Foldable Display Bending Protection Layer for Delamination Control
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Solution Overview
Problem
Foldable display devices face challenges in minimizing defect rates due to stress concentrations during folding operations, which can lead to delamination and cracking, particularly at the bending areas where the display module interacts with protective layers.
Innovation Solution
A display device design incorporating a bending protection layer with a first portion overlapping the display and bending areas, having a specific thickness, inclined angle, and elastic modulus, which is spaced apart from the anti-reflection layer to manage stress and prevent delamination, along with a step compensation layer to absorb external impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bending protection layer is added to prevent delamination and cracking during folding, then reliability is improved, but device complexity increases
Solution Approach 1:
The bending protection layer is divided into a first portion and a second portion with different thicknesses and properties. The first portion (thicker, 40-85 μm) is positioned at the bending area to provide enhanced protection, while the second portion (thinner) extends to the display area, creating a segmented structure that optimizes protection where needed without uniformly increasing complexity across the entire device.
Solution Approach 2:
The bending protection layer exhibits local quality by having different thicknesses and elastic moduli in different regions. The first portion has a maximum thickness of 40-85 μm and elastic modulus of 50-300 MPa, while the second portion has reduced thickness. This local variation provides targeted protection at the bending area while maintaining overall structural integrity.
2Stress or pressure
If the bending protection layer is positioned closer to the anti-reflection layer, then stress concentration is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The bending protection layer is designed with specific dimensional parameters (thickness of 40-85 μm for the first portion, inclined angle of 10°-30°) that are predetermined to preemptively manage stress distribution. By establishing these parameters in advance, the design prevents stress concentration before folding occurs, reducing the need for post-manufacturing adjustments.
Solution Approach 2:
The invention specifies precise parameter ranges for the bending protection layer, including thickness (40-85 μm), inclined angle (10°-30°), and elastic modulus (50-300 MPa). These parameter changes optimize the balance between stress reduction and manufacturing feasibility, allowing for controlled positioning relative to the anti-reflection layer.
3Strength
If the first portion has greater thickness to provide better protection, then strength is improved, but device complexity increases
Solution Approach 1:
The bending protection layer implements local quality by concentrating greater thickness (40-85 μm) in the first portion at the bending area where protection is most critical, while the second portion has reduced thickness. This localized approach provides enhanced strength where needed without uniformly increasing the complexity of the entire layer structure.
Solution Approach 2:
The protection layer is segmented into two portions with different thickness characteristics. The first portion (thicker) handles the high-stress bending area, while the second portion (thinner) covers the display area. This segmentation allows optimized protection capability without requiring the entire structure to be thick, thereby managing overall 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 concentrations and defect rates by distributing stress evenly and preventing delamination, ensuring the display device maintains integrity during folding and external impact.
Implementation Method 1
the first portion has a maximum thickness greater than that of the second portion, and 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
AI summary
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.