Circuit arrangement for electrode pre-heating of a fluorescent lamp

A circuit arrangement for pre-heating electrodes of at least one flourescent lamp operated with electronic ballast equipment, said electrodes being respectively disposed at opposite ends of said flourescent lamp, the circuit arrangement comprising:

• means for supplying a stabilized intermediate circuit voltage;
• inverter means for emitting a half-bridge voltage in the form of a high frequency pulse sequence, said inverter means having an input connected to said means for supplying a stabilized intermediate circuit voltage and having an output;
• a load circuit including a lamp throttle, connected to a first of said electrodes, an ignition capacitor connected across said electrodes, and a half-bridge capacitor connected to a second of said electrodes, said load circuit connected between said output of said inverter and a ground reference potential;
• a switchable voltage source including a transformer having a primary winding, connected to said output of said inverter and to said ground reference potential, said switchable voltage source further comprising secondary windings having outputs connected in parallel with said electrodes, said secondary windings having a synchronized winding direction;
• and
• means, connected to said switchable voltage source, for activating said switchable voltage source during a predetermined pre-heating period of said electrodes.