Foldable Substrate Structure for Small Fold Radius and Impact Resistance
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Solution Overview
Problem
Existing foldable displays and protective covers face challenges in achieving a small parallel plate distance while maintaining good impact and puncture resistance, with conventional glass-based substrates either lacking in resistance or having large plate distances.
Innovation Solution
The use of glass-based or ceramic-based substrates with compressive stress regions and controlled lithium oxide concentration profiles, combined with recessed central portions and transition regions, enhances impact and puncture resistance while allowing for foldability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional glass-based substrates are used with small parallel plate distance, then foldability is achieved, but impact and puncture resistance deteriorate
Solution Approach 1:
The substrate employs different thicknesses in different regions: a thinner central portion (first thickness) for foldability and a thicker peripheral portion (second thickness) for strength. This local variation in thickness allows the substrate to be flexible where needed while maintaining structural integrity at the edges, resolving the contradiction between foldability and impact resistance.
Solution Approach 2:
The substrate integrates multiple material properties through its composite structure, combining glass-based or ceramic-based materials with controlled density and compositional gradients. This composite approach enables simultaneous achievement of flexibility in the central region and high strength in the peripheral regions, addressing both foldability and resistance requirements.
2Strength
If conventional glass-based substrates are used with good impact and puncture resistance, then strength is improved, but parallel plate distance increases
Solution Approach 1:
The substrate employs different thicknesses in different regions: a thinner central portion (first thickness) to minimize parallel plate distance and a thicker peripheral portion (second thickness) to provide impact and puncture resistance. This local variation in thickness allows the substrate to be flexible where needed while maintaining structural integrity at the edges, resolving the contradiction between foldability and impact resistance.
3Length of moving object
If ultra-thin glass-based sheets are used, then parallel plate distance is reduced, but impact and puncture resistance deteriorate
Solution Approach 1:
The substrate employs different thicknesses in different regions: a thinner central portion (first thickness) for foldability and a thicker peripheral portion (second thickness) for strength. This local variation in thickness allows the substrate to be flexible where needed while maintaining structural integrity at the edges, resolving the contradiction between foldability and impact resistance.
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 provides foldable substrates with improved mechanical stability, reduced buckling, and optical clarity, enabling small parallel plate distances and effective folding performance.
Implementation Method 1
The portions can comprise glass-based and/or ceramic-based portions comprising one or more compressive stress regions
Data Source
AI summary
In aspects, a concentration of lithium oxide at a surface is greater than a concentration of lithium oxide at a midpoint by from about 0.2 mol % to about 2 mol %. In aspects, a concentration of lithium oxide at a surface is from about 0.2 mol % to about 2 mol %. In aspects, a total concentration of potassium oxide, rubidium oxide, cesium oxide, and francium oxide at a surface is from about 5 mol % to about 15 mol %. In aspects, a ratio of the total concentration of potassium oxide, rubidium oxide, cesium oxide, and francium oxide at a surface to a concentration of lithium oxide at the surface is from about 1 to about 20. Methods include immersing a substrate in a molten salt bath at 380° C. or more for from about 1 minute to about 10 minutes or for from about 3 minutes to about 2 hours.