Abstract: A roller blind for a window features a fixed shaft and a one-way bearing received thereon which is arranged for rotational motion about the fixed shaft in only one rotational direction. A tube is received over the bearing and is arranged for rotational motion relative thereto. The roller blind also features a torsion spring received on the shaft, having longitudinally opposing spring ends respectively coupled to the tube and the fixed shaft. A screen is arranged to be wound about the tube in the rotational direction of the bearing. Furthermore, the screen has a free end with a weighted element coupled thereto. As such, the free end of the screen is positioned at a stable height by mechanism of a frictional interface between the tube and the bearing, a torsion force of the torsion spring, and a weight of the weighted element.