A few days ago we reported about a new color e-paper prototype by Ricoh, and now we have some more details. Ricoh used a novel method which involves stacking three layers of electrochromic panels, one on top of the other, each reflecting different colors (yellow, cyan, magenta). This can create color pixels without sub pixels. All three layers are driven by one LTPS TFT.
The display on show was 3.5" in size (113ppi) with a 27% color gamut (NTSC).