Black Colorant Mixture for LCD Black Matrix and Column Spacer
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Solution Overview
Problem
Current black colorants for LCDs face challenges in achieving high optical density, low conductivity, and NIR transparency while maintaining low electric conductivity, particularly in the context of black matrices and column spacers, where existing solutions like carbon black and inorganic pigments have limitations such as high conductivity, poor UV transparency, and environmental safety concerns.
Innovation Solution
A colorant mixture comprising a bis-oxodihydro-indolylene-benzodifuranone pigment combined with a perylene colorant, which improves optical density and maintains low conductivity, is used in the manufacturing of black matrices and column spacers for LCDs, enhancing their performance by providing a neutral black color with wide spectrum coverage and reduced UV absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If carbon black is used as black colorant, then high optical density and blackness are achieved, but high electric conductivity and poor UV transparency occur
Solution Approach 1:
The patent uses a composite colorant system combining multiple organic pigments (C.I. Pigment Violet 29 perylene, C.I. Pigment Red 122 quinacridone, and C.I. Pigment Blue 60 phthalocyanine) to achieve the desired optical properties without relying on conductive carbon black. This composite approach allows simultaneous optimization of optical density, conductivity, and UV transparency.
Solution Approach 2:
The patent changes the chemical composition parameters by replacing inorganic carbon black with specific organic pigment combinations, and adjusts the particle size parameter to 50-200 nm range to optimize both optical density and UV transparency while maintaining low conductivity through the organic nature of the pigments.
2Illumination intensity
If carbon black is used as black colorant, then high optical density and blackness are achieved, but high absorption in UV region for photolithography occurs
Solution Approach 1:
The patent changes the chemical composition from carbon black to organic pigments with specific UV absorption characteristics. The selected organic pigments (perylene, quinacridone, phthalocyanine) have molecular structures that naturally transmit UV wavelengths while absorbing visible light, achieving UV transparency without sacrificing optical density.
Solution Approach 2:
The patent applies different quality requirements to different wavelength regions: high absorption in the visible spectrum (400-700 nm) for blackness, and high transmission in the UV region (200-400 nm) for photolithography. The organic pigment combination is specifically selected to provide this spectral differentiation.
3Ease of operation
If transparent column spacer is used, then proper gap maintenance is achieved, but polarized light scattering occurs reducing contrast ratio
Solution Approach 1:
The patent changes the optical property of the column spacer by incorporating black colorants (organic pigment mixture) into the transparent spacer material. This transforms the spacer from transparent to optically absorbing in the visible region, preventing polarized light scattering while maintaining the mechanical gap maintenance function.
4Illumination intensity
If black colorant with narrow particle size is used, then light scattering is minimized, but poor dispersibility and aggregation occur
Solution Approach 1:
The patent uses a composite pigment system where the combination of multiple organic pigments with complementary properties provides both optimal optical performance and improved dispersibility. The specific particle size range of 50-200 nm is optimized to minimize light scattering while maintaining stable dispersion through the synergistic effect of the pigment mixture.
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 colorant mixture significantly enhances the optical density and contrast ratio of LCDs, offering improved brightness and reduced power consumption, while maintaining low electric conductivity and NIR transparency, thus addressing the limitations of previous black colorants.
Implementation Method 1
a black colorant with very low conductivity in the black matrix in order to avoid malfunction of the TFT array due to a conductive black colorant
Implementation Method 2
a black colorant is also required to have a relatively high transmission in the ultra violet (UV) region for a black column spacer of a thickness of several μm by a photolithography method
Data Source
Figure 1
AI summary
Provided is a black colorant mixture comprising a bis-oxodihydro-indolylene-benzodifuranone colorant and a perylene colorant. The colorant mixture provides high blackness and NIR transparency with low conductivity for coating films used in display devices, and can be used in manufacturing a black matrix for a color filter, a black column spacer for a LCD device or a black bezel of a display device.