Rollo device, especially for a sliding roof system

Roller blind device, in particular for a sliding roof system, comprising a roller blind web (3) which can be wound by a winding device at least one end winding core free to a roller blind winding (12), wherein the winding device has at least one to the blind web (3) connected to the constant force spring (10) and a winding (20 ) (for the constant force spring 10), characterized in that the winding (20) around a winding axis (23) is rotatably mounted, wherein at least one or more winding aids (14) are present and are shaped such that at least in a partial region of the Roller blind roll (12) that is flattened oval in cross section wound.