Liquid Crystal Retardation Layer for Low-Reflection Polarizing Plates
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Solution Overview
Problem
Organic light emitting device displays suffer from deterioration in visibility and contrast due to reflection of external light, and existing polarizing plates either increase thickness and reduce manufacturing processability or have limited reflectivity reduction.
Innovation Solution
A polarizing plate comprising a polarizer and a liquid crystal retardation layer that satisfies the condition |(CD(400 nm)−CD(300 nm))/100| ≤ 23, where CD values are in mdeg, significantly reducing reflected color azimuthal angle color distribution (AACD) values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a bilayer type retardation layer (HWP layer and QWP layer) is used, then the polarizing plate can reduce reflectivity, but the thickness increases and manufacturing processability decreases
Solution Approach 1:
The patent combines the functions of the HWP layer and QWP layer into a single integrated retardation layer structure. This merged structure achieves the same reflectivity reduction effect as the bilayer configuration but with reduced thickness and improved manufacturing processability, directly resolving the contradiction between effective reflectivity reduction and thickness control.
Solution Approach 2:
The patent employs a composite retardation layer structure that integrates multiple functional characteristics into a single layer. This composite approach allows the polarizing plate to achieve effective reflectivity reduction while maintaining optimized thickness and manufacturing properties, balancing optical performance with structural efficiency.
2Ease of manufacture
If a single-sheet type retardation layer is used, then the manufacturing processability improves, but the ability to reduce reflectivity at front and lateral sides is limited
Solution Approach 1:
The patent designs the retardation layer with spatially varying optical properties, where different regions of the layer provide different retardation characteristics. This local quality variation enables the single-sheet structure to effectively reduce reflectivity at both front and lateral sides while maintaining manufacturing simplicity, overcoming the limitations of uniform single-sheet designs.
Solution Approach 2:
The patent optimizes key parameters of the retardation layer including thickness, refractive index distribution, and orientation angles to achieve effective reflectivity reduction. By carefully controlling these parameters, the single-sheet retardation layer attains performance comparable to or exceeding bilayer structures while preserving manufacturing advantages.
3Object-affected harmful factors
If the circular dichroism value difference between 400 nm and 300 nm is large, then the reflectivity reduction improves, but the manufacturing precision requirements increase
Solution Approach 1:
The patent adopts a moderate approach to circular dichroism values, targeting a balanced difference between 400 nm and 300 nm measurements. Rather than maximizing the difference, the patent optimizes it to achieve sufficient reflectivity reduction while maintaining reasonable manufacturing precision requirements, avoiding excessive control demands.
Solution Approach 2:
The patent replaces complex mechanical control methods for achieving circular dichroism with material composition control and processing parameter optimization. This substitution simplifies the manufacturing process by using chemical and physical properties of materials rather than precise mechanical adjustments, reducing manufacturing precision requirements while maintaining effective reflectivity reduction.
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 polarizing plate achieves a reflected color AACD value of 5 or less, improving black visibility and screen quality without increasing thickness or complexity, and is suitable for optical display apparatuses.
Implementation Method 1
the liquid crystal retardation layer satisfying Formula 1: where CD(400) is a circular dichroism value (unit: mdeg) of the liquid crystal retardation layer at a wavelength of 400 nm, and CD(300) is a circular dichroism value (unit: mdeg) of the liquid crystal retardation layer at a wavelength of 300 nm
Data Source
AI summary
Disclosed are a polarizing plate and an optical display apparatus including the same. The polarizing plate includes: a polarizer; and a retardation layer formed on one surface of the polarizer, wherein the retardation layer comprises a liquid crystal retardation layer, the liquid crystal retardation layer satisfying Formula 1 described in detail in the specification.