Illinois Tool Works Inc.

Ken S Foo

Michael A Jacobs

John A Gorczyca

An ionizer includes an alternating current (AC) voltage source having an output outputting a waveform with a positive half-cycle and a negative half-cycle, an electrode electrically coupled to the output of the AC voltage source, a reference proximate the electrode and a sensing circuit. The sensing circuit includes a return current nulling node electrically coupled to the output of the AC voltage source and the reference, a ground node separately electrically coupled to ground, a positive ion current sensor and a negative ion current sensor. The positive ion current sense node is configured to output a positive ion signal proportionate to a sensed positive ion current. The negative ion current sense node is configured to output a negative ion signal proportionate to a sensed negative ion current.

Alternating current monitor for an ionizer power supply

A control circuit for an ionizer controls an output of at least one of a positive voltage direct current (DC) power supply (PS) and a negative voltage DC PS. Each PS is connected to at least one ionizing pin. The control circuit controls the output of the power supplies so as to cause a flow of positive and negative ions from the ionizer and directed towards a target. The control circuit includes a positive PS return current sense resistor that biases the negative voltage PS to decrease the output of the negative voltage PS when the current detected by the positive sense resistor increases and to increase the output of the negative voltage PS when the current detected by the positive sense resistor decreases. The control circuit includes a similar negative PS return current sense resistor and associated bias circuitry for controlling the negative voltage power supply.

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Lansdale, PA, United States of America

Ken S Foo