Organic Light Emitting Display Pixel Layout Asymmetry
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Solution Overview
Problem
Existing organic light emitting displays face challenges in extending the life span due to limitations in sub pixel region fabrication, leading to high manufacturing costs and potential misalignment issues with multiple masks required for different colors, which deteriorate resolution and increase costs.
Innovation Solution
The solution involves altering the pixel layout by increasing the area of sub pixel regions with lower luminous efficiency, such as the blue sub pixel, and forming an electron blocking layer over the entire surface between sub pixel emission layers, reducing the number of masks needed for emission layer formation and improving luminous efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different sub pixels are patterned using different masks for each color, then the display can achieve full color capability, but misalignment occurs and resolution deteriorates
Solution Approach 1:
The patent merges the patterning process for multiple colors into a single mask step. By designing the emission layer pattern to inherently define all sub-pixel regions (R, G, B) in one go, the patent eliminates the need for separate masks for each color, thereby preventing misalignment and maintaining high resolution while still achieving full color display capability.
Solution Approach 2:
The emission layer is segmented into different material regions (first, second, and third materials) within a single patterned structure. This segmentation allows different colors to be formed from a single patterned layer, eliminating the need for multiple masks while maintaining precise alignment and resolution.
2Adaptability or versatility
If multiple masks are used for forming different color sub pixels, then full color display is achieved, but manufacturing cost increases
Solution Approach 1:
The patent combines multiple patterning operations into a single mask step. By designing the emission layer pattern to simultaneously define all sub-pixel regions, the patent reduces the number of masks required, thereby lowering manufacturing costs while maintaining full color display capability.
3Ease of manufacture
If sub pixel regions are formed with equal areas, then fabrication is simplified, but life span is limited due to low luminous efficiency of certain colors
Solution Approach 1:
The patent introduces asymmetry in the area distribution of sub-pixel regions. By making the first sub-pixel region (with lower luminous efficiency) larger than the second and third sub-pixel regions, the patent compensates for the lower efficiency of certain colors, thereby extending the overall display life span while maintaining a relatively simple fabrication process.
4Duration of action of stationary object
If the area of sub pixel regions with lower luminous efficiency is increased, then life span is improved, but the pixel layout becomes more complex
Solution Approach 1:
The patent applies asymmetry by increasing the area of the first sub-pixel region compared to the second and third sub-pixel regions. This asymmetric layout compensates for the lower luminous efficiency of the first region, extending display life span. The complexity is managed by integrating this area variation into a single patterned emission layer, avoiding the need for additional structural elements.
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 approach enhances the life span and resolution of organic light emitting displays by improving the luminous efficiency of the blue sub pixel to match that of red and green sub pixels, reducing manufacturing costs, and minimizing misalignment issues, resulting in a more stable and efficient display.
Implementation Method 1
an organic emission layer disposed between the anode electrode and the cathode electrode for emitting light by means of a combination of electrons and holes
Implementation Method 2
an organic light emitting device having an electron blocking layer to confine electrons to specific regions of the device
Data Source
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Figure 3
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AI summary
In an organic light emitting display and a method for fabricating the same, a layout of respective pixels is changed in order to improve life span so that one pixel region having low luminous efficiency is increased. The organic light emitting display includes at least one pixel comprising sub pixels having a plurality of colors. A first sub pixel emission layer is formed over an entire surface of a pixel region. At least two second sub pixel emission layers are formed at the first sub pixel emission layer so as to have a closed curve. The layout of respective pixels is changed so as to increase an area of one sub pixel region having low luminous efficiency in order to improve the life span and aperture ratio of the organic light emitting display. In addition, during formation of an emission layer, the number of masks is reduced. Accordingly, the possibility of misalignment is reduced, thereby maximizing resolution, improving yield, and reducing manufacturing cost.