Koninklijke Philips Corporation N.v.

Jan Alfons Julia Stoffels

Holger Joachim Moench

Pavel Pekarski

Wouter Jozef Maes

Edmond Mariette Emile Verstraeten

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.

Method and circuit arrangement for operating a discharge lamp

A cooling unit () having a pump () for generating an airflow is provided for cooling a High Power lamp () during operation. The value of the airflow is controlled by a control unit () which comprises a driver () for determining a required value of the airflow on the basis of the operating power of the lamp (). The control unit () comprises two pressure sensors () for measuring a pressure of the airflow as well as a pressure drop of the airflow across an orifice (). The driver () 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 () in order to obtain a match of the actual value of the airflow and the required value of the airflow.

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Turnhout, Belgium

Jan Alfons Julia Stoffels