Pixel Electrode Slits for Vertical Alignment LCD Aperture Ratio

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Solution Overview

Problem

Vertical alignment liquid crystal display devices face issues with display unevenness and low aperture ratio due to the need for wide X-shaped slits to prevent domain interaction, which reduces the area where opposing and pixel electrodes face each other.

Innovation Solution

The device incorporates pixel electrodes with slits that separate them into sub-pixels, maintaining a connecting portion with a width smaller than 1/5 of the pixel electrode width, allowing stable lying alignment of liquid crystal molecules without interference from adjacent sub-pixels, thus maintaining a high aperture ratio.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an X-shaped slit is formed in the opposing electrode to create multiple domains with different alignment directions, then display unevenness is reduced and view angle is widened, but the slit width must be sufficiently large to prohibit domain interaction, which increases the non-controllable area and reduces the aperture ratio

Engineering Contradiction:

Improvealignment stabilityVSAvoidaperture ratio

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The pixel electrode is divided into multiple electrode portions by forming slits, creating multiple domains within each pixel. This segmentation allows independent alignment control in each domain while maintaining overall pixel functionality, resolving the contradiction between needing wide slits for domain separation and maintaining high aperture ratio.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of forming slits in the opposing electrode as in conventional designs, the invention forms slits in the pixel electrode. This inversion of the slit formation location allows for better control of the electric field distribution and maintains higher aperture ratio while achieving the same domain multiplication effect.

Inventive Principle:

Principle #13The other way round (Inversion)

2Stability of the object's composition

If the slit width is increased to prevent interaction between domains, then alignment stability is improved, but the area where opposing electrode and pixel electrode face each other is reduced, resulting in low aperture ratio

Engineering Contradiction:

Improvedomain separationVSAvoideffective electrode area

Core Design Contradiction:

Stability of the object's compositionVSArea of stationary object

Solution Approach 1:

The slit width is optimized to provide sufficient domain separation locally while minimizing the overall impact on aperture ratio. The connecting portions between electrode portions are designed with specific width ratios to ensure proper electric field distribution without excessive material removal.

Inventive Principle:

Principle #3Local quality

3Reliability

If connecting portions with sufficient width are formed to connect adjoining electrode portions, then electrical connectivity is ensured, but the aperture ratio is reduced due to the additional non-controllable area

Engineering Contradiction:

Improveelectrical connectivityVSAvoidaperture ratio

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The width of connecting portions is precisely controlled as a parameter, set to be smaller than 1/5 of the pixel electrode width. This parameter optimization ensures sufficient electrical connectivity for reliable pixel operation while minimizing the area occupied by connecting portions to maintain high aperture ratio.

Inventive Principle:

Principle #35Parameter changes

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 design enables high-quality, bright displays with wide view angles and stable liquid crystal alignment, preventing display roughness and maintaining a sufficient aperture ratio.

Implementation Method 1

aligning the liquid crystal molecules in each pixel stably into the lying alignment by applying a voltage

Methodology Applied

Scientific EffectElectric field: Electric Field

Implementation Method 2

a liquid crystal layer having a negative dielectric anisotropy filled in the gap between the front substrate and the back substrate

Methodology Applied

Scientific EffectDielectric anisotropy: Dielectric Permittivity

Data Source

PatentUS8068200B2Vertical alignment liquid crystal display device in which a pixel electrode has slits which divide the pixel electrode into electrode portions

Publication Date: 2011.11.29 ORTUS TECH CO LTD

AI summary

A liquid crystal display device has an opposing substrate on which an opposing electrode is formed, a TFT substrate on which pixel electrodes arranged in matrix, thin film transistors connected to the pixel electrodes respectively, and gate lines and data lines for the thin film transistors are formed, vertical alignment films formed on the opposing inner surfaces of these substrates, and a liquid crystal layer disposed between the vertical alignment films and having negative dielectric anisotropy. Each pixel electrode has a slit formed for separating each pixel into a plurality of sub-pixels by partially eliminating the pixel electrode with a connecting portion left at which adjoining electrode portions of each pixel electrode is connected with each other. The width W1 of the pixel electrode that runs in a direction in which the slit is formed and width W2 of the connecting portion have a ratio W2/W1 of 0.13 or lower.