Constant Surface Speed implementation

Any kind of speed / distance measurement will be disturbed by dust etc. building up on a roller. And you must avoid any kind of "unbalanced" stress in your foil, otherwise it will not rollup "true".

Found an old image that shows a bit of such equipment:
www.eitel.ch/job/digitran/Image10.jpg

Mike_Eitel wrote: Any kind of speed / distance measurement will be disturbed by dust etc. building up on a roller. And you must avoid any kind of "unbalanced" stress in your foil, otherwise it will not rollup "true".

Good point. So either optical distance or full-width sense rollers (or encoder on an existing roller) seem to be the way to go.

If you have a look on the image: The lowest roller is a "dancer". The up/down position on a slider of that roller controls the speed of the rolling-up motor.. In that machine we had more than only one zone, so it's not so easy to see on that image.