Osram Ag

Patent-treuhand-gesellschaft Fur Elektrisch Gluhlampen Mbh

Wolfgang Langgaβner

Axel Pilz

Marcus Skatulla

A circuit arrangement for operating a discharge lamp including an inverter, which at its output provides a signal with a preselectable frequency; at least one lamp inductance between the output of the inverter and the discharge lamp; at least one capacitor and, coupled to the lamp inductance, an actuating device for actuating the inverter with the signal; a control device for controlling a control parameter which is dependent on the lamp current, wherein the control device has a first time constant; wherein the discharge lamp has a second smaller time constant; the circuit arrangement has at least one area with a first and a second stable operating point and between these an unstable region of operation, and the actuating device varies the preselectable frequency during the operation of the discharge lamp in such a way that the circuit arrangement is operated in the unstable region of operation.

Circuit arrangement and method for operating a discharge lamp

A light regulation device includes at least one light sensor which provides at its output a real brightness value, at least one regulator to which a set brightness value can be supplied, besides the real value, and a number n of output connections, n being greater than or equal to two. Each output connection is coupled to the output of a regulator in order to modify the light flux which can be supplied to at least one of the lighting elements. The regulator is designed to determine a difference between set and real values, to verify whether this difference lies within or outside a predeterminable tolerance range, and, in the event that the difference lies outside the tolerance range, to modify accordingly the light flux from the lighting elements which can be connected to the n output connections. At least one limit of the tolerance range depends on the actual light flux value.

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Bad Aibling, Germany

Wolfgang Langgaβner