Patent ID: 6144568
Filing Date: 2000-11-07
Classification: H02M,H05B,Y02B,Y10S

Abstract:
A circuit arrangement for operating electrical lamps witha free-running invertor (WR) with current feedback in a half- or full-bridge circuit,a coupling circuit, which is connected to the invertor (WR) and adapts a high-frequency voltage of the invertor to electrical lamp(s) (La; HG; LL) to be operated,a trigger generator connected to the invertor (WR), witha voltage-dependent switching element (DC1; DC1'),a drive circuit for the voltage-dependent switching element (DC1; DC1'), an output terminal (V) of the drive circuit being connected to the invertor (WR) via the voltage-dependent switching element (DC1; DC1'), and the voltage-dependent switching element (DC1; DC1') turning on and, in the process, oscillation of the invertor (WR) starting as soon as a potential of the junction point (V) between drive circuit and voltage-dependent switching element (DC1; DC1') exceeds a threshold value,wherein the drive circuit essentially comprises a high-pass filter circuit having a capacitor (C1; C1'), and in which an input terminal (W) and the output terminal (V) of the high-pass filter circuit are formed by a first terminal and a second terminal, respectively, of the capacitor (C1; C1'), the high-pass filter circuit additionally has a first resistor (R1; R1'), which is connected to a junction point (V) between capacitor (C1; C1') and the voltage-dependent switching element (DC1; DC1'), and to a reference-ground potential of the circuit.