Flexible Display Window Member Bonding Layer Modulus Design
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Solution Overview
Problem
Flexible display devices face challenges in achieving both flexibility and high impact resistance, particularly in bending areas where stress is applied, as existing window members often compromise on either flexibility or protection.
Innovation Solution
A flexible display device design featuring a window member with a bonding layer composed of two types of resins, where a first bonding part with a lower modulus (0.1-100 MPa) overlaps the bending area for flexibility and a second bonding part with a higher modulus (100-700 MPa) overlaps the non-bending area for enhanced impact resistance, using tempered glass substrates and a polyurethane resin-based bonding layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single bonding layer is used in the window member, then the structure is simple, but the window member cannot simultaneously achieve high flexibility in bending areas and high impact resistance in non-bending areas
Solution Approach 1:
The bonding layer is divided into two distinct parts with different moduli: a first bonding part with lower modulus (0.1-100 MPa) positioned in the bending area to provide flexibility, and a second bonding part with higher modulus (100-700 MPa) positioned in the non-bending area to provide impact resistance. This local differentiation of material properties resolves the contradiction between flexibility and strength.
Solution Approach 2:
The bonding layer uses a composite structure combining two types of resin materials with different mechanical properties. The first bonding part uses a softer resin material for flexibility, while the second bonding part uses a harder resin material for impact resistance, creating a composite bonding layer that achieves both contradictory requirements simultaneously.
2Strength
If a bonding layer with high modulus is used throughout the window member, then impact resistance is improved, but flexibility in bending areas deteriorates
Solution Approach 1:
Instead of uniformly applying high modulus material throughout, the invention locally applies high modulus material only in the non-bending area where impact resistance is needed, while using low modulus material in the bending area where flexibility is required. This spatially differentiated approach resolves the contradiction.
Solution Approach 2:
The bonding layer is segmented into two functionally distinct parts: the first bonding part for flexibility and the second bonding part for impact resistance. This segmentation allows each part to be optimized for its specific function without compromising the other.
3Adaptability or versatility
If a bonding layer with low modulus is used throughout the window member, then flexibility is improved, but impact resistance deteriorates
Solution Approach 1:
The invention applies low modulus material locally only in the bending area where flexibility is needed, while applying high modulus material in the non-bending area where impact resistance is required. This localized material selection resolves the contradiction between flexibility and strength.
Solution Approach 2:
The bonding layer is divided into two segments with different material properties: the first bonding part with low modulus for flexibility and the second bonding part with high modulus for impact resistance, allowing simultaneous achievement of both properties in different locations.
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 minimizes bending stress while providing high impact resistance, allowing the flexible display device to maintain desired deformation characteristics and protect the display panel effectively against external impacts.
Implementation Method 1
the bonding layer includes: a first bonding part overlapping the bending area; and a second bonding part overlapping the non-bending area and having a modulus greater than a modulus of the first bonding part
Data Source
AI summary
A flexible display device, which has a bending area and a non-bending area, includes a display panel, and a window member disposed on the display panel and including a first glass substrate, a second glass substrate disposed opposite to the second glass substrate, and a bonding layer disposed between the first glass substrate and the second glass substrate. The bonding layer includes a first bonding part overlapping the bending area and a second bonding part overlapping the non-bending area and having a modulus greater than a modulus of the first bonding part.