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 lighting device comprising a lamp comprising a burner with an ionizable filling and an amount of mercury contained herein, having at least one mercury absorbing/adsorbing and/or blocking means located outside the burner for the fixation of mercury in case of an explosion of the burner.

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.

Abstract: The present invention relates to a ceramic gas tight high-pressure burner (1) comprising an ionisable filling, a method of manufacturing said ceramic gas tight high-pressure burner (1), and a lamp comprising said ceramic gas tight high-pressure burner (1), whereby said ceramic gas tight high-pressure burner (1) comprises a discharge vessel (2) having a discharge cavity (3) with a C)volume in the range of 3 mm3 to 30 mm3, and an internal filling pressure of the discharge cavity (3) in the range from 0.1 MPa to 4 MPa at room temperature. Furthermore the present invention relates to an end closure construction designed as a three-part, a two-part or a one-part end closure device (4) with a reduced crevice (11).