TFT-LCD Transparent Drain Electrode Aperture Ratio
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Solution Overview
Problem
The manufacturing method of thin film transistor liquid crystal displays (TFT-LCDs) faces challenges with the five-patterning process, which results in a small effective light transmitting area and low aperture ratio due to the increased size of the drain electrode, necessitating a solution to enhance light transmission and aperture ratio.
Innovation Solution
The implementation of a transparent drain electrode in the TFT-LCD array substrate, formed through a specific patterning process involving a gate metal film, active layer, and passivation layer, with a transparent conductive film deposited to create an integral structure connected with the pixel electrode, thereby increasing the light transmitting area and improving the aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the width of the drain electrode is increased to prevent ultraviolet light from passing through into the TFT channel region, then the etching quality of the TFT channel region is improved, but the effective light transmitting area decreases and the aperture ratio becomes low
Solution Approach 1:
The drain electrode is segmented into two parts: an upper drain electrode (first conductive layer) and a lower drain electrode (second conductive layer). The upper drain electrode has a smaller width than the lower drain electrode, allowing the upper part to be transparent for light transmission while the lower part provides sufficient width for etching quality and UV blocking. This segmentation resolves the contradiction by distributing different functions to different segments of the same electrode structure.
Solution Approach 2:
The drain electrode is constructed as a composite structure with two different conductive layers. The first conductive layer (upper) uses a transparent conductive material that allows light transmission, while the second conductive layer (lower) uses a conductive material that provides electrical connection and blocks UV light. This composite structure enables the drain electrode to simultaneously achieve light transmission and etching quality requirements.
2Manufacturing precision
If the width of the drain electrode is increased to ensure etching quality, then the etching quality is improved, but the aperture ratio becomes low
Solution Approach 1:
The drain electrode is divided into upper and lower segments with different widths. The upper segment (first conductive layer) has reduced width to maximize aperture ratio, while the lower segment (second conductive layer) maintains sufficient width for proper etching quality. This segmentation allows the structure to achieve both high aperture ratio and good etching quality simultaneously.
Solution Approach 2:
The drain electrode structure is extended into the vertical dimension with two distinct layers at different heights. The upper layer (first conductive layer) is positioned closer to the liquid crystal layer to maintain aperture ratio, while the lower layer (second conductive layer) is positioned closer to the TFT channel region to ensure etching quality. This dimensional arrangement resolves the area conflict by utilizing vertical positioning.
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 effectively increases the light transmitting area and aperture ratio, leading to enhanced brightness and reduced power consumption, allowing for a decrease in backlight necessity and associated costs.
Implementation Method 1
depositing a transparent conductive film on the substrate after step 2, forming patterns of a transparent drain electrode and a pixel electrode
Data Source
AI summary
An embodiment of the invention relates to a TFT-LCD array substrate comprising a substrate, a gate line and a data line formed on the substrate, a pixel electrode and a thin film transistor formed in a pixel region defined by the gate line and the data line, wherein the thin film transistor comprises a gate electrode, a source electrode, and a transparent drain electrode, and the transparent drain electrode is electrically connected with the pixel electrode.