Flexible Display Hard Coating Stress Neutral Surface
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Solution Overview
Problem
Conventional flexible display devices face challenges in folding and unfolding due to surface scratches and image distortion, as they lack adequate protection and stability, especially when bent, and are difficult to integrate into foldable mobile devices.
Innovation Solution
A flexible display device design featuring multiple panels with an outer and inner hard coating layer on a transparent substrate, an adhesive layer with transparent fine particles, and strategically positioned stress neutral surfaces to manage stress distribution and prevent image distortion during bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a flexible display device is bent during folding, then the display can be folded into a smaller size for portability, but the surface layer may be scratched and image distortion may occur
Solution Approach 1:
The patent applies composite materials by stacking multiple panels (display panel, polarization panel, touch panel, protective panel) with different material properties. Each panel is made of flexible materials that can be bent, and the combination provides both flexibility and protection against scratches and image distortion during folding.
Solution Approach 2:
The patent uses flexible panels made of thin film materials that can be bent without breaking. The display panel, polarization panel, touch panel, and protective panel are all constructed using flexible substrates that maintain their integrity during folding and unfolding operations.
2Reliability
If multiple panels are stacked to provide protection and functionality, then scratch resistance and image stability improve, but device complexity increases
Solution Approach 1:
The patent divides the display device into multiple functional segments or panels: display panel, polarization panel, touch panel, and protective panel. Each panel performs a specific function and can be independently optimized, manufactured, and assembled, which simplifies the overall development process despite the multi-layer structure.
Solution Approach 2:
The patent integrates multiple functions into a single stacked structure. The same panel stack provides display functionality, polarization, touch sensing, and physical protection simultaneously, eliminating the need for separate components and reducing overall device complexity.
3Strength
If hard coating layers are applied to protect against scratches, then surface durability improves, but stress distribution during bending becomes uneven causing image distortion
Solution Approach 1:
The patent applies different properties to different locations within the panel structure. The hard coating layers are applied locally on the outer surfaces of specific panels (display panel, polarization panel, touch panel) where scratch resistance is most needed, while the inner layers maintain flexibility. This localized application provides protection without creating uneven stress distribution that would cause image distortion.
Data Source
AI summary
A plurality of panels include: a display panel; and a protective panel that is disposed outside the display panel, and includes a transparent substrate and an outer hard coating layer and an inner hard coating layer that are respectively formed on an outer surface and an inner surface of the transparent substrate, and each have a hardness greater than a hardness of the transparent substrate. A thickness of the outer hard coating layer is greater than a thickness of the inner hard coating layer, and a stress neutral surface of the flexible display device is configured so that a compressive stress is applied to the inner hard coating layer when the flexible display device is bent.