Seven-segment displays have been around ... that flip the red segments in and out of view. The display can cycle through all ten states in a single rotation of the discs, so the cam paths are ...

But as it states in the patent, “Referring again to Fig. 1, the novel arrangement of the lamp compartments will be readily understood.” Technically it’s not a seven-segment display at all.

The above illustration highlights one segment of the liquid crystal layer in a monochrome twisted nematic (TN) seven-segment display (Image courtesy of LXD, Inc.) In their natural state ...