LCD Common Electrode Slits and Organic Passivation
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Solution Overview
Problem
Existing liquid crystal display (LCD) devices face issues with light leakage during black gradation and reduced aperture ratio due to the placement of electrodes and the use of silicon nitride as a passivation layer, leading to parasitic capacitance and mis-alignment risks.
Innovation Solution
The solution involves forming a common electrode with slits on an insulating interlayer, using a metal line overlapping the data line, and employing a low dielectric constant organic insulating layer, such as photoacryl, to reduce resistance and prevent light leakage, while increasing the aperture ratio by widening the opening adjacent to the data line and removing the common line that divides the pixel into two regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon nitride is used as a passivation layer, then manufacturing is simplified, but parasitic capacitance increases and light leakage occurs during black gradation
Solution Approach 1:
The patent changes the dielectric constant parameter of the passivation layer by replacing silicon nitride (high dielectric constant) with organic insulating layers having lower dielectric constants (1.3-1.5), thereby reducing parasitic capacitance while maintaining manufacturing feasibility
Solution Approach 2:
The patent employs composite insulating structures combining organic insulating layers with other materials to achieve both low dielectric constant properties and effective passivation, replacing the single-layer silicon nitride approach
2Ease of operation
If a common line is added to divide the pixel region, then electrode control is improved, but the aperture ratio decreases due to the dividing line occupying pixel area
Solution Approach 1:
The patent removes the common line structure from the pixel region, extracting the electrode control function to the gate line instead, thereby eliminating the area occupation that reduced aperture ratio while maintaining electrode controllability
Solution Approach 2:
The gate line is enhanced to serve multiple functions: it acts as both the transistor gate electrode and the common electrode for the pixel region, eliminating the need for a separate common line and maximizing aperture ratio
3Ease of manufacture
If the pixel electrode is placed on the gate insulating layer, then fabrication is simplified, but light leakage occurs during black gradation
Solution Approach 1:
The patent introduces an insulating interlayer between the pixel electrode and the gate insulating layer, acting as an intermediary that prevents direct contact and the resulting light leakage during black gradation, while maintaining fabrication simplicity
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 effectively prevents light leakage, increases the aperture ratio, and reduces parasitic capacitance by using a low resistance material for data lines and a transparent common electrode, enhancing the overall performance of the LCD device.
Implementation Method 1
an LC director is controlled by a horizontal electric field generated between the two electrodes
Implementation Method 2
a liquid crystal (LC) director is arranged to be twisted by 90°
Implementation Method 3
A fringe field is generated between the common electrode 11 and the pixel electrode 29 having the plurality of slits 29a
Data Source
AI summary
A liquid crystal display (LCD) device includes an array substrate; a gate line formed on the array substrate; a data line formed on the array substrate crossing the gate lines; a thin film transistor formed on the array substrate, the thin film transistor being formed at an intersection between the gate line and the data line; a pixel electrode formed on the array substrate and connected to the thin film transistor; an insulating interlayer formed on an entire surface of the array substrate; a common electrode formed on the insulating interlayer and having a plurality of slits; a metal line formed on the insulating interlayer overlapping the data line and the common electrode; a color filter substrate attached to the array substrate; and a liquid crystal layer formed between the array substrate and the color filter substrate.