Polarizing Plate Adhesive Layer for Bend and Light-Leakage Control

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Solution Overview

Problem

Horizontal alignment liquid crystal displays suffer from anisotropy in visibility and light leakage due to pre-tilt in liquid crystal alignment, which is exacerbated by the use of multiple retardation layers causing thickness imbalance and bending of the polarizing plate.

Innovation Solution

A polarizing plate design incorporating a polarizer, a first retardation layer, a first adhesive layer, and a second retardation layer, where the first adhesive layer has a specific storage modulus and glass transition temperature, to provide diagonal compensation and suppress bending.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If two or more retardation layers are used to solve anisotropy and visibility imbalance, then visibility uniformity is improved, but thickness imbalance and bending occur causing light leakage

Engineering Contradiction:
Improvevisibility uniformityVSAvoidlight leakage
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the physical parameters of the adhesive layer, specifically setting its storage modulus within a specific range (10^4 to 10^6 Pa) and glass transition temperature (-50°C to 0°C) to balance the mechanical properties of the multi-layer structure, preventing bending while maintaining visibility uniformity

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The adhesive layer acts as an intermediary between the retardation layers, with its specifically controlled mechanical properties serving to bond the layers while compensating for thickness differences, thereby preventing bending and light leakage without compromising the diagonal compensation effect

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If multiple retardation layers are stacked to achieve diagonal compensation, then viewing angle is improved, but bending and edge lifting occur

Engineering Contradiction:
Improveviewing angleVSAvoidbending
Core Design Contradiction:
Adaptability or versatilityVSShape

Solution Approach 1:

The patent modifies the mechanical parameters of the adhesive layer (storage modulus and glass transition temperature) to create a balanced multi-layer structure that maintains flatness while achieving diagonal compensation effect for improved viewing angle

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite structure consisting of multiple retardation layers with an intermediate adhesive layer, where the composite's overall mechanical properties are optimized through the specific selection of adhesive layer parameters to prevent bending while maintaining the optical compensation function

Inventive Principle:
Principle #40Composite materials

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 achieves diagonal compensation on side surfaces and prevents light leakage by reducing bending, enhancing visibility uniformity and reducing edge lifting.

Implementation Method 1

a first adhesive layer, wherein the first adhesive layer has a storage modulus of 4 x 10^4 to 4 x 10^5 Pa at 25°C and a glass transition temperature of -50°C to 0°C

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 2

the first adhesive layer has a storage modulus of 4 x 10^4 to 4 x 10^5 Pa at 25°C and a glass transition temperature of -50°C to 0°C

Methodology Applied
Scientific EffectViscoelasticity: Viscoelasticity

Implementation Method 3

a laminate of a first retardation layer, a first adhesive layer, and a second retardation layer stacked on one surface of the polarizer

Methodology Applied
Scientific EffectBirefringence: Birefringence

Data Source

PatentEP4621452A1Polarizing plate and optical display device
Publication Date: 2025.09.24 WUXI HENGXIN OPTOELECTRONIC MATERIALS CO LTD
  • EP4621452A1 patent drawingFigure 1~2
  • EP4621452A1 patent drawingFigure 3
  • EP4621452A1 patent drawing

AI summary

Polarizer; and a first phase layer, a first phase layer, and a second phase layer laminated on one side of the polarizer, and The first adhesive layer is a polarizer, in which the storage modulus is 4 x 104Pa to 10 x 104Pa at 25°C, and the glass transition temperature is -60°C to -35°C.