Variable Thickness Adhesive Layer for Flexible Display Wrinkle Prevention
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Solution Overview
Problem
Flexible display devices often develop wrinkles when bent or unbent multiple times, which can be visually recognized and deteriorate the display quality due to stress transmission to the window, leading to deformation.
Innovation Solution
A flexible display device design featuring an adhesive layer with varying thickness in the bendable portion to accommodate deformation of the display panel and polarizing layer, while maintaining a constant thickness in non-bendable portions, and a wrinkled surface facing the display panel to prevent wrinkles on the window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the adhesive layer has constant thickness, then the manufacturing process is simple, but wrinkles form on the window when the display panel is bent
Solution Approach 1:
The adhesive layer is designed with different thickness characteristics in different regions: the bendable portion has variable thickness to accommodate deformation, while the non-bendable portion maintains constant thickness for structural stability. This local differentiation resolves the contradiction between manufacturing simplicity and window flatness.
Solution Approach 2:
The adhesive layer is segmented into distinct functional portions: a bendable portion with varying thickness located at the bending axis, and a non-bendable portion with constant thickness at the edges. This segmentation allows each region to perform its specific function independently.
2Manufacturing precision
If the adhesive layer thickness varies to prevent wrinkles, then the display quality improves, but the manufacturing complexity increases
Solution Approach 1:
The adhesive layer implements local quality by having different thickness characteristics in specific regions - the bendable portion has variable thickness with a maximum at the bending axis, while the non-bendable portion maintains constant thickness. This targeted approach achieves wrinkle prevention without requiring complex variable thickness throughout the entire layer.
Solution Approach 2:
The thickness parameter of the adhesive layer is changed strategically - the bendable portion has variable thickness ranging from a minimum to a maximum value, while the non-bendable portion maintains a constant thickness parameter. This controlled parameter change achieves the desired wrinkle prevention with manageable complexity.
3Adaptability or versatility
If the adhesive layer is thin, then the device flexibility is improved, but the stress compensation capability is reduced
Solution Approach 1:
The adhesive layer is segmented into bendable and non-bendable portions with different thickness characteristics. The bendable portion with variable thickness provides flexibility and stress compensation, while the non-bendable portion with constant thickness provides structural support.
Solution Approach 2:
Different regions of the adhesive layer have different thickness qualities optimized for their specific functions - the bendable portion has greater thickness variation to accommodate stress, while the non-bendable portion has uniform thickness for structural integrity.
Data Source
AI summary
A flexible display device includes a display panel including a bendable area and a non-bendable area which is adjacent to the bendable area in a direction, a window facing the display panel, and an adhesive layer between the display panel and the window. The adhesive layer includes a bendable portion corresponding to the bendable area and having a thickness which varies along the direction to define a wrinkled shape of the bendable portion, and a non-bendable portion corresponding to the non-bendable area and having a thickness which is constant along the direction.