Koninklijke Philips Corporation N.V.

U.S. Philips Corporation

Hendrik W J De Groot

Thomas A J Haus

Petrus C J Laros

A power supply arrangement is provided for supplying power to a plurality of back and/or edge illumination devices () in a liquid crystal display unit (), comprising a mains connection (), a power converter () and at least one inverter (). The power converter () is arranged to convert an AC voltage input to a DC voltage output, and the inverter () is connected to said DC voltage output, and arranged to convert said output to a DC voltage level adequate for driving said illumination devices (). Furthermore, the inverter () is provided with mains isolation. By virtue of this arrangement, no conventional adapter is required, and the LCD can be connected directly to the mains. The conversion down to a low DC voltage is eliminated, without violating the current-limitation safety requirements. This leads to a more effective power supply.

Inverter for liquid crystal display, and power supply arrangement comprising such an inverter

A ballast circuit includes an equalizer transformer for equalizing current between two or more lamps operated in parallel, combined on one core with a choke. In a 2-lamp embodiment, four windings are provided on one main core. The first and second are closely coupled and have N turns each, each connected separately to one of the lamps. A third and fourth winding are loosely coupled with respect to each other, and are arranged symmetrically about the first and second windings on the main core. These latter windings may be connected in series or in parallel to be an inductive impedance in the ballast circuit.

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Eindhoven, Netherlands

Hendrik W J De Groot