Phosphor Glass Composition for Low-Temperature Wavelength Conversion
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Solution Overview
Problem
Wavelength conversion members used in light sources, particularly those containing phosphors, face degradation during production and have limited weather resistance due to the use of conventional resin matrices and high-softening point glasses, which affect luminance and color rendition.
Innovation Solution
A glass composition with 30-75% SiO2, 1-30% B2O3, over 4-20% Al2O3, 0.1-10% Li2O, and 0-10% MgO+CaO+SrO+BaO+ZnO is used to create a wavelength conversion member with a low softening point for reduced phosphor degradation and excellent weather resistance, while being free from lead and arsenic components to ensure environmental sustainability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a low-softening point glass is used to reduce phosphor degradation during firing, then phosphor degradation is reduced, but weather resistance deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters of the glass matrix. Specifically, it limits alkali metal oxide content (Na2O + K2O) to 9% or less and alkaline earth metal oxide content (MgO + CaO + SrO + BaO + ZnO) to 10% or less, while setting Al2O3 content at 4% or more. This compositional parameter optimization enables the glass to achieve both low softening point (for reduced phosphor degradation) and good weather resistance simultaneously.
2Object-affected harmful factors
If SiO2 content is increased to improve weather resistance, then weather resistance is improved, but sintering temperature increases
Solution Approach 1:
The patent balances the SiO2 content parameter within the range of 30-75%, avoiding excessive SiO2 that would raise sintering temperature too high. This parameter optimization is combined with controlled additions of B2O3 (1-30%) which acts as a flux to lower the softening point, and controlled levels of Al2O3 (4-20%) which contributes to both structural stability and weather resistance. This balanced compositional approach achieves both weather resistance and manageable sintering temperature.
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 glass composition enables the production of wavelength conversion members with reduced phosphor degradation and enhanced weather resistance, improving the luminance and durability of light-emitting devices while maintaining high light transmittance in the ultraviolet region.
Implementation Method 1
heat or high-energy short-wavelength (ultraviolet) light emitted from the LED or the phosphor degrades the molded resin
Implementation Method 2
high-energy short-wavelength (ultraviolet) light emitted from the LED or the phosphor degrades the molded resin
Implementation Method 3
the glass can be sintered at a low temperature, so that thermal degradation of a phosphor powder can be reduced
Data Source
AI summary
Provided is a glass that is used in a phosphor-containing wavelength conversion material and from which can be produced a wavelength conversion member less degraded in characteristics of a phosphor owing to firing during production of the wavelength conversion member and having excellent weather resistance. The glass is for use in a wavelength conversion material and contains, in terms of % by mass, 30 to 75% SiO2, 1 to 30% B2O3, over 4 to 20% Al2O3, 0.1 to 10% Li2O, 0 to below 9% Na2O+K2O, and 0 to 10% MgO+CaO+SrO+BaO+ZnO.