Dual-Mode Pixel Electrode Structure for LCD Viewing Angle and Contrast

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Solution Overview

Problem

Conventional liquid crystal display (LCD) devices, such as TN and VA types, face challenges including complex manufacturing, asymmetric viewing angles, low contrast, high image luminance in dark states, and color shift, which affect display performance.

Innovation Solution

The LCD device incorporates an array of pixel regions where liquid crystal molecules operate in both twisted nematic (TN) and vertical alignment (VA) modes, utilizing negative liquid crystal molecules and a design with slits in pixel electrodes to achieve dual operation modes, ensuring pre-tilting and alignment by alignment layers, and polarizers to manage light transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If twisted nematic (TN) mode is used, then wide viewing angle is achieved, but asymmetric viewing angle and low contrast occur

Engineering Contradiction:

Improveviewing angleVSAvoidcontrast and symmetry

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The pixel electrode is divided into multiple independent segments or regions, each capable of generating electric fields in different directions. This segmentation allows different regions to control liquid crystal molecules in distinct orientations, simultaneously achieving wide viewing angles through TN-mode regions and high contrast through VA-mode regions within the same pixel.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the pixel electrode are designed with different properties - some regions have electrode patterns optimized for TN mode operation while others are optimized for VA mode. This local differentiation allows each region to exhibit its optimal characteristics, with TN regions providing wide viewing angles and VA regions providing high contrast and symmetric viewing properties.

Inventive Principle:

Principle #3Local quality

2Reliability

If vertical alignment (VA) mode is used, then high contrast is achieved, but slow response speed and color shift occur

Engineering Contradiction:

ImprovecontrastVSAvoidresponse speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent merges TN mode and VA mode operations within a single pixel structure. By combining the advantages of both modes - the fast response of TN mode and the high contrast of VA mode - the dual-mode pixel achieves both high contrast and quick response simultaneously, eliminating the trade-off between these two parameters.

Inventive Principle:

Principle #5Merging (Combining)

3Stability of the object's composition

If alignment layer is used to align liquid crystal molecules, then molecular orientation is achieved, but manufacturing complexity increases

Engineering Contradiction:

Improvemolecular alignmentVSAvoidmanufacturing process

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent extracts or removes the alignment layer from the structure, replacing it with electric field-based alignment methods. By using patterned pixel electrodes to generate electric fields that directly orient the liquid crystal molecules, the manufacturing process is simplified while maintaining effective molecular alignment, eliminating the complexity associated with alignment layer deposition and rubbing processes.

Inventive Principle:

Principle #2Taking out (Extraction)

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 dual-mode operation enhances contrast, light transmittance, response speed, and color stability, providing symmetric viewing angles and improved display characteristics like low image luminance in dark states and reduced color shift.

Implementation Method 1

The alignment layer 220 covers the common electrode 210, and is adjacent the liquid crystal layer 300. The alignment layer 220 pre-tilts the liquid crystal molecules of the liquid crystal layer 300

Methodology Applied

Scientific EffectAlignment layer alignment effect:

Implementation Method 2

When a voltage is applied between the pixel electrode 110 and the common electrode 210, the liquid crystal molecules 310 are induced to tilt and/or rotate

Methodology Applied

Scientific EffectElectric field effect on liquid crystal: Electric Field

Implementation Method 3

a first polarizer 400 and a second polarizer 500. The first polarizer 400 is disposed on a surface of the first substrate 100 away from the liquid crystal layer 300

Methodology Applied

Scientific EffectLight polarization: Polarisation

Data Source

PatentUS7782432B2Liquid crystal display device having a pixel electrode structure and an alignment layer causing pixel regions to operate in both twisted nematic and vertical alignment modes

Publication Date: 2010.08.24 RED OAK INNOVATIONS LTD

AI summary

A liquid crystal display device is provided that has a plurality of pixel regions where some of the pixel regions have liquid crystal molecules that operate according to both twisted nematic mode and vertical alignment mode.