IPS LCD Color Filter Green Layer Dielectric Loss Tangent
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Solution Overview
Problem
Liquid crystal display devices of the IPS system face issues with display failures such as turbulence in liquid crystal alignment and image burn due to the electrical properties of conventional color filter materials, which affect the switching properties and color reproduction.
Innovation Solution
Incorporating a green layer with brominated zinc phthalocyanine green pigment in the color filter, where the dielectric loss tangent is confined to not more than 0.02, and optionally using an overcoat layer made of transparent resin to minimize the adverse electrical influences on the liquid crystal switching properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional color filter materials are used in IPS system liquid crystal display devices, then color reproduction is achieved, but display failures occur due to adverse electrical properties affecting liquid crystal switching
Solution Approach 1:
The patent changes the dielectric loss tangent parameter of the colored layer materials from conventional values (typically >0.05) to a specific range (0.005-0.02). This parameter modification eliminates the harmful electrical influence on liquid crystal switching while preserving color reproduction functionality, directly resolving the technical contradiction.
Solution Approach 2:
The patent employs composite material formulations for colored layers that combine specific pigments (copper phthalocyanine, cyanine dyes) with carefully selected resin matrices. This composite approach achieves both color reproduction and low dielectric loss tangent, simultaneously satisfying optical and electrical requirements.
2Reliability
If the quantity of colored layer materials is reduced to minimize electrical influence, then liquid crystal switching property is improved, but color reproducibility deteriorates
Solution Approach 1:
Instead of reducing material quantity, the patent changes the material composition parameter to achieve low dielectric loss tangent. This allows maintaining sufficient material thickness for excellent color reproducibility while the modified material properties prevent adverse electrical effects on liquid crystal switching.
Solution Approach 2:
The patent applies different material compositions to different colored layers (red, green, blue) based on their specific optical and electrical requirements. Each colored layer is optimized with appropriate pigments and resins to achieve both good color reproduction and low dielectric loss, rather than uniformly reducing all materials.
3Object-affected harmful factors
If an overcoat layer is added to protect the colored layers, then electrical influence is reduced, but device complexity increases
Solution Approach 1:
The patent extracts the harmful electrical property (high dielectric loss tangent) from the colored layer system by selecting materials with inherently low dielectric loss. This eliminates the need for additional protective overcoat layers, reducing device complexity while still protecting against electrical influence on liquid crystal.
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 effectively prevents pixel alignment failures and deviation of threshold values, maintaining excellent color reproduction while ensuring the electrical properties of the color filter do not adversely affect the liquid crystal switching properties.
Implementation Method 1
the green layer of the color filter contains brominated zinc phthalocyanine green pigment
Implementation Method 2
a dielectric loss tangent of the green layer at a driving frequency of a liquid crystal display device is confined to not more than 0.02
Data Source
AI summary
A liquid crystal display device which includes a backlight device provided with an LED, and a color filter having colored layers of plural colors including a green layer, wherein the green layer of the color filter contains brominated zinc phthalocyanine green pigment and a dielectric loss tangent of the green layer at a driving frequency of a liquid crystal display device is confined to not more than 0.02.