Auxiliary Capacitor Insulation Segmentation for Aperture Ratio
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Solution Overview
Problem
In liquid crystal display panels, there is a trade-off between the electric capacity of the auxiliary capacitor and the aperture ratio of the pixel, as increasing the thickness of the gate insulating film to enhance dielectric strength reduces the electric capacity of the auxiliary capacitor, necessitating a larger area which decreases the aperture ratio.
Innovation Solution
The protective film covering the thin film transistor serves as the insulating film for the auxiliary capacitor, reducing the thickness of the insulating film between the capacitor line and the pixel electrode, thereby increasing the electric capacity while minimizing the decrease in aperture ratio by using a thinner protective film instead of the thicker gate insulating film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the gate insulating film is increased to enhance dielectric strength, then the reliability is improved, but the electric capacity of the auxiliary capacitor decreases
Solution Approach 1:
The insulating film structure is segmented into two distinct parts: a gate insulating film (first insulating film) for dielectric strength and a protective film (second insulating film) for capacitor insulation. This segmentation allows each layer to be optimized independently - the gate insulating film can be thick for reliability while the protective film is thin for high capacitance, resolving the contradiction between dielectric strength and electric capacity.
Solution Approach 2:
Different regions of the insulating structure have different thicknesses and materials tailored to their specific functions. The gate insulating film has greater thickness for dielectric strength where needed, while the protective film has minimal thickness for capacitance where required. This local differentiation of quality allows simultaneous optimization of both reliability and electric capacity.
2Quantity of substance
If the area of the auxiliary capacitor is increased to maintain electric capacity, then the electric capacity is improved, but the aperture ratio of the pixel decreases
Solution Approach 1:
The key parameter changed is the thickness of the insulating film in the auxiliary capacitor. By reducing the thickness of the protective film (second insulating film) while maintaining adequate insulation, the electric capacity increases (C ∝ 1/d). This parameter change allows the capacitor to achieve required capacitance in a smaller area, preserving the aperture ratio.
3Quantity of substance
If the thickness of the insulating film is reduced to increase electric capacity, then the electric capacity is improved, but the dielectric strength decreases
Solution Approach 1:
The insulating function is segmented between two layers: the gate insulating film provides the dielectric strength barrier, while the protective film provides the capacitance-forming insulation. This segmentation resolves the contradiction by assigning different thicknesses to different functional requirements - thick for strength, thin for capacitance.
Solution Approach 2:
The insulating structure uses a composite of two different insulating films with different properties. The gate insulating film (first insulating film) and protective film (second insulating film) are combined, where each material is selected and dimensioned for its optimal performance - one for dielectric strength and one for capacitance formation.
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 configuration allows for a larger electric capacity of the auxiliary capacitor with a smaller area, reducing the decrease in the aperture ratio of the pixel, thus enhancing the performance of the liquid crystal display panel.
Implementation Method 1
the protective film covering the thin film transistor serves as the insulating film of the auxiliary capacitor
Data Source
AI summary
An active matrix substrate includes a plurality of pixels arranged in a matrix, a plurality of capacitor lines (11b) extending in one of directions in which the pixels are aligned and in parallel to each other, a plurality of TFTs (5), one for each of the pixels, a protective film (16a) covering the TFTs (5), a plurality of pixel electrodes (18a) arranged in a matrix on the protective film (16a) and connected to the respective corresponding TFTs (5), and a plurality of auxiliary capacitors (6), one for each of the pixels. Each of the auxiliary capacitors (6) includes the corresponding capacitor line (11b), the corresponding pixel electrode (18a), and the protective film (16a) between the corresponding capacitor line (11b) and the corresponding pixel electrode (18a).