Patent ID: 6100644
Filing Date: 2000-08-08
Classification: H05B

Abstract:
An electronic ballast for operating a lighting load of at least two fluorescent lamps, said ballast comprising:(a) a protection and noise filter circuit arranged to be connected to an AC power source for generating a filtered AC power signal;(b) a rectifier and DC filter circuit coupled to said protection and noise filter circuit to provide two independent levels of DC power from said filtered AC power signal;(c) a voltage-to-frequency circuit coupled to said rectifier and DC filter circuit, said voltage-to-frequency circuit using one of said two levels of DC power to generate an output signal of a high frequency;(d) an inverter circuit coupled to said rectifier and DC filter circuit and to said voltage-to-frequency circuit, said inverter circuit being activated by said output signal to generate a lamp power signal of said high frequency from said other level of DC power provided by said rectifier and DC filter circuit; and(e) an output circuit coupled to said inverter circuit and comprising an output transformer coupled to said lamps and arranged for maintaining a constant voltage of said lamp power signal independent of changes to said high frequency.