Variable Index Light Extraction Layer for Optical Clarity
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Solution Overview
Problem
Traditional light extraction layers in optical stacks, such as those used in displays and lighting applications, often suffer from being non-transparent or distorting, making it difficult to view images or graphics without significant haze or distortion due to light scattering features.
Innovation Solution
A variable index light extraction layer is introduced, comprising regions of nanovoided polymeric material and non-nanovoided polymeric material with different refractive indices, selectively extracting light from a lightguide based on geometric arrangement, allowing for transparent and distortion-free illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If traditional light scattering features are used in extraction layers, then light extraction from lightguide is achieved, but optical transparency and image clarity deteriorate due to haze and distortion
Solution Approach 1:
The patent applies local quality by creating extraction regions with varying refractive indices at different locations within the extraction layer. The layer includes a first region with a first refractive index and a second region with a second refractive index, where the refractive indices are different. This spatial variation in optical properties enables selective light extraction while maintaining overall optical clarity, resolving the contradiction between extraction efficiency and image quality.
Solution Approach 2:
The patent changes the refractive index parameter across different regions of the extraction layer. By configuring regions with different refractive indices (first region with first refractive index, second region with second refractive index), the layer can selectively extract light based on angle while maintaining transparency. This parameter variation resolves the contradiction by enabling both effective light extraction and optical clarity simultaneously.
2Ease of operation
If extraction layers with light scattering features are implemented, then light is directed out of lightguide, but viewing difficulty increases due to non-transparent or distorting characteristics
Solution Approach 1:
The extraction layer implements local quality by having different refractive index regions (first region with first refractive index, second region with second refractive index) that perform different functions. This spatial differentiation enables the layer to extract light effectively while specific regions maintain transparency, reducing viewing distortion and resolving the contradiction between extraction function and viewing quality.
Solution Approach 2:
The patent uses composite material structure by combining regions with different refractive indices within a single extraction layer. This composite approach allows the layer to simultaneously provide light extraction functionality and maintain optical transparency, eliminating viewing distortion while preserving ease of operation.
3Illumination intensity
If variable index regions with different refractive indices are used, then selective light extraction at supercritical angles is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by creating regions with different refractive indices in specific locations in the extraction layer. This spatial variation enables selective light extraction at supercritical angles while the overall layer structure remains relatively simple, managing the complexity through functional zonation rather than complex overall architecture.
Solution Approach 2:
The patent changes the refractive index parameter across different regions to achieve selective light extraction. By varying this single optical parameter across the layer rather than changing the entire layer structure, the patent achieves complex optical functionality with relatively simple structural modifications, managing the device complexity effectively.
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 variable index light extraction layer effectively extracts light at supercritical angles while minimizing scattering of subcritical light, maintaining high clarity and resolution, and can be manufactured using simple and cost-effective coating and printing techniques.
Implementation Method 1
The first region has a lower effective index of refraction than the second region and the first and second regions of the layer are disposed such that, when optically coupled to a lightguide, the layer selectively extracts light from the lightguide based on the geometric arrangement of the first and second regions
Implementation Method 2
the layer selectively extracts light from the lightguide based on the geometric arrangement of the first and second regions
Data Source
AI summary
Variable index light extraction layers that contain a first region with a first material and a second region including a second material are described, where the first region has a lower effective index of refraction than the second region. Optical films and stacks may use the variable index light extraction layers in front lit or back lit display devices and luminaires.