Patent ID: 6933681

Claim:
A circuit arrangement for starting and operating discharge lamps (L, Lp 1 , Lp 2 ), with the following features: a first and a second line terminal (J 1 , J 2 ) for the connection of a line voltage, a rectifier (D 1 , D 2 , D 3 , D 4 ), the rectifier input of which is coupled to the line terminals and at the rectifier output (N 21 ) of which the rectified line voltage is present, the rectifier output (N 21 ) is coupled to an electronic pumping switch (UNI, D 7 , D 8 ), with the effect of forming a first pumping node (N 1 , N 23 ) at the electronic pumping switch (UNI, D 7 , D 8 ), the side of the electronic pumping switch facing away from the rectifier output (N 21 ) is coupled to a main energy store (C 3 ), the main energy store (C 3 ) supplies energy to an inverter (INV), which produces at an inverter output (N 25 , N 26 ) an inverter voltage which has an inverter frequency that is much higher than the frequency of the line voltage, the inverter output (N 25 ) is coupled to the first pumping node (N 1 , N 23 ) via a pumping network (PN, L 3 , C 6 , C 7 ), discharge lamps (L, Lp 1 , Lp 2 ) can be connected to the inverter output (N 25 ) via a matching network (MN, L 3 , C 6 , C 7 ), which has a resonant circuit (L 3 , CE, C 7 ) with a natural frequency, a controller (CONT), the controller output of which outputs an actuating signal, the controller output being coupled to the inverter (INV) in such a way that the actuating signal influences the inverter frequency, a first controller input (B 1 ), into which there is fed a first electrical variable, which corresponds to a first operating variable, a second controller input, into which there is fed via a threshold switch (TH, MOV), a second electrical variable, which corresponds to a second operating variable (B 2 ), which is a measure of the reactive energy that resonates in the resonant circuit (L 3 , C 6 , C 7 ), the value of the second electrical variable bringing about a greater value of the inverter frequency if the threshold value of the threshold switch (TH, MOV) is exceeded.