Today, I saw two impressive ePaper displays for eBook readers (EBRs) at Flat Panel Display International (FPDI) in Yokohama.

Ken Werner
Senior Analyst and Editor

The first display was something I had been skeptical of ever seeing: A color electrophoretic display (EPD) that uses a matrix color filter (MCF) and is still bright enough that you actually want to use it. This prototype was shown at the E Ink / PVI booth, and is the result of years of work at E Ink. The key is the use of an RGBW MCF instead of the conventional RGB pattern, on top of a highly reflective monochrome display.

There is still a bit more reflectivity to be wrung out of this design, said E Ink marketing VP Sri Peruvemba, before it appears in customer products.

The challenge to using an MCF with a reflective display is that the filter, if it’s an RGB filter, absorbs roughly two thirds of the incoming light. If you start off with a monochrome display with a very good 45% reflectivity, you’re down to something like a 15% reflectivity when you apply the MCF, and that’s not good enough. In general, with an appropriate remapping of the color coding, RGBW can double the transmittance of the color filter. Although I didn’t obtain E Ink’s numbers specifically, that would bring the reflectivity up to about 30%, which is very acceptable and looked about like what I was seeing on the E Ink display

The second display was the color version of Liquavista’s new electrowetting EBR display. I saw it as soon as the exhibits opened Thursday morning (Yokohama time), where Commercial Development VP Anthony Slack noted that I was the first non-Liquavista employee to see it. With the help of the accompanying photograph, you can see it too!

The significant thing about this display (as well as its monochrome cousin, which was also on display) is that it is a true video-rate display. The monochrome version was showing a clip from Modern Times in a half-page window at 50 frames per second. Another, and perhaps even more important, benefit of fast refresh, is the smooth a responsive touch interface it enables. The Liquavista panels were using a very slick touch interface developed by engineer Peter Notermans. Pages can be "turned" (see photo) as quickly or as slowly as the user wants, and pen touches get nearly instant results. Liquavista will make the interface IP available to customers. By the way - the black vertical bar is a result of a bad TAB bond to the column driver.

The responsiveness also makes Web browsing practical, and brings cross-bred products having characteristic of both EBRs and Netbooks closer to reality.

The color panel needs to be brighter - that is, more reflective - even with its RGBW MCF, and a 30 to 40% improvement should be coming with the implementation of new design rules, said Engineering VP Eric Derckx.

CEO Guy Demuynck said Liquavista is seeing intense interest from some panel makers. The company’s roadmap calls for process development and technology transfer to manufacturing partners in 2010, and monochrome products from partners in 2011.

There’s much more to say about the ePaper displays shown at FPDI, as well as the 3D; AMOLED; and reduced-power, thinner-and-lighter, and higher-contrast LCDs being demonstrated in Yokohama. Check our newsletter coverage for more behind the scenes intelligence.