Composite Film Elastic Modulus Gradient for Foldable Display Impact Resistance
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Solution Overview
Problem
Bendable or foldable display devices face reduced reliability against external impacts due to their flexible properties, which can lead to damage to the display panel.
Innovation Solution
A display device design incorporating a display panel with a first film and a second film, where the first film has a high elastic modulus and a second layer with a lower elastic modulus, both with specific adhesive layers, to enhance impact resistance and folding properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If flexible members are used in bendable or foldable display devices, then folding properties and flexibility are improved, but reliability against external impact deteriorates
Solution Approach 1:
The first film is constructed as a composite structure with a first layer and a second layer having different elastic moduli. The first layer (closer to the display panel) has a higher elastic modulus (600-1500 MPa) to provide impact resistance, while the second layer (closer to the external environment) has a lower elastic modulus (5-30 MPa) to maintain flexibility and absorb impact energy. This composite material approach allows the film to simultaneously achieve both flexibility for folding and reliability against external impact.
Solution Approach 2:
Different regions of the first film have different elastic moduli to perform different functions. The first layer near the display panel has high elastic modulus for structural support and impact resistance, while the second layer at the outer surface has low elastic modulus for flexibility and impact energy absorption. This local differentiation of material properties resolves the contradiction between flexibility and impact resistance.
2Ease of manufacture
If a single-layer film with uniform elastic modulus is used, then manufacturing simplicity is maintained, but both flexibility and impact resistance cannot be simultaneously optimized
Solution Approach 1:
The patent employs a composite film structure with two layers of different materials having distinct elastic moduli. This composite approach enables simultaneous optimization of flexibility (through the lower modulus layer) and impact resistance (through the higher modulus layer), which cannot be achieved with a single uniform material while maintaining reasonable manufacturing complexity.
Solution Approach 2:
The first film is segmented into two distinct layers: a first layer with higher elastic modulus (600-1500 MPa) and a second layer with lower elastic modulus (5-30 MPa). This segmentation allows each layer to be optimized for its specific function - the first layer for impact resistance and the second layer for flexibility - thereby achieving superior overall performance compared to a single-layer film.
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 design effectively minimizes damage from external impacts while maintaining flexibility, allowing for easy folding and improved resilience of the display device.
Implementation Method 1
a first film on the display panel, a second film on the first film, and a first adhesive layer between the first film and the display panel, where the first film includes a first layer adjacent to the second film, and a second layer between the first layer and the first adhesive layer, where an elastic modulus of the second layer is different from an elastic modulus of the first layer
Data Source
AI summary
A display device includes a display panel in which a display element is disposed, a first film on the display panel, a second film on the first film, and a first adhesive layer between the first film and the display panel, wherein the first film includes a first layer adjacent to the second film, and a second layer between the first layer and the first adhesive layer, where an elastic modulus of the second layer is different from an elastic modulus of the first layer.