OLED Convex Bank Structure for Precise RGB Vapor Deposition
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Solution Overview
Problem
The existing RGB separate coating method for organic EL display devices faces issues with vapor deposition position accuracy and display defects due to foreign matter on the vapor deposition mask, which can damage the light emitting layer and lead to pixel defects.
Innovation Solution
The introduction of convex portions on the bank between pixel apertures, where the first convex portion is covered by the organic material layer for one color and not covered for others, allows for precise vapor deposition by adjusting the distance between the substrate and the vapor deposition mask, reducing the risk of defects and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the distance between the substrate and the vapor deposition mask is increased to prevent foreign matter damage, then the reliability is improved, but the manufacturing precision deteriorates
Solution Approach 1:
The invention introduces convex portions that protrude in the thickness direction from the bank surface, creating a three-dimensional structure. These convex portions serve as spacers that maintain a controlled distance between the vapor deposition mask and substrate, resolving the contradiction by using vertical dimensionality to control horizontal deposition precision while preventing foreign matter damage.
Solution Approach 2:
The convex portions are selectively formed only in specific regions between pixel apertures, not across the entire substrate. This localized approach provides spacing functionality exactly where needed for vapor deposition mask positioning, while maintaining close contact in other areas to ensure deposition precision.
2Manufacturing precision
If the distance between the substrate and the vapor deposition mask is decreased to improve vapor deposition position accuracy, then the manufacturing precision is improved, but the reliability deteriorates due to foreign matter damage
Solution Approach 1:
The convex portions are formed in advance on the bank surface before vapor deposition occurs. These pre-formed structures act as protective spacers that cushion the substrate from foreign matter on the vapor deposition mask, allowing the mask to be positioned closely without risking damage to the light emitting layer.
Solution Approach 2:
The convex portions serve as intermediary structures between the substrate and the vapor deposition mask. They mediate the interaction by maintaining an optimal gap distance, enabling both close proximity for precision and sufficient separation for protection against foreign matter.
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 vapor deposition position accuracy and reduces the likelihood of display defects by minimizing the distance between the substrate and the vapor deposition mask, while also preventing foreign matter from damaging the already deposited layers.
Implementation Method 1
a light emitting layer is vapor-deposited on an opening thereof
Data Source
AI summary
In a display device in which an OLED is formed by a separate coating method, improving the accuracy of vapor deposition position and reducing display defects are established. In the array substrate, a display unit that displays an image configured with a plurality of pixels is formed. A first convex portion and a second convex portion are provided on a surface of a boundary region between the pixels of the array substrate. A first organic layer including a layer exhibiting a first emission color is stacked on the pixel electrode of the pixel, and second organic layers including a layer exhibiting a second emission color are stacked on the pixel electrode of the pixels. The first organic layer is provided to cover only the first convex portion. The second organic layers are provided not to cover any one of the first convex portion and the second convex portion.