Micro Pattern Film for OLED Color Shift and Brightness
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Solution Overview
Problem
Organic light-emitting displays face issues with low light efficiency due to refractive index differences causing light to be directed unnecessarily, resulting in reduced brightness and increased color shift, and high reflectivity from the anode material decreases visibility in external light conditions.
Innovation Solution
An optical filter with a micro pattern film having non-circular engraved shapes with a depth greater than width is applied to the organic light-emitting panel, combined with a circular polarizer film to minimize color shift and increase brightness by redirecting sideward light and blocking external light, thereby enhancing visibility and contrast ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a micro cavity structure is used to increase brightness and improve color purity, then light intensity and color reproducibility are improved, but color viewing angle is limited due to color shift
Solution Approach 1:
The patent introduces a micro pattern film with multiple micro patterns (such as microlenses or reflective structures) that segment and redirect light from different angles. Each micro pattern acts as an independent light redirecting element, collectively improving color viewing angle while maintaining the micro cavity structure's brightness enhancement
Solution Approach 2:
The patent employs asymmetric micro pattern designs that are optimized for specific viewing angles. The asymmetric structures redirect light preferentially in directions that compensate for the color shift caused by the micro cavity structure, thereby expanding the effective color viewing angle without sacrificing brightness
2Productivity
If a high-reflectivity anode material is used to send emitted light toward the front, then light extraction efficiency is improved, but visibility decreases in external light conditions due to very high reflectivity
Solution Approach 1:
The patent modifies the optical parameters of the anode or adjacent layers by introducing micro patterns that change the reflectivity characteristics. The micro patterns create angle-dependent reflectivity, maintaining high front-directional extraction while reducing reflectivity in other directions, thereby improving visibility in external light conditions
Solution Approach 2:
The patent introduces a micro pattern film as an intermediary layer between the high-reflectivity anode and the external environment. This intermediary structure mediates the light interaction by redirecting front-emitted light while allowing external light to pass through more effectively, thus maintaining extraction efficiency while improving visibility
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 color shift, increases brightness, and improves visibility by redirecting sideward light while maintaining central light extraction, and reduces reflectivity to enhance the bright-room contrast ratio.
Implementation Method 1
The light efficiency of the organic light-emitting display is determined by the refractive indices of individual component layers
Implementation Method 2
when incident on the interface between the substrate and the air at an angle greater than a critical angle, totally reflects from the interface
Implementation Method 3
combined with a circular polarizer film to minimize color shift and increase brightness by redirecting sideward light and blocking external light
Implementation Method 4
When a voltage is applied between the anode and the cathode, holes are injected from the anode into the organic light-emitting layer, and electrons are injected from the cathode into the organic light-emitting layer. Holes and electrons that are injected into the organic light-emitting layer recombine with each other in the organic light-emitting layer, thereby generating excitons. When such excitons transit from the excited state to the ground state, light is emitted.
Data Source
AI summary
An optical filter which minimizes color shift, increases brightness and improves visibility and an organic light-emitting display having the same. The optical filter includes a micro pattern film disposed on an organic light-emitting panel. The micro pattern film includes a base material and a micro pattern engraved from the surface of the base material that adjoins the organic light-emitting panel. The micro pattern has a plurality of engraved shapes with a non-circular cross-section which has a depth greater than a width.