Device for operating a high pressure discharge lamp

Abstract

A device which improves the starting of a high pressure discharge lamp containing a large amount of mercury, in which the amount of mercury adhering to the lamp electrodes is not the same, by shortening the formation time of the glow discharge in order to reduce the sputtering of the electrodes to a minimum. When the discharge lamp starts, an AC voltage with rectangular waves produced by the full bridge circuit is applied to the discharge lamp. Next, a high voltage pulse is superimposed and applied by an igniter device; the pulse is synchronized to the polarity of the above described AC voltage with rectangular waves. As a result, an alternating current discharge is started in the discharge lamp. Then, the ON/OFF state of the switching devices in the full bridge circuit is fixed and a direct current voltage is applied to the lamp. After a pre-selected time has expired after the transition into direct current operation, the full bridge circuit is operated such that rectangular alternating current waves form. The AC voltage with rectangular waves is then applied to the discharge lamp and a transition into steady-state operation is carried out.

Dependencies are inferred from the claim text.