How does Intense Field Dielectric air filter work?


I’m currently cleaning my AC filter unit and was curious about the middle plate with needles. It is exactly the set-up in the image on the top left:

As far as I know, it’s supposed to give charge to the particles in the air. The charged particles then pass though a filter that has the opposite charge, which attracts the oppositely charged particles, giving filtered air.

But HOW does the needle and metal plate give the air particles charge? Why is it a needle instead of a cylinder?

In: Engineering

Very high voltage is applied to the spikes, the spikes create a very intense electric field at the sharp point, this field can pull electrons from the dust particles which changes the electrical charge on the dust particles which allows them to be attracted to an opposite charge.