Patent ID: 6568774
Filing Date: 2003-05-27
Classification: H05B,Y02B

Abstract:
An operating method for a discharge lamp (L) with a dielectric layer between at least one electrode and a discharge medium,which method uses a ballast having a power-supplied primary circuit (P), a secondary circuit (S) containing the discharge lamp (L), and a transformer (T) connecting the primary circuit (P) to the secondary circuit (S), and in which method a voltage pulse is impressed on the secondary circuit (S) from the primary circuit (P) via the transformer (T) using the forward transformer principle and leads to an external voltage (UL) across the discharge lamp (L) which effects ignition, and to an internal counterpolarization in the discharge lamp (L), characterized in that, after the impression of the voltage pulse, the secondary circuit (S) executes a half wave by means of which the charge effecting the external voltage (UL) across the discharge lamp (L) is removed from the discharge lamp (L), as a result of which the discharge lamp (L) is caused to execute a back ignition owing to the remaining internal counterpolarization, and in that an inductance (LW1, LW2) governing the temporal variation in a current (IW1, IW2) through the transformer (T) is varied temporally within a period including a forward ignition and a back ignition such that the altered inductance (LW1, LW2) is substantially larger in an initial phase of the impression of the voltage pulse which leads to the forward ignition than in at least a portion of the back ignition phase, in which the charge is removed from the discharge lamp (L) after the forward ignition and the back ignition is performed.