U.S. Philips Corporation

Etienne N Eberson

Arnold Willem Buij

Antonius A Marinus

Paulus P Arts

A ballast for a compact fluorescent lamp includes a down-converter for operating the lamp with a DC current during stable operation and a charge pump for igniting the lamp. The converter includes an inductor and a first series circuit of a first diodie and a first switching element. An output capacitor shunts the lap terminals. The charge pump includes a second series circuit of second diodie and a second switching element coupled to the lamp terminals with the second diode polarized to prevent the discharge of the output capacitor when the second switching element is conductive. The inductor cooperates with the first and second diodes and the second switching element to build up the voltage across the outpout capacitor to the ignition voltage level of the lamp.

Discharge lamp ballast circuit with charge pump igniter

A circuit for supplying a discharge lamp, comprising a converter for generating a high-frequency current at a frequency f from a supply voltage and a circuit portion I for adjusting the power consumed by the discharge lamp through adjustment of the frequency. The circuit portion I is provided with a circuit portion II for low-frequency square-wave modulation of the frequency f and for the adjustment of the duty cycle of the square-wave modulation. As a result, the discharge lamp can be dimmed over a very wide range without striations or moding occurring and without undesirable shifts in the color point of the light.

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Eindhoven, Netherlands

Etienne N Eberson