If you thought the E-Ink screen on your Kindle or Sony Reader was the epitome of high-tech for the printed page, hang on to your hat. By the end of this year, newer models - with newer display technologies - will start to make today's e-book readers look like Model T versions.

These next-generation readers will sport colour displays with refresh rates capable of supporting video. They'll also use flexible display technologies - but that doesn't mean you'll be able to roll them up (yet). Rather, they will make the devices a lot less fragile.

Taken together, these upgrades will usher in a new age of e-book content, including books and periodicals that depend heavily on detailed colour graphics (think children's books or textbooks), video content (think magazines and newspapers), and superior durability (all of the above).

While you can read printed content on just about any computer or smartphone these days, the LCD displays on most computers and smartphones aren't particularly well suited to serve as paper substitutes. For one thing, they are backlit, and gazing at a backlit display for extended periods of time can fatigue the human eye.

The Case for E-Ink

The overwhelming majority of the e-readers on the market today use so-called electronic paper displays from a company called E-Ink (now owned by Taiwanese display company Prime View International). E-Ink's Vizplex products use electrophoretic technology, in which tiny microcapsules containing even tinier black and white particles suspended in fluid are sealed into a film that is in turn laminated to a sheet of electronic circuitry.

The blacks and whites respond differently to negative and positive charges: depending on which group rises and becomes visible, the surface of the display will look white or black.

Several characteristics of electrophoretic displays make them appealing for e-books. They are thin, and they support very high resolutions, which allows for sharp, crisp fonts on a relatively skinny and lightweight device. They consume relatively little power, in part because they don't use a backlight: the technology is reflective, meaning that, as with paper, you need ambient light to see E-Ink pages. In fact, an E-Ink display gains contrast in bright sunlight, while transmissive displays such as LCDs generally fade outdoors. Lack of a backlight makes for a display with less glare that's easier on the eyes.

Another reason why electronic paper consumes less power than LCDs: they are bistable, meaning they don't need power to maintain an image - only to form a new one. (Bistable refers to the fact that electronic paper will retain an image whether it's powered on or off, so they maintain an image in two states.) For that reason, power consumption on readers based on electronic paper displays are commonly measured in page turns.

E-Paper Drawbacks

Today's electronic paper displays do have some significant drawbacks, starting with response time. One of the most common complaints of new e-book customers is the time required to change pages, and the flickering effect of the image change.

That's because the response time of current E-Ink displays is at least a couple of hundred milliseconds: by way of comparison, LCDs - some of which now boast response times of just a couple of milliseconds - still battle the perception that they are less capable of handling fast-moving video than plasmas and other phosphor-based displays. While e-book fans usually adjust to the page-change times (which are, after all, not really slower than the time required to turn a physical paper page), the slow response time clearly makes today's e-book readers unsuited for video.

If you thought the E-Ink screen on your Kindle or Sony Reader was the epitome of high-tech for the printed page, hang on to your hat. By the end of this year, newer models - with newer display technologies - will start to make today's e-book readers look like Model T versions.

Lack of colour isn't a serious problem for text-only content. But there's a universe of printed content that depends on colour, including periodicals, children's books, textbooks, and anything else involving photographs and illustrations.

Also, first-generation e-books don't make good candidates for books that might be subjected to a certain amount of wear and tear, such as textbooks and children's books. Flexible displays are less likely to break if dropped. In addition, a lightweight flexible display might make a large-format reader more portable - today's Amazon Kindle DX is a relatively heavy 19 ounces.

The LCD Connection

LCDs, of course, can display gorgeous colour and video. But they also consume a lot of power - a long-standing issue for all mobile devices, but a real problem if you're going to be spending hours on end reading a book. And finally, especially with larger displays, the potential for breakage is significant - but ruggedising technologies tend to be bulky and heavy, qualities that aren't at all desirable in an e-book reader you might want to hold for long periods of time.

Monochrome LCDs are another approach. Aluratek, for example, offers the Libre Pro, which uses a Toshiba-developed 5-inch monochrome, reflective-light LCD that has no backlight. Because it's an LCD, the display sidesteps the page refresh issue; and with no backlight to consume battery life, Aluratek estimates you can read with the device for 22 to 24 hours between charges (assuming you turn the page, on average, every 60 seconds).

A Competitive Industry

E-Ink is addressing some of these issues in products it's developing with some 20 partners, says Sri Peruvemba, the company's vice president of marketing. For example, the Hearst-backed Skiff reader, previewed at CES, is designed to display newspaper content; it has an 11.5-inch shatterproof, flexible metal-foil touchscreen display (developed by E-Ink in conjunction with LG), with built-in 3G and Wi-Fi support.

E-Ink's new parent, PVI, is helping to develop a colour e-paper display, Peruvemba said. "It's one of the reasons we agreed to be acquired," he added. In fact, Chinese e-reader manufacturer Hanvon (also known as Hanwang) has announced plans to begin mass production of a reader based on a colour E-Ink display by the end of this year. However products that significantly improve response time are still in the research phase, Peruvemba acknowledged.

E-Ink Competitors

While E-Ink has been the dominant player in the electronic paper market so far, it's getting more and more competition. A search for "colour" and "bistable" in the US Patent Office database brought up more than 1200 hits, including ones from Intel, Fujitsu, and Kodak.

In a report last summer, DisplaySearch analyst Jenny Colgrove identified several other companies competing in the electronic paper market, including Taiwan's SiPix (whose display technology is being used by Asus) and Japan's Bridgestone (the same people that make the tires). Both have also shown prototypes of colour e-book displays. Dutch company Irex has announced plans to begin distributing a colour e-reader in 2011.

One of the most intriguing upcoming e-reader technologies comes from Qualcomm, the company best known for its mobile network technologies. Qualcomm MEMS (microelectromechanical systems ) Technologies has been showing a display technology it calls Mirasol for several years now. Mirasol is an interferometric modulation (IMOD) technology that, like its electrophoretic rivals, is reflective and doesn't use a backlight. But there the similarities appear to end. Mirasol uses two conductive plates that pull apart when a charge is applied to them; much the way a prism creates rainbows, a Mirasol display will create different colours as light passes through it depending on the distance between the plates.

Qualcomm executives say Mirasol is superior to the electrophoretic technologies used by E-Ink and others for several reasons. Response time is orders of magnitude faster, so video will not be a problem, and it's more energy-efficient, Qualcomm says.

Mirasol is already starting to appear on mobile phones - in China, Hisense's C108 sports a monochrome Mirasol display, and at the recent Mobile World Congress in Barcelona, Qualcomm MEMS Technologies and Taiwanese electronics manufacturer Inventec announced a Windows phone, the Inventec V112, that will use Mirasol in a 1.1-inch secondary display. An e-reader with a 5.7-inch colour Mirasol display (rumor mill says it will be a next-gen Kindle) will be introduced this autumn, according to Qualcomm MEMS Technologies marketing director Cheryl Goodman.

Forrester Research analyst James McQuivey says another possible contender in the e-reader display market might be a hybrid technology that blends some of the benefits of an LCD with those of a reflective display. A company called Pixel Qi has been showing prototypes of its 10-inch transflective display for netbooks and e-book readers; it claims to offer superior readability (especially indoors, when the LCD backlighting kicks in) and image quality. That's all we know for now; the company didn't respond to repeated requests for an interview.

Whichever technology prevails, 2010 is set to be a huge year for e-book readers. DisplaySearch's Colgrove predicts shipments to triple, from 5 million last year to 15 million this year.

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E-book reader reviews