Patent ID: 7170235

Claim:
Circuit arrangement for operating a high pressure discharge lamp, equipped with a DC-AC-converter comprising input terminals for connection to a supply voltage source for supplying a first DC voltage, a first series arrangement of a first and a second switching element coupled between the input terminals, a first control circuit, coupled to respective control electrodes of the first and second switching element, for controlling the conductive state of the first and second switching elements, a load circuit shunting one of the switching elements and comprising a first inductive element and terminals for lamp connection, characterized in that the circuit arrangement is further equipped with a resonant capacitive element coupled between the terminals for lamp connection, a second inductive element coupled in series with the resonant capacitive element, a third switching element coupled between a terminal of the second inductive element and one of the input terminals, and a second control circuit coupled to a control electrode of the third switching element for rendering the third switching element alternatingly conductive and non-conductive with frequency f and thereby generating an AC ignition voltage over the resonant capacitive element.