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e-Ink Technology Explained

By Best-eReaders, March 11, 2010

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For nearly 2 centuries, ink on paper was the only way to display texts and images. The invention of computers and other digital devices ushered in a new era in print technology. Computer displays, however, have many limitations. It is expensive, causes eyestrains, and consumes too much power. 

A number of companies such as VizPlex and Xerox began developing a digital display that could replace books, newspapers, and magazines. Called electronic ink or eInk, this innovative display is as readable as paper. Unlike paper, however, eInk is flexible. When a page is turned, the ink simply rearranges to form a new one. Imagine a newspaper you don’t have to throw gain. Instead, the pages simply typeset themselves into the next day’s headlines. 

eInk Technology Explained: The Beachball Metaphor   

eInk’s components give it the ability to re-arrange itself upon command. Electronic paper displays (EPD) contain millions and millions of hair-thin microcapsules sandwiched between liquid-filled films. Some of these microcapsules are positively charged (white capsules) and some are negatively charged (black capsules). In eReaders, the microcapsules would cover the entire length of the display, which is usually made of thin plastic. Cells, such as those found on graph paper, separate the microcapsules. The cells are individually wired to the microelectronics implanted in the plastic sheet.

At the basic level, text and images are created by moving “e-ink” capsules around. To put in another way, grayscale is produced by changing the positions of white and black capsules.

To change the pattern of the capsules, electric charge is applied. When negative charge is applied, for instance, the white capsules move to the front of the black spheres. The surface in that spot then appears white. When black particles are pulled to the top, the surface then appears black.

Imagine the microcapsules are clear beach balls. Half of each ball is filled with hundreds of white ping-pong balls. The other half is filled with blue-painted ping-pong balls. Looking from the top of the beach ball, what you will see is white, but if you look from the bottom, you will see blue.

Now picture a field strewn with thousands of such beach balls. Imagine yourself having a power to make the white ping-pong balls move on top of the blue at will so you can change the color of the field. That, in essence, is how eInk works.  

Benefits of eInk Technology

eInk has radically changed for the better the way we read books. It offers several advantages over other display technologies, including:

• Paper-like readability. EPDs rival the readability of printed text on paper. They are easy on the eyes, have no back light, and don’t have the glare typical of liquid crystal displays (LCDs). To read, natural or artificial light is also needed.

• Low Power Usage. eInk uses 50 to 100 percent less power than LCDs because it consumes power only with each change of display. Once the display is set, the device doesn’t draw any power anymore. With EPDs, you can curl up with a novel without connecting to a power source.   
• Readable under varied lighting conditions. Like books, EPDs can be read under direct sunlight and in low lighting conditions.
• Flexibility. eInk can be scaled, making it the perfect medium for both small and large applications.  E-ink can be used not only for digital devices like eReaders, but also on billboards, grocery sign boards, Tshirts, and product labels.

eInk display may not completely replace physical books or encourage people to throw away their PCs. All the same, it has inspired many to choose digital books over physical books. Just imagine the thousands of acres of trees saved in the process.

Now, if e-Ink can only start producing displays with color.