Patent ID: 6104142
Filing Date: 2000-08-15
Classification: H05B

Abstract:
A circuit arrangement for the high-frequency operation of a low-power low-pressure discharge lamp (LP) from an AC voltage source, the circuit arrangement having the following features:a mains rectifier (2) with a downstream DC link capacitor (C2),a half-bridge circuit which is connected to the DC output of the mains rectifier (2) and has two alternately switching transistors (T1,T2) and a drive circuit, a center tap (M1) being provided between the two transistors (T1,T2),a series resonant circuit which is assigned to the low-pressure discharge lamp (LP) and comprises a resonance inductor (L1) and a resonance capacitor (C6),connecting lines for the low-pressure discharge lamp (LP), a line connecting the first electrode (E1) of the lamp (LP) via the resonance inductor (L1) to the center tap (M1) between the two transistors (T1,T2), and in each case a further line connecting the second electrode (E2) of the lamp (LP) to the positive or negative pole of the mains rectifier (2),whereina diode (D1) is connected in series and in the DC non-conducting direction in the connecting line between the second electrode (E2) of the lamp (LP) and the positive or negative pole of the mains rectifier (2), and a tap (M2) between the diode (D1) and a direct connection to the second electrode (E2) is connected via a capacitor (C1) to the other pole of the mains rectifier (2).