Patent ID: 7382093

Claim:
Device for operating a discharge lamp, comprising: a discharge lamp of the short arc type having a silica glass arc tube containing at least 0.15 mg/mm 3 of mercury, a rare gas and a halogen in an amount in the range of from 1×10 −6 μmole/mm 3 to 1×10 −2 μmole/mm 3 , and a pair of opposed electrodes spaced at a distance of at most 2 mm; a feed device which supplies a direct current to the discharge lamp when operation starts and afterwards supplies an alternating current; and control means for ascertaining whether the discharge lamp is in a hot or cold start operating state at the start of lamp operation; wherein at least one of the electrodes has a coil part wound about a rod of the electrode and a melt part formed of a melted front end portion of the coil, the coil part adjoining the melt part, wherein, at the start of operation, the feed device is adapted to supply a direct current to the discharge lamp that is smaller than the rated current and to subsequently increase the direct current to at least the rated current, and wherein the control means establishes a value for at least one of the following parameters according to the ascertained hot or cold start operating state: the value of the direct current which is at least as great as the rated current; the feed duration of the direct current which is at least as great as the rated current.