Patent ID: 6392353
Filing Date: 2002-05-21
Classification: H05B,Y10S

Abstract:
A circuit device for feeding a discharge lamp, comprisinginput terminals for connecting the circuit device to a supply-voltage source, a ballast circuit for generating a lamp current from a supply voltage supplied by the supply-voltage source, a circuit part I, which is coupled to the ballast circuit, for controlling the power consumed by the discharge lamp in dependence upon a dim signal, a circuit part II, which is coupled to the circuit part I, for generating the dim signal, which dim signal has a first value immediately after the ignition, which value corresponds, during stationary operation, to a first value of the power consumed by the discharge lamp, and is maintained at a second value after a predetermined time interval, which value corresponds, during stationary lamp operation, to a second value of the power consumed by the discharge lamp, which second value is lower than the first value of the power consumed by the discharge lamp, a circuit part V which enables a user to set a dim signal to the second value or a third value which, during stationary lamp operation, corresponds to a third value of the power consumed by the discharge lamp, which third value is higher than the second value of the power consumed by the discharge lamp, characterized in that, during the predetermined time interval, the dim signal is adjusted by the circuit part II in such a manner that, during the predetermined time interval, the luminous flux of the discharge lamp differs less than 25% from the luminous flux which, during stationary operation, corresponds to the second power consumed by the discharge lamp.