The E-book Reader Display

One complaint some people had about early e-book readers was that it can be difficult to read words on an LCD display. Some users complained that longer reading sessions put too much strain on their eyes. Amazon's solution to this problem was to use electronic ink technology. The Kindle's electronic ink screen looks more like paper than an LCD screen. It reflects light in much the same way that paper does. The screen lacks a backlight, so you'll need an external light source in order to read anything.

A company called E Ink in Cambridge, Mass. developed the technology the Kindle relies upon to display text and images. Rather than use the liquid crystals you'd find in an LCD or the ionized gas you'd find in a plasma display, electronic ink actually uses millions of microcapsules, only a few microns wide. Each microcapsule contains a clear fluid and thousands of white and black particles. The white particles carry a positive magnetic charge and the black particles have a negative charge.

It's these positively- and negatively-charged particles inside the microcapsules that make electronic ink displays possible. An array of thousands of tiny electrodes lies beneath the electronic ink display. When an electrode emits a negative charge, it repels the negatively-charged black balls, pushing them to the top of the microcapsule. At the same time, the charge attracts the positively-charged white particles to the bottom of the microcapsule. When the electrode emits a positive charge, the white and black particles switch places and the screen appears to be blank.

© Amazon.com
Although the shape of the Kindle is unusual, many reviewers praise the device's ergonomic design.

­But if the electrode emits a positive charge, then it will attract the balls, pulling them down through the ink. The display then reveals the ink to the viewer. Working together, thousands of electrodes and millions of microcapsules generate the text and images you can see on an electronic ink display. Through precise charges the Kindle can display a range of grays to provide shading in images. You can even adjust the Kindle's font settings to display text in a larger or smaller font size.

The Kindle uses less energy to generate a page view than a comparable LCD or plasma screen. The company's Web site states that the Kindle pulls power from its battery only during the initial page generation. It doesn't require more power until the user changes the page view. Because of this feature, the Kindle's battery can provide power for up to a week on a single charge (assuming the user doesn't have the wireless feature turned on).

The Kindle is a monochromatic display, which means it can only display images in black and white; however, companies like E Ink are working on color electronic ink displays. It's possible that a future version of the Kindle will be full-color. But for now, users will have to settle for images and text in black, white and shades of gray.

The electronic ink display is one of the Amazon Kindle's top selling points. Another is the way it interfaces with Amazon's inventory of electronic books. We'll look into that more in the next section.