Polarizing Plate Retardation Stack for Low-Reflectivity OLED Displays
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Solution Overview
Problem
Organic light emitting diode displays face issues with visibility and contrast due to external light reflection, and existing polarizing plates suffer from iodine contamination and durability problems under high temperature/humidity conditions.
Innovation Solution
A polarizing plate design featuring a polarizer with sequentially stacked negative C, negative A, and positive A retardation layers, where the negative C layer has specific out-of-plane retardation, and a laminate of negative A and positive A layers with negative wavelength dispersion characteristics, minimizing reflectivity and iodine contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a double sheet-type retardation layer with liquid crystals is used to reduce thickness, then thickness is reduced, but iodine elution from the polarizer causes contamination and durability deterioration under high temperature/humidity conditions
Solution Approach 1:
The retardation layer is divided into multiple distinct sheets (first retardation layer, second retardation layer, and third retardation layer) with different optical characteristics. This segmentation allows each layer to contribute differently to the overall performance, achieving both thickness reduction and durability improvement by combining liquid crystal layers with protective structures.
Solution Approach 2:
The invention uses a composite structure combining multiple retardation layers with different materials and properties. The first and second retardation layers provide the required optical retardation with thinner profiles, while the third retardation layer provides additional protection against iodine elution, creating a composite system that achieves both thickness reduction and enhanced durability.
2Device complexity
If a single sheet-type retardation layer is used to simplify structure, then structure is simplified, but negative wavelength dispersion characteristics are achieved with larger thickness compared to double sheet-type
Solution Approach 1:
The single sheet-type retardation layer is segmented into multiple thinner layers (first, second, and third retardation layers) with different optical characteristics. This segmentation allows the system to achieve the required negative wavelength dispersion characteristics while reducing overall thickness compared to a single thick sheet.
Solution Approach 2:
The invention changes the optical parameters of each individual retardation layer to achieve the desired overall performance. By carefully controlling the retardation values and wavelength dispersion characteristics of each layer, the system achieves negative wavelength dispersion with reduced thickness compared to a single sheet approach.
3Reliability
If conventional polarizing plate structure is used to maintain basic functionality, then basic antireflection function is achieved, but reflectivity at lateral side is not sufficiently reduced and black visibility is poor
Solution Approach 1:
The invention uses a composite structure of multiple retardation layers with different optical characteristics to achieve superior antireflection performance. The combination of positive and negative wavelength dispersion layers creates destructive interference for reflected light at lateral angles, significantly reducing reflectivity and improving black visibility while maintaining the basic antireflection function.
Solution Approach 2:
The invention optimizes various optical parameters including retardation values, wavelength dispersion characteristics, and layer thicknesses to achieve minimal reflectivity at lateral sides. By carefully tuning these parameters, the system achieves excellent black visibility and antireflection performance that conventional single-layer structures cannot achieve.
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 low reflectivity and good black visibility while preventing iodine contamination and thickness reduction, enhancing durability under high temperature/humidity conditions.
Implementation Method 1
the negative C layer has an out-of-plane retardation of 20 nm to 60 nm at a wavelength of 550 nm
Implementation Method 2
the laminate of the negative A layer and the positive A layer has negative wavelength dispersion characteristics
Implementation Method 3
The polarizing plate can realize an antireflection function through reduction in reflectivity with respect to reflected external light
Data Source
Figure 1~2
Figure 3
AI summary
Provided are a polarizing plate and an optical display device comprising same, wherein the polarizing plate comprises: a polarizer; and a phase retardation layer laminated on a lower surface of the polarizer, the phase retardation layer including a negative C layer, a negative A layer, and a positive A layer, which are sequentially laminated from the lower surface of the polarizer, wherein the negative C layer has a thickness-dependent phase retardation of 20 nm to 60 nm at a wavelength of 550 nm.