Flexible Display Adhesive Layer Moduli Gradient
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Solution Overview
Problem
Flexible display apparatuses face issues with interface separation and stress distribution when bent, leading to wrinkles and cracks due to differing bend radii and shear stress between components.
Innovation Solution
A flexible display apparatus with stacked components and optical adhesive layers, where the adhesive layers have varying storage moduli and thicknesses to facilitate deformation and reduce stress, including a first adhesive layer with higher storage modulus and adhesive strength, and a second adhesive layer with lower storage modulus for easier deformation and decoupling of shear stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single adhesive layer is used between stacked components, then the structure is simple and manufacturing is easy, but interface separation and wrinkles occur due to uniform stress distribution
Solution Approach 1:
The adhesive layer is segmented into multiple sub-layers with different storage moduli. The first adhesive sub-layer has a first storage modulus and the second adhesive sub-layer has a second storage modulus that is lower than the first. This segmentation allows different regions of the adhesive layer to handle different stress conditions, preventing interface separation while maintaining manufacturing feasibility.
Solution Approach 2:
Different portions of the adhesive layer are assigned different local qualities through varying storage moduli. The first adhesive sub-layer with higher storage modulus provides strong bonding, while the second adhesive sub-layer with lower storage modulus provides flexibility and stress relief. This local quality differentiation resolves the contradiction between manufacturing simplicity and interface separation resistance.
2Strength
If adhesive layers with high storage modulus are used, then adhesive strength is high and components are firmly bonded, but the structure becomes rigid and prone to cracks during bending
Solution Approach 1:
The adhesive system is divided into multiple sub-layers with different storage moduli. The first adhesive sub-layer maintains high adhesive strength for firm bonding, while the second adhesive sub-layer with lower storage modulus provides flexibility to accommodate bending deformations, preventing cracks and wrinkles.
Solution Approach 2:
The storage modulus parameter is changed across different adhesive sub-layers. By transitioning from a uniform storage modulus to a gradient structure where the second sub-layer has a lower storage modulus than the first, the system achieves both high strength and flexibility, eliminating cracks and wrinkles during bending operations.
3Adaptability or versatility
If adhesive layers with low storage modulus are used, then the structure is flexible and easy to deform, but adhesive strength decreases and components may separate
Solution Approach 1:
The adhesive layer is segmented into functional sub-layers: the first adhesive sub-layer with higher storage modulus provides the necessary adhesive strength, while the second adhesive sub-layer with lower storage modulus provides bending flexibility. This segmentation allows the system to simultaneously achieve both flexibility and strong adhesion.
Solution Approach 2:
Different local qualities are assigned to different sub-layers of the adhesive system. The first sub-layer is designed with high storage modulus for strong bonding, while the second sub-layer is designed with low storage modulus for flexibility. This local quality differentiation resolves the contradiction between bending flexibility and adhesive strength.
4Ease of manufacture
If uniform thickness adhesive layers are used, then manufacturing is simple, but stress distribution is uneven during bending causing interface separation
Solution Approach 1:
The adhesive layer is segmented into multiple sub-layers with different thicknesses. The first adhesive sub-layer and second adhesive sub-layer can have different thickness configurations optimized for their respective functions. This segmentation enables better stress distribution during bending while maintaining manufacturing simplicity through standardized layering processes.
Solution Approach 2:
Different thickness parameters are assigned to different adhesive sub-layers based on their functional requirements. The first adhesive sub-layer may have a smaller thickness for strong bonding, while the second adhesive sub-layer may have a larger thickness for flexibility and stress distribution. This local quality optimization resolves the contradiction between manufacturing simplicity and stress distribution uniformity.
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 reduces the probability of wrinkles and cracks, enhances bending reliability, and extends the service life of the flexible display apparatus by managing stress distribution and preventing interface separation.
Implementation Method 1
One of the at least one first adhesive layer is adhered to one of the two adjacent components
Implementation Method 2
A storage modulus of each second adhesive layer is less than a storage modulus of each first adhesive layer
Data Source
AI summary
A flexible display apparatus includes at least two components that are stacked, and at least one optical adhesive layer. Each optical adhesive layer is disposed between two adjacent components of the at least two components, and includes at least two adhesive layers stacked in a stacking direction of the at least two components. The at least two adhesive layers include at least one first adhesive layer and at least one second adhesive layer. One of the at least one first adhesive layer is adhered to one of the two adjacent components, and a storage modulus of each second adhesive layer is less than a storage modulus of each first adhesive layer.