Abstract: A method and a circuit arrangement for operating a discharge lamp, in particular during the first hours of operation after lamp manufacture, are described. The method and the circuit arrangement are provided in particular for high-pressure gas discharge lamps (HID or high intensity discharge lamps or UHP or ultra high performance lamps). Furthermore, a lighting unit with a discharge lamp and such a circuit arrangement and a projection system with a projection display and such a lighting unit are described. Switching-over between various modes of operation with different operating frequencies serves to avoid that the burning voltage of the lamp drops into a region of a minimum voltage of a lamp driver unit below which the latter can no longer drive the lamp with its rated power or a desired power.

Abstract: The invention relates to a lamp, e.g. a UHP-Lamp, comprising a burner (10) with an ionizable filling and an amount of mercury contained therein, having a housing (30, 60; 20, 30) with at least one port (40), whereby the inner opening surface (50) area of the port/s is adapted to reduce the amount of mercury which is able to expose to the outside after an explosion of the burner (10).

Abstract: The invention relates to a cooled high-pressure gas-discharge lamp, at least comprising a cooled envelope (43) that seals off hermetically a discharge chamber (431) filled with a gas, there being, at least in the discharge chamber (431), a non-uniform temperature distribution at the time of the gas discharge, and comprising a cooling means (7) having a coolant, which cooling means (7) produces a directed flow (9) of coolant, there being a liquid coolant acting on the envelope (43) of the lamp, it being possible for the lamp to be operated at a higher power, and the flow (9) of coolant being such that, when the power consumption of the lamp is increased, any devitrification of the envelope (43) of the lamp and any condensation of the gas is substantially prevented.

Abstract: A cooling unit (2) having a pump (20) for generating an airflow is provided for cooling a High Power lamp (10) during operation. The value of the airflow is controlled by a control unit (3) which comprises a driver (30) for determining a required value of the airflow on the basis of the operating power of the lamp (10). The control unit (3) comprises two pressure sensors (32, 33) for measuring a pressure of the airflow as well as a pressure drop of the airflow across an orifice (31). The driver (30) is designed for processing the measuring results in order to determine an actual value of the airflow. The value of the airflow is accurately controlled by adjustment of the power supply to the pump (20) in order to obtain a match of the actual value of the airflow and the required value of the airflow.