Patent ID: 6566822
Filing Date: 2003-05-20
Classification: H05B,Y10S

Abstract:
An electronic operating device for operating one or more gas discharge lamps which contain filaments, the operating device comprising:a first circuit part (SD) which employs a signal at its input (EDC) to the effect that in the event of overshooting or undershooting of prescribed thresholds over the prescribed period the operating device is put into a safe state which is intended to prevent overloading of the operating device and/or overheating of the lamps and/or putting people at risk of electric shock, said first circuit part (SD) includes a controlled switch (T4) which permits a capacitor (C7) to be charged upon undershooting of a voltage threshold at its control electrode and, upon overshooting of the voltage across this capacitor (C7) beyond a prescribed value, this operating device is put into a safe state, an AC voltage generator (G), which outputs at its output (O) an AC voltage which has a DC voltage component, and a load circuit which includes at least one capacitor (C5) which at least partially absorbs said DC voltage component, wherein, the voltage across said capacitor (C5) is fed to said input (EDC) of the first circuit part (SD), specifically via at least one filament and via a second circuit part (AV) which supplies a signal which corresponds at least approximately to the mean value of the voltage across said capacitor (C5), said input (EDC) of the first circuit part (SD) having, apart from via the lamp, no electrical connection to the output (O) of the AC voltage generator (G).