Patent ID: 6400511
Filing Date: 2002-06-04
Classification: H04N

Abstract:
A method of controlling a square-wave current light source (2) in a projection system (1) having a color wheel (4) with differently colored segments (R, G, B), which square-wave current (I) is controlled to constantly change the polarity of the square-wave current (I), to provide a constant power to the light source (2) from polarity change to polarity change, and to provide each time before changing polarity, a current pulse (Ip, 12, 15, 17, 23) driving the square-wave current (I) to a predetermined current strength (Ipk) which is larger than the current strength in between the current pulses (Ip, 12, 15, 17, 23), characterized by controlling the timing of occurrence (22, 24, 30, 32, 34) of the current pulses (Ip, 12, 15, 17, 23) to constantly coincide in time and, on average, an equal number of times with all colors (R, G, B, Rp, Gp, Bp) of the color wheel.