E-Ink: What Is It and How Does It Work?

Once the main tech behind e-readers, e-ink has since expanded its use

Electronic ink technology produces a low-power, paper-like display for e-readers, such as the Amazon Kindle.

Initial research on e-ink started at the MIT Media Lab, where the first such patent was filed in 1996. The rights to the technology are currently owned by the Massachusetts-based E Ink Corporation, which was acquired by Taiwanese company Prime View International in 2009.

How Does E-Ink Work?

With e-ink technology, tiny microcapsules are suspended in a liquid that is encased within a film layer. The microcapsules, which are roughly the width of a human hair, contain positively charged white particles and negatively charged black particles.

Applying a negative electrical field causes the white particles to rise to the surface. Conversely, applying a positive electrical field causes the black particles to rise to the surface. By applying different fields at different parts of a screen, e-ink produces a monochromatic text display.

E-ink displays are especially popular because of they resemble printed paper. In addition to being easier on the eyes than other display types, e-ink consumes less power, especially when compared to backlit liquid crystal display (LCD) screens.

These advantages, along with its early adoption by major e-reader manufacturers such as Amazon and Sony, caused e-ink to dominate the early e-book reader market.

Uses of E-Ink

In the early 2000s, e-ink was popular among the many e-readers on the market, most notably the Amazon Kindle, Barnes & Noble Nook, Kobo eReader, and Sony Reader. It was praised for its clarity in bright sunlight. It is still available on some Kindle and Kobo e-readers, but other screen technologies have taken over much of the e-reader market.

E-ink technology appeared in a few early cellphones. It spread to applications that included traffic signage, electronic shelf signage, and wearables.

Limitations of E-Ink

Despite its popularity, e-ink technology has limitations. Until recently, e-ink could not display color. Also, unlike traditional LCD displays, typical e-ink displays don't have backlighting, making them a challenge to read in dim places. They also cannot display video.

To counter competition from rival display technologies, such as reflective LCD, E Ink Corporation worked to improve its technology. It added touch-screen capabilities, launched its first color display in late 2010, and produced limited-color screens through 2013.

Advanced Color ePaper

In 2016, E Ink Corporation announced Advanced Color ePaper (ACEP), which displays thousands of colors. The technology is considered a breakthrough, as each pixel contains all the pigments necessary to reproduce any color.

This color technology is mainly aimed at the signage market. E-ink technology, which gained recognition primarily through the e-book reader market, has expanded to the manufacturing, architecture, and product labeling sectors, among others.