Semi-Transmissive Metal Grid Polarizer for OLED Contrast
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Solution Overview
Problem
Portable organic light emitting display apparatuses face challenges in maintaining contrast and visibility due to external light reflection, particularly from metal reflection films, which limits their performance in outdoor use.
Innovation Solution
A polarizer is designed with a base and grids comprising semi-transmissive metal layers and intermediate layers that generate destructive interference, improving contrast by reducing external light reflection. The polarizer is integrated into an organic light emitting display apparatus, which includes a quarter wave layer and a linear polarization layer to minimize external light impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a metal reflection film is used in the organic light emitting display apparatus, then the brightness and visibility are improved, but the external light reflection increases causing severe contrast deterioration
Solution Approach 1:
The patent uses a composite structure consisting of multiple metal layers (first metal layer and second metal layer) with different reflectances, combined with an intermediate layer. This composite material approach allows the system to maintain high brightness while reducing external light reflection through destructive interference between reflections from different metal layers.
Solution Approach 2:
The patent applies different properties to different parts of the reflection film structure. The first metal layer has high reflectance for brightness, while the second metal layer has low reflectance for reducing external light reflection. The intermediate layer with specific optical properties is positioned locally between them to enable destructive interference, creating local quality differentiation to resolve the contradiction.
2Device complexity
If a circularly polarized panel with a metal wire grid is used to address reflection, then the panel structure is simplified, but the contrast improvement is limited due to metal reflection
Solution Approach 1:
The patent replaces the simple metal wire grid with a composite multi-layer structure consisting of alternating high-reflectance and low-reflectance metal layers separated by intermediate layers. This composite structure maintains the polarizing function while significantly reducing external light reflection through destructive interference, thereby improving contrast without substantially increasing device complexity.
Solution Approach 2:
The patent converts the harmful effect of metal reflection into a beneficial effect by using destructive interference. The reflections from the first metal layer and second metal layer are designed to interfere destructively, converting what would be harmful reflected light into reduced overall reflection, thereby improving contrast while maintaining the metal-based polarizer structure.
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 enhances the contrast and visibility of organic light emitting display apparatuses by reducing external light reflection, thereby improving their performance in bright environments.
Implementation Method 1
at least two semi-transmissive metal layers that each reflects a part of external light incident thereon and each transmits a part of the external light incident thereon
Implementation Method 2
the semi-transmissive metal layers and the intermediate layer are formed to generate destructive interference within the external light reflected by the grids
Data Source
AI summary
A polarizer includes a base and a plurality of grids arranged on a surface of the base parallel to one another. Each of the grids comprises an intermediate layer and a semi-transmissive metal layer that reflects a part of external light incident thereon and transmits a part of the external light incident thereon. The semi-transmissive metal layer and the intermediate layer are alternately deposited to include at least two semi-transmissive metal layers. The thicknesses of the semi-transmissive metal layers increases in a direction in which the semi-transmissive metal layer is disposed away from the external light. An organic light emitting display apparatus includes the polarizer and has improved contrast and brightness.