What is E-Paper? Evolution of technology

“It’s not the same as a real paper, I much prefer a book, the scent of paper, ink, and glue to this tablet” – a similar statement could be heard several years ago when e-book readers using e-paper technology were starting to exist in the minds of consumers. In the past, pulling out such a device in public space was very intriguing and attracting attention, but nowadays, having an e-book reader with an e-paper display is pretty much an ordinary thing.

It was only a matter of time before EPD (Electronic Paper Display) would also be used in industrial applications. At first, they were pretty expensive, and function rather as curiosities, but are now seen more and more often in the urban space. EPD solutions could be used wherever it is essential to minimize power consumption by the display – especially in digital signage systems.

California – not just Apple. The beginnings of electronic paper

There are at least a few approaches to telling the story of e-paper. The most cross-sectional and comprehensive one would probably begin with the origins of regular paper in ancient China. Fortunately, in our case, there is no need to go back that far – the seventies of the last century are the perfect starting point of our story.

It was then that the very first version of the technology that we could now call “e-paper” was created. Its originator was Nick Sheridon of Xerox’s Palo Alto Research Center, California, and it was patented under the name of Gyricon. The main premise was to make tiny, two-color – half white and half black – polyethylene balls placed in a transparent silicone sheet to rotate freely and display color. Sheridon achieved this by suspending them in oil and magnetizing them, the white side of the ball had a positive charge, and the black side had a negative one. Thanks to this, each sphere reacted to the electric field applied to a given place of the sheet. This made it possible to manipulate the movement of the balls and display a specific image by rotating their black halves towards the screen surface.

Jacobson and the founding of the E Ink company

The next step in the evolution of e-paper was the solution developed by Joseph Jacobson, a crucial figure in the context of the entire history of EPD displays. This method, known as Vizplex, was implemented as part of the first generation of technology by E Ink. Leading in e-paper solutions, founded by, among others, Jacobson and operating to this very day,  the company replaced the two-color spheres with capsules filled with clear liquid with black and white particles of pigments suspended in it.

As in Sheridon’s solution, the colored particles inside the capsules were electrically charged (again, white positively and black negatively), which allowed them to move under the influence of an electric field and thus obtain the desired image. The glass screen, used in earlier versions of devices, was replaced with a coating of flexible plastic – this is how the first iteration of electronic paper technology as we know it today came to be. E Ink is still developing it.

The evolution of e-paper

One of the research directions on e-paper is the constant introduction of new solutions that allow using more colors than just black and white. This is already happening – screens using three, four, or even more pigments are already available, which increases the possibilities of use cases for this technology.

From electronic price tags, through e-book readers mentioned at the beginning – displaying a wide range of colors would be warmly welcomed especially by comic book fans – to advertising surfaces, billboards, and general use in architecture and decorative art. Among the more specific implementations, it is worth mentioning the office badges using e-paper and NFC technology, and small EPD displays placed in the public transport on grab handles, providing additional space for potential advertisers.

The cost of projects using e-paper displays is constantly decreasing. EPD solutions are also moving on in the field of better refresh rate, which significantly reduces ghosting, i.e., the remains of the previous page being still visible after switching to the next one. It even allows you to play simple animations – at one of the fairs, Unisystem showed the adventure of Simon’s Cat on one of the E Ink’s displays:

As time passes and the development of this technology progresses, new possibilities of its use appear, more and more similar to those we expect to find in science fiction novels rather than in the world around us.

Universal electronic paper – science fiction or reality?

This genre is mentioned here not by accident. Today, the way we use EPD solutions coincides with the vision of Stanislaw Lem, globally acclaimed Polish sci-fi writer, from his 1961 book A Return from the Stars. The author surprisingly accurately predicted the creation of e-book readers almost ten years before the first version of the e-paper technology:

„The books were crystals with recorded contents. They could be read with the aid of an opton, which was like a book but had only one page between the covers. At a touch, successive pages of the text appeared on it.”

Solutions based on electronic paper will always look like a sheet of paper to be perfectly visible in both natural and artificial light. At night, however, it is necessary to illuminate the display additionally – such solutions do not emit light by themselves, unlike their LCD or OLED counterparts.

E-paper is also energy-efficient – it requires only a little power when updating or refreshing the content on the screen, which remains on display without any further energy consumption. The lack of a liquid crystal matrix does not limit the viewing angles in any way, and the small thickness and weight of the modules favor the use of this type of solution in more unconventional and demanding projects.

EPD technology is not yet as affordable as LCD, but it is only a matter of time. Thanks to the continuous development of e-paper displays, they will often be more advanced and use in more exciting implementations. Want to learn more about how to get the most out of e-paper in your project? Contact us.