Polarization Film Stretched-Axis Alignment for Foldable Display Durability
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Solution Overview
Problem
Existing display devices, particularly foldable ones, suffer from damage in the folding area during manufacturing due to the stress and deformation of the polarization layer.
Innovation Solution
A polarization film is designed with a stretched axis aligned parallel to the folding axis, incorporating a phase retardation layer and deformation portions to minimize damage during the folding process, featuring specific angles and dimensions of the deformation portions to withstand laser cutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the polarization layer is unitarily formed on the display panel, then the manufacturing process is simplified, but damage occurs in the folding area during the folding process
Solution Approach 1:
The polarization layer is divided into a first polarization layer and a second polarization layer that are separately formed on the display panel. This segmentation allows each layer to be independently optimized and positioned, reducing stress concentration in the folding area while maintaining manufacturing feasibility through sequential application.
Solution Approach 2:
Different regions of the polarization layer structure are given different properties: the first polarization layer is positioned at specific regions while the second polarization layer covers other regions, creating local variations in polarization orientation and stress distribution. This local quality differentiation enhances durability in the folding area while maintaining overall manufacturing efficiency.
2Adaptability or versatility
If the polarization layer is made flexible for foldable devices, then the device can be folded, but damage and deformation occur during the folding process
Solution Approach 1:
The polarization functionality is segmented into two separate layers with different orientations and positions. The first polarization layer is placed at specific regions while the second polarization layer covers other regions, allowing each layer to accommodate folding stress independently and preventing concentrated damage that would occur in a single-unitary structure.
Solution Approach 2:
The polarization structure uses a composite approach with multiple polarization layers having different optical properties and orientations. This composite structure provides both the flexibility needed for folding and the distributed stress management required to prevent damage, achieving adaptability while maintaining manufacturing precision.
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 damage in the folding area of foldable display devices by aligning the stretched axis with the folding axis and optimizing deformation portions, ensuring structural integrity and improved durability.
Implementation Method 1
a linear polarization layer in which the stretched axis is defined
Implementation Method 2
a phase retardation layer on the linear polarization layer
Data Source
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AI summary
A polarization film includes: a base substrate in which a folding axis and a stretched axis are defined; and a deformation portion located at an edge of the base substrate. The stretched axis forms an angle of less than about 45° with respect to the folding axis. The display device, in which a folding area at which a folding axis is located and a non-folding area neighboring the folding area are defined, includes a display panel; a first adhesive layer on the display panel; and a polarization film on the first adhesive layer, where a stretched axis is defined in the polarization film. An angle between the folding axis and the stretched axis is less than about 45°.