The invention relates to an illumination system (100), a projection device, and a color wheel (20, 22, 24). The illumination system comprises a light source comprising a first light-emitting unit (50) and a second light-emitting unit each emitting light towards a light output window (110). The illumination system comprises the color wheel including a spoke (40) between two adjacent color segments. The system is configured to prevent the spoke when transiting the optical path (80) between the light source and the light output window to simultaneously transit a first optical path between the first light-emitting unit and the light output window and a second optical path between the second light-emitting unit and the light output window. The illumination system further comprises a drive unit (92) which is configured for switching off the first light-emitting unit during a time interval (p1) when the spoke transits the first optical path.