Circuit arrangement for starting and operating a high-pressure gas discharge lamp operating by controlled alternating current

Abstract

A direct voltage source (1) delivers a voltage (U.sub.B) at its output terminals, which is then converted by a direct voltage/direct voltage converter (2) to a higher value. This higher voltage value (U.sub.D) constitutes the input voltage for a controlled full bridge circuit (3), which generates a controlled alternating current (I.sub.L) or an alternating voltage (U.sub.L) from the supplied input voltage. This alternating voltage is present at the output terminals (4, 5) and constitutes the supply voltage for a high-pressure gas discharge lamp. A control circuit (7), which supplies its control pulses via a line (8) is provided to control the full bridge circuit. In addition, an ignition circuit (9) is provided, which supplies the ignition voltage via the line (10) to the high-pressure gas discharge lamp (6). In accordance with the invention, the full bridge circuit (3) is controlled by the control circuit (7) in such a way that the duration of the half-wave phases of the lamp voltage (U.sub.L) or the lamp current (I.sub.L) is variable. In this case, the variability is selected in dependence on the respective temperature of the electrodes (11, 12) of the high-pressure gas discharge lamp.

Dependencies are inferred from the claim text.