KAIST Secures Fundamental "Zero-Crease Foldable" Technology, Aiming for Global Leadership

A fundamental technology that could eliminate the biggest weakness of foldable displays—creases—has been developed in South Korea. Due to the nature of foldable displays, which must be repeatedly folded and unfolded, creases on the screen have been the biggest obstacle to market expansion. Global companies such as Samsung Electronics and Huawei have tried various methods to address this issue, but have failed to completely remove creases, resulting in limitations on consumer satisfaction and the speed of market adoption. This is why the smartphone industry has considered "implementing a crease-free foldable display" as the most urgent technical challenge. The newly developed technology is expected to enhance the completeness of foldable devices in the global market, accelerating both their popularization and growth.

Professor Ilseung Lee and Master’s Graduate Junhan Bae (top left). KAIST

On April 20, KAIST announced that a research team led by Professor Ilseung Lee from the Department of Mechanical Engineering has developed and patented a fundamental technology designed to fundamentally solve the crease problem occurring at the folding area of foldable smartphone displays.

The research team has also filed patent applications for this technology in the United States, China, and the European Union, in an effort to secure global technological competitiveness.

Until now, global smartphone manufacturers have invested heavily in research and development to solve the issue of creases. However, even recently, the inability to completely eliminate creases has been regarded as the greatest barrier to the expansion of the foldable smartphone market.

The research team began their study to resolve the discomfort they experienced while personally using mobile foldable phones. They disassembled dozens of used foldable phones and conducted a variety of experiments, eventually devising a solution that involves radically redesigning the "adhesive area" between the display and the support panel.

The key to this redesign is to distribute the deformation so that it does not concentrate on a specific folding area, but is instead dispersed to surrounding areas. This perfectly demonstrated the feasibility of achieving a "crease-free foldable" while ensuring that the smartphone functions operate normally.

For performance verification, when the research team shone a straight LED light across the prototype, the reflected light maintained a clear straight line without distortion. This addressed a major issue of commercial products, in which the light bends at the fold, causing the straight line to appear warped.

Adhesive and non-adhesive areas of a typical foldable smartphone (a), adhesive and non-adhesive areas (b), stress distribution of a typical foldable smartphone display (c), stress distribution of a foldable smartphone display with the technology developed by the research team applied (d). KIAST

Notably, in the prototype, there was no visual distortion even under conditions capable of detecting micro-curvatures less than 0.1mm in crease depth.

The technology developed by the research team is significant in that it presents a new design paradigm that surpasses the limitations faced by the existing industry. Most importantly, it not only fundamentally suppresses crease formation but also ensures excellent durability by minimizing display deformation even after tens of thousands of repeated folds and unfolds.

Its structure is intuitive and simple, making it easy to apply to existing manufacturing processes. This advantage extends beyond smartphones to a variety of foldable display devices such as tablets and laptops, highlighting the potential for broad industrial applications.

Industry insiders believe that if this technology is commercialized, it will encourage global companies that had hesitated to enter the market due to the crease problem to participate. Consequently, consumer satisfaction is expected to rise, and the growth rate of the stagnant foldable market will accelerate even further.

Professor Lee commented, "Our research team has succeeded in solving a challenge that even global companies could not overcome, and we did so in a relatively simple and clear way. We hope that this technology will spread not only to smartphones but also to next-generation displays such as laptops and tablets, strengthening Korea's technological competitiveness."

This research was supported by the "2022 Daedeok Innopolis Campus Project." The fundamental technology patent secured through this research was registered in September last year.

This content was produced with the assistance of AI translation services.