Today’s electronic paper was invented in 1974 by scientists in California at Xerox’s Palo Alto Research Center. It was called Gyricon. In 1997, researchers from the MIT Media Lab founded E Ink, and their company introduced an active-matrix electronic paper display. The first e-reader using an electronic paper display, the LIBRIé, came from Sony three years later.


The way E Ink paper works is relatively simple. Imagine a glass hemisphere filled with a clear liquid. Inside there are two kinds of particles—the white ones are negatively charged, and the black ones are positively charged. Countless numbers of these spheres are embedded in a sheet, and when you change the electronic fields above and below the sheet, the dots rearrange and appear from above as patterns, forming letters and images.

There are several dramatic advantages for printing with this field of microcapsules. On its single page, the E Ink display can instantaneously recall millions of words and illustrations, providing you with a focused library of hundreds of volumes in a pocket-size reader that weighs perhaps 10 or 12 oz. Wi-Fi can extend your reach to libraries around the world, so the content held in one hand can be virtually limitless. In 2007, a national survey of school library media programs found most school libraries have collections of up to 25,000 volumes. That number of book files can fit on the storage of any e-reader that has 32GB of internal memory, including today’s Kindle Paperwhite and Kobo Forma.

The E Ink display is easier on your eyes than computer screens. E Ink is designed to be read with the ambient lighting in a room, just like traditional paper. Light reflected from the page is more comfortable than the light from a phone or computer’s LCD display. Those direct a strong light source through crystals in what one writer called a stained-glass‑like experience. Also, the self-illuminating systems on modern e-readers direct their light from the sides of the screen across the screen, and most have a blue-canceling function at night to further reduce eyestrain. A Kindle, Kobo, or Nook with a light system can be read anywhere, anytime, with libraries of content easily within reach. An interesting experiment in 2012 involved the Victoria Square subway station in Bucharest. The walls of the station were covered with posters depicting library shelves, creating the impression of a large library. Commuters could scan the QR codes displayed on the book spines to access a website where they could download free versions of e-books and audiobooks.

The copy of Stephen King’s ’Salem’s Lot on the library shelf in town doesn’t have an operating system, but the digital copy of that same book you can buy for your e-reader will be made smarter by the OS on your e-reader. If you see a word you don’t understand, you can hold a finger on it, and a dictionary will open with the definition. A phrase or passage in another language can be translated without leaving the page. Some e-readers will even read the text aloud as you follow along. Bookmarks, highlighting, and notes are also often possible, and usually there’s a list kept of the text and page to help you find all the markings you’ve added. No stranger to the potential of e-books, in March 2007, King’s own novella Riding the Bullet became the world’s first mass-market e-book, crashing Simon & Schuster’s servers and ultimately selling 400,000 downloads in the first 24 hours.

Electronic paper does require an energy source, but e-book readers have batteries that can last for weeks on a charge, especially if you read mostly in ambient light or sunlight. In most circumstances, phones and laptops are difficult or even impossible to read in direct sunlight.

What’s next for e-readers is the addition of color and notebook functions. In the last 12 months, 12 new color e-readers have been released, many featuring E Ink’s Kaleido color system. For students and others, handwritten-note-taking functions are growing in popularity, as are the many applications of electronic paper used for public signage, indoor display and price markers, and even watch faces. Overall, electronic paper has accumulated an impressive track record for its brief 47-year evolutionary curve when compared alongside the 2,000-year arc for Cai Lun’s original, civilization-changing idea.

About the Authors