LCD Spacer Layout Around TFTs to Prevent Bright Spot Defects
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Solution Overview
Problem
Liquid crystal display devices experience alignment failures and display defects like bright spot defects due to the presence of main photo spacers, which affect the uniformity of light blocking and spacer arrangement.
Innovation Solution
The display device incorporates an array substrate and a counter substrate with color filters, pixel electrodes, and spacers of varying overlapping relationships with thin film transistors, including spacers with different distances and positions to minimize the impact of alignment failures and enhance light blocking uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If main photo spacers are provided in the liquid crystal display device, then the cell gap is maintained and substrate spacing is ensured, but alignment failure of liquid crystal molecules occurs and bright spot defects are more likely to occur
Solution Approach 1:
The patent applies local quality by providing different types of spacers (main photo spacers and sub photo spacers) with different functions and characteristics at different locations. Main photo spacers are positioned at specific regions where cell gap maintenance is critical, while sub photo spacers are distributed in other areas to reduce alignment failures. This localized differentiation allows the system to maintain reliability where needed while minimizing harmful effects in other regions.
Solution Approach 2:
The patent segments the spacer function by dividing spacers into multiple types (main photo spacers and sub photo spacers) rather than using a single uniform spacer design. This segmentation allows different spacer types to perform specialized functions - main photo spacers for critical cell gap maintenance and sub photo spacers for reducing alignment failures - thereby resolving the contradiction between maintaining cell gap and preventing defects.
2Manufacturing precision
If light blocking ranges in the vicinities of main photo spacers are made uniform, then consistent spacer performance is achieved, but display failure such as bright spot defects is likely to be visually recognized
Solution Approach 1:
The patent applies asymmetry by intentionally designing sub photo spacers with different light blocking characteristics compared to main photo spacers. Rather than making all spacers uniform, the invention creates asymmetric spacer types where sub photo spacers have reduced light blocking capability in specific regions. This asymmetry prevents the formation of visually recognizable bright spot defects while maintaining adequate cell gap maintenance through the main photo spacers.
3Manufacturing precision
If spacers are disposed to overlap thin film transistors, then cell gap control is improved, but alignment failure and display quality degradation occur
Solution Approach 1:
The patent applies local quality by positioning different spacer types at different locations relative to thin film transistors. Main photo spacers are strategically placed where they overlap with thin film transistors to provide precise cell gap control in critical regions, while sub photo spacers are positioned in other areas to minimize alignment failures. This localized differentiation resolves the contradiction between improved cell gap control and maintained display quality.
Data Source
AI summary
A display device includes an array substrate, a counter substrate facing the array substrate at an interval therebetween, a plurality of pixels constituted by the plurality of pixel electrodes and the plurality of color filters, and a plurality of thin film transistors. The plurality of pixels include a plurality of first pixels each having the highest relative luminous efficiency, a plurality of second pixels each having the lowest relative luminous efficiency, and a plurality of third pixels each having relative luminous efficiency lower than the relative luminous efficiency of the first pixels and higher than the relative luminous efficiency of the second pixels, a plurality of spacers include a plurality of spacers having different overlapping relationships with the thin film transistors being overlapping targets.