Drive device for driving a roller blind device of a frameless vehicle window

A roller device for a frameless vehicle window of a vehicle, comprising a roller curtain which can be wound up and unwound on a winding shaft between a cover position and a release position, and a drive device for driving the roller curtain of the frameless vehicle window, wherein the drive device comprises a drive rod with an upper roller end for the fixation to a curtain rod of the roller curtain and a lower covering end, wherein the drive rod is movably supported between the cover position and the release position, wherein the drive device further comprises a drive drum assembly that comprises a first drum section and a second drum section, and an at least partially flexible drive element that comprises a first drive element subsection and a second drive element subsection, wherein the first drive element subsection is fixed at a first end to the covering end of the drive rod and at a second end to the first drum section, and at least partially wraps around the first drum section in a force-transmitting manner for transmitting a drive force to the drive rod for a movement of the drive rod between the release cover position and the cover position during a rotation of the first drum section to drive the roller curtain between the release position and the cover position, and wherein the second drive element subsection is fixed at a first end to a winding drum of the winding shaft of the roller device and at a second end to the second drum section, wherein a center of the first drum section is offset laterally from the drive rod along an axis parallel to the curtain rod, and the laterally offset first drum section rotates about a rotation axis that is perpendicular to the curtain rod.