Foldable Substrate Structure for Small Bend Radius and Impact Resistance
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Solution Overview
Problem
Foldable displays and covers with small minimum bend radii suffer from poor impact and puncture resistance, and thicker glass-based sheets with good resistance have large minimum bend radii and mechanical reliability issues due to fatigue-related failures.
Innovation Solution
The development of foldable substrates with glass-based and ceramic-based materials incorporating compressive stress regions and second portions with significantly lower Young’s modulus than adjacent portions, reducing bend-induced stresses and mechanical instabilities, while allowing for small effective minimum bend radii and improved impact and puncture resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If plastic displays and covers with small minimum bend radii are used, then the bendability is improved, but the impact and puncture resistance deteriorates
Solution Approach 1:
The patent employs a composite structure consisting of a first portion (rigid glass-based or ceramic-based substrate) and a second portion (flexible polymer-based substrate) bonded together. This composite configuration allows the rigid portion to provide impact and puncture resistance while the flexible portion accommodates small bend radii, thereby resolving the contradiction between bendability and mechanical strength.
2Shape
If ultra-thin glass-based sheets with small minimum bend radii are used, then the bendability is improved, but the impact and puncture resistance deteriorates
Solution Approach 1:
The patent combines ultra-thin glass-based substrate (first portion) with a flexible polymer-based substrate (second portion) to create a composite structure. The glass-based portion maintains small minimum bend radius capability while the polymer portion compensates for the reduced impact and puncture resistance inherent in ultra-thin glass sheets.
3Strength
If thicker glass-based sheets with good impact and puncture resistance are used, then the strength is improved, but the minimum bend radius increases and mechanical reliability deteriorates
Solution Approach 1:
The patent uses a composite structure where a thinner glass-based substrate (first portion) is bonded to a flexible polymer-based substrate (second portion). This allows achieving good impact and puncture resistance through the composite effect while maintaining small minimum bend radius, avoiding the fatigue-related failures associated with thicker glass sheets.
4Strength
If thicker glass-based sheets are used, then the impact and puncture resistance is improved, but the mechanical reliability deteriorates due to fatigue-related failures
Solution Approach 1:
The patent employs a composite structure with a glass-based substrate (first portion) and a flexible polymer-based substrate (second portion). This composite design provides good impact and puncture resistance while the flexible portion absorbs bending stresses, thereby improving mechanical reliability and reducing fatigue-related failures compared to using thicker glass sheets alone.
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 enables foldable substrates with enhanced impact and puncture resistance, reduced fatigue, and improved mechanical reliability by minimizing bend-induced stresses, allowing for low user-applied forces to fold the apparatus and maintaining durability.
Implementation Method 1
providing a second portion comprising a much lower (e.g., from about 500 times to about 500,000 times, from about 10,000 times to about 100,000 times) Young's modulus than an adjacent pair of first portions can reduce bend-induced stresses on one or more of the first portions
Implementation Method 2
The foldable apparatus can comprise glass-based and/or ceramic-based materials comprising one or more compressive stress regions, which can further provide increased impact resistance and/or puncture resistance while simultaneously facilitating good bending performance
Data Source
AI summary
Foldable apparatus comprise a plurality of first portions and at least one second portion positioned between a corresponding adjacent pair of first portions of the plurality of first portions. Each second portion of the at least one second portion comprises a maximum Young’s modulus ranging from about 500 times to about 500,000 times less than a minimum Young’s modulus of the corresponding adjacent pair of first portions. In some embodiments, the at least one second portion comprises at least five second portions. In some embodiments, each second portion of the at least one second portion comprises a thickness ranging from about 10 micrometers to about 250 micrometers. In some embodiments, each first portion comprises a first neutral plane and each second portion comprises a second neutral plane. In some embodiments, an apparatus bend force ranges from about 0.5 times to about 1 times a total bend force.