LTPS TFT Array Substrate Light-Shielding Layer Alignment
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Solution Overview
Problem
Current LTPS-TFT LCDs face challenges in achieving high-definition, high brightness, and low power consumption due to alignment deviations between the black matrix and source/drain metal layer, leading to variations in aperture ratios and decreased contrast ratios.
Innovation Solution
An array substrate with a LTPS TFT, a light-shielding layer, insulation layers, and photo spacers is designed, along with a bare second substrate for alignment, ensuring precise alignment and consistent aperture ratios by eliminating pattern-dependent alignment considerations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a black matrix on the CF substrate is used to shield pixel edges and prevent light leakage, then light leakage is prevented and contrast ratio is improved, but alignment deviation between the black matrix and source/drain metal layer occurs leading to aperture ratio variations
Solution Approach 1:
The patent introduces a light-shielding layer as an intermediary component between the CF substrate and the array substrate. This light-shielding layer serves as a new reference for alignment with the source/drain metal layer, replacing the traditional black matrix alignment approach. By forming the light-shielding layer directly on the array substrate and aligning it with the metal layer, the invention eliminates the cumulative alignment errors that occur when aligning through multiple layers (black matrix to array substrate to metal layer), thereby resolving the contradiction between preventing light leakage and maintaining alignment precision.
2Manufacturing precision
If alignment precision between black matrix and source/drain metal layer is improved, then aperture ratio consistency is improved, but manufacturing complexity and process difficulty increase
Solution Approach 1:
The patent extracts the light-shielding function from the black matrix on the CF substrate and relocates it to a light-shielding layer on the array substrate. This separation allows the light-shielding layer to serve dual purposes: preventing light leakage and providing an alignment reference for the source/drain metal layer. By taking out the alignment reference function from the black matrix and embedding it in the light-shielding layer on the same substrate as the metal layer, the invention simplifies the alignment process and improves aperture ratio consistency without significantly increasing manufacturing complexity.
Data Source
AI summary
An array substrate for a liquid crystal display panel is disclosed. The array substrate includes a first substrate, a Lower Temperature Polycrystal Silicon (LTPS) Thin-Film-Transistor (TFT) disposed on the first substrate, a color photoresist layer disposed on the LTPS TFT, and multiple photo spacers disposed above the color photoresist layer. A liquid crystal display panel including the array substrate and a second substrate disposed oppositely to the array substrate is also disclosed. The present invention utilizes the second substrate to be aligned with the LTPS TFT array substrate in order to form the liquid crystal display panel. Because the second substrate is a bare substrate (without a pattern), when the second substrate is aligned with the array substrate, the alignment precision is not under consideration. Accordingly, apertures ratios of the liquid crystal display panel do not have difference.