Prime View International (PVI) of Hsinchu, Taiwan will begin volume production of flexible electrophoretic displays (EPDs) in 2Q’09, and color EPDs by year’s end, Susie Pan and Yvonne Yu of Digitimes reported today, citing "market sources" for the story.

Ken Werner
Senior Analyst and Editor

Hydis, the Korean display company PVI acquired in July of last year, is also expected to start shipping EPDs by 2Q. Since the Hydis acquisition, PVI has been transferring part of its EPD production to the Korean company, and PVI intends that over half of Hydis’ capacity will be devoted to EPD production by 2010, reported Pan and Yu. The transition could signal a significant ramp-up of EPD production capacity since PVI has a single Gen 2.5 manufacturing facility in Hsinchu, while Hydis has three: one each of Gen 2.5, Gen 3, and Gen 3.5.

EPD technology, pioneered in the modern era by E Ink, is the rare case of a new display technology that reaches critical mass. PVI, an E Ink partner and licensee, takes the Vizplex imaging film made by E Ink and combines it with a traditional TFT backplane to make active-matrix EPD modules.

Typically, a new display technology that becomes successful rides to its success on the back of a major new application that requires the characteristics of the new display and forgives its shortcomings. In the case of EPD, that major application is eBook readers, and the display’s key benefits are extremely low power consumption coupled with very good text-display quality. The slow ramp-up of eBook readers themselves delayed the ramp-up of EPD displays, although smart cards, watches, shelf-edge labels and other applications helped fill the gap. Now, though, with the significant help of Amazon’s Kindle, the eBook reader market itself is reaching critical mass, with a variety of new suppliers scheduled to come on the scene this year.

Since EPD’s main focus has been that of a rewritable book page, two of its shortcomings — slow rewrite speed and lack of practical full color — have not been significant impediments. But the next generation of EPD readers will include products focused on textbook and business-document reading, where color would be highly desirable. In that context, the PVI announcement is interesting.

Here’s the problem. Any color reflective display — such as an EPD — that uses matrix color filters to produce color throws away a large amount of the incident light. In the case of an RGB filter, roughly two thirds of the light is absorbed, and the reflected light passes through the filter twice. So, roughly one ninth of the incident light makes it back to the viewer. The latest generation of Vizplex film can reflect in excess of 40% of the incoming light, which makes for a very readable black-and-white display. One ninth of that is something like 5%, which is just plain dark under most ambient lighting conditions.

There are things that can be done. Putting a white sub-pixel in the matrix color filter and remapping the colors accordingly can double the light passing through the filter. And you can reduce the density of the color filters, trading more luminance for reduced color gamut, a trick that makers of notebook PC displays have played for years.

Nonetheless, recent color prototypes I’ve seen have not impressed me. I look forward to seeing if E Ink, PVI, and Hydis have combined the technological tricks available to them in a strikingly more effective way than has been done in the past. If they have, EPD technology will be in position to make another leap forward.