Tridonic Bauelemente Gmbh

Stefan Koch

G&uuml;nter Marent

Norbert Primisser

Stefan Rhyner

Reinhard B&ouml;ckle

An electronic ballast for at least one low-pressure discharge lamp contains an inverter which is connected to a direct-voltage source (U ), a load circuit which is connected to the inverter and contains the lamp (LA) and a series resonant circuit, and an evaluating circuit arrangement (M ) which reacts to different operating states of the lamp (LA) and in the case of a defect or removal of the lamp (LA) generates corresponding signals for switching off the inverter. A heating transformer, for heating the coils (W W ), the primary winding (Tp) of which is connected in series with a switch (S ) to the output of the inverter and in any case is connected to the direct-voltage source (U ) if the inverter is switched off on account of the heating-coil defect or the removal of the lamp (LA), with the switch (S ) being clocked in this off-phase.

Electronic ballast for at least one low-pressure discharge lamp

Process for the recognition of the rectifier effect appearing in a gas discharge lamp (G , G ) and an electronic ballast, for the operation of gas discharge lamps (G , G ), with which such a process finds employment. The electronic ballast includes a monitoring or control circuit (IC ) which monitors an operating parameter of a load circuit (E) of the electronic ballast, whereby this operating parameter corresponds to the lamp voltage or is dependent thereon. The monitoring circuit (IC ) integrates this monitored operating parameter over a full period and determines upon the presence of a rectifier effect if the integration result deviates from a predetermined integration desired value. Further, for the recognition of the rectifier effect, the duration of the positive and negative half-waves of the monitored parameter can be compared.

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Dornbirn, Austria

Stefan Koch