Foldable Flexible Display Protection Layers for Crease Reduction

The protection layer is divided into multiple separate layers (first protection layer, second protection layer, third protection layer) with different thicknesses and material properties. Each layer serves a specific function: the thinner first layer provides initial protection, the thicker second layer prevents burnout deformation, and the third layer maintains surface quality. This segmentation allows the system to achieve both structural simplicity and high reliability during folding operations.

Different regions of the protection layer structure have different thicknesses and material compositions tailored to specific functional requirements. The second protection layer is made thicker than the first and third layers specifically in regions prone to burnout deformation, while maintaining appropriate thickness in other areas. This local differentiation optimizes both durability and surface quality without unnecessarily increasing overall complexity.

The multi-layer protection structure is designed in advance to prevent delamination before it occurs. Each layer is bonded to adjacent layers and the display panel using optimized adhesive layers with specific thicknesses and material properties. The thicker second protection layer acts as a buffer that absorbs stress during folding, preventing stress concentration at the interface between the display panel and protection layer, thereby preventing delamination before it can happen.

The protection layer system uses composite material construction with at least two different polymer materials having distinct glass transition temperatures. The first protection layer uses a polymer with a first glass transition temperature, while the second and third layers use polymers with different glass transition temperatures. This composite approach creates a gradient of material properties that accommodates thermal and mechanical stress during folding, maintaining layer adhesion while enabling frequent folding operations.

Instead of increasing the thickness of a single protection layer, the solution adds another dimension to the protection structure by creating multiple layers with different thicknesses. The first layer remains thin to maintain flexibility, while the second layer is thicker to prevent burnout deformation. This multi-dimensional approach allows the system to achieve both flexibility and surface quality without compromising either property.

The invention changes the parameters of the protection layer system by varying the thickness and material composition across multiple layers. The second protection layer is specifically designed with greater thickness than the first and third layers, creating a thickness gradient that optimizes both flexibility and burnout prevention. The glass transition temperatures of the polymer materials are also carefully selected to match specific functional requirements at different locations in the structure.