E Ink delivers color
Overlay provide color
Very large ePaper
We had a chance to talk to E Ink as part of our CES 2011 coverage.
E Ink introduced the world to e-readers with its ePaper technology. Its reflective technology looks like paper and is very readable in sunlight, the bane of other display technologies. It is also bistable and very low power making it ideal for battery powered, mobile devices like e-readers. Its disadvantage for some applications such as video streaming is refesh speed.
E-readers were doing great until the Apple iPad (see The iPad Initiates The Tablet Tsunami) arrived. The iPad uses a conventional color LCD screen. Barnes and Noble moved from the Nook e-reader to the NOOKColor (see NOOKColor As An Embedded User Interface) that also uses a color LCD screen. We saw many color tablets at CES 2011 (watch Freescale Showcases Tablets with i.MX51 and i.MX53 Family of Processors) but we saw something else that piqued our interest, color ePaper (watch Color Active Matrix E Ink Triton Imaging Film).
E Ink was showing off a color ePaper tablet (Fig. 1) at the show. This actually uses the same technology as the grey scale version found on most e-readers. E Ink simply added a color filter over the top (Fig. 2). The filter reduces the contrast and brightness some so the colors tend to be muted compared to an LCD but the approach retains ePaper's advantages. On the plus side, the incremental cost is marginal so expect many of the e-readers to become more colorful over the next year or two.
We also talked with E Ink about a number of other features of ePaper that many designers may not be aware of. For example, ePaper can be used to make very large displays (Fig. 3). The ePaper displays are also flexible and they do not have to be rectangular. Need a display to go around a wheel? An ePaper display is probably a good way to go.
The bistable and low power aspects should also be considered by designers. It is possible to equip a micro with a small capacitor so when power is lost the micro changes the ePaper display to something like "Time To Panic". The display will stay in this state even after power is completely removed.