Foldable screen prototypes point to smaller handheld devices

One of the more difficult problems in designing mobile devices is finding ways to minimize the size of the device while simultaneously maximizing the display. To get the best of both worlds, researche…

One of the more difficult problems in designing mobile devices is finding ways to minimize the size of the device while simultaneously maximizing the display. To get the best of both worlds, researchers from the Samsung Advanced Institute of Technology in South Korea have designed and built a prototype of a seamless foldable display that folds in half without a visible crease in the middle. As the researchers explain in their study, published in a recent issue of Applied Physics Letters, recently there has been a great deal of interest in flexible, extendable displays. Most of these flexible displays are bendable or rollable. Fabricating a display that can fold completely in half would have the advantage of providing a large screen in a small, portable form, but so far it has been a challenge to eliminate the visible crease between panels. In the new study, the researchers have overcome this problem, demonstrating a seamless foldable active matrix organic-light-emitting-diode (AMOLED) display with no visible crease. The display consists of two AMOLED panels, silicone rubber (a hyperelastic material), a protective glass cover, and a module case. The display has a very small folding radius of just 1 mm, so that one panel lies almost completely on top of the other when the display is folded at a 180 angle. The glass cover not only prevents scratches, but can serve as a touch screen as well. Researchers tested the foldable display“s mechanical and optical robustness by performing 100,000 folding-unfolding cycles, and found that the relative brightness at the junction decreased by just 6%. Since this difference is hardly recognizable by the human eye, the deterioration is considered negligible. As the researchers explained, the key to making a display with no visible crease involved controlling the optical properties of the materials. As for applications, a foldable display could be useful in a wide variety of small, mobile devices, such as mobile games, cellular phones, tablet PCs, and notebook PCs. The hyperelastic silicone rubber is commercially available, which could make it suitable for mass production. In addition, the researchers plan to investigate applying this design to fabricate large-size flexible displays.