OLED Substrate Pixel Layout for Evaporation Tolerance
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Solution Overview
Problem
The challenge in producing high-resolution OLED displays lies in the non-uniformity and color casting issues due to overlapping emission layers during the evaporating process, which is exacerbated by the limitations of the evaporating process's tolerance design.
Innovation Solution
The solution involves a display substrate structure with a base plate and a display structure that includes sub-pixels arranged in a specific pattern, where third sub-pixels with longer light emitting regions surround the first and second sub-pixels, compensating for non-equidistance errors and reducing color mixing by adjusting the evaporating process's precision requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the evaporating process uses a fine metal mask for coating individual colors of light emitting films, then the display structure can be formed, but different colors of emission layers may overlap causing non-uniform display performance and color casting due to process tolerance limitations
Solution Approach 1:
The patent applies local quality by creating different sub-pixel configurations in different regions of the display. Specifically, corner regions contain three sub-pixels of the same color (e.g., three red sub-pixels), while central regions contain sub-pixels of different colors. This local variation compensates for alignment errors in the evaporating process, as the overlapping regions in corners with identical colors do not produce color casting issues, thereby maintaining display performance uniformity despite process tolerances
Solution Approach 2:
The patent changes the parameter of sub-pixel arrangement configuration based on position. By adjusting which colors are placed in corner regions versus central regions, and by varying the number of sub-pixels per color in different locations, the design accommodates evaporating process tolerance. This parameter change allows the display to maintain uniform performance despite variations in emission layer alignment during manufacturing
2Measurement precision
If the image resolution of the OLED display is increased, then higher display quality is achieved, but the evaporating process tolerance design becomes more critical and difficult to control
Solution Approach 1:
The patent implements local quality by designing corner regions with three sub-pixels of the same color, which are less sensitive to alignment precision requirements. This local configuration allows higher overall image resolution to be achieved while the corner regions provide a buffer against evaporating process tolerance issues, as identical-color overlaps do not create visible defects
Solution Approach 2:
The patent applies beforehand cushioning by pre-positioning sub-pixels in corner regions such that even if evaporating process alignment deviates within tolerance ranges, the resulting overlaps occur in regions where identical colors meet. This prior arrangement cushions against potential display defects, allowing higher resolution designs to be manufactured with standard process tolerances
Data Source
AI summary
A display substrate and a display device applying the same are provided. The display substrate includes a base plate and a display structure. The display structure is disposed on the base plate and includes first region. The first region includes a first sub-pixel, a second sub-pixel and two third sub-pixels. One of the two third sub-pixels has a first light emitting region having a first end point and a second end point. The other one of the two third sub-pixels has a second light emitting region having a third end point and a fourth end point. The first sub-pixel has a third light emitting region and the second sub-pixel has a fourth light emitting region. The third light emitting region and the fourth light emitting region are inside a quadrilateral region enclosed by the first, second, third and fourth end points.