Bending Protection Layer for Display Device Stress Management
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Solution Overview
Problem
Existing display devices face challenges with high defect rates due to the interaction of bending areas and anti-reflection layers, leading to issues such as delamination and stress concentration during folding operations.
Innovation Solution
A display device design incorporating a bending protection layer with a first portion overlapping the display and bending areas, spaced apart from the anti-reflection layer, featuring a specific thickness, inclined angle, and elastic modulus to manage stress and prevent interference, along with a step compensation layer to accommodate structural changes during folding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If an anti-reflection layer is disposed on the display module overlapping the first area, then reflection of light is reduced, but stress concentration and delamination occur during folding operations
Solution Approach 1:
A bending protection layer is introduced as an intermediary element between the anti-reflection layer and the bending area. This protection layer has a first portion overlapping the first area and a second portion overlapping the bending area, with the first portion having a maximum thickness greater than the second portion. The bending protection layer acts as a mediator that prevents direct stress transmission to the anti-reflection layer during folding, thereby reducing delamination while maintaining anti-reflection functionality.
Solution Approach 2:
The bending protection layer is disposed beforehand on the display module to prevent stress concentration and delamination during folding operations. The first portion of the bending protection layer, with its greater maximum thickness (40-85 μm), provides cushioning protection to the anti-reflection layer before stress is applied during bending. This prior cushioning prevents the harmful effects of stress concentration and delamination.
2Reliability
If the bending protection layer is disposed close to the anti-reflection layer, then protection effectiveness is increased, but interference between layers occurs
Solution Approach 1:
The bending protection layer exhibits local quality variations through its different portions. The first portion overlapping the first area has a maximum thickness greater than the second portion overlapping the bending area. This local variation in thickness allows the first portion to provide adequate protection near the anti-reflection layer while the thinner second portion reduces interference in the bending area, thus resolving the contradiction between protection effectiveness and layer interference.
Solution Approach 2:
The bending protection layer is segmented into a first portion and a second portion with different thickness characteristics. The first portion (thicker, 40-85 μm) is disposed closer to the anti-reflection layer to provide protection, while the second portion (thinner) overlaps the bending area to minimize interference. This segmentation allows different regions of the same layer to serve different functions, resolving the contradiction between protection and interference.
3Reliability
If a thick bending protection layer is used to prevent delamination, then stress protection is improved, but device complexity increases
Solution Approach 1:
The bending protection layer uses local quality variation with a first portion having maximum thickness (40-85 μm) greater than the second portion. This localized thickness variation provides adequate stress protection where needed (first portion near anti-reflection layer) while reducing material usage and structural complexity in other areas (second portion over bending area), thus resolving the contradiction between delamination prevention and device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces stress and prevents defects like delamination, ensuring a low defect rate and enhanced durability of the display device during folding operations.
Implementation Method 1
the first portion has a maximum thickness greater than that of the second portion, the first portion has a maximum thickness in a range from about 40 μm to about 85 μm, a maximum inclined angle in a range from about 10° to about 30°, and an elastic modulus in a range from about 50 MPa to about 300 MPa
Data Source
Figure 1A~1B
Figure 2A
Figure 2B
AI summary
Provided is a display device including a display module, an anti-reflection layer, and a bending protection layer. The display module includes a first area, a second area, and a bending area disposed between the first area and the second area and having a predetermined curvature radius. The bending protection layer includes a first portion overlapping at least the first area and a second portion overlapping at least the bending area. The first portion has a maximum thickness in a range from about 40 µm to about 85 µm, a maximum inclined angle in a range from about 10° to 30°, and an elastic modulus in a range from about 50 MPa to about 300 MPa.