Cover Window With Gradient Stiffness For Foldable Displays
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Solution Overview
Problem
Foldable display devices face challenges with cover windows that have interfaces between soft and hard regions, leading to issues with optical properties and display quality due to differences in modulus and refractive indices, causing light refraction and a poor appearance.
Innovation Solution
A cover window design using a block-copolymer with varying mole fractions of low and high stiffness units, where the first region has a higher mole fraction of the low stiffness unit and the second regions have a higher mole fraction of the high stiffness unit, ensuring a gradual change in stiffness and surface morphology, and maintaining the same refractive index across regions to prevent light refraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a cover window is made with distinct soft and hard regions for folding capability, then flexibility is improved, but optical quality deteriorates due to visible interfaces and light refraction
Solution Approach 1:
The patent applies local quality by creating distinct soft and hard regions within the cover window, where each region has specific modulus properties tailored to its function. The soft region enables folding while the hard region provides structural support, and the interface region gradually transitions between these properties to minimize optical disruption.
Solution Approach 2:
The patent utilizes parameter changes by varying the modulus property across different regions of the cover window. The interface region specifically implements a gradual change in modulus from the soft region to the hard region, which reduces the refractive index difference and minimizes light refraction at the interface.
2Ease of manufacture
If the modulus property changes abruptly at the interface between soft and hard regions, then manufacturing is simplified, but optical quality deteriorates due to light refraction
Solution Approach 1:
The patent implements a gradual parameter change in the interface region, where the modulus property transitions smoothly from the soft region to the hard region. This gradual transition reduces the refractive index difference between regions, thereby minimizing light refraction and improving optical quality while maintaining manufacturing feasibility through multi-component injection molding.
3Adaptability or versatility
If different materials are used for soft and hard regions, then functional requirements are met, but refractive index differences cause visible interfaces and poor appearance
Solution Approach 1:
The patent employs composite materials by combining multiple polymer components with different modulus properties in a single cover window structure. The soft region uses a soft polymer, the hard region uses a hard polymer, and the interface region uses a composite or gradient material that transitions between these properties, achieving both functional performance and optical clarity.
Solution Approach 2:
The patent applies local quality by assigning different material compositions to different regions of the cover window. Each region has optimized material properties suited to its specific function, with the interface region using a transitional material composition that minimizes optical disruption while maintaining the structural integrity needed for folding.
Data Source
AI summary
There is provided a cover window including a first region; and second regions at both sides of the first region, wherein the first region has a stiffness being different from the second regions, and the stiffness of an interface region between the first region and the second region is gradually changed.