Patent ID: 7731370
Filing Date: 2010-06-08
Classification: H04N,H05B,Y02B

Abstract:
1. Projection system including a discharge lamp, driving means for operating said lamp with a basic lamp current, wherein the basic lamp current is an alternating current; and color filter means for filtering light emitted from said lamp to generate a light sequence with different colors in sequential color time periods, wherein spoke time periods are arranged in between said color time periods, wherein said driving means provide first current pulses superimposed on said basic lamp current, where each of said first current pulses is generated during one of said color time periods, and second current pulses superimposed on said basic lamp current, each of said second current pulses being generated during one of said spoke time periods, and wherein the amplitude of said first current pulse is selected in relation to a mean current during one half period of said alternating current, said mean current being calculated without regard to the current pulses, such that the ratio of the light output due to said mean current and the light output due to said first current pulse is essentially constant.