The display contains some kind of phosphorescent layer, on what a diode (UV, Brought or possibly a CRT) writes. The diode is attached to two hypocyclic segments, that rotate to reach virtually any point on the deal with. Thus, time can be shown in almost any manner, because the images show. Whenever possible, the display generally is a combination of phosphorescent and phoretic, to help readability under diverse lighting conditions. The particular writing diode should also have a very variable focus, to match thinner or thicker lines to be drawn. Ideally, the falling time of the show should be controlled also.
This concept sprung from my thoughts on how to make a highly customisable watch with a feasible circular display. I wanted to get away from the rectangularity of LCD, TFT and the like. I came upon this idea, which evolved into something considerably more advanced than I was aiming for.