Array Substrate Black Matrix for LCD Aperture Ratio
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Solution Overview
Problem
The existing liquid crystal display (LCD) devices using hydrogenated amorphous silicon thin film transistors (a-Si TFTs) face instability due to metastability caused by light or electric fields, leading to degraded electrical characteristics and poor reliability, which complicates the implementation of driving circuits and affects image quality due to light leakage and aperture ratio deterioration.
Innovation Solution
The method involves forming a black matrix directly on the array substrate instead of the color filter substrate, allowing for the omission of the align margin and increasing the aperture region, thereby improving image quality and brightness by using a p-type and n-type driving TFTs and a switching TFT on a single substrate with a gate insulating layer, interlayer insulating layer, and passivation layer to create a pixel electrode and data line structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a black matrix is formed on the color filter substrate, then light leakage is prevented, but an align margin is required which reduces the aperture ratio
Solution Approach 1:
The patent inverts the conventional location of the black matrix from the color filter substrate to the array substrate. This inversion eliminates the need for align margin between the black matrix and color filter, thereby increasing the aperture ratio while still preventing light leakage effectively.
Solution Approach 2:
The patent changes the dimensional relationship by forming the black matrix in a different layer position (on array substrate instead of color filter substrate). This dimensional repositioning allows the black matrix to extend to the edge of the pixel electrode without requiring lateral alignment margin, thus maximizing the aperture area.
2Productivity
If hydrogenated amorphous silicon is used for TFT, then productivity is improved and low temperature processing is enabled, but electrical characteristics are degraded due to metastability under light or electric field
Solution Approach 1:
The patent changes the material parameter from hydrogenated amorphous silicon to polysilicon for the TFT active layer. This material parameter change eliminates the metastability issue under light or electric field while still allowing for acceptable fabrication productivity and temperature control.
3Ease of manufacture
If switching element and driving circuit are formed on a single substrate, then production cost is reduced, but electrical characteristics are degraded due to use of hydrogenated amorphous silicon
Solution Approach 1:
The patent changes the semiconductor material parameter from hydrogenated amorphous silicon to polysilicon for both the switching element and driving circuit on the same substrate. This material change simultaneously improves field effect mobility and electrical characteristic stability while maintaining the cost benefits of single-substrate integration.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the aperture ratio and reduces light leakage, resulting in improved image quality and increased brightness by eliminating the need for an align margin, while maintaining the stability of the LCD device.
Implementation Method 1
an electric field is generated that changes the orientation of liquid crystal molecules of the liquid crystal layer due to optical anisotropy within the liquid crystal layer
Implementation Method 2
When a voltage is supplied to the common electrode and the pixel electrode, an electric field is generated
Data Source
AI summary
A liquid crystal display (LCD) device and a method fabricating the same are provided. The LCD device and the method of fabricating the same have the shielding means formed directly on the array substrate instead of the color filter substrate of the opposite substrate to the array substrate.