Liquid Crystal Display Alignment Films Anchoring Strength

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Solution Overview

Problem

Liquid crystal displays using lateral electric field modes face issues with burn-in and display unevenness due to incomplete alignment capability on alignment films, especially when the rubbing method is used, and photo-alignment methods can lead to color filter fading and impurity formation.

Innovation Solution

The implementation of a liquid crystal display with a first alignment film using a photo-alignment method and a second alignment film using a rubbing method, both with high anchoring strength, ensures uniform alignment and prevents burn-in and display unevenness, while avoiding ultraviolet irradiation to maintain the color filter's integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the rubbing method is used for alignment treatment on the alignment film, then alignment capability is provided on the alignment film, but projections and depressions on the alignment film surface cause incomplete alignment capability in some areas, leading to burn-in and display unevenness

Engineering Contradiction:

Improvealignment capability uniformityVSAvoidburn-in and display unevenness

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical rubbing method with a photo-alignment method that uses ultraviolet light irradiation to provide alignment capability. This substitution eliminates the mechanical contact that causes projections and depressions on the alignment film surface, thereby preventing incomplete alignment and the resulting burn-in and display unevenness issues.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts and eliminates the harmful mechanical rubbing process from the alignment treatment. By removing the rubbing step entirely and using only photo-alignment, the source of surface projections and depressions is eliminated, preventing the alignment defects that lead to burn-in and display unevenness.

Inventive Principle:

Principle #2Taking out (Extraction)

2Manufacturing precision

If the photo-alignment method is used for alignment treatment on the alignment film, then alignment capability is provided uniformly on the alignment film, but ultraviolet irradiation causes color filter fading and impurity formation

Engineering Contradiction:

Improvealignment uniformityVSAvoidcolor filter fading and impurity formation

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent applies different alignment methods to different substrates based on their specific requirements. The photo-alignment method is applied to the array substrate where uniform alignment is critical, while the rubbing method is applied to the counter substrate where the color filter is not present, thus avoiding ultraviolet-induced damage to color filters while maintaining alignment uniformity where needed.

Inventive Principle:

Principle #3Local quality

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 approach effectively prevents burn-in and display unevenness by ensuring high anchoring strength on both alignment films and avoids color filter degradation, resulting in improved display quality and reliability.

Implementation Method 1

the alignment treatment by the photo-alignment method is performed on the first alignment film

Methodology Applied

Scientific EffectPhoto-alignment: Photopolymerisation

Implementation Method 2

the alignment treatment by the rubbing method is performed on the second alignment film

Methodology Applied

Scientific EffectRubbing method: Friction

Implementation Method 3

a liquid crystal molecule of the liquid crystal layer is switched in a lateral electric field substantially parallel to the main surface of the array substrate

Methodology Applied

Scientific EffectLateral electric field switching: Electric Field

Data Source

PatentUS9500907B2Liquid crystal display comprising first and second alignment films having first and second anchoring strengths respectively and manufacturing method thereof

Publication Date: 2016.11.22 MAGNOLIA WHITE CORP

AI summary

According to one embodiment, a liquid crystal display includes a first substrate, a second substrate and a liquid crystal layer. The first substrate includes a first line, a second line, a switching element, a pixel electrode, a common electrode, and a first alignment film. The second substrate includes a second alignment film. The liquid crystal layer includes a liquid crystal molecule kept between the first alignment film and the second alignment film. First anchoring strength is provided on the first alignment film which is a photo-alignment film, second anchoring strength is provided on the second alignment film which is a rubbing alignment film, and the first anchoring strength is substantially equal to or greater than the second anchoring strength.