Patent ID: 8008872
Filing Date: 2011-08-30
Classification: H04N,H05B,Y02B

Abstract:
1. A method of shutting down a high pressure discharge lamp ( 1 ) in which a pair of electrodes ( 2 ) is disposed in an arc tube ( 3 ), which method comprises reducing, upon receipt of a shut-down request (SR), the lamp power (P) towards a reduced power level (PR) required to sustain a long-term arc discharge between the electrodes ( 2 ), and driving the lamp ( 1 ) towards the reduced power level (PR) for a reduced power duration before completely shutting down the lamp power (P), whereby, prior to reducing the lamp power (P) towards the reduced power level (PR), the lamp power (P) is reduced to an undershoot power level (PU), which undershoot power level (PU) is lower than the reduced power level (PR) required to sustain a long-term arc discharge between the electrodes (