OLED Polarizing Plate with Pattern Layer for Color Shift Reduction
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Solution Overview
Problem
Existing polarizing plates for OLED displays face challenges in minimizing lateral color shift and undesirable white angular dependence (WAD) due to limitations in light transmittance, diffusibility, and reliability, particularly when viewing angles change.
Innovation Solution
A polarizing plate design incorporating a polarizer, first and second retardation layers, and a pattern layer with engraved patterns, where the pattern layer is filled with a filler of lower refractive index, and optionally includes adhesive, optical, and light spreading layers, to manage light refraction and dispersion effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional polarizing plate structure is used, then the device is simple to manufacture, but lateral color shift and white angular dependence are not minimized
Solution Approach 1:
The polarizing plate is segmented into multiple functional layers including a polarizer layer, first and second retardation layers with different optical properties, and a pattern layer with engraved patterns. Each layer performs a specific optical function to collectively minimize lateral color shift and white angular dependence while maintaining manufacturability through standardized layering processes.
Solution Approach 2:
The invention employs composite material structures where the pattern layer combines resin material with engraved patterns, and the retardation layers use different polymer compositions (e.g., cycloolefin polymer for the first layer, acrylic resin for the second layer). This composite approach enables precise control of optical properties to reduce color shift and angular dependence.
2Illumination intensity
If light transmittance is increased, then brightness is improved, but color shift with viewing angle increases
Solution Approach 1:
Different layers are assigned specific optical properties tailored to their functions: the first retardation layer uses material with positive birefringence for wavelength dispersion control, the second retardation layer uses material with negative birefringence for color compensation, and the pattern layer provides localized light diffusion. This local optimization of material properties maintains color consistency across viewing angles while preserving high light transmittance.
Solution Approach 2:
The invention controls the refractive index difference between the pattern layer and surrounding materials, adjusts the thickness and optical retardation of each layer, and optimizes the engraving pattern geometry. These parameter adjustments enable the system to maintain both high light transmittance and color consistency by fine-tuning the optical path through the layered structure.
3Illumination intensity
If the pattern layer uses high index of refraction material, then light diffusion is improved, but WAD phenomenon increases
Solution Approach 1:
The pattern layer acts as an intermediary element between the retardation layers and the OLED panel. By controlling its refractive index to be higher than the surrounding materials and incorporating engraved patterns, it provides the necessary light diffusion to improve brightness while the surrounding retardation layers compensate for the resulting white angular dependence, achieving a balance between light diffusion and color stability.
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 minimizes lateral color shift, reduces WAD, and enhances light transmittance and diffusibility, while maintaining reliability and process efficiency, even at varying viewing angles.
Implementation Method 1
The pattern layer may have an index of refraction of about 1.46 to about 1.80. Each of the engraved patterns may include a filling section that is filled with a filler, the filler having a lower index of refraction than that of the pattern layer.
Implementation Method 2
a light spreading layer between the base layer and the pattern layer
Implementation Method 3
a first retardation layer on a lower side of the polarizer; a second retardation layer on a lower side of the first retardation layer
Data Source
AI summary
A polarizing plate for an OLED and an OLED display, the polarizing plate including a polarizer; a first retardation layer on a lower side of the polarizer; a second retardation layer on a lower side of the first retardation layer; and a pattern layer on a lower side of the second retardation layer, the pattern layer including a plurality of engraved patterns on a lower side thereof.