Bringing the Paper Display to Your Door

By William Stanek
October 28, 2009

William here, talking about bringing the paper display to your door. As I wrote about in my last blog post, tomorrow's displays are here today and the technologies at the forefront of these changes are E-ink and Electronic Paper Displays (EPDs). One of the first EPDs was demonstrated by Lucent and E Ink Corporation in November 2000. This display was an early prototype that used flexible transistors. By June 2002, E Ink Corporation developed a 2mm thick flexible active-matrix display on steel foil transistor substrates. In December 2004, Plastic Logic and E Ink Corporation unveiled a flexible all-plastic display. This was the first EPD display that truly was suitable for use with electronic devices.

Many EPD variants are available, including segmented displays and active matrix displays. Segmented displays are low-power, low-performance displays that can be used to convey basic information using letters, numbers, and pre-defined icons. As the name implies, segmented displays are divided into discrete segments that can be controlled individually and attached to a surface, such as a shelf display or a mini MP3 player. Active matrix displays are high-resolution, high-performance displays that are designed to be used with electronic devices.

EPDs with black and white particles and active matrix displays are able to reproduce the feel of printed books, newspapers and magazines. They offer true black and true white as well as gradients of black and white referred to as grayscale. Early EPDs support 4 grayscale levels (also referred to as 2-bit grayscale). This means they effectively display black, dark gray, medium gray, and white.

Newer EPDs with black and white particles support higher grayscale levels for richer, more dynamic viewing experiences. With 3-bit grayscale, an EPD supports eight grayscale levels, allowing for six gradients of gray between black and white. With 4-bit grayscale, an EPD supports sixteen grayscale levels, allowing for fourteen gradients of gray between black and white. Generally, the resolution of these displays is at least 170 pixels per inch or higher.

EPDs with color particles are becoming available. E Ink Corporation and Toppan Printing Co. Ltd. demonstrated a color EPD in October 2005. This display supports 12-bit color with a resolution of 83 pixels per inch. By using microcapsules that combine red, green, blue, and white particles, the display preserves the paper-like whiteness of a printed page while enabling rich blacks for text and a range of colors and tones for images. The color particles also are used to smooth black and white text for enhanced legibility. Although EPDs with color particles need to achieve higher resolutions and lower production costs to be practical for reader devices, just imagine the possibilities and what it'll mean to have widely available full-color electronic paper displays. Not only will color EPDs be able to display full color for novels and textbooks, but they'll also be ideal for magazines, comics, graphic novels, children's picture books and much more.

And remember, one of the most wonderful things about EPDs is that they only use power when you turn the page or display something new. Once a page is displayed, the EPD doesn't use power to maintain the display. That means low power consumption in general and a lot of page turns for little power usage.

Next up, I'll talk about the evolution of popular readers and the wider uses of EPDs.

William R. Stanek
williamstanek at aol dot com

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