Electronic Paper Display Device with Soft Adhesive Layer
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Solution Overview
Problem
Traditional flexible display panels suffer from electronic ink layer damage due to shear force during repeated bending, as the ink layer is softer than the surrounding film materials, leading to fatigue and failure.
Innovation Solution
Incorporating an upper and lower supporting layer with a storage modulus in the range of 1 kPa to 100 kPa, which acts as a soft adhesive material to reduce shear force on the electronic ink layer, allowing it to withstand more bending cycles and extend the device's service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the electronic ink layer is made softer to maintain flexibility, then the flexibility and bendability are improved, but the electronic ink layer suffers from larger shear force during bending leading to fatigue and failure
Solution Approach 1:
The patent introduces an adhesive layer as an intermediary between the electronic ink layer and the encapsulation layer. This adhesive layer has a storage modulus specifically designed to be lower than the encapsulation layer but higher than the electronic ink layer, allowing it to act as a stress buffer that protects the electronic ink layer from shear force during bending while maintaining overall structural integrity
Solution Approach 2:
The patent changes the mechanical parameter (storage modulus) of the adhesive layer to be within a specific range (1 kPa to 100 kPa at 0°C to 70°C), which is lower than the encapsulation layer's storage modulus. This parameter adjustment allows the adhesive layer to deform more easily during bending, reducing the shear force transmitted to the electronic ink layer
2Reliability
If the storage modulus of the adhesive layer is reduced to protect the electronic ink layer, then the resistance to bending-induced shear force is improved, but the structural strength and support may be compromised
Solution Approach 1:
The patent applies different storage modulus values to different layers of the display device. The adhesive layer has a low storage modulus (1 kPa to 100 kPa) specifically at the location where it contacts the electronic ink layer to protect against shear force, while the encapsulation layer has a higher storage modulus to provide overall structural support. This local differentiation of material properties allows both protection and structural integrity to coexist
Solution Approach 2:
The patent creates a composite structure with multiple layers having different storage moduli. The combination of the soft adhesive layer (1 kPa to 100 kPa) and the stiffer encapsulation layer creates a composite system where the adhesive layer absorbs shear stress during bending while the encapsulation layer maintains structural support, achieving both protection and strength
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 system stress and increases the number of bending cycles, enabling a smaller bend radius of curvature and extending the service life of the electronic paper display device by distributing shear force away from the microcapsules.
Implementation Method 1
the electronic ink layer will bear a very large shear force in the bending state because the electronic ink layer is a very soft material as compared with the film materials
Implementation Method 2
has a storage modulus in a range from 1 kPa to 100 kPa in 0° C. to 70° C.
Implementation Method 3
the electronic ink layer will be damaged by the shear force at the edge of the bending area due to fatigue effect and fail
Data Source
AI summary
An electronic paper display device includes an upper supporting layer, a lower supporting layer, and an electronic ink layer. The lower supporting layer is opposite to the upper supporting layer. At least one of the upper supporting layer and the lower supporting layer has a thickness in a range from 1 μm to 50 μm and has a storage modulus in a range from 1 kPa to 100 kPa in 0° C. to 70° C. The electronic ink layer is located between the upper supporting layer and the lower supporting layer.