A domestic research team has solved the crease problem on screens, long cited as the biggest weakness of the foldable smartphone market.
A research team led by Professor Lee Pil-seung in the mechanical engineering department at KAIST said on the 20th that it developed a technology that suppresses creases forming at the fold of foldable smartphone displays and completed patent registration in Sept. last year. The team also filed the technology not only in Korea but in the United States, China and the European Union (EU), moving to secure a lead in the global market.
The central crease on a foldable smartphone's screen has been the most immediately felt inconvenience for users and a key benchmark for judging product completeness. Global smartphone manufacturers have poured massive research and development budgets into solving the crease issue, but there have been limits to finding a complete solution.
The team disassembled dozens of used foldable phones and conducted repeated experiments. As a result, it concluded that a core solution could be to newly design the "adhesion area" structure between the display and the support plate. The key is a structure that prevents deformation from concentrating in a specific area and disperses the forces generated during folding to the surroundings.
The team said this design demonstrated the feasibility of a crease-free foldable even while actual smartphone functions operate normally. The difference was also clear in performance verification. When a straight-line LED (light-emitting diode) light was shone on the screen, ordinary commercial products showed the straight line appearing bent as light refracted at the fold, but in the prototype the reflected line remained straight without distortion.
The significance of this technology goes beyond a mere cosmetic upgrade. It is differentiated from existing approaches in that it structurally suppresses crease formation while reducing deformation from repeated folding, thereby improving durability. It secured excellent durability by minimizing deformation even after tens of thousands of repeated uses.
According to the team, the technology's structure is relatively simple and intuitive, making it easy to apply to existing manufacturing processes. As a result, expansion to various foldable display products—including tablets and laptops as well as smartphones—also appears feasible.
Professor Lee Pil-seung said, "We solved a problem that even global corporations had not resolved with a relatively clear and simple approach," and added, "We hope this technology spreads beyond smartphones to next-generation displays such as tablets and laptops, becoming a catalyst to enhance Korea's technological competitiveness."