Polarizing Plate Retardation Layers for Display Reflectivity
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Solution Overview
Problem
Organic light emitting diode displays face deterioration in visibility and contrast due to external light reflection, with existing polarizing plates struggling to improve black visibility at the front side while reducing lateral reflectivity, leading to compromised screen quality.
Innovation Solution
A polarizing plate is designed with a specific configuration of a polarizer, a first retardation layer, and a second retardation layer, where the first retardation layer has an in-plane retardation of 200-250 nm and the second layer has an in-plane retardation of 80-140 nm, both stacked on the polarizer, along with a total transmittance difference between 450 nm and 420 nm, to achieve low reflectivity at both the front and lateral sides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a polarizing plate is designed to reduce lateral reflectivity to improve reflection visibility, then lateral reflectivity is reduced, but black visibility at the front side deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the in-plane retardation values of two retardation layers (first layer: 200-250 nm, second layer: 80-140 nm at 550 nm wavelength) and the total transmittance difference between 450 nm and 420 nm (2% or more). These parameter adjustments enable simultaneous reduction of lateral reflectivity and maintenance of front-side black visibility, resolving the technical contradiction between lateral reflectivity reduction and black visibility preservation.
Solution Approach 2:
The patent employs composite materials by combining a polarizer with two distinct retardation layers having different retardation characteristics. This composite structure allows the polarizing plate to achieve both low lateral reflectivity and good black visibility, as the combined optical effects of the multiple layers address both contradictory requirements that cannot be satisfied by a single material layer.
2Illumination intensity
If color values of the polarizing plate are controlled to improve black visibility, then black visibility improves, but there is a limit to further improvement
Solution Approach 1:
The patent overcomes the limitation of color value control by introducing additional optical parameters - specifically the in-plane retardation of two separate layers and the total transmittance difference between wavelengths. By changing from single-parameter color control to multi-parameter optical property control, the patent achieves superior black visibility that cannot be obtained through color value adjustment alone.
3Object-affected harmful factors
If a polarizing plate structure is designed to achieve low reflectivity at both front and lateral sides, then reflectivity is reduced, but structural complexity increases
Solution Approach 1:
The patent uses a composite structure of a polarizer combined with two retardation layers to achieve low reflectivity at both front and lateral sides. This composite material approach provides the optical performance benefits while maintaining a relatively compact and integrated structure that does not excessively increase device complexity.
Solution Approach 2:
The patent applies segmentation by dividing the retardation function into two separate layers with different retardation values, rather than using a single complex layer. This segmentation allows each layer to contribute differently to the overall optical performance, achieving low reflectivity at multiple viewing angles while keeping the overall structure manageable through functional division.
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 significantly improves black visibility and screen quality by maintaining low reflectivity at the front and lateral sides, ensuring the display appears black and reducing reflectivity, as demonstrated by the specified reflective color values and transmittance ranges.
Implementation Method 1
the first retardation layer has an in-plane retardation (Re) of 200 nm to 250 nm at a wavelength of 550 nm; the second retardation layer has an in-plane retardation (Re) of 80 nm to 140 nm at a wavelength of 550 nm
Implementation Method 2
a polarizing plate including a polarizer and a retardation film may be utilized. The polarizing plate can realize (e.g., provide) an antireflection function by preventing or substantially preventing reflected external light from leaking out
Data Source
AI summary
A polarizing plate and an optical display apparatus including the same are provided. The polarizing plate includes: a polarizer; and a first retardation layer and a second retardation layer sequentially stacked on a lower surface of the polarizer. The first retardation layer has an in-plane retardation (Re) of 200 nm to 250 nm at a wavelength of 550 nm; the second retardation layer has an in-plane retardation (Re) of 80 nm to 140 nm at a wavelength of 550 nm; and the polarizing plate has a total transmittance difference of 2% or more between total transmittance at a wavelength of 450 nm and total transmittance at a wavelength of 420 nm.