Glass-Ceramic Optical Diffuser for Thermal Stability
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Solution Overview
Problem
Current diffusers in display devices, made from polymeric materials like polycarbonate and poly(methyl)methacrylate, suffer from yellowing, poor thermal stability, and dimensional instability, leading to a need for materials with high transparency, haze, and stability that do not degrade over time.
Innovation Solution
The development of glass-ceramic articles with lithium disilicate crystals and ß-spodumene or ß-quartz crystals, which provide high light transmittance and haze, along with improved mechanical and thermal stability, achieved through specific compositions and thermal processing techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polymeric materials are used for diffusers, then manufacturing ease is improved, but thermal stability and dimensional stability deteriorate
Solution Approach 1:
The patent uses glass-ceramic composite material that combines the ease of manufacturing with glass while providing superior thermal stability and dimensional stability. The glass-ceramic structure allows for stable thermal and dimensional properties unlike pure polymeric materials.
2Ease of manufacture
If polymeric materials are used for diffusers, then manufacturing ease is improved, but dimensional stability deteriorates
Solution Approach 1:
The glass-ceramic composite material provides excellent dimensional stability while maintaining manufacturability. The crystalline phase within the glass matrix prevents dimensional changes that occur with polymeric materials under thermal and environmental conditions.
3Object-generated harmful factors
If glass-ceramic articles with high haze are produced, then hiding power is improved, but light transmittance deteriorates
Solution Approach 1:
The patent employs local quality by creating specific crystal phases (lithium disilicate, ß-spodumene, or ß-quartz) with controlled grain sizes (500 nm to 10 µm) distributed within the glass-ceramic matrix. This localized crystalline structure provides high haze and hiding power while the overall glass-ceramic composition maintains high light transmittance.
4Object-generated harmful factors
If crystal grain size is increased to improve light scattering, then haze is improved, but mechanical strength deteriorates
Solution Approach 1:
The patent optimizes the crystal grain size parameter within a specific range (500 nm to 10 µm, preferably 1 µm to 5 µm) to achieve the right balance between light scattering (haze) and mechanical strength. This parameter optimization ensures that crystals are large enough to scatter visible light effectively but small enough to maintain the mechanical integrity of the glass-ceramic article.
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
These glass-ceramic articles enhance brightness uniformity and illumination efficiency while maintaining stability, with lithium disilicate crystals increasing mechanical strength and interlocking crystals further enhancing stability, and the specific crystal sizes and compositions optimizing light scattering and hiding power.
Implementation Method 1
ß-spodumene or ß-quartz crystals can increase light scattering of the glass-ceramic article, which can increase the haze and hiding power of the glass-ceramic article
Data Source
AI summary
An optical diffuser can comprise an amorphous phase and a crystalline phase comprising lithium disilicate and one or more of ß-spodumene orß-quartz comprising a median grain size ranging from about 500 nanometers to about 1,000 nanometers. The crystalline phase can be dispersed throughout a volume of the optical diffuser. The optical diffuser can comprise, on an oxide basis in mol %, SiO2: 60-75; Al2O3: 2-9; Li2O: 17-25; and Na2O+K2O: 0.5-6. Methods of making an optical diffuser can comprise forming a mixture by melting together, on an oxide basis in mol %, SiO2: 60-75; Al2O3: 2-9; Li2O: 17-25; and Na2O+K2O: 0.5-6. Methods can comprise forming a ribbon from the mixture. Methods can comprise heating the ribbon about 850° C. to about 900° C. for about 0.5 hours to about 6 hours.