A rotary drive device for a winding shaft of a seat belt retractor has preformed drive bodies arranged one behind the other, which are guided and can be driven in a guide path. A feed in device feeds to the extrusion apparatus material that is to be extruded. Then, image data corresponding to the information data is generated by processing the received information data, and image data to be displayed on said display unit is switched to the image data corresponding to the information data from the image data corresponding to the partial data after the reception of the information data is started.