Dual-Emission Subpixel Layout for Uniform OLED Light Extraction
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Solution Overview
Problem
Light emitting display apparatuses face reduced light extraction efficiency due to total reflection at interfaces, leading to decreased luminance and color temperature, particularly when fine structures like microlens or uneven patterns are applied, causing inefficiencies in wavelength-specific luminance increases.
Innovation Solution
A light emitting display apparatus with a substrate featuring subpixel areas having distinct light emission and non-emission portions, where the light emission portions have different light extraction structures, including an uneven pattern portion with convex and concave features to enhance light extraction efficiency and maintain color temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a white opening is added to a unit pixel having red, green and blue openings to improve luminance and color temperature, then luminance and color temperature are improved, but efficiency in the red and green openings is reduced
Solution Approach 1:
The white opening is divided into two separate light emission portions (first and second light emission portions) with different light extraction structures. This segmentation allows each portion to be optimized for different wavelength ranges, thereby improving overall luminance and color temperature while maintaining efficiency in red and green openings.
Solution Approach 2:
Different light extraction structures are applied to different portions of the white opening. The first light emission portion has a first light extraction structure optimized for certain wavelengths, while the second light emission portion has a second light extraction structure optimized for other wavelengths. This local differentiation resolves the trade-off by ensuring that each region contributes efficiently to the overall performance.
2Loss of energy
If a fine structure such as a microlens or uneven pattern is applied to an opening to improve light extraction efficiency, then light extraction efficiency is improved, but a difference in luminance increase rate between wavelength ranges occurs
Solution Approach 1:
Different light extraction structures are applied to different light emission portions within the white opening. The first light extraction structure is optimized for extracting light in certain wavelength ranges, while the second light extraction structure is optimized for other wavelength ranges. This local differentiation ensures uniform luminance increase across all wavelengths while maintaining high light extraction efficiency.
Solution Approach 2:
The light extraction structures are designed with different parameters (such as different patterns, depths, or materials) to optimize light extraction for different wavelength ranges. By varying the structural parameters across different portions, the patent achieves both high extraction efficiency and uniform luminance increase across the spectrum.
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
Improves luminance and color temperature by optimizing light extraction efficiency across different wavelengths, reducing the trade-off between pure color and white luminance, and extending the lifespan of light emitting devices by dispersing driving stress.
Implementation Method 1
Some of the light emitted from a light emitting device is not emitted to the outside due to the total reflection on an interface between the light emitting device and an electrode and/or an interface between a substrate and an air layer
Data Source
AI summary
A light emitting display apparatus includes a substrate including a subpixel area having a non-light emission portion, a first light emission portion and a second light emission portion; a driving transistor disposed in the non-light emission portion; an overcoat layer disposed on the substrate to overlay the driving transistor; first and second anode electrodes disposed to be spaced apart from each other on the overcoat layer of each of the first light emission portion and the second light emission portion and commonly connected to the driving transistor; a self-light emitting device on the first anode electrode and the second anode electrode; and a second electrode on the self-light emitting device. The first light emission portion and the second light emission portion can have light extraction structures different from each other.