LCD Electrode Structure Reducing Parasitic Capacitance
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Solution Overview
Problem
Large liquid crystal display devices face issues with decreased driving speed due to increased parasitic capacitance as the number of pixels increases, and existing electrode structures fail to adequately address the deterioration of the liquid crystal layer under high voltage applications, limiting contrast ratio and moving image quality.
Innovation Solution
A liquid crystal display device with a novel electrode structure featuring a first and second electrode layer, a connection electrode, and a third insulating film, where the electrode layers are metal films with specific thicknesses and configurations to reduce parasitic capacitance and enhance electric field application across the liquid crystal layer, allowing for increased white transmittance and contrast ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of pixels is increased to achieve larger size and higher definition, then display quality is improved, but parasitic capacitance increases causing signal delay and decreased driving speed
Solution Approach 1:
The patent segments the electrode structure into multiple layers (first electrode layer, second electrode layer, connection electrode) and separates signal lines from scan lines in the vertical direction. This spatial segmentation reduces parasitic capacitance between intersecting lines while maintaining high pixel density for high-definition display.
Solution Approach 2:
The patent introduces a vertical dimension to the electrode arrangement by stacking electrode layers at different heights (using insulating films to separate them). This three-dimensional configuration reduces parasitic capacitance between signal lines and scan lines that would otherwise intersect in the same plane, thereby maintaining driving speed despite increased pixel count.
2Illumination intensity
If high voltage is applied to generate electric field in large region for higher white transmittance, then contrast ratio is improved, but liquid crystal layer deteriorates
Solution Approach 1:
The patent changes the electrical parameters by applying voltage to the second electrode layer in an alternating pattern (sometimes connected to potential, sometimes to ground potential). This alternating voltage application reduces cumulative stress on the liquid crystal layer while maintaining effective electric field generation for high white transmittance and contrast ratio.
Solution Approach 2:
The patent implements periodic action by alternately connecting the second electrode layer to ground potential and floating it. This periodic voltage modulation reduces liquid crystal layer deterioration caused by continuous high voltage application, while still achieving the necessary electric field strength for high contrast ratio and white transmittance during active display periods.
3Ease of manufacture
If conventional electrode structure is used in horizontal electric field mode, then manufacturing is simplified, but contrast ratio and moving image quality are insufficient
Solution Approach 1:
The patent merges the functions of multiple electrodes into a integrated structure where the first electrode layer, second electrode layer, and connection electrode work together as a unified system. This combined structure achieves superior contrast ratio and moving image quality while remaining manufacturable using standard thin-film deposition and patterning processes.
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
The proposed structure effectively suppresses the decrease in driving speed, enhances contrast ratio, and improves moving image quality by reducing parasitic capacitance and expanding the electric field application across the liquid crystal layer, particularly when using a liquid crystal exhibiting a blue phase.
Implementation Method 1
it is important to form an electric field in a large region of a liquid crystal layer and liquid crystal molecules are controlled using the electric field
Implementation Method 2
liquid crystal molecules are driven by applying an electric field in a direction parallel to a substrate
Implementation Method 3
total parasitic capacitance between the scan lines and the signal lines is increased, and a problem of signal delay may be caused
Data Source
AI summary
Provided are a liquid crystal display device with horizontal electric field mode, in which a decrease in driving speed can be suppressed by reducing the resistance of a wiring even when the number of pixels is increased, and a manufacturing method thereof. One of a scan wiring and a signal wiring is divided in an intersection portion where the scan wiring and the signal wiring intersect with each other, and the separated wirings are connected with a connection electrode positioned over a thick insulating film. Accordingly, parasitic capacitance at the intersection portion can be reduced, preventing the decrease in the driving speed. The connection electrode is formed at the same time as formation of a pixel electrode and a common electrode using a low-resistance metal, which contributes to the reduction in manufacturing process of the liquid crystal display device.