OLED Mask Corner Chamfers for High-Resolution Color Separation
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Solution Overview
Problem
High-resolution organic light emitting diode displays face challenges in manufacturing due to small pixel sizes, leading to deteriorated mask manufacturing yield and light color mixing issues as the edge of the organic emission layer intrudes into adjacent pixels.
Innovation Solution
The design incorporates a pixel defining layer with polygonal openings and chamfers or convex portions for the organic emission layers, allowing for distinct light emission colors and improved mask pattern formation, preventing color mixing and enhancing manufacturing yield by using mask units with corresponding pattern portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high resolution is implemented in a limited display area, then display quality is improved, but mask manufacturing yield deteriorates due to small pixel sizes making pattern formation difficult
Solution Approach 1:
The pixel defining layer openings are segmented into non-square polygonal shapes (rectangular, triangular, or trapezoidal) with specific aspect ratios. This segmentation allows the mask patterns to be divided into manageable geometric forms that are easier to manufacture while still achieving high resolution display requirements.
Solution Approach 2:
The invention introduces asymmetric chamfers at the corners of the polygonal openings instead of symmetric square corners. These chamfers create asymmetric pattern portions in the mask that improve manufacturability by reducing the difficulty of forming sharp small-angle corners, thereby improving mask manufacturing yield while maintaining high resolution.
2Measurement precision
If pixel size is reduced for high resolution, then display area density is improved, but light color mixing occurs as emission layer edges intrude into adjacent pixels
Solution Approach 1:
The invention applies different geometric characteristics to different parts of the pixel structure. Specifically, chamfers are applied only at the corner regions of the polygonal openings where color mixing is most likely to occur, while the central regions maintain their original dimensions. This local modification prevents color mixing at critical boundaries without affecting the overall pixel area and luminance.
Solution Approach 2:
The chamfered corners create a preliminary geometric barrier that prevents the organic emission layer from intruding into adjacent pixel regions. By modifying the corner geometry in advance during the mask fabrication process, the invention proactively prevents color mixing before it can occur during organic layer deposition.
3Ease of manufacture
If square pixel openings are used, then manufacturing simplicity is maintained, but mask pattern formation becomes difficult due to small corner angles in high resolution displays
Solution Approach 1:
The invention replaces the sharp 90-degree corners of square openings with chamfered edges, creating a transition from angular to slightly rounded geometry. This curvature modification at the corners eliminates the manufacturing difficulty associated with forming very small acute angles in high-resolution masks, while still maintaining a relatively simple polygonal overall structure.
Solution Approach 2:
Instead of trying to manufacture perfect square corners at high resolution which is difficult, the invention inverts the approach by using polygonal shapes with chamfered corners that are easier to manufacture. The design prioritizes manufacturability of the mask pattern over the simplicity of the opening shape definition.
Data Source
AI summary
An organic light emitting diode display including a first electrode, a pixel defining layer positioned on the first electrode and including a first opening having a first polygonal shape opening the first electrode, and a first organic emission layer positioned on the pixel defining layer through the first electrode corresponding to the first opening and including a first chamfer adjacent to a corner of the first opening.