Patent ID: 8188675
Filing Date: 2012-05-29
Classification: H04N,H05B

Abstract:
1. A method for operating an illumination system comprising the steps: operating a high-pressure discharge lamp with a commutating lamp current (IL), wherein an intermediate phase (ZP) during which the light of the high-pressure discharge lamp is suppressed occurs at least at the end of the commutation half waves, and filtering the light of the high-pressure discharge lamp in a plurality of sequential color segments (A, B, D, E, G, H) in time within the commutation half waves with a color filter system, in which method the lamp current, within one of the intermediate phases at the end of one of the commutation half waves, passes through an intermediate-phase pulse (DP) with a lamp current which is increased in comparison with the mean value of the lamp current variation preceding the intermediate phase in this commutation half wave, and furthermore comprising the steps: changing the lamp current variation of this half wave preceding the intermediate phase in comparison with the immediately preceding half wave of the same polarity so that the light emitted by the illumination system assumes the desired color temperature, and changing the duration and/or amplitude of the intermediate-phase pulse (DP) of this half wave so that the discharge is stabilized, wherein the change in the effect of the intermediate-phase pulse on the electrode temperature at the time of the following commutation and the change in the effect of the lamp current variation preceding the intermediate phase on the electrode temperature at least partially compensate for one another at the time of the following commutation; and in which the lamp current of one of the half waves, before the commutation, passes through a total pulse (DP) which also comprises the intermediate-phase pulse with a lamp current (IL) which is increased in comparison with the mean value of the lamp current variation of the half wave preceding the intermediate phase, wherein a first part of the total pulse lies before the intermediate phase (ZP) and a second part lies within it and the method comprises the steps: changing the duration and/or amplitude of the first part of the total pulse (DP) in comparison with the total pulse (DP) of the immediately preceding half wave of the same polarity so that the light emitted by the illumination system assumes the desired color temperature, changing the lamp current (IL) during the second part of the total pulse (DP) of this half wave so that the discharge is stabilized, wherein the change in the effect of the second part of the total pulse (DP) on the electrode temperature at the time of the following commutation and the change in the effect of the first part of the total pulse (DP) on the electrode temperature at the time of the following commutation at least partially compensate for one another; and in which a change of the adjustment of the duration and/or amplitude of the first part of the total pulse (DP) of this half wave in comparison with a total pulse (DP) of the immediately preceding half wave of the same polarity is compensated for by a change of the lamp current (IL) during the second part of the current total pulse (DP) in such a manner that the integral over the total pulse (DP) of this half wave in comparison with the total pulse (DP) of the preceding half wave of the same polarity deviates maximally by up to 20%.