Light Guide Plate Refractive Index Matching for HMDs
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Solution Overview
Problem
Conventional light guide plates for head mount displays (HMDs) using resin materials suffer from restricted angle of view and significant color changes due to refractive index differences between the glass substrate and resin layer, leading to undesirable color deviations in transmitted light.
Innovation Solution
A light guide plate comprising a glass plate with a resin layer containing metal oxide fine particles, where the refractive index difference between the glass and resin is minimized over the visible range by selecting appropriate glass compositions and metal oxide particles, ensuring an absolute difference of 0.07 or smaller, thereby reducing color changes and enhancing the angle of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a glass plate is used as substrate to increase refractive index for wider angle of view, then angle of view is improved, but color changes occur due to large refractive index difference between glass and resin layer
Solution Approach 1:
The patent changes the refractive index parameter of the resin layer by incorporating metal oxide fine particles (such as TiO2, ZrO2, SnO2) to increase the resin layer's refractive index from typical values (1.4-1.6) to match the glass substrate's refractive index (1.7-2.0), thereby reducing the refractive index difference and eliminating color changes while maintaining the wide angle of view enabled by the high-index glass substrate
Solution Approach 2:
The patent creates a composite resin layer by dispersing metal oxide fine particles within the resin matrix, forming a composite material that combines the optical properties of both components to achieve the desired refractive index matching between the resin layer and glass substrate, thus resolving the color change issue while preserving the wide angle of view capability
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 solution provides a light guide plate with minimal color changes and a wider angle of view for HMDs, particularly in augmented reality applications, by optimizing the refractive index matching between the glass and resin layers, resulting in improved visibility and reduced color deviations.
Implementation Method 1
the refractive index of the resin layer can be increased so as to come closer to the refractive index of the glass plate by dispersing metal oxide fine particles in the resin
Implementation Method 2
the resin layer is made of a resin containing metal oxide fine particles dispersed
Data Source
AI summary
The present invention relates to a light guide plate containing a glass plate and a resin layer that is formed on at least one major surface of the glass plate, in which the resin layer is made of a resin containing metal oxide fine particles dispersed, and an absolute value of a refractive index difference between the glass plate and the resin layer is 0.07 or smaller over an entire range of a wavelength of 430 nm to 700 nm.