Foldable Substrate Thickness Gradient for Impact-Resistant Folding
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Solution Overview
Problem
Conventional foldable glass-based substrates with small minimum bend radii suffer from poor impact and puncture resistance, while thicker glass-based substrates with good impact and puncture resistance have large minimum bend radii, necessitating the development of foldable apparatus with low minimum bend radii and enhanced mechanical stability.
Innovation Solution
The foldable substrates incorporate glass-based or ceramic-based portions with varying thickness profiles, including compressive stress regions and recesses, allowing for a central portion with reduced thickness to facilitate a circular folded configuration, reducing stress concentrations and mechanical instabilities, and enabling the use of stiffer materials for improved impact and puncture resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If glass-based substrates are made thinner to achieve small minimum bend radii, then foldability is improved, but impact and puncture resistance deteriorate
Solution Approach 1:
The substrate employs varying thickness across different regions: a thinner central folding region (first thickness) for flexibility and small bend radius, and thicker edge regions (second thickness greater than first thickness) for enhanced impact and puncture resistance. This local differentiation resolves the contradiction by optimizing each region for its specific function.
Solution Approach 2:
The invention transitions from a uniform two-dimensional substrate to a three-dimensional structure with varying thickness. By introducing the thickness dimension as a gradient (thinner in center, thicker at edges), the substrate achieves both foldability in the central region and structural strength at the edges simultaneously.
2Strength
If glass-based substrates are made thicker to improve impact and puncture resistance, then mechanical stability is improved, but minimum bend radius increases
Solution Approach 1:
Different regions of the substrate have different thicknesses optimized for different functions: edge regions are thicker for strength and impact resistance, while the central folding region is thinner to enable small bend radii and good foldability.
Solution Approach 2:
The substrate is segmented into functionally distinct regions: a central folding region and peripheral support regions. This segmentation allows each region to be independently optimized - the central region for flexibility and the edges for structural integrity.
3Ease of manufacture
If uniform thickness substrate is used, then manufacturing is simplified, but stress distribution becomes uneven during folding
Solution Approach 1:
The substrate intentionally introduces non-uniform thickness distribution with the central folding region being thinner than the edge regions. This local variation in thickness creates a more favorable stress distribution during folding, reducing stress concentrations at the edges while maintaining manufacturability through controlled thickness gradients.
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 described thickness profile enables foldable substrates to achieve a circular folded configuration with reduced stress concentrations and mechanical instabilities, enhancing impact and puncture resistance while maintaining good folding performance.
Implementation Method 1
The portions can comprise glass-based and/or ceramic-based portions comprising one or more compressive stress regions, which can further provide increased impact resistance and/or increased puncture resistance
Data Source
AI summary
Foldable substrates comprise a first portion, a second portion, and a central portion positioned therebetween. The first portion comprises a substrate thickness and a first depth of compression. The central portion comprises a folding region positioned between a first transition region and a second transition region. A local thickness of the folding region between a first folding surface area and a second folding surface area, excluding any teeth, increases as a distance from a midline of the folding region decreases. In aspects, the folding region comprises a plurality of teeth extending from the first folding surface area. In aspects, the local thickness of the folding region as a function of the position along the folding width of the folding region can be proportional to a cube root of a sine of a fractional position, the fractional position scaled to range from 0 to pi radians across the folding width.