Blue Color Filter Pigment Combination for OLED Display Gamut
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Solution Overview
Problem
Existing color filters for displays, particularly those used with broadband OLED devices, struggle to provide improved color rendition and gamut, often resulting in compromised color purity due to inadequate spectroscopic characteristics, especially when compared to standards like NTSC and HDTV references.
Innovation Solution
A blue color filter is developed with specific pigment combinations, including a first pigment with maximum absorption between 550 to 650 nm and a second pigment with maximum absorption between 500 to 600 nm, optimized to achieve chromaticity coordinates within the 1931 CIE XYZ colorimetric system that satisfy 0.134≦x≦0.15 and 0.03≦y≦0.06, enhancing color gamut and spectral curve shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional color filters are used with broadband OLED devices, then device simplicity is maintained, but color purity and gamut are compromised due to inadequate spectroscopic characteristics
Solution Approach 1:
The patent applies composite materials by combining multiple pigments (cyanine pigment and phthalocyanine pigment) in specific layers to achieve superior spectroscopic characteristics. This composite approach enables the filter to meet stringent color purity requirements (x≤0.15, y≤0.06) while maintaining a practical device structure that can be integrated with broadband OLEDs.
2Reliability
If color filters with narrow transmission bands are used to improve color gamut, then color purity is enhanced, but light transmittance efficiency is reduced
Solution Approach 1:
The patent applies local quality by creating different layer structures with specific pigment compositions tailored to different spectral regions. The first layer uses cyanine pigment optimized for absorbing red light, while the second layer uses phthalocyanine pigment optimized for absorbing green light. This localized optimization allows each layer to efficiently block its target wavelength range while minimizing impact on other regions, achieving high color gamut without excessive light loss.
Solution Approach 2:
The patent applies parameter changes by precisely controlling pigment concentration ratios and layer thicknesses to optimize the balance between color purity and light transmittance. By adjusting these parameters, the filter achieves chromaticity coordinates within the specified range (x≤0.15, y≤0.06) while maintaining sufficient overall transmittance for practical display applications.
3Reliability
If thicker filter layers are used to improve color gamut, then color purity is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies segmentation by dividing the color filter into multiple distinct layers, each with specific pigment compositions and thicknesses. This segmentation allows for better control of the overall filter characteristics by optimizing each layer independently, reducing the cumulative manufacturing variability that would occur in a single thick layer while achieving the same or superior color gamut performance.
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 provides improved color rendition and gamut with reduced efficiency loss, resulting in better color purity and adherence to color standards, outperforming conventional filters by minimizing unwanted transmittance in the green region and maximizing transmittance in the blue spectrum.
Implementation Method 1
a first pigment having a maximum absorption at a wavelength within the range of from 550 to 650 nm
Implementation Method 2
a second pigment having a maximum absorption at a shorter wavelength than the first pigment within the range of from 500 to 600 nm
Data Source
AI summary
A blue color filter having a blue filter layer comprising a first pigment having a maximum absorption at a wavelength within the range of from 550 to 650 nm, and a second pigment having a maximum absorption at a shorter wavelength than the first pigment within the range of from 500 to 600 nm, wherein the blue filter layer has chromaticity coordinates (x, y) in the 1931 CIE XYZ calorimetric system, calculated using CIE Standard Illuminant D65, that satisfy the expressions 0.134≦x≦0.15 and 0.03≦y≦0.06.