Color Filter Substrate Spacer Height Control
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Solution Overview
Problem
Existing color filter substrates for LCDs face challenges in uniformly controlling the heights of columnar spacers, leading to variations in cell gap and display quality issues, such as low-temperature bubbling and reduced withstand load, due to difficulties in arranging spacers at uniform density and controlling their heights across display and non-display areas.
Innovation Solution
A color filter substrate with a base substrate, light-shield layer, and color filter layer, featuring columnar spacers made of resin and an undercoat layer between the spacers and the substrate, where the undercoat layer's area and shape are adjusted to control spacer heights, allowing for continuous and arbitrary height adjustment of spacers, ensuring uniform cell gap and improved display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bead-like or rod-like spacers are scattered on the substrate surface, then spacers are provided to control cell gap, but uniform arrangement at uniform density cannot be achieved leading to cell gap variation and display defects
Solution Approach 1:
The invention divides the substrate surface into multiple regions (first region with first columnar spacers, second region with second columnar spacers, third region with third columnar spacers) and forms columnar spacers in each region with different densities. This segmentation allows each region to contribute differently to cell gap control, achieving overall uniformity that cannot be obtained with a single uniform spacer density across the entire substrate.
Solution Approach 2:
The invention applies different spacer densities to different regions of the substrate based on local requirements. The first region has a first density, the second region has a second density, and the third region has a third density. This local quality approach ensures that each area has the appropriate spacer density for its specific function, resulting in uniform cell gap control across the entire display area.
2Manufacturing precision
If columnar spacers are formed by photolithographic process, then spacer heights can be controlled, but difficulties remain in controlling heights uniformly across display and non-display areas
Solution Approach 1:
The invention segments the columnar spacers into three distinct groups located in different regions of the substrate. Each group has a different density distribution pattern, allowing independent optimization of spacer heights and densities for display and non-display areas. This segmentation simplifies the overall control strategy by treating different regions separately rather than attempting uniform control across the entire substrate.
Solution Approach 2:
The invention employs dynamic density distribution where the spacer density varies across different regions and positions. The first, second, and third columnar spacers have different densities tailored to their respective regions, enabling adaptive cell gap control that accounts for the different requirements of display and non-display areas while maintaining uniformity where needed.
3Reliability
If spacers are arranged within picture elements, then cell gap control is achieved, but aperture ratio decreases substantially and bright spots are sensed
Solution Approach 1:
The invention segments the substrate into display areas (picture elements) and non-display areas, and places columnar spacers primarily in the non-display areas with different density distributions. This spatial segmentation ensures that spacers do not interfere with the picture element aperture while still providing effective cell gap control through the combined effect of multiple spacer regions.
4Strength
If two types of columnar spacers with different heights are provided, then withstand load is increased, but low-temperature bubbling occurs due to cell gap not catching up with liquid crystal layer shrinkage
Solution Approach 1:
The invention segments the spacer system into three distinct groups with different density distributions rather than using just two heights. This segmentation allows for more nuanced control of cell gap behavior across different regions, enabling the cell gap to accommodate liquid crystal layer shrinkage at low temperatures while still providing sufficient withstand load through the combined support of all three spacer groups.
Solution Approach 2:
The invention changes the density parameter of columnar spacers across different regions rather than relying solely on height variations. By adjusting the density distributions of the first, second, and third columnar spacers in different regions, the invention achieves both low-temperature reliability and withstand load capability through parameter optimization rather than simple binary height classification.
Data Source
AI summary
A color filter substrate includes: a base substrate; a light-shield layer and a color filter layer provided on the base substrate; a plurality of columnar spacers, which are made of a resin and provided so as to stick out of the base substrate; and an undercoat layer, which is provided between the columnar spacers and the base substrate. The color filter layer includes a first type of color filter, a second type of color filter and a third type of color filter, which transmit light rays in mutually different colors. The undercoat layer is made of the same film as one of the first, second and third types of color filters and the light-shield layer. A portion of the undercoat layer, associated with a first one of the columnar spacers, has a different area and/or shape from another portion of the undercoat layer, associated with a second one of the columnar spacers. The first and second columnar spacers have mutually different heights.