Liquid Crystal Display Polarizing Plate Adhesion Stress Management

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Solution Overview

Problem

Liquid crystal display devices face durability issues due to peeling between polarizing plates and liquid crystal cells, especially under high temperatures, caused by shrinkage of stretched polarizer films, leading to display quality degradation.

Innovation Solution

The solution involves using polarizing plates with different adhesion strengths and conductivity on opposite sides of the liquid crystal cell, with a higher adhesion strength for the plate with the larger absorption axis dimension and conductivity for the plate with the smaller dimension, to distribute stress and prevent peeling, while also using adhesives with varying elastic modulus and resistance to manage internal stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the absorption axis length of the polarizer is increased, then the polarizing performance is improved, but the shrinkage under high temperature increases causing peeling at corners

Engineering Contradiction:

Improvepolarizing performanceVSAvoiddimensional stability under heat

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent applies different adhesive properties to different regions of the polarizing plate. Specifically, the adhesive layer has different adhesion strength or elastic modulus at the corner regions compared to the center region, allowing the corners to accommodate shrinkage stress better while maintaining overall polarizing performance

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the adhesive parameters (adhesion strength and elastic modulus) based on the position within the polarizing plate. By varying these parameters spatially, the adhesive layer can accommodate the shrinkage stress that occurs in the absorption axis direction without causing peeling, while still providing sufficient bonding

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the stretched film is stretched to several times original length, then the polarizer absorption axis is established, but shrinkage occurs under severe environment causing peeling

Engineering Contradiction:

Improvepolarizer functionVSAvoidshrinkage under high temperature

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent prepares the adhesive layer in advance with specific physical properties (lower adhesion strength or higher elastic modulus at corners) that allow it to cushion or absorb the shrinkage stress before it causes peeling. This preemptive design ensures that when the stretched film shrinks under high temperature, the adhesive layer can accommodate the stress without failing

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Ease of manufacture

If uniform adhesive strength is used across the polarizing plate, then manufacturing is simplified, but stress concentration at corners causes peeling

Engineering Contradiction:

Improveadhesive applicationVSAvoidpeeling resistance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent transitions from uniform adhesive properties to non-uniform adhesive properties distributed across the polarizing plate. The adhesive layer has different characteristics at corner regions versus center regions, optimizing stress distribution while maintaining manufacturability through appropriate adhesive formulation and application methods

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 reduces stress concentration on display surface corners, preventing warpage and peeling, thereby enhancing the durability and display quality of liquid crystal display devices under high-temperature conditions.

Implementation Method 1

adhered to the first surface side of the liquid crystal cell with an adhesive layer

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 2

a polarizer having an absorption axis

Methodology Applied

Scientific EffectPolarization absorption: Absorption (EM radiation)

Data Source

PatentUS9019447B2Liquid crystal display device with polarizing plates

Publication Date: 2015.04.28 MAGNOLIA WHITE CORP

AI summary

A liquid crystal display device comprising: a liquid crystal cell including a quadrilateral display surface and a liquid crystal layer enclosed between glass substrates and controlling light entering from a second surface side and exiting to a first surface side; a first polarizing plate including a polarizer having an absorption axis and adhered to the first surface side with an adhesive layer; and a second polarizing plate including a polarizer having an absorption axis and adhered to the second surface side with an adhesive layer such that one of the polarizing plates including the polarizer with a larger maximum dimension in an absorption axis direction on the display surface is adhered to the glass substrate with an adhesive layer having higher adhesion strength to the glass substrate than the adhesive layer of other polarizing plates including the polarizer with a smaller maximum dimension in the absorption axis direction.