U.S. Philips Corporation

Jurgen M Willaert

Chin Chang

Paulus P Arts

Wilhelmus H Langeslag

A circuit arrangement for operating two or more discharge lamps in parallel, includes a transformer in a resonant load circuit. Each of the lamps is part of a series arrangement of the lamp and a capacitor. The operating frequency is chosen below the frequency for which the phase shift between the voltage and current in the load circuit is minimal. During operation, the amplitude of the current in the load circuit is relatively low so that power dissipation in the load circuit is also very low.

Circuit arrangement

The invention relates to a circuit arrangement for operating a discharge lamp with a high frequency current comprising a power feedback circuit and a electrode preheater. The circuit arrangement comprises an antiboost switch for disabling the power feedback circuit before the lamp has ignited and enabling the power feedback circuit after the lamp has ignited- In accordance with the invention the antiboost switch is also used to enable the electrode preheater before the lamp has ignited and to disable the electrode preheater after the lamp has ignited.

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Eindhoven, Netherlands

Jurgen M Willaert