Strengthened Glass Substrate for Display Screen Protector
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Solution Overview
Problem
The persistent issue of breakage of cover glass in electronic devices due to flexural failure and sharp contact damage, which existing solutions struggle to address effectively while maintaining aesthetic and functional requirements.
Innovation Solution
A strengthened glass substrate with a central tension value between 0 MPa and 20 MPa and a Knoop lateral cracking scratch threshold of at least 3 N, which is applied as a screen protector to provide enhanced durability and resistance to damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If hard coatings are applied to strong ion exchanged glass to prevent sharp contact failure, then scratch resistance is improved, but flexural strength deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the glass substrate by incorporating specific amounts of Al2O3 (5-20 wt%), B2O3 (2-10 wt%), and other oxides to create a glass composition that inherently achieves both high scratch resistance (Knoop lateral cracking scratch threshold ≥3 N) and adequate flexural strength (central tension value 0-20 MPa) without requiring hard coatings that would compromise flexural strength
Solution Approach 2:
The patent uses a composite glass-ceramic material system that combines multiple glass phases with specific crystalline phases to achieve synergistic effects where the material structure itself provides both scratch resistance and flexural strength, eliminating the need for separate protective coatings that would create the contradiction
2Object-affected harmful factors
If coatings are applied to cover glass and bezels to prevent contact with ground during drops, then impact resistance is improved, but aesthetic and functional requirements are compromised
Solution Approach 1:
The patent extracts the protective function from separate surface coatings and relocates it to the bulk material properties of the glass substrate itself, allowing the glass to inherently resist impact and sharp contact without requiring additional layers that would affect aesthetics or functionality
Solution Approach 2:
The patent modifies the fundamental parameters of the glass substrate (chemical composition, ion exchange depth, compressive stress distribution) to achieve intrinsic impact resistance, allowing the material itself to withstand drop events without compromising the surface properties needed for aesthetics and function
3Object-affected harmful factors
If the central tension value is increased to improve scratch resistance, then surface strength is improved, but the glass becomes more prone to flexural failure
Solution Approach 1:
The patent precisely controls the central tension value parameter within the optimal range of 0-20 MPa through controlled ion exchange processes and glass composition selection, achieving the right balance where the glass has sufficient surface compressive stress for scratch resistance (Knoop lateral cracking scratch threshold ≥3 N) while maintaining low central tension to prevent flexural failure
Solution Approach 2:
The patent creates different stress states at different locations within the glass substrate - high compressive stress at the surface for scratch resistance and low central tension for flexural stability - achieving local optimization of properties that would otherwise be mutually exclusive
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 significantly improves the survivability of electronic device screens by providing improved resistance to scratches and drops, with enhanced durability and resistance to damage, outperforming comparative glass substrates in drop and scratch tests.
Implementation Method 1
the first strengthened substrate having a central tension value in the range greater than 0 MPa and less than 20 MPa
Implementation Method 2
a surface having a Knoop lateral cracking scratch threshold of at least 3 N
Data Source
AI summary
Disclosed are device display screen protectors comprising a first strengthened substrate sized to cover a display screen of an electronic device, the first strengthened substrate having a central tension value in the range greater than 0 MPa and less than 20 MPa, a surface having a Knoop lateral cracking scratch threshold of at least 3 N.