Solid state power switch for gas discharge lamps

Abstract

A solid state power switch for gas discharge lamps is disclosed which is capable of providing a bipolar signal to a lamp and which substantially eliminates losses due to switching delays of internal devices. A timing control signal of a predetermined frequency and wave shape is provided to a pair of threshold comparators, which respectively receive a first and second threshold signal such as first and second reference voltages. The first comparator produces an output signal only when the timing control signal is below the first threshold signal and the second comparator provides an output signal only when the timing control signal is above the second threshold signal. The signals from the two comparators are used to control the on time of power switches of opposite polarity. Thus, the time that the control signal is between the two thresholds represents the switching delay interval. By adjusting the two threshold signals relative to each other, a delay interval of any desired duration may be created between the turn off of one power switch and turn on of the other, thus allowing independent and precise control of switching of the power switching devices.