Polarizer with Anisotropic Half-Wave Plate for Display Contrast
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Solution Overview
Problem
OLED displays face challenges in representing deep black and maintaining high contrast ratios due to light reflection from external sources, particularly in bright environments, as they lack effective polarizing solutions.
Innovation Solution
A polarizer configuration comprising a linear polarizer, a quarter-wave plate, and a half-wave plate with a refractive index anisotropic layer, where the half-wave plate includes a liquid crystal layer with a discotic compound, is used to prevent external light reflection by converting linearly polarized light to circularly polarized light, ensuring effective phase retardation and polarization axis variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polarizer film is formed to prevent reflection of external light, then the contrast ratio is improved, but the device complexity increases due to multiple layers and materials
Solution Approach 1:
The patent combines multiple functional layers (linear polarizer, quarter-wave plate, half-wave plate with liquid crystal layer) into a single integrated polarizer assembly that works together to prevent external light reflection while maintaining contrast ratio improvement
Solution Approach 2:
The invention uses composite material structures including dichroic dye-impregnated PVA film for linear polarization, stretched cyclic olefin polymer for quarter-wave plate, and liquid crystal compounds in the half-wave plate, creating a multi-material composite system that achieves superior reflection prevention
2Object-affected harmful factors
If multiple wave plates and layers are added to the polarizer, then the reflection prevention is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent employs preliminary alignment actions during manufacturing, including stretching the cyclic olefin polymer film in specific directions before forming the quarter-wave plate, and pre-aligning liquid crystal molecules in the half-wave plate to ensure proper optical axis orientation and reduce alignment errors
Solution Approach 2:
The invention controls manufacturing precision by adjusting physical parameters such as stretching ratios (e.g., 3-6 times in machine direction, 1-3 times in transverse direction), temperature ranges, and thickness specifications (e.g., 5-20 μm for quarter-wave plate) to achieve desired optical properties without excessive precision requirements
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 polarizer effectively reduces external light reflection across various incident angles, enhancing the display's ability to represent black colors and maintaining high contrast ratios, even in bright environments.
Implementation Method 1
a phase retardation layer on the linear polarizer and comprising a quarter-wave plate and a half-wave plate
Implementation Method 2
the refractive index anisotropic layer has a refractive index Nx in a direction of an x axis, a refractive index Ny in a direction of a y axis, and a refractive index Nz in a direction of a z axis
Implementation Method 3
The refractive index anisotropic layer comprises a liquid crystal layer
Implementation Method 4
converting linearly polarized light to circularly polarized light, ensuring effective phase retardation and polarization axis variation
Data Source
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AI summary
A polarizer for a display device is disclosed. In one aspect, the polarizer includes a linear polarizer and a phase retardation layer on the linear polarizer and comprising a quarter-wave plate and a half-wave plate. The half-wave plate includes a refractive index anisotropic layer. The refractive index anisotropic layer has a refractive index Nx defined in a direction of an x axis, a refractive index Ny defined in a direction of a y axis, and a refractive index Nz defined in a direction of a z axis, wherein Nx = Nz > Ny.