Display technology has gotten very good in the last decade. Whether you’re talking about LCD, AMOLED, or e-paper, the cost has dropped as quality has gone up. Still, there are times you just need to jot down a note or write something large enough for a whole room to see. You might not have to retreat to the pre-digital world of whiteboards and dead trees for long. Researchers from the University of Tokyo have repurposed some decades old technology to create a type of inexpensive e-paper you can write on.
When it comes to efficiency and readability, e-paper is the clear winner among display technologies. However, writing on e-paper is lagging behind. There are low-quality versions of handwriting-enabled e-paper displays in toys, and very expensive versions that rely on smart pens, but nothing in between. That’s what the “twisting ball” display developed by the Japanese team could be.
The display is based on technology originally developed in the 1970s. It relies on a network of microparticles about 0.1mm in diameter. The ball is divided into two hemispheres, one black and the other white. The black side has a negative charge, and the white is positive. The balls are suspended between two transparent electrodes that can switch the direction of voltage across the display, causing it to flip back and forth between black and white.
Okay, so that’s an e-paper display, but it’s not enough to finally do away with regular paper. The trick is that the black side of the spheres contains magnetic nanoparticles that allow you to write on the display. Basically, you can flip the microparticles in small areas by dragging a magnet across them. Attach that magnet to a pen, and you’ve got a writing surface. The spheres are small enough that you can get a clean line that’s good for writing. The magnet only needs to be as strong as a standard refrigerator magnet to work. Flipping the voltage for a moment will instantly erase the display.
Durability, cost, and size are all important concerns when dealing with e-paper displays. The technology developed at the University of Tokyo seems to check all the boxes. It is composed of acrylic polymer, silicone elastomer, and silicone oil, all of which are tough and inexpensive. Since the functionality is independent of the color of the balls, the display color can be changed by using different pigments on the microparticles.
The team is currently working to improve the contrast of its display technology, which should be possible by increasing the amount of pigment used on the microparticles. Once that is done, these displays might be just what we need to leave paper and whiteboards behind. The smart whiteboards that have been popping up in recent years have more advanced features, but they consume much more power as well. Large e-paper screens could work in more places at a much lower cost.