Shielding Electrode Reduces Parasitic Capacitance in Liquid Crystal Display
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Solution Overview
Problem
Existing liquid crystal display devices suffer from capacitance leakage due to the dielectric nature of the color filter element on the TFT array substrate, which affects the quality of the display image by forming unwanted capacitance that can lead to image distortion and reduced aperture ratio.
Innovation Solution
The implementation of a shielding electrode that overlaps the color filter layer and is electrically connected to the pixel electrodes, reducing parasitic capacitance between the pixel electrodes and the data lines, gate signal lines, and common signal lines, thereby minimizing the adverse effects of capacitance leakage on the display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a color filter element is disposed on the TFT array substrate to increase aperture ratio, then the aperture ratio is improved, but capacitance leakage occurs and affects display image quality
Solution Approach 1:
A shielding electrode is introduced as an intermediary component between the color filter layer and the pixel electrode. This shielding electrode is electrically connected to the pixel electrode and positioned to overlap with the data lines and gate signal lines, thereby mediating the electric field interactions and reducing parasitic capacitance effects while preserving the aperture ratio benefits of the COA structure
Solution Approach 2:
The patent converts the harmful parasitic capacitance effect into a beneficial shielding effect. By strategically positioning the shielding electrode to overlap with signal lines, the structure that originally caused capacitance leakage is transformed into a protective element that actively compensates for and reduces the parasitic capacitance, turning the problem into a solution
2Area of moving object
If the color filter element is disposed on the TFT array substrate, then the aperture ratio increases, but the capacitance formed with conductive structures causes image quality degradation
Solution Approach 1:
The shielding electrode serves as a protective intermediary layer that is electrically connected to the pixel electrode. It is positioned between the color filter layer and the signal lines, creating an electric field shield that prevents direct capacitive coupling between the pixel electrode and adjacent signal lines, thereby eliminating the harmful capacitance leakage while maintaining the high aperture ratio design
3Device complexity
If wiring structures are placed close to pixel electrodes to reduce space, then device complexity is reduced, but parasitic capacitance increases and affects display quality
Solution Approach 1:
The shielding electrode acts as a mediating structure that enables close positioning of wiring to pixel electrodes without suffering from parasitic capacitance issues. By being electrically connected to the pixel electrode and positioned to overlap with signal lines, it creates an equipotential region that eliminates voltage differences and thus parasitic capacitance, allowing dense wiring layouts without compromising display quality
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
The shielding electrode effectively reduces capacitance leakage, enhancing the aperture ratio and image quality by minimizing the impact of parasitic capacitance, allowing for more efficient use of wiring space and reducing the electric field between the pixel electrodes and common electrodes.
Implementation Method 1
reducing parasitic capacitance between the pixel electrodes and the data lines, gate signal lines, and common signal lines
Implementation Method 2
minimizing the electric field between the pixel electrodes and common electrodes
Data Source
AI summary
A display device includes a first substrate, a first metal layer, a gate insulating layer, semiconductor channels, a second metal layer, a color filter layer, a shielding electrode, an insulating layer, pixel electrodes, a liquid crystal layer, a second substrate and a second common electrode. The first metal layer is located on the first substrate and includes scan lines, gates and first common electrodes. The gate insulating layer is located on the first metal layer. The semiconductor channels are located on the gate insulating layer. The second metal layer is located on the gate insulating layer, and includes sources, drains and data lines. The color filter layer is located on the second metal layer. The shielding electrode at least partially overlaps the second metal layer. The insulating layer is located on the color filter layer. The second common electrode is located on the second substrate.