High Refractive Index Glass UV Solarization Resistance
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Solution Overview
Problem
Conventional glasses with high refractive indices often experience a decrease in transmittance due to coloring, impurity mixing, and temporal changes, particularly when used in wearable devices like head-mounted displays for augmented, virtual, and mixed reality applications.
Innovation Solution
A glass composition with specific oxide content ranges, including TeO2, P2O5, B2O3, Li2O, Na2O, K2O, TiO2, Ta2O5, WO3, Nb2O5, ZrO2, Bi2O3, ZnO, SrO, and SiO2, optimized to maintain a high refractive index while suppressing transmittance degradation under ultraviolet irradiation, with parameters A and B calculated to minimize degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the refractive index is increased to meet high optical performance requirements, then the light guiding efficiency is improved, but the transmittance decreases due to coloring and impurity mixing
Solution Approach 1:
The patent changes the chemical composition parameters of the glass by precisely controlling the content ranges of multiple oxides (TeO2: 10-30 mol%, P2O5: 5-20 mol%, B2O3: 10-30 mol%, etc.) to achieve a refractive index of 1.85 or more while maintaining transmittance of 70% or more at 440 nm, resolving the contradiction between high refractive index and high transmittance
Solution Approach 2:
The patent creates a composite glass material combining multiple oxide components (TeO2-P2O5-B2O3 base system with Li2O, Na2O, K2O, TiO2, Ta2O5, WO3, Nb2O5, ZrO2, Bi2O3, ZnO, SrO, SiO2) that work synergistically to achieve both high refractive index and high transmittance, preventing the coloring and impurity mixing issues that occur in conventional single-component or simple composite glasses
2Illumination intensity
If conventional glass composition is used to achieve high refractive index, then the refractive index is improved, but the transmittance degrades over time due to ultraviolet irradiation and temporal changes
Solution Approach 1:
The patent incorporates specific oxide components (TiO2: 0.1-5 mol%, Ta2O5: 0.1-5 mol%, Nb2O5: 0.1-5 mol%) in advance into the glass composition to prevent ultraviolet-induced solarization and temporal degradation, ensuring the glass maintains its transmittance stability over time when used in wearable devices exposed to UV radiation
Solution Approach 2:
The patent converts potentially harmful ultraviolet irradiation effects into beneficial outcomes by using specific oxide combinations that not only resist UV degradation but also improve the overall optical stability and durability of the glass, transforming the challenging UV exposure environment into an opportunity to demonstrate superior material performance
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 achieves a refractive index of 1.94 or more with internal transmittance of 70% or more at 440 nm and a degradation degree of 2.2% or less in ultraviolet irradiation tests, ensuring high transmittance and resistance to ultraviolet-induced solarization.
Implementation Method 1
a glass having a high refractive index has been required. In particular, for example, in a wearable device such as a head mounted display that implements augmented reality (AR), virtual reality (VR), mixed reality (MR), and the like as disclosed in WO 2020/090051 A, a high refractive index with respect to visible light is required as a light guide plate.
Implementation Method 2
a degradation degree ΔT of 2.2% or less in an ultraviolet irradiation test, wherein the degradation degree ΔT in the ultraviolet irradiation test is obtained by formula (1) below. The transmittance T1 is an external transmittance of the glass with respect to light having a wavelength of 470 nm after a surface of the glass having a thickness of 1 mm is irradiated with ultraviolet rays having a wavelength of 365 nm
Data Source
AI summary
Provided is a glass having a high refractive index and capable of suppressing a decrease in transmittance with respect to visible light. A glass (10) has a refractive index of 1.94 or more, an internal transmittance of 70% or more with respect to light having a wavelength of 440 nm at a plate thickness of 10 mm, and a degradation degree (ΔT) of 2.2% or less in an ultraviolet irradiation test.