OLED Circular Polarizer Tuning for Stable Oblique White Tint
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Solution Overview
Problem
Existing organic electroluminescent display devices exhibit significant changes in oblique tint (white) at different azimuthal angles due to varying transmission rates of P-polarized and S-polarized light, which is not adequately addressed by combining a circular polarization plate and an organic electroluminescent display element.
Innovation Solution
The device incorporates a circular polarization plate with an optically anisotropic layer and a polarizer, where the ratio of P-polarized light to S-polarized light brightness and the in-plane retardation ratio are optimized to satisfy specific requirements, reducing the variation in tint across azimuthal angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a circular polarization plate is combined with an organic electroluminescent display element, then reflection of external light is suppressed, but significant changes in oblique tint (white) occur at different azimuthal angles
Solution Approach 1:
The patent applies parameter changes by optimizing the in-plane retardation values of the optically anisotropic layer at different wavelengths. Specifically, the in-plane retardation at 600nm is set to 100-200nm and at 440nm to 50-100nm, creating a specific ratio relationship that compensates for the azimuthal angle dependence and maintains consistent oblique tint across different viewing angles while preserving the circular polarization function
Solution Approach 2:
The patent uses composite materials by combining the optically anisotropic layer with specific wavelength-dependent retardation properties with the circular polarization plate structure. This composite approach creates a system where the optically anisotropic layer's wavelength-selective phase retardation works synergistically with the circular polarization elements to suppress external light reflection while stabilizing the oblique tint characteristics
2Stability of the object's composition
If the transmission rates of P-polarized and S-polarized light are optimized, then oblique tint consistency is improved, but device complexity increases due to multiple optical layers
Solution Approach 1:
The patent applies universality by designing the optically anisotropic layer to perform multiple functions simultaneously: it provides wavelength-dependent phase retardation to control oblique tint consistency while also integrating with the circular polarization plate to suppress external light reflection. This multi-functional design reduces the need for separate compensation layers, thereby managing device complexity
Solution Approach 2:
The patent applies local quality by implementing the optically anisotropic layer with specific localized optical properties at different wavelength ranges. The layer exhibits different retardation characteristics at 600nm versus 440nm, creating locally optimized optical performance that addresses the oblique tint issue at specific wavelengths while maintaining overall system simplicity
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
This configuration results in a display device with minimized changes in oblique tint (white) at each azimuthal angle, maintaining consistent brightness and reducing reflectivity variations.
Implementation Method 1
the circular polarization plate includes an optically anisotropic layer and a polarizer
Implementation Method 2
a ratio of an in-plane retardation at a wavelength of 600 nm to an in-plane retardation at a wavelength of 440 nm in the optically anisotropic layer
Data Source
AI summary
An organic electroluminescent display device includes a circular polarization plate and an organic electroluminescent display element. The circular polarization plate includes an optically anisotropic layer and a polarizer from an organic electroluminescent display element side. When a ratio of brightness of P-polarized to S-polarized light during white display in a direction in which a polar angle with respect to a normal direction of the display is 60° is determined at each azimuthal angle rotated by 45° with reference to a direction parallel to a transmission axis of the polarizer, an arithmetic mean value of the ratios of the brightness of the P-polarized to the S-polarized light at the azimuthal angles is defined as x and a ratio of in-plane retardation at wavelengths of 600 nm to 440 nm in the optically anisotropic layer is defined as y, x and y satisfy a predetermined relationship.