Multilayer Substrate with Graded Refractive Index for Display Reflection Reduction
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Solution Overview
Problem
Existing display devices suffer from reduced contrast ratios due to light reflection issues, particularly in brightly lit environments, where internal reflection within the device structure contributes significantly to decreased image clarity and visibility, especially when displaying black colors.
Innovation Solution
A multilayer substrate configuration is introduced where the refractive index varies continuously between layers, reducing internal reflection by minimizing discontinuities in refractive index at interfaces, and a low-reflection layer with a moth eye structure is applied to further reduce surface reflectance, achieving a reflectance of less than 1.0%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a transparent inorganic thin film is arranged between the transparent substrate and the metal light-blocking film, then light reflection at the substrate interface is reduced, but light reflection occurs at the boundaries between layers with different refractive indexes
Solution Approach 1:
The patent introduces an intermediate layer with a refractive index that gradually transitions between the transparent substrate and the metal light-blocking film. This intermediate layer acts as a mediator that reduces the abrupt refractive index difference at interfaces, thereby minimizing light reflection while maintaining a manageable structural complexity.
Solution Approach 2:
The patent changes the refractive index parameter gradually across multiple layers rather than having abrupt transitions. By using layers with progressively changing refractive indexes (from the substrate through intermediate layers to the metal film), the patent reduces reflection at each interface while keeping the overall structure practical for manufacturing.
2Object-affected harmful factors
If the transparent inorganic thin film is disposed on the entire transparent substrate, then light reflection is reduced in the light-blocking region, but new reflected light is generated in the pixel region, increasing overall reflected light
Solution Approach 1:
The patent applies the low-reflection layered structure selectively only in the light-blocking film region rather than across the entire substrate. This local application ensures that reflection is reduced where the light-blocking film is present while avoiding the generation of unwanted reflected light in the pixel regions where such structure is not needed.
Solution Approach 2:
The patent segments the substrate into different functional regions (light-blocking regions and pixel regions) and applies the low-reflection layered structure only to the light-blocking regions. This segmentation allows the patent to reduce reflection where necessary while maintaining optimal performance in pixel regions.
3Object-affected harmful factors
If multiple layers with different refractive indexes are stacked, then light reflection at individual interfaces is reduced through gradual transition, but the device structure becomes more complex
Solution Approach 1:
The patent uses a limited number of intermediate layers with progressively changing refractive indexes to achieve sufficient reflection reduction without creating excessive structural complexity. The number and refractive index values of the intermediate layers are optimized to balance reflection reduction performance with manufacturing feasibility.
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
This configuration enhances the contrast ratio in display devices, maintaining high image quality even in bright surroundings by significantly reducing both surface and internal reflections, thereby improving visibility and display clarity.
Implementation Method 1
the refractive index varies continuously between layers, reducing internal reflection by minimizing discontinuities in refractive index at interfaces
Implementation Method 2
a low-reflection layer with a moth eye structure is applied to further reduce surface reflectance
Implementation Method 3
a low-reflection layer with a moth eye structure is applied to further reduce surface reflectance
Data Source
AI summary
A display device is provided in which reduction of reflected light is realized. Also a multilayer substrate is provided in which light reflectance is reduced even when the substrate has a plurality of layers that differ in refractive index from each other. In the display device of one embodiment, the reflectance of light reflected by the internal structure, of light incident on the internal structure through a display screen, is less than 1.0%. The multilayer substrate of one embodiment includes a first layer and a second layer disposed adjacently to the first layer. The refractive index of the second layer varies continuously from an interface where the second layer is adjacent to the first layer in a direction from the first layer, with the variation being started at a value of the refractive index at the interface where the first layer is adjacent to the second layer.