E Ink’s latest foray: self-darkening windows

With E Ink Corp.’s technology, a window can turn black, blocking light, at the push of a button.
With E Ink Corp.’s technology, a window can turn black, blocking light, at the push of a button.

E Ink Corp., which created the “electronic paper” video displays for e-book readers such as the Amazon Kindle, is moving to the rest of your house. The Billerica company said it can now make electronic window shades that can control the amount of light entering a room by changing the transparency of the window itself.

The JustTint system uses a transparent film that can be laminated inside two panes of window glass, or attached to an existing window. The film works on the same principles as the company’s e-book screens, which use electric fields to arrange tiny black particles into the shapes of letters and numbers. But instead of spelling out words, the particles darken or lighten the film, affecting how much light can come through the windowpane.


At the touch of a button, a window with JustTint film can go from being completely clear to totally opaque, plunging a room into darkness. It can also be adjusted to vary the amount of light at different times of day, admitting less light at noontime, for example, or more in the evening.

And like the company’s e-book screens, JustTint uses electric power only when changing its appearance. Once a level of brightness is set, the self-tinted window will remain in that state without consuming any more power.

E Ink demonstrated JustTint windows at a trade show in San Jose, Calif., this week. The trade show demo was a black-and-white version of the product. But Paul Apen, E Ink’s chief strategy officer, said the company can also make colored versions, so windows could be tinted to match the walls.

Just as it did with electronic paper, E Ink is searching for business partners willing to incorporate JustTint in their products. Paul Apen, E Ink’s chief strategy officer, said they’re targeting makers of windows and skylights for residential and commercial buildings and the automotive industry.


“If it catches on, it means huge things for the company,” said Apen.

The idea behind JustTint isn’t new. A host of major glass makers produce “smart glass” systems that can change color or transparency. They’re used in the windows of the Boeing 787 Dreamliner aircraft instead of traditional window shades, reducing the weight of the plane.

In some buildings, smart-glass windows automatically darken when hit with bright sunlight. In other cases, they’re manually controlled. A homeowner or office dweller can touch a wall-mounted button or use a smartphone app to dim or brighten the room.

Windows made of smart glass can cost $50 to $100 per square foot, compared to $10 to $15 for regular glass, according to the National Renewable Energy Laboratory. Apen said E Ink’s product should be cost-competitive with other offerings.

Konkana Khaund, director of consulting for smart buildings at Frost & Sullivan, estimated $8 billion in worldwide smart glass sales in 2017, the most recent year her company surveyed the market. But the market hasn’t exactly taken off, Khaund said, in part because the higher price of smart-glass systems makes them a tough sell for many construction projects.

“It is difficult for manufacturers to justify the return on investment to end users,” she said. As a result, smart windows are a slow-growing niche market.

However, Khaund said, JustTint could get a foothold if E Ink can identify new applications for the product, or if E Ink and its manufacturing partners can bring the glass to market at lower cost than other forms of smart glass.


Hiawatha Bray can be reached at hiawatha.bray@globe.com. Follow him on Twitter @GlobeTechLab.