Frequency controlled quick and soft start gas discharge lamp ballast and

Abstract

A gentle start electronic ballast operates one or more gas discharge lamps in a dimming or non-dimming mode. The ballast has a power supply section and a frequency-dependent control section. A power supply section includes a rectifier circuit, a power boosting circuit, a power factor compensation chip for the ballast, a control circuit to insure startup of the power factor compensation chip on the first haversine produced by the rectifier circuit and an in-rush current limiter that is removed from the operational circuit path of the ballast by the control circuit once the power factor compensation chip is rendered self-sustaining by the power boosting circuit. The control section receives power from the power supply section creating a reference voltage that is applied to a voltage controlled oscillator to develop an output signal the frequency of which varies from an initial high value to a lower operating value through a range that corresponds with the permissible range of power to be applied to the lamps and separately to their filaments as determined by the values of elements employed in a frequency adjustment circuit that is coupled to the oscillator. The output oscillator's signal is thereafter applied to a current limiting, shunted transformer having an air gap and turns ratio that is selected in accordance with the load profile and operating characteristics of the gas discharge lamps to ultimately apply power to the lamps as a function of the frequency of the signal applied to the transformer.