Dual-Layer Black Matrix for LCD Light Leakage
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Solution Overview
Problem
Current LCD devices face challenges in achieving high contrast ratios due to light leakage caused by black matrix layers formed from acrylic resin, which have insufficient optical density, especially at higher luminance levels, leading to reduced picture quality and increased step differences in color filter layers.
Innovation Solution
A dual-layered black matrix structure is implemented, where a first black matrix layer made of a high optical density metal material, such as chrome Cr, is covered by a second black matrix layer made of acrylic resin, enhancing the optical density to 4.5 or more without increasing thickness, thereby reducing light leakage and improving contrast ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-layer black matrix layer made of acrylic resin is used, then the manufacturing process is simple, but the optical density is insufficient (below 4.5) causing light leakage and reduced contrast ratio
Solution Approach 1:
The patent applies composite materials by combining a first black matrix layer made of metal oxide (such as chromium oxide with high optical density) and a second black matrix layer made of acrylic resin. This composite structure achieves an optical density of 4.5 or more while maintaining manufacturing simplicity, as the layers are formed through sequential coating processes without requiring complex additional steps.
2Reliability
If the thickness of the black matrix layer is increased to improve optical density, then light leakage is reduced, but step differences in the color filter layer are increased
Solution Approach 1:
The patent segments the black matrix layer into two distinct functional layers: a first black matrix layer (metal oxide) providing high optical density with thin thickness (50-200 nm), and a second black matrix layer (acrylic resin) providing planarization and color filter support. This segmentation allows achieving high optical density without increasing overall thickness, thereby minimizing step differences in the color filter layer.
3Reliability
If a metal material black matrix layer is used to achieve high optical density, then light leakage is reduced, but the IPS mode electric field is adversely affected
Solution Approach 1:
The patent applies local quality by assigning different materials to different layers based on their specific functions: the first black matrix layer uses metal oxide for high optical density where light blocking is critical, while the second black matrix layer uses acrylic resin where electrical neutrality and planarization are more important. This localized material selection optimizes both optical performance and electrical field compatibility in IPS mode displays.
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 dual-layered black matrix structure effectively increases optical density, reduces light leakage, and enhances the contrast ratio of LCD devices, particularly at higher luminance levels, while preventing adverse effects on the IPS mode electric field and maintaining the thin profile and low power consumption of LCD devices.
Implementation Method 1
a first black matrix layer made of a high optical density metal material, such as chrome Cr
Implementation Method 2
enhancing the optical density to 4.5 or more without increasing thickness
Data Source
AI summary
A TN mode or IPS mode LCD device includes lower and upper substrates that face each other and a liquid crystal disposed therebetween. Pixel regions are defined on the substrates. A multi-layer structure of black matrix layers are formed in regions of one of the substrates other than the pixel regions. The first black matrix layer is formed from an opaque metal while the second black matrix layer is formed from resin. The second black matrix layer completely covers the first black matrix layer. The combined multi-layer black matrix structure has an optical density of about 4.5 to 5.