E Ink announced (on May 24, 2016) a breakthrough in their Advanced Color ePaper. This is big news that most people I know don't understand. After all, we've had color displays since ... forever, right? Well, yeah, but there is a big difference in the technology that is being used. I thought it would be fun to take a closer look at what we see (but don't ever see) every day.
Let's look at three common display technologies that are used today.
LCD (Liquid Crystal Display) - Like the name implies, this display technology uses liquid crystals. The crystals do not emit light directly. They have a light source (usually behind them) that shines through the liquid. The liquid crystals fill picture elements called pixels and represent only one of three colors. Usually these colors are either Red, Green and Blue (and White in some cases). When you see an orange image, you are actually seeing light shining through Red, Green and Blue liquid crystals. For every 765 tiny pixels in an orange box, there maybe 243 Red pixels, 112 Green pixels and 33 Blue pixels—utilizing just 50% of the available pixels.
LED (Light-Emitting Diode) - Unlike the LCD technology, the diode, which is an electronic component usually made of silicon, actually produces light when enough voltage is supplied. LED is superior to LCD in that it requires less energy, lasts longer and can be a lot smaller. As opposed to the three color limitation, LED produces nine different visible colors. However, most LED displays still use the RGB pixel grid.
EPD (ElectroPhoretic Display or Electronic Paper Display) - e-Paper is not back-lit, but it doesn't emit light either. e-Paper displays actually reflect light (just like a piece of paper reflects light rather than produces light). This typically makes the displays easy on the eyes, more visible in direct sunlight and more legible from different angles. e-Paper also uses the pixels like LCD and LED, but each pixel, until now, has represented a single color. (In some cases ePapers would use the same RGB model from before.)
Now we can make sense of the big news.
ACeP (Advanced Color ePaper) - With ACeP, the e-Paper is able to achieve a full color gamut which includes the whole rainbow of colors plus white. The pixel spaces are filled with electrophoretic fluid (like with LCD) controlled by low voltages. The color has the potential to be much more rich than those produced with LCD or even LED because each pixel is not limited to only one of three color choices.
In a traditional display, a bright red box would contain pixels of either Red, Green or Blue. Because Red is the only color needed, only up to 255 of the 765 pixels would be lit. That's only 33%! With the ACeP technology, all 765 pixels could be filled with red electrophoric fluid—utilizing 100% of the pixels—and creating some very rich colors!
See, wasn't that fun!? Now when everyone starts buying up color ePaper tablets and readers you'll know why—they won't know why, but you will.