The invention pertains to a window shade with a shade panel, with a rotatable winding shaft 1 for winding up the panel onto the winding shaft 1 to form a roll 2 and for unwinding the panel from this winding shaft 1 to form a panel surface 3, and with a drive M. The invention is characterized in that control means R are provided upline of the winding shaft 1 to vary the rotational speed of the winding shaft in such a way that the winding shaft 1 has several periods in each revolution, where the angular velocity changes in a predetermined manner within each period.