Optical Glass Composition Suppressing Surface Devitrification

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Solution Overview

Problem

Optical glass with high refractive index often experiences surface devitrification, leading to yield reduction and difficulty in quality checking, which complicates the manufacturing of optical elements and light guide plates.

Innovation Solution

An optical glass composition including SiO2, B2O3, TiO2, Nb2O5, Y2O3, La2O3, and Gd2O3 with specific mass ratios and refractive index values, suppressing surface devitrification and maintaining high refractive index, is developed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If optical glass with high refractive index is used, then the optical system can be made compact and viewing angle can be widened, but surface devitrification occurs leading to yield reduction and quality checking difficulty

Engineering Contradiction:

Improverefractive indexVSAvoidsurface devitrification resistance

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the optical glass by specifying precise mass ratios of B2O3 to SiO2 (less than 1.000) and Y2O3 to total rare earth oxides (more than 0.020), while maintaining a high refractive index nd of more than 2.00000. This parameter optimization resolves the contradiction by achieving high refractive index while suppressing surface devitrification through controlled composition

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite glass material combining multiple oxide components (SiO2, B2O3, TiO2, Nb2O5, Y2O3, La2O3, Gd2O3) in specific proportions. This composite composition achieves both high refractive index and improved resistance to surface devitrification, resolving the technical contradiction between optical performance and surface stability

Inventive Principle:

Principle #40Composite materials

2Area of stationary object

If optical glass with high refractive index is used, then the viewing angle of light guide plate can be widened, but surface devitrification causes fogging making quality check difficult

Engineering Contradiction:

Improveviewing angleVSAvoidquality check difficulty

Core Design Contradiction:

Area of stationary objectVSDifficulty of detecting and measuring

Solution Approach 1:

The patent optimizes composition parameters including B2O3/SiO2 ratio less than 1.000 and Y2O3/(Y2O3+La2O3+Gd2O3+Yb2O3) ratio more than 0.020, maintaining refractive index nd more than 2.00000. These parameter changes suppress surface devitrification, preventing fogging and enabling easy quality inspection while maintaining wide viewing angle performance

Inventive Principle:

Principle #35Parameter changes

3Weight of moving object

If optical glass with high refractive index is used, then optical elements can be made with reduced weight, but surface devitrification leads to yield reduction

Engineering Contradiction:

Improveoptical element weightVSAvoidmanufacturing yield

Core Design Contradiction:

Weight of moving objectVSProductivity

Solution Approach 1:

The patent specifies precise composition parameters: B2O3/SiO2 mass ratio less than 1.000, Y2O3/(Y2O3+La2O3+Gd2O3+Yb2O3) mass ratio more than 0.020, and refractive index nd more than 2.00000. These parameter optimizations suppress surface devitrification during manufacturing, reducing waste and improving yield while maintaining the weight reduction benefits of high refractive index glass

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20240327269A1Optical glass, optical element, light guide plate and image display device

Publication Date: 2024.10.03 HOYA CORPORATION

AI summary

The optical glass includes SiO2, B2O3, TiO2, Nb2O5, Y2O3, La2O3, and Gd2O3 as essential components, in which, on a mass basis, a mass ratio of a B2O3 content to a SiO2 content (B2O3/SiO2) is less than 1.000, a mass ratio of Y2O3 content to a total content of Y2O3, La2O3, Gd2O3 and Yb2O3 (Y2O3/(Y2O3+La2O3+Gd2O3+Yb2O3)) is more than 0.020, and a refractive index nd is more than 2.00000.