Smoke detection using change in permittivity of capacitor air dielectric

A smoke detector using an air dielectric capacitor as a smoke sensor, said smoke detector comprising:

• an air dielectric capacitor having a plurality of plates, wherein when clean air flows over surfaces of the plurality of plates the air dielectric capacitor has a first capacitance value and when smoke is in the air flowing over the plurality of plates the air dielectric capacitor has a second capacitance value;
• a capacitance change detection circuit coupled to the air dielectric capacitor, wherein the capacitance change detection circuit determines when the air dielectric capacitor changes from the first capacitance value to the second capacitance value;
• and
• an alarm circuit coupled to the capacitance change detection circuit, wherein when the capacitance change detection circuit indicates that the first capacitance value has changed to the second capacitance value the alarm circuit is actuated, otherwise the alarm circuit is not actuated.

A method for detecting smoke in air, said method comprising the steps of:

• flowing clean air over a plurality of plates of an air dielectric capacitor;
• determining a capacitance value of the air dielectric capacitor when the clean air is flowing over the plurality of the plates of the air dielectric capacitor;
• detecting an increase in the capacitance value of the air dielectric capacitor indicating smoke in the flowing air;
• and
• generating a smoke alarm when the increase in the capacitance value of the air dielectric capacitor is detected.

A method for detecting smoke in air, said method comprising the steps of:

• flowing air over a plurality of plates of an air dielectric capacitor;
• detecting when an increase in a capacitance value of the air dielectric capacitor occurs, thereby indicating smoke in the flowing air;
• and
• generating a smoke alarm when the increase in the capacitance value of the air dielectric capacitor is detected.