Color Filter on Array Aperture Ratio Optimization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The application of the color filter-on-array (COA) structure in ultra-high resolution liquid crystal display devices leads to a decrease in aperture ratio due to the need for contact holes to electrically connect thin film transistors (TFTs) to pixel electrodes, which also causes light leakage and reduces contrast ratio.
Innovation Solution
The design includes an active matrix substrate with a color filter and an intermediate layer electrode made of transparent conductive material, connecting the TFT's drain electrode to the pixel electrode through a contact hole that overlaps the TFT's gate electrode, reducing the need for a separate light blocking layer and allowing the gate electrode to function as a light blocker, thus optimizing the aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a color filter is provided on an active matrix substrate (COA structure), then color deviation caused by bonding displacement is prevented, but aperture ratio decreases due to the need for contact holes
Solution Approach 1:
The patent merges the light blocking function with the gate electrode structure. The gate electrode is extended to overlap with the contact hole region, serving dual purposes: electrical connection and light blocking. This eliminates the need for separate light blocking layers while maintaining color alignment accuracy in COA structures.
Solution Approach 2:
The gate electrode is designed to perform multiple functions: controlling the TFT, providing electrical connection, and blocking light in the contact hole region. This multi-functional design reduces the number of additional layers needed, thereby improving aperture ratio while maintaining the COA structure's color alignment benefits.
2Reliability
If contact holes are formed in color filters for electrical connection, then TFT to pixel electrode connection is achieved, but light leakage occurs and contrast ratio decreases
Solution Approach 1:
The patent combines the light blocking function with the gate electrode, which is extended to overlap the contact hole. This integrated approach blocks light leakage through the contact hole while maintaining the necessary electrical connection between TFT and pixel electrode, thereby improving contrast ratio without compromising connection reliability.
3Object-generated harmful factors
If a separate light blocking layer is added to prevent light leakage, then contrast ratio improves, but device complexity and manufacturing steps increase
Solution Approach 1:
The patent eliminates the need for separate light blocking layers by integrating the light blocking function into the existing gate electrode structure. This reduces device complexity and manufacturing steps while effectively preventing light leakage through the contact holes, thereby maintaining contrast ratio improvement without additional structural complexity.
4Manufacturing precision
If the COA structure is applied to ultra-high resolution displays, then color accuracy is maintained, but aperture ratio decreases due to contact hole requirements
Solution Approach 1:
The patent merges the light blocking function with the gate electrode in COA structures, allowing contact holes to be covered by the extended gate electrode. This maintains color filter alignment accuracy while reducing the aperture ratio penalty associated with contact holes, thereby improving the effective display area in ultra-high resolution displays.
Solution Approach 2:
The gate electrode is designed to serve multiple functions including TFT control, electrical connection, and light blocking in contact hole regions. This multi-functional design maintains the COA structure's color alignment benefits while minimizing the impact on aperture ratio, thereby optimizing the effective display area.
Data Source
AI summary
A display device includes: an active matrix substrate including a plurality of pixels arrayed in a matrix shape, wherein the active matrix substrate includes, in each of the plurality of pixels, a TFT, an insulating layer substantially covering the TFT, a pixel electrode formed of a transparent conductive material and electrically connected to the TFT, a color filter located between the TFT and the pixel electrode, and an intermediate layer electrode formed of a transparent conductive material, at least partially located between the insulating layer and the color filter, and electrically connecting a drain electrode of the TFT to the pixel electrode, the pixel electrode is connected to the intermediate layer electrode at a contact hole formed in the color filter, and when viewed in a normal direction of a display surface, the contact hole at least partially overlaps a gate electrode of the TFT.