Photo-Aligned LCD Alignment Layer Eliminates Rubbing Defects

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Solution Overview

Problem

Conventional liquid crystal display (LCD) manufacturing processes face challenges with afterimage and spot occurrences due to the need for a separate rubbing process to form alignment layers, which increases production costs and reduces display quality.

Innovation Solution

The use of a mixture of a major alignment material and a vertical photo-alignment material containing a first vertical functional group, where the alignment layer is formed by illuminating ultraviolet rays, eliminating the need for a rubbing process and enhancing the alignment of liquid crystal molecules without afterimages and spots.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a rubbing process is used to form alignment layers, then liquid crystal molecules can be aligned, but afterimage and spot occurrences increase and production costs increase

Engineering Contradiction:

Improvealignment qualityVSAvoidafterimage and spot occurrences

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the mechanical rubbing process with a photo-alignment method using ultraviolet light. The alignment layer is formed by irradiating UV light onto a photo-alignment material, which chemically aligns without mechanical contact, thereby eliminating afterimage and spot defects caused by rubbing while maintaining proper liquid crystal alignment.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental parameter of alignment layer formation from mechanical rubbing to photochemical alignment. By using UV light irradiation to induce molecular orientation in the photo-alignment material, the process achieves alignment without the harmful mechanical contact that causes display defects.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If a rubbing process is used to form alignment layers, then liquid crystal molecules can be aligned, but production costs increase

Engineering Contradiction:

Improvealignment qualityVSAvoidproduction cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts and eliminates the rubbing process from the manufacturing sequence entirely. By using photo-alignment, the harmful and costly rubbing step is removed, leaving only the UV irradiation step to achieve the same alignment function without the associated costs and defects.

Inventive Principle:

Principle #2Taking out (Extraction)

3Manufacturing precision

If conventional alignment materials are used, then alignment layers can be formed, but vertical alignment and pre-tilt angle control are insufficient

Engineering Contradiction:

Improvealignment uniformityVSAvoidvertical alignment performance

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent uses a composite photo-alignment material containing both vertical alignment functional groups and pre-tilt control functional groups. This composite material structure enables simultaneous achievement of vertical alignment and controlled pre-tilt angles, solving the insufficiency of conventional single-function alignment materials.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent introduces different functional groups at different locations within the alignment layer molecule structure. The vertical functional groups provide vertical alignment, while pre-tilt functional groups provide angle control, creating local quality differentiation that achieves both alignment requirements simultaneously.

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 method reduces afterimage and spot occurrences, improves display quality, and decreases production costs by forming alignment layers solely through ultraviolet illumination, resulting in more efficient and cost-effective LCD manufacturing.

Implementation Method 1

the alignment layer is formed by illuminating ultraviolet rays

Methodology Applied

Scientific EffectPhotopolymerization: Photopolymerisation

Implementation Method 2

a vertical photo-alignment material containing a first vertical functional group

Methodology Applied

Scientific EffectPhotoisomerization: Photochromism

Data Source

PatentUS9417484B2Liquid crystal display and manufacturing method thereof

Publication Date: 2016.08.16 SAMSUNG DISPLAY CO LTD

AI summary

A liquid crystal display includes; a first substrate, a second substrate disposed facing the first substrate, an alignment layer disposed on at least one of the first substrate and the second substrate, wherein the alignment layer comprises a major alignment material and a vertical photo-alignment material, and the vertical photo-alignment material comprises a first vertical functional group, and a liquid crystal layer interposed between the first substrate and the second substrate.