Polarizing Plate with Haze Coating for LCD Light Leakage
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Solution Overview
Problem
Conventional liquid crystal displays (LCDs) face issues with color stains and display deterioration due to light leakage from polarizing plates, particularly when using polyethylene terephthalate films as protection layers, which lack the anti-glare properties and mechanical strength of triacetyl cellulose films but are more cost-effective.
Innovation Solution
A polarizing plate design incorporating a polyethylene terephthalate film with an in-plane phase difference of 500 nm to 3000 nm and a coating layer with a haze value of 15% to 35% to prevent light leakage, combined with adhesive layers and auxiliary adhesive layers for improved adhesion and durability, and optionally including UV absorbers for protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a polyethylene terephthalate film is used as a protection layer instead of triacetyl cellulose film, then cost is reduced, but anti-glare properties and mechanical strength deteriorate
Solution Approach 1:
The patent uses a composite structure consisting of a polyethylene terephthalate film combined with a coating layer having specific haze properties (15-35%). This composite approach allows the base film to provide cost-effectiveness while the coating layer compensates for the lack of anti-glare properties, achieving a balance between cost and performance that neither material could achieve alone.
2Ease of manufacture
If a polyethylene terephthalate film is used as a protection layer instead of triacetyl cellulose film, then cost is reduced, but anti-glare properties deteriorate
Solution Approach 1:
The patent modifies the optical parameters of the protection layer by applying a coating with controlled haze values (15-35%). This parameter change introduces light scattering properties that provide anti-glare functionality, transforming the polyethylene terephthalate film from a purely transparent material into one with effective anti-glare characteristics without requiring expensive alternative materials.
3Reliability
If the in-plane phase difference (Ro) is increased to reduce light leakage, then display characteristics improve, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies a broad range for the in-plane phase difference (Ro) of 500-3000 nm, which provides flexibility in manufacturing while ensuring effective light leakage prevention. This parameter range is optimized to achieve good display characteristics without requiring extremely precise control, thus balancing performance with manufacturability.
4Strength
If adhesive layers with cross-linking agents are used to improve adhesion, then bonding strength improves, but manufacturing complexity increases
Solution Approach 1:
The patent specifies a controlled amount of cross-linking agent (0.5-1.5 wt% based on polyvinyl alcohol) to achieve optimal adhesion. This quantitative parameter control ensures sufficient bonding strength while maintaining relatively simple manufacturing processes, avoiding the need for complex multi-step curing or processing procedures.
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 solution effectively reduces light leakage, prevents color stains, and enhances the mechanical strength and adhesion of the polarizing plate, thereby improving the display characteristics and cost-effectiveness of LCDs.
Implementation Method 1
a coating layer disposed on one side of the thin film and having a haze value of about 15% to about 35%
Implementation Method 2
the thin film having an in-plane phase difference (Ro) of about 500 nm to about 3000 nm
Implementation Method 3
The polyethylene terephthalate film may include an ultraviolet (UV) absorber, and has transmittance of less than about 10% at about 380 nm
Data Source
AI summary
A polarizing plate includes a polarizer, a thin film on the polarizer, the thin film having an in-plane phase difference (Ro) of about 500 nm to about 3000 nm, and a coating layer disposed on one side of the thin film and having a haze value of about 15% to about 35%.