Borosilicate Glass Light Guide Plate for LCD Backlighting
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Solution Overview
Problem
Conventional liquid crystal display (LCD) light guide plates made of PMMA suffer from degradation due to moisture uptake, brittleness under light irradiation, high thermal expansion coefficients, and thickness limitations, leading to increased device thickness and instability, which are not adequately addressed by existing solutions.
Innovation Solution
A borosilicate glass light guide plate with a composition of at least 70 weight percent B2O3 and SiO2, low metal oxide content, and specific thermal expansion properties is used, offering high transmission, uniform absorption, and stability, reducing the need for spacer gaps and enhancing the structural integrity of LCDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If PMMA plastic is used for light guide plates, then ease of manufacture and cost-effectiveness are improved, but reliability deteriorates due to moisture uptake and brittleness
Solution Approach 1:
The patent changes the material parameter from PMMA plastic to borosilicate glass, fundamentally altering the material properties to eliminate moisture uptake and brittleness while maintaining optical performance. This parameter change resolves the reliability issue without sacrificing manufacturability.
Solution Approach 2:
The patent employs borosilicate glass as a composite material that combines high optical transmission properties with superior chemical stability and resistance to moisture. This composite material approach allows achieving both reliability and ease of manufacture by selecting a material that inherently possesses both qualities.
2Ease of manufacture
If PMMA light guide plates are used, then ease of manufacture is improved, but device thickness increases due to required spacer gaps for thermal expansion compensation
Solution Approach 1:
The patent changes the thermal expansion parameter of the light guide plate material from high (PMMA) to low (borosilicate glass), matching it closer to the display glass. This parameter change eliminates the need for compensatory spacer gaps, allowing the light guide plate to be integrated directly without increasing device thickness.
Solution Approach 2:
The patent addresses thermal expansion by selecting borosilicate glass with a coefficient of thermal expansion that closely matches display glass, thereby minimizing differential expansion. This thermal expansion matching eliminates the need for spacer gaps and reduces overall device thickness while maintaining ease of manufacture.
3Ease of manufacture
If PMMA light guide plates are used, then ease of manufacture is improved, but structural stability deteriorates due to low material stability
Solution Approach 1:
The patent changes the material composition parameter from PMMA to borosilicate glass, fundamentally improving chemical stability and resistance to environmental factors. This parameter change enhances structural stability while maintaining ease of manufacture through standard glass processing techniques.
Solution Approach 2:
The patent uses borosilicate glass as a composite material that inherently possesses superior stability properties compared to PMMA. This composite material selection allows achieving both ease of manufacture and structural stability by leveraging the inherent properties of glass chemistry.
4Reliability
If glass is used instead of PMMA, then reliability and stability are improved, but transmission quality deteriorates due to higher absorption
Solution Approach 1:
The patent changes the glass composition parameters (borosilicate ratio, purity levels) to optimize optical transmission. By adjusting these parameters, the patent achieves both high reliability and high transmission quality, eliminating the trade-off between material stability and optical performance.
Solution Approach 2:
The patent employs specially formulated borosilicate glass as a composite material that combines high optical transmission properties with superior stability. This composite material approach allows simultaneous achievement of reliability and transmission quality by selecting glass with optimized composition and purity.
5Reliability
If spacer gaps are provided for thermal expansion compensation, then reliability is improved, but device complexity and thickness increase
Solution Approach 1:
The patent changes the thermal expansion parameter of the light guide plate to match display glass, eliminating the need for compensatory spacer gaps. This parameter change reduces device complexity and thickness while maintaining reliability through direct integration of components.
Solution Approach 2:
The patent resolves the thermal expansion issue by selecting borosilicate glass with matched expansion characteristics. This thermal expansion matching eliminates the need for additional spacer gaps and structural complexity, allowing straightforward integration without compromising reliability.
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 borosilicate glass light guide plate achieves high transmission and stability, allowing for thinner, more compact LCDs with reduced thermal expansion and moisture sensitivity, enabling the production of slim, high-quality displays with improved aesthetic appeal and reduced weight.
Implementation Method 1
Light in-coupled into a lateral face is guided by total reflection between two parallel lateral faces
Implementation Method 2
the absorption spectrum of the light guide plate more uniform, in particular for long light paths, in the visible wavelength region
Data Source
AI summary
A light guide plate for guiding of visible light for the backlighting of a liquid crystal display is provided. The light guide plate has two parallel lateral faces and at least one edge face, which serves preferably as a light input face. The light guide plate is a glass that contains B2O3 and SiO2 as components, wherein the total content of B2O3 and SiO2 is at least 70 weight percent and the B2O3 content is greater than 10%. The total content of metal oxide of divalent metals in the composition of the glass is less than 3 weight percent. Al2O3 is contained between 1 weight percent and 5 weight percent in the composition.