For those who are apprehensive about spending almost $300 on a Kindle, Nook or Sony Reader, the onslaught of e-readers shown at CES 2010 should serve as a clear hint. Sorry, guys – it’s only a matter of time before you, too, will be publicly ridiculed for your arcane affinity for old-fashioned books.

In all seriousness, paper books have a long way ahead of them, and even our grandchildren will probably still have a bookcase at home, but e-readers are the future, and will make the reading experience better in the same way iPods made the music experience better. What is it that makes e-readers a big deal? We’ve had flat screens for decades, so why now?

The answer is E-Ink, the technology behind the e-readers’ special screens. The major drawback to LCD screens is their power consumption. An LCD screen has to apply a current to each pixel to keep the image constant, as well as a back-light that sits behind the pixel grid. Even with the advanced Lithium-Ion batteries of today, an e-reader with an LCD screen won’t last more than a few hours on one charge. This might not be terrible if you just like to read your book for a few minutes before bedtime, but for any serious reader, this won’t do. E-Ink, on the other hand, is built on a completely different concept.

The differences will become more apparent in the coming weeks and months as more companies -- including Hewlett-Packard and Apple -- roll out multipurpose, slate-style computers with e-reading applications designed to compete against dedicated e-reader devices.

To understand how this works, let’s compare the two technologies. An LCD screen is based on a grid of cells, each of which contains a special chemical that is a liquid, but under specific circumstances behaves like a crystal. Normally, the material is “twisted”, and allows the passage of light. When current is applied to the material, it straightens, and blocks the passage of light, becoming partially or fully opaque, depending on how much electricity was used. Behind the cell, there’s a backlight, which is simply a row of three or four very thin fluorescent light bulbs. The screen’s electronics control each cell, and set it to a level of brightness -- if no power is applied, the cell is transparent, and we see a bright dot. If power is applied, the cell is opaque, and light cannot come through, making the dot dim or dark.

To create the various colors we see, each pixel is actually a set of three dots – red, blue and green. The electronics set the brightness of each of these dots to create a color combination – if we set the red dot to full brightness, the green one to half and the blue one to dark, we get a mix that looks to the naked eye like the color orange. The main problem with this design is that to keep the image on, we have to apply current to all the cells all the time, as well as the backlight, and this drains the batteries pretty fast.

E-Ink also uses a grid of cells, but the cells are built differently. Each of these cells contains a clear fluid, which has both white and black microscopic particles floating in it. The particles are magnetically charged – positive charge for one color, and negative charge for the other. By applying electricity to the cell, the electronics can cause one of the “poles” of the cell (top part or bottom part) to become magnetically charged as well. If the top part has a negative charge, it attracts the white particles, while the bottom part attracts the dark particles. We see the top part of the cell, so it appears to be a white dot – like looking at the window of a lit room. Apply a reverse current, and the black particles rise to the top, making the dot appear black.

The process of changing the color, by the way, is a bit slow compared to an LCD. An LCD can refresh itself over 100 times a second, but an E-Ink display takes almost a full second to do a single refresh. The actual “color” of each dot comes from light reflected from the black or white particles, and not from a backlight, so there’s no need for that huge energy waste. The best part, though, is that the magnetic charge holds on its own, so once the computer creates the pattern of black-and-white on the E-Ink screen, there’s no need to apply any power to it. In fact, the E-Ink image can stay “on” for a long time with hardly any power consumption.

The only part that does need some power is the process of changing the contents, in which the computer applies power to the cells to cause them to reverse their magnetic charges. This is why the battery life on these devices is measured in “page turns” or “screen changes”. Typically, a charge would last for several hundred page turns, which would be many days or even weeks for the average person. In theory, once an image has been drawn on E-Ink, it would stay forever, although the little computer that’s inside the eBook does consume some power, and additionally, rechargeable batteries do lose their charge even when not used. Also, some e-readers come with a wireless connection to download books, and that has an impact on the battery-life. In reality, most e-readers do need a recharge once every two-three weeks.

At CES 2010, many companies introduced e-reader solutions, and some of those were actually based on LCD screens. Because of their popularity, LCDs are cheaper, and so e-reader using them are cheaper too. One such device is the MiBook, which costs around $100. The LCD limits the battery life of this device to only about 3-4 hours, but on the other hand, the color LCD screen allows not only the use of color, but allows the screen to display video, for which E-Ink is way too slow.

Currently, all E-Ink based e-readers are black-and-white only, but the same concept that allows color in LCD screens can be applied to E-Ink as well. Researchers are working on it, and pretty soon we’ll have color E-Ink devices too, and hopefully, at some point, they will refresh fast enough to serve as a reasonable screen for video. Once that happens, we might see them take the place of LCDs as monitors, and perhaps even TVs.

Another challenge with e-reader is that their screens are a little small, in order to keep costs down, and this requires some adjustments to some books, in terms of text-flow and images. Using such a device instead of an Atlas, for example, would be a problem at this point. This means that each book, when offered for e-readers, must be carefully adjusted, to make sure it’s convenient to read. Many people want to use their e-readers to read one of many freely available electronic books, but when they try to display a PDF that was designed for a letter-sized page on a 6” screen, they discover that the letters are too small to be recognized. It’s still possible to convert those files to a readable version, but that requires quite a bit of know-how.

In the next few months, we are about to see another type of the device pop-up on store shelves – a “slate” or “tablet” computer. Such devices have been shown-off by HP, Lenovo, Dell and others, and Apple is expected to announce one very shortly. Current devices of this family are based on LCDs, because their primary usage is for daily computer tasks. They will be usable for book-reading, but not as adequately as the dedicated e-readers. After all, one can read text from any screen, including a mobile phone or laptop, if you can handle having to recharge the device all the time, but most of us wouldn’t want to have to carry a charger around, and hunting for one in the middle of a class at school, right?

Erez Ben-Ari is a Seattle-area journalist and technology guru who has worked in the high-tech industry for more than 15 years, for companies including Microsoft and Intel. His written work has been published worldwide in the printed and online media, as well as television and radio. Contact him directly at ohlord@gmail.com

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