OLED Pixel Layout for Wider Mask Alignment Process Margin
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Solution Overview
Problem
Existing OLED display devices face challenges in securing a satisfactory process margin during pixel patterning due to alignment deviations in vapor deposition masks, which unnecessarily narrow the light-emitting region in each pixel.
Innovation Solution
The display device is designed with a substrate configuration where the shortest width between certain contact surfaces in one direction is smaller than in orthogonal directions, and the pixel arrangement includes specific placements of light-emitting elements to accommodate larger alignment deviations in orthogonal directions, using edge cover layers to define openings for vapor deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional pixel configuration with symmetric arrangement of light-emitting elements is used, then the process margin is widened, but the area of the light-emitting region in one pixel is unnecessarily narrowed
Solution Approach 1:
The patent applies asymmetry by configuring the pixel structure with different spacing relationships in different directions. Specifically, the light-emitting elements are arranged such that the distance between adjacent light-emitting elements in the first direction is different from the distance in the second direction orthogonal to the first direction. This asymmetric arrangement compensates for the larger alignment deviation in the stretching direction of the vapor deposition mask, thereby widening the process margin without unnecessarily reducing the light-emitting region area.
Solution Approach 2:
The patent applies local quality by creating non-uniform spacing between light-emitting elements based on their specific positions and the mask alignment characteristics. The spacing is optimized locally in different regions and directions to account for the directional alignment deviations, rather than using a uniform symmetric arrangement throughout the pixel array.
2Device complexity
If the alignment deviation of vapor deposition openings in the direction orthogonal to the stretching direction is not considered, then the pixel configuration can be simplified, but the process margin is insufficient
Solution Approach 1:
The patent applies preliminary action by pre-configuring the pixel structure with asymmetric spacing that anticipates and compensates for the known alignment deviations of the vapor deposition mask. The spacing between light-emitting elements is designed in advance to account for the larger deviations in the direction orthogonal to the stretching direction, thereby ensuring adequate process margin before the actual deposition process occurs.
3Manufacturing precision
If the shortest width between contact surfaces in the first direction is increased to accommodate alignment deviations, then the process margin is improved, but the light-emitting region area is reduced
Solution Approach 1:
The patent resolves this contradiction by implementing asymmetric spacing where the shortest width between contact surfaces in the first direction is optimized differently from the spacing in the second direction. This allows the design to accommodate alignment deviations in the direction orthogonal to stretching without uniformly increasing spacing in all directions, thereby preserving light-emitting region area while maintaining adequate process margin.
Data Source
AI summary
A display device includes a substrate, a first light-emitting element, a second light-emitting element, and a third light-emitting element on the substrate, and a shortest width along a first direction between a first contact surface where a first electrode of the first light-emitting element and a function layer of the first light-emitting element contact with each other and a second contact surface where a first electrode of the second light-emitting element and a function layer of the second light-emitting element contact with each other is smaller than a shortest width along a second direction orthogonal to the first direction between a third contact surface where a first electrode of the third light-emitting element and a function layer of the third light-emitting layer contact with each other and at least one of the first contact surface and the second contact surface.