Blue Phase LCD Electrode Arrangement for Transmittance

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Solution Overview

Problem

Liquid crystal display devices face challenges in achieving high white transmittance and contrast ratio, particularly in liquid crystal display modes using blue phase liquid crystals, where maintaining high contrast while allowing for high-speed response is essential.

Innovation Solution

A liquid crystal display device design incorporating a blue phase liquid crystal layer with a pair of common electrode layers and a pixel electrode layer, where the pixel electrode layer is positioned between the common electrode layers in the thickness direction, creating oblique electric fields to control liquid crystal molecules and enhance white transmittance and contrast ratio.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a blue phase liquid crystal is used to achieve high-speed response, then the response speed is improved, but the white transmittance and contrast ratio deteriorate

Engineering Contradiction:

Improveresponse speedVSAvoidwhite transmittance

Core Design Contradiction:

SpeedVSIllumination intensity

Solution Approach 1:

The patent introduces a thickness direction dimension by positioning the pixel electrode layer between the first and second common electrode layers in the thickness direction of the liquid crystal layer. This three-dimensional electrode arrangement creates oblique electric fields that extend throughout the liquid crystal layer, improving white transmittance while maintaining the high-speed response characteristic of blue phase liquid crystals.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent applies different electrode configurations to different regions: the pixel electrode layer is positioned between the common electrode layers in the thickness direction, while the common electrode layers extend in the planar direction. This local differentiation creates oblique electric fields in specific regions, optimizing both white transmittance and response speed.

Inventive Principle:

Principle #3Local quality

2Illumination intensity

If the pixel electrode layer is positioned between the common electrode layers in the thickness direction, then white transmittance and contrast ratio are improved, but device complexity increases

Engineering Contradiction:

Improvewhite transmittanceVSAvoidelectrode arrangement complexity

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The pixel electrode layer serves multiple functions: it acts as an electrode for applying electric fields, serves as a positioning reference for the liquid crystal layer thickness, and creates oblique electric fields when positioned between the common electrode layers. This multi-functionality justifies the increased structural complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The electrode system is segmented into three distinct layers: the first common electrode layer, the pixel electrode layer positioned between them in the thickness direction, and the second common electrode layer. Each layer has a specific function, and their segmented arrangement creates the necessary oblique electric fields while maintaining manufacturability through standard thin-film fabrication processes.

Inventive Principle:

Principle #1Segmentation

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 design improves white transmittance and contrast ratio by ensuring liquid crystal molecules respond effectively across the entire liquid crystal layer, including the thickness direction, thereby increasing the display's performance and efficiency.

Implementation Method 1

electric fields are applied between the pixel electrode layer and the first common electrode layer and between the pixel electrode layer and the second common electrode layer, so that the electric fields are applied to the liquid crystal in an oblique direction

Methodology Applied

Scientific EffectElectric Field: Electric Field

Implementation Method 2

a liquid crystal display device including a blue phase liquid crystal layer

Methodology Applied

Scientific EffectLiquid Crystal: Liquid Crystals

Data Source

PatentUS8395740B2Liquid crystal display device having blue phase liquid crystal and particular electrode arrangement

Publication Date: 2013.03.12 SEMICON ENERGY LAB CO LTD

AI summary

In a liquid crystal display device including a blue phase liquid crystal layer, first and second common electrode layers, which are positioned to face each other, sandwich the blue phase liquid crystal layer therebetween and have opening patterns (slits), and a pixel electrode layer has an opening pattern. The pixel electrode layer is formed over a structure body which projects into the liquid crystal layer from a surface of a first substrate on a liquid crystal layer side, and the pixel electrode layer is positioned between the first and second common electrode layers in the liquid crystal layer. Electric fields are applied between the pixel electrode layer and the first and second common electrode layers, so that the electric fields are formed in the entire liquid crystal layer and liquid crystal molecules can be controlled by using the electric fields.