TFT-LCD Array Substrate Passivation Layer Thickness Optimization
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Solution Overview
Problem
Conventional FFS type TFT-LCD array substrates have a high aspect ratio due to the common electrode being formed above the signal lines, leading to disturbances in liquid crystal molecule rotation and increased power consumption, as the thick passivation layer affects the electrical field and driving voltage.
Innovation Solution
A passivation layer with varying thicknesses is implemented, with a thinner thickness over the pixel electrode and thicker thicknesses over the gate and data lines, allowing the common electrode to be formed above the signal lines, reducing parasitic capacitance and optimizing the aspect ratio while minimizing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the common electrode is formed above the signal lines to increase the aspect ratio, then the aspect ratio is improved, but the thick passivation layer causes disturbances in liquid crystal molecule rotation and increases power consumption
Solution Approach 1:
The passivation layer is designed with different thicknesses in different regions: a first thickness in the pixel electrode region, a second thickness in the gate line region, and a third thickness in the data line region. This local differentiation allows the common electrode to be formed above the signal lines (increasing aspect ratio) while controlling the passivation layer thickness to minimize interference with liquid crystal molecules and reduce power consumption.
2Area of stationary object
If the passivation layer thickness is increased to allow common electrode formation above signal lines, then the aspect ratio is improved, but the electrical field distortion and power consumption increase
Solution Approach 1:
By setting different thicknesses for the passivation layer in different regions (first thickness over pixel electrode, second thickness over gate line, third thickness over data line), the invention locally optimizes the electrical field distribution. This allows the common electrode to extend above signal lines for better aspect ratio while controlling field distortion through appropriate thickness selection in each region.
3Area of stationary object
If a uniform thick passivation layer is used to form the common electrode above signal lines, then the aspect ratio is improved, but the manufacturing complexity increases
Solution Approach 1:
The passivation layer is configured with three distinct thickness regions corresponding to different functional areas (pixel electrode, gate line, data line). This localized thickness variation achieves the desired aspect ratio improvement while maintaining a relatively simple overall structure that can be manufactured using standard semiconductor fabrication processes.
Data Source
AI summary
A TFT-LCD array substrate comprising a transparent substrate and a gate line, a data line, a thin film transistor, a pixel electrode and a passivation layer that are formed on the transparent substrate. The passivation layer includes a first region corresponding to the pixel electrode, a second region corresponding to the gate line and a third region corresponding to the data line, the first region has a first thickness, the second region has the second thickness, and the third region has the third region. The first thickness is smaller than the second thickness, the second thickness is smaller or equal to the third thickness.