Method and apparatus for air ionization

Abstract

Ionizing method and apparatus includes a pair of inverters to supply ionizing voltages to ionizing electrodes only during alternate halves of a duty cycle in which one inverter is actuated to operate at high oscillating frequency while the other inverter is inactive, and thereafter in an alternate half of the duty cycle in which the one inverter is inactive and the other inverter is actuated to operate at high oscillating frequency. Each inverter includes a return current path that combines in a common return path in which return currents may be monitored for selective control of one or both of the inverters. Small step-up transformers and other components operating at high oscillation frequency promote confined packaging of high voltage generators for convenient mounting adjacent a pair of ionizing electrodes to reduce lengths of heavily-insulated high-voltage cables between generators and electrodes. Each electrode only operates on one polarity of high voltage derived from half-wave rectified high-frequency oscillations during the actuation of the associated inverter. Closely-spaced mounting of the electrodes adjacent a web of material having net electrostatic charge to be neutralized facilitates alternately supplying ions of each polarity from separate ones of the electrodes to neutralize charge on the web.