COA Active Matrix Substrate Layout to Suppress LCD Light Leakage
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Solution Overview
Problem
In liquid crystal display devices with a color filter-on-array (COA) structure, the formation of steps in the capacitance insulating film during the creation of an anti-reflection layer leads to light leakage due to alignment disorder of the liquid crystal layer, degrading optical characteristics.
Innovation Solution
The anti-reflection layer is formed with a belt-shaped configuration comprising a first metal layer, a capacitance insulating film, and a second metal layer, with the common electrode covering the second metal layer, to prevent the formation of steps in the capacitance insulating film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the anti-reflection layer is formed by dry etching, then the anti-reflection layer can be created, but the capacitance insulating film exposed from the common electrode is etched, causing steps to form at edges
Solution Approach 1:
The patent applies preliminary action by forming the anti-reflection layer structure (first metal layer, capacitance insulating film, and second metal layer) before the common electrode is formed. This sequence prevents the capacitance insulating film from being exposed and etched during subsequent common electrode formation, thereby avoiding step formation at the edges while still achieving the anti-reflection function.
2Ease of manufacture
If steps are formed at edges of the capacitance insulating film, then the anti-reflection layer can be formed, but light leakage occurs due to alignment disorder of the liquid crystal layer
Solution Approach 1:
By forming the anti-reflection layer structure before the common electrode, the patent prevents step formation at the capacitance insulating film edges. This eliminates the harmful effect of light leakage caused by alignment disorder, as the liquid crystal layer can align properly without steps disrupting the alignment process.
3Manufacturing precision
If the common electrode covers the second metal layer, then steps in the capacitance insulating film are suppressed, but the anti-reflection layer structure becomes more complex
Solution Approach 1:
The patent merges the anti-reflection layer formation with the existing capacitance insulating film structure. The capacitance insulating film serves dual purposes: as part of the auxiliary capacity structure and as a component of the anti-reflection layer. This integration reduces overall device complexity while maintaining surface flatness and preventing light leakage.
Data Source
AI summary
A base substrate; a plurality of TFTs provided on the base substrate, the plurality of TFTs corresponding to a plurality of subpixels; a color filter provided on the plurality of TFTs, the color filter being disposed with colored layers of predetermined colors corresponding to the plurality of subpixels; a plurality of pixel electrodes provided on an upper side of the color filter, the plurality of pixel electrodes corresponding to the plurality of subpixels; a capacitance insulating film provided on the plurality of pixel electrodes; a common electrode provided commonly to the plurality of subpixels on the capacitance insulating film; and an anti-reflection layer having belt shapes, each belt shape of the anti-reflection layer overlapping a boundary portion between the colored layers having different colors from each other in the color filter, the anti-reflection layer being formed by layering a first metal layer, the capacitance insulating film, and a second metal layer in order are provided, and the common electrode covers the second metal layer.