Fringe Field Switching LCD Electrode Segmentation

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Solution Overview

Problem

Conventional fringe field switching (FFS) liquid crystal display (LCD) apparatuses face issues with long charging times and assembly difficulties due to large capacitance of the counter electrode, leading to increased response time and potential light leakage affecting contrast ratio.

Innovation Solution

The FFS LCD apparatus features a first electrode with a defined area and a second electrode with penetrating vacancies or slits that reduce the overall area of the counter electrode, allowing for shorter charging times and improved response performance while maintaining the desired electrical field alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the counter electrode area is increased to cover the entire pixel, then the electrical field coverage is improved, but the capacitance charging time increases leading to longer response time

Engineering Contradiction:
Improveelectrical field coverageVSAvoidcapacitance charging time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The counter electrode is segmented into multiple strips that are disposed between the pixel electrode strips, rather than using a continuous plane electrode. This segmentation reduces the total electrode area and capacitance while maintaining effective electrical field coverage in the liquid crystal layer through the fringe field effect at the electrode edges.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The electrode structure uses different configurations for different regions: the pixel electrode has strips with spacings that define active regions, while the counter electrode has corresponding strips positioned in the spacing regions. This local differentiation optimizes the electrical field distribution and reduces overall capacitance.

Inventive Principle:
Principle #3Local quality

2Loss of time

If the counter electrode strips interleave the pixel electrode strips, then the capacitance is reduced, but the assembly difficulty increases due to positioning precision requirements

Engineering Contradiction:
Improvecapacitance charging timeVSAvoidassembly difficulty
Core Design Contradiction:
Loss of timeVSEase of manufacture

Solution Approach 1:

The counter electrode strips are positioned in the spacing regions between pixel electrode strips viewed from the top, but in the stacked relationship (vertical dimension), they are disposed between the pixel electrode strips. This three-dimensional arrangement reduces top-view overlap and capacitance while maintaining electrical field effectiveness, and simplifies assembly by providing clear positional guidance.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Manufacturing precision

If the electrode strips are positioned with high precision to maintain uniform electrical field, then the display quality is improved, but the manufacturing complexity increases

Engineering Contradiction:
Improveelectrode alignment precisionVSAvoidmanufacturing complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The electrode structures are designed with predetermined strip widths, spacing dimensions, and relative positions that are established during the electrode formation process. This preliminary design of geometric parameters ensures that when electrodes are assembled, the fringe fields naturally align to create uniform electrical fields in the liquid crystal layer without requiring post-assembly positioning adjustments.

Inventive Principle:
Principle #10Preliminary action

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 solution significantly reduces the capacitance of the counter electrode, resulting in shorter charging times and enhanced display performance with improved contrast ratio by maintaining uniform electrical field alignment.

Implementation Method 1

a fringe field switching (FFS) liquid crystal display (LCD) apparatus includes a first electrode and a second electrode

Methodology Applied
Scientific EffectFringe field switching: Electric Field

Implementation Method 2

the liquid crystal alignments thereof occur in the plane (horizontal) direction rather than the vertical direction

Methodology Applied
Scientific EffectLiquid crystal alignment: Liquid Crystals

Implementation Method 3

the second electrode has at least a penetrating vacancy, which has a projection onto the first electrode located outside the first area

Methodology Applied
Scientific EffectCapacitance reduction: Capacitance

Data Source

PatentEP2479606B1Fringe field switching liquid crystal display apparatus
Publication Date: 2014.05.14 HANNSTAR DISPLAY CORP
  • EP2479606B1 patent drawingFigure 1
  • EP2479606B1 patent drawingFigure 2
  • EP2479606B1 patent drawingFigure 3A~3C

AI summary

A fringe field switching liquid crystal display apparatus is provided. This apparatus includes a first electrode (11) and a second electrode (12, 22, 23, 24). The second electrode (12, 22, 23, 24) is disposed in a stacked relationship with the first electrode (11) without liquid crystal material disposed therebetween, has a polygonal shape having n sides, and has a projection onto the first electrode (11), wherein the n is an integer larger than four.