Inward Foldable Display Lamination to Prevent Layer Lift-Off
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Solution Overview
Problem
The encapsulation layer and light-emitting layer in flexible displays of inward foldable screen devices tend to lift off from each other after repeated folding, leading to display failures.
Innovation Solution
The flexible display is designed with a specific laminated structure that includes a support sheet and base film with adjusted thickness and modulus, positioning the neutral layer away from the interface between the encapsulation and light-emitting layers, utilizing principles of material mechanics to apply reverse normal compressive stress and prevent lift-off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the flexible display is folded repeatedly, then the device achieves portability and compactness, but the encapsulation layer and light-emitting layer lift off from each other causing display failure
Solution Approach 1:
The patent changes the physical parameters of the base film by adjusting its thickness to 15-25 μm and modulus to 3-5 GPa. This parameter optimization shifts the neutral layer position during bending, reducing tensile stress at the encapsulation-light-emitting layer interface and preventing lift-off while maintaining foldability
Solution Approach 2:
The patent employs a composite laminated structure consisting of multiple layers with different mechanical properties (support sheet, base film, substrate, light-emitting layer, encapsulation layer). This composite design allows each layer to contribute its specific mechanical characteristics, creating a balanced structure that withstands repeated folding without layer separation
2Strength
If a thicker base film is used to strengthen the flexible display structure, then structural strength is improved, but the neutral layer position shifts causing increased stress at the interface between encapsulation and light-emitting layers
Solution Approach 1:
The patent identifies and optimizes the base film thickness parameter to a specific range of 15-25 μm. This precise parameter control achieves the optimal balance: the base film is thick enough to provide structural support but thin enough to position the neutral layer away from the encapsulation-light-emitting layer interface, preventing stress concentration and layer separation
3Strength
If the support sheet thickness is increased to improve bending resistance, then the flexible display maintains better structural integrity, but the overall flexibility and foldability are reduced
Solution Approach 1:
The patent optimizes the support sheet thickness to a precise range of 0.02-0.03 mm. This parameter optimization ensures the support sheet provides sufficient bending resistance and structural support while maintaining the overall flexibility needed for repeated folding. The thin support sheet allows the neutral layer to position appropriately during bending, preventing interface stress concentration
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
This design effectively reduces the likelihood of the encapsulation and light-emitting layers separating, enhancing the reliability and durability of the flexible display by maintaining structural integrity during bending and unfolding.
Implementation Method 1
when the flexible display is in a bent state, a neutral layer of a region that is of the bending region and that is adjacent to the flat region is located on a side that is of the interface and that is away from the encapsulation layer
Implementation Method 2
utilizing principles of material mechanics to apply reverse normal compressive stress and prevent lift-off
Data Source
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AI summary
An inward foldable screen electronic device (10) having a flexible display (14) is provided. The flexible display (14) includes an encapsulation layer (144), a light-emitting layer (145), a substrate (146), a base film (147), and a support sheet (148) that are sequentially stacked. An interface (S) exists between the encapsulation layer (144) and the light-emitting layer (145), and the support sheet (148) has a complete surface. A thickness of the base film (147) is 15 µm to 25 µm, and/or a modulus of the base film (147) is 3 GPa to 5 GPa, and/or a thickness of the support sheet (148) is 0.02 mm to 0.03 mm, so that when the flexible display (14) is in a bent state, a neutral layer (L) of a region that is of a bending region (B) and that is adjacent to a flat region (F1, F2) is located on a side that is of the interface (S) between the encapsulation layer (144) and the light-emitting layer (145) and that is away from the encapsulation layer (144). Therefore, the encapsulation layer (144) and the light-emitting layer (145) of the flexible display (14) are not prone to lift off from each other.