Transflective LCD Floating Electrode Parasitic Capacitance Reduction
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Solution Overview
Problem
Transflective thin film transistor substrates in liquid crystal display devices face challenges with increased parasitic capacitance due to overlapping electrodes, leading to vertical cross talk and higher power consumption, and have complex fabrication processes.
Innovation Solution
The solution involves a floating reflection electrode that does not overlap the data line, reducing parasitic capacitance and simplifying the fabrication process by using a multi-layer conductive structure with a transparent first conductive layer and an opaque second conductive layer, and forming a transmission hole to expose the first conductive layer of the pixel electrode, while the reflection electrode extends along the side surface of the transmission hole to connect the pixel and drain electrodes without overlapping the data line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the reflection electrode overlaps the data line to simplify the fabrication process, then the device complexity is reduced, but the parasitic capacitance increases leading to vertical cross talk and higher power consumption
Solution Approach 1:
The pixel electrode is divided into two separate conductive layers: a transparent first conductive layer and an opaque second conductive layer. The reflection electrode overlaps only the second conductive layer, not the data line, thereby segmenting the electrode structure to reduce parasitic capacitance while maintaining fabrication simplicity
Solution Approach 2:
The pixel electrode uses a composite structure of transparent and opaque conductive layers. This composite material approach allows the reflection electrode to function without overlapping the data line, reducing parasitic capacitance while maintaining the necessary electrical and optical properties
2Ease of manufacture
If the pixel electrode overlaps both sides of the data line to simplify fabrication, then the ease of manufacture is improved, but the parasitic capacitance increases causing vertical cross talk
Solution Approach 1:
The pixel electrode is segmented into transparent and opaque conductive layers. The reflection electrode is positioned to overlap only the opaque second conductive layer, preventing harmful electrical interaction with the data line while maintaining fabrication simplicity
Solution Approach 2:
The opaque second conductive layer acts as an intermediary between the reflection electrode and the data line. It allows the reflection electrode to be positioned for easy fabrication while preventing direct electrical interaction that would cause vertical cross talk
3Illumination intensity
If a thick organic insulating film is formed under the reflection electrode to equalize light path length, then the illumination intensity is improved, but the device complexity increases
Solution Approach 1:
The insulating film structure is segmented with different thicknesses in different regions. The organic insulating film is formed thicker under the reflection electrode to equalize light path length, while maintaining overall process simplicity through integrated formation with other insulating layers
Data Source
AI summary
This invention relates to a liquid crystal display device that reduces a parasitic capacitance, and a fabricating method thereof.A liquid crystal display device, including: a gate line with a multi-layer structure having a transparent first conductive layer and an opaque second conductive layer; a data line crossing the gate line with a gate insulating film in between to define a pixel area; a thin film transistor connected to the gate line and the data line; a pixel electrode formed of the first conductive layer in the pixel area, wherein the second conductive layer remains along an edge of the first conductive layer at an edge of the pixel area; a transmission hole that penetrates from an organic insulating film on the thin film transistor to the gate insulating film to expose the first conductive layer of the pixel electrode; a reflection electrode on the organic insulating film extending along a part of a side surface of the transmission hole to connect the pixel electrode and a drain electrode of the thin film transistor; and a floating electrode on the organic insulating film that overlaps both sides of the data line.