically collected in the detecting unit;
• and
• a sensor control unit that detects a particle count of the particulate matter that is electrostatically collected in the detecting unit, based on a sensor output that is transmitted from the sensor unit, wherein
• the sensor control unit includes
• a collection control unit that applies a first voltage between the pair of electrodes of the detecting unit and electrostatically collects the particulate matter in the detecting unit, and
• a particle count calculating unit that, after changing the applied voltage between the pair of electrodes to a second voltage that differs from the first voltage in a state in which the sensor output at the first voltage has reached a threshold, detects resistance values between the pair of electrodes at a plurality of voltages of which the magnitude differs, and calculates the particle count using an average particle diameter of the particulate matter that is estimated from the resistance values and a mass of the particulate matter that is estimated from the sensor output.

A particulate matter detection apparatus that detects particulate matter contained in a gas to be measured, the particulate matter detection apparatus comprising:

• a sensor unit that includes a detecting unit in which a pair of electrodes that are separated from each other are arranged on a surface of a substrate that is exposed to the gas to be measured, and outputs a signal based on an amount of particulate matter that is electrostatically collected in the detecting unit;
• and
• a sensor control unit that detects a particle count of the particulate matter that is electrostatically collected in the detecting unit, based on a sensor output that is transmitted from the sensor unit, wherein
• the sensor control unit includes
• a collection control unit that applies a first voltage between the pair of electrodes of the detecting unit and electrostatically collects the particulate matter in the detecting unit, and
• a particle count calculating unit that, after changing the applied voltage between the pair of electrodes to a second voltage that differs from the first voltage in a state in which the sensor output at the first voltage has reached a threshold, detects resistance values between the pair of electrodes at a plurality of voltages of which the magnitude differs, and calculates the particle count using an average particle diameter of the particulate matter that is estimated from an inclination in a relationship between the plurality of voltages and the resistance values, and a mass of the particulate matter that is estimated from the sensor output.

A particulate matter detection apparatus that detects particulate matter contained in a gas to be measured, the particulate matter detection apparatus comprising:

• a sensor unit that includes a detecting unit in which a pair of electrodes that are separated from each other are arranged on a surface of a substrate that is exposed to the gas to be measured, and outputs a signal based on an amount of particulate matter that is electrostatically collected in the detecting unit;
• and
• a sensor control unit that detects a particle count of the particulate matter that is electrostatically collected in the detecting unit, based on a sensor output that is transmitted from the sensor unit, wherein
• the sensor control unit includes
• a collection control unit that applies a first current between the pair of electrodes of the detecting unit and electrostatically collects the particulate matter in the detecting unit, and
• a particle count calculating unit that, after changing the applied current between the pair of electrodes to a second current that differs from the first current in a state in which the sensor output at the first current has reached a threshold, detects a resistance value between the pair of electrodes, and calculates the particle count using an average particle diameter of the particulate matter that is estimated from the resistance value and a mass of the particulate matter that is estimated from the sensor output.