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eBooks and Electronic Paper

"How does it work" is perhaps the most frequently asked question of people who are interested. With a great pleasure, I always answer, working for MyMathDone.com (http://www.mymathdone.com/) it is not a rare case. Therefore, in this article I want to clarify for you how such a popular gadget as eBook works!

The vast majority of gadgets for reading textual information (eBooks) use so-called "electronic paper" as a display. This technology was developed in order to bring visual information performed by the eBook in line with properties of a simple printed paper.

Electronic Paper and e-ink

Despite the fact that the concept of eBook display performance was developed in 1970s as an extension of Liquid Crystal Display technology, it is in stark contrast to the latter. When in LCD displays, the image is formed through gleaming, with the electronic paper, the electrophoresis phenomenon was used - particles in motion under external electric field activity. Moreover, the image in eBooks is formed by means of reflective light, but not translucent one - the same as on a paper page - light impinging on it is reflected differently from light and dark parts (of text or image).

Microcapsues display light or dark areas depending on the charge of the underlying electrodes.

Performance of modern eBook displays is based upon the concept developed in 1990s. The soon patented technology was named e-ink. So, how does it work? The whole display is divided into small parts called microcapsules. Each of them contains microparticles. Some of them are painted in the dark colour and have negative electric charge, others are white and are positively charged. The display's base is a net of controlled electrodes. If a positive charge is applied to a particular part, negatively charged black particles will be found near the electrode, and the positively charged white ones will be against the surface. If a negative charge is applied to an electrode, everything will be quite opposite.

Color display is achieved by adding red, green, and blue filters above the microcapsules.

The image formed in this way will constitute dark and light parts on the display surface. Sun or artificial light, impinging on the eBook display, will be reflected in different ways, as in case with an ordinary paper book page. In turn, we will see a finished image in the form of text.

Usually, eBooks have mono displays, but in order to broaden their features, polychromatic (many-coloured) technology of presenting textual and graphical information was invented. In fact, it is almost similar to the previous one - the same capsules with black and white particles. However, in the polychromatic eBook display, there is one more upper layer in form of colour filters. In this way, three capsules are divided into one pixel and are covered with different colour filters: red, green and blue. The process is the same as in a simple TV set. By combining three primary colours, it is possible to get all the colors.

By the way, for the eBook to function it is necessary to have not only a sophisticated display, but also the programs that control the performance of the whole device or its particular functions. The program for reading eBooks is a range of rules or algorithms. An electronic device performs them and displays information in a user-friendly way, such as text or graphical image.

-Stacy Galvan

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