Liquid Crystal Display Insertion Material Refractive Index Control
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Solution Overview
Problem
High-definition liquid crystal display devices experience significant color purity degradation due to light leakage and color mixture between adjacent pixels, particularly at smaller pixel pitches, where conventional solutions fail to effectively prevent light from passing through adjacent color filters.
Innovation Solution
Incorporating an insertion material with a refractive index different from the overcoat film and liquid crystal between the black matrix and color filters in the liquid crystal display device, where the refractive index is either larger or smaller than the liquid crystal, to reduce light leakage and color mixture by increasing reflection and altering the light's path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pixel pitch is reduced to achieve high definition, then the screen resolution is improved, but color purity deteriorates due to increased light leakage to adjacent pixels
Solution Approach 1:
The patent introduces a translucent material layer with a different refractive index as an intermediary between adjacent color filters. This intermediate layer acts as a mediator that redirects light paths through refraction, preventing light from one pixel from directly reaching adjacent pixels. The refractive index difference causes light to bend at the interface, directing it back toward the original pixel or toward the black matrix, thereby maintaining color purity even at reduced pixel pitches
Solution Approach 2:
The patent changes the optical parameter (refractive index) of the material in the region between color filters. By selecting a translucent material with a refractive index different from both the color filter and the surrounding medium, the light propagation characteristics are modified. This parameter change alters the light path through refraction, effectively reducing light leakage to adjacent pixels while maintaining the high definition requirement
2Object-affected harmful factors
If a translucent material with different refractive index is provided between color filters to prevent color mixture, then color purity is improved, but device complexity increases
Solution Approach 1:
The translucent material layer serves multiple functions simultaneously: it acts as a refractive index barrier to prevent color mixture, maintains the structural integrity of the display stack, and can be integrated into existing manufacturing processes. By combining these functions into a single layer, the patent avoids the need for multiple separate components, thereby limiting the increase in device complexity while achieving color purity improvement
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 effectively reduces light leakage and color mixture, maintaining color purity even at high definition and small pixel pitches, with the insertion material's width varying by ±1 μm relative to the black matrix, thereby minimizing color mixture until alignment deviations exceed 3 μm.
Implementation Method 1
an insertion material with a refractive index different from the refractive index of an overcoat film is formed in a layer of the overcoat film at a position corresponding to the black matrix
Implementation Method 2
to reduce light leakage and color mixture by increasing reflection and altering the light's path
Data Source
AI summary
In order to prevent light leakage between adjacent pixels or prevent color mixture, a liquid crystal display device includes: a TFT substrate having a pixel in which a pixel electrode and a TFT are formed; a counter substrate in which a color filter is formed corresponding to the pixel, a black matrix is formed between each of the color filters, and an overcoat film is formed so as to cover the color filter; and a liquid crystal sandwiched between the TFT substrate to the counter substrate. When seen from a direction perpendicular to the main surface of the counter substrate, an insertion material with a refractive index different from the refractive index of the overcoat film is formed in the layer of the overcoat film at a position corresponding to the black matrix. The refractive index of the insertion material is different from the refractive index of the liquid crystal.