Abstract: A dimming circuit provides power from an ac source to a compact fluorescent lamp. The circuit generally includes a resonant circuit driven by a high-frequency switching inverter and a current feedback control system. The circuit is essentially an ac current source of unusually high impedance and provides substantially symmetrical high-frequency current to the lamp. This allows flicker-free dimming of compact fluorescent lamps over a wide range with good light output stability. A small amount of dc or low-frequency ac current may be simultaneously provided to the lamp. The resulting composite current waveform flowing through the lamp substantially eliminates visible striations over a dimming range from about 100% to 1% of full light output.

Abstract: A dimming circuit provides power from an ac source to a compact fluorescent lamp. The circuit generally includes a resonant circuit driven by a high-frequency switching inverter. The resonant circuit is essentially an ac current source and provides sinusoidal current to the lamp, which loads the resonant circuit in parallel. A small amount of dc current is simutaneously provided to the lamp. The resultant asymmetric current waveform flowing through the lamp substantially eliminates striation over a dimming range from about 100% to 1% of full light output.