Polymer film electret air filter

Claim 1

An electret air filter adapted as an adjunct to a room air conditioner having filtering means for removing large particles and comprising a duct having an admission end connected to the output of a room air conditioner for developing an air flow through the duct, and an exit end, means for electrically charging smaller particles not removed by the air conditioner filtering means and which may be in the air flow in the duct, and at least one thin film of permanently electrically charged polymer material disposed within and across said duct and oriented perpendicular to the air flow therein, said thin film being of thickness in the range of 0.25 to 10 mils, said thin film provided with a plurality of randomly spaced, randomly sized small holes therethrough for passage of the air to the exit end of said duct, the small holes being of size in a range of 1 to 1,000 microns and of spacing to obtain 103 to 104 holes per square inch, electrostatic fields produced by fringe effects around the small holes by the permanent charge on the polymer film being in the order of 10 volts per mil thickness of polymer film and causing electrostatic collection of the charged particles on the polymer film so that the air flow from the exit end of said duct has a significantly smaller amount of the particles as compared to the air flow at the admission end.