US 7,888,879 B2Granted

Circuit arrangement and method for operating at least one electric lamp

AssigneeOsram Gesellschaft Mit Beschaenkter Haftung

InventorKlaus Fischer

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Abstract

A circuit arrangement for operating at least one electric lamp having an inverter has at least one first and one second bridge transistor arranged in series with one another, a first drive circuit for the first bridge transistor; a second drive circuit for the second bridge transistor; the and second drive circuits being designed to drive the first and second bridge transistors to switch alternately completely on and off during normal lamp operation; and at least one protective apparatus; the at least one protective apparatus being designed, in the case of a value for a reference voltage, which is correlated with the voltage across the bridge transistor which has just been switched off, above a predeterminable limit value, to drive the bridge transistor, which has just been completely switched on, such that it is no longer completely switched on. A related method is also described.

Claims19

Dependent claims

A circuit arrangement for operating at least one electric lamp (EL) having an inverter having at least one first bridge transistor (T3) and one second bridge transistor (T4) which are arranged in series with one another, a first drive circuit (AS1) for the first bridge transistor (T3);

a second drive circuit (AS2) for the second bridge transistor (T4);
the first drive circuit (AS1) and the second drive circuit (AS2) being designed to drive the first bridge transistor (T3) and the second bridge transistor (T4) such that they switch alternately completely on and off during normal operation of the lamp (EL);
and at least one protective apparatus (TS1;
TS2);
characterized in that the at least one protective apparatus (TS1;
TS2) is designed, in the case of a value for a reference voltage, which is correlated with the voltage across the bridge transistor (T3;
T4) which has just been switched off, above a predeterminable limit value, to drive the bridge transistor (T4;
T3), which has just been completely switched on, of the series circuit such that it is no longer completely switched on.

5 more elements

Dependencies are inferred from the claim text.