Variable Thickness Polymer Film for Foldable Display Durability
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Solution Overview
Problem
Existing foldable or rollable displays face challenges in maintaining durability while reducing the repulsive force and driving resistance, which affects user convenience and the ability to achieve larger screen sizes within a compact device form factor.
Innovation Solution
The electronic device incorporates a display assembly with a protective layer featuring a polymer film, a display panel, glass, and an adhesive layer. The polymer film has varying thicknesses in different areas – thicker in the flat area and thinner in the deformable area – and the adhesive layer also has varying thicknesses to optimize the balance between durability and reduced repulsive force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of the polymer film is increased to improve durability, then the repulsive force of the display increases, but user convenience is reduced
Solution Approach 1:
The polymer film is designed with non-uniform thickness distribution, having a first thickness in the first area and a second thickness smaller than the first thickness in the second area. This local quality variation allows the film to provide adequate durability in the first area while reducing repulsive force in the second area, thereby improving ease of operation without sacrificing overall durability.
Solution Approach 2:
The invention changes the physical parameter of the polymer film thickness from a uniform value to a spatially varying value. By controlling the thickness parameter to differ across different areas of the film, the solution optimizes both durability and ease of operation simultaneously, resolving the technical contradiction between these two features.
2Volume of moving object
If a fixed display structure is used, then the device can be downsized, but the screen size is limited to the size of the electronic device
Solution Approach 1:
The display assembly is designed with deformable characteristics, allowing it to change shape and size dynamically. The polymer film with varying thickness enables the display to be folded or rolled, transforming from a rigid fixed structure to a dynamic flexible structure. This allows the screen area to exceed the device footprint when unfolded, while maintaining compact form factor when folded.
Solution Approach 2:
The flexible display assembly can be folded or rolled to fit within the compact device housing, similar to a nested doll structure. When not in use, the larger screen folds into a smaller configuration that nests within the device boundaries, enabling both large screen area and small device volume.
3Adaptability or versatility
If thin glass and polymer film are used to enable display deformation, then the display can be folded or rolled, but durability is reduced
Solution Approach 1:
The polymer film is designed with spatially varying thickness, having greater thickness in the first area and reduced thickness in the second area. This local quality differentiation provides enhanced durability in regions requiring structural support while maintaining deformability in regions where flexibility is prioritized, thereby resolving the contradiction between adaptability and strength.
Solution Approach 2:
The display assembly employs a composite structure combining glass, polymer film with varying thickness, and adhesive layers. This composite material approach integrates the rigidity and durability of glass with the flexibility of the polymer film, creating a hybrid structure that achieves both deformability and enhanced durability simultaneously.
Data Source
AI summary
An electronic device includes: a housing including a first housing, and a second housing connected to the first housing and configured to be movable with respect to the first housing; and a display assembly including a flat area connected to the housing, and a deformable area extending from the flat area and configured to be at least partially folded or rolled based on a movement relative to the housing, where the display assembly includes: a protective layer for protecting the display assembly from an external impact to the electronic device, the protective layer including a polymer film; a display panel configured to output an image; a glass disposed on the display panel; and an adhesive layer disposed between the glass and the polymer film, where a first area of the polymer film positioned in the flat area has a first thickness.