OLED Mask Plate Segmentation for High PPI Manufacturing
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Solution Overview
Problem
Current OLED display manufacturing methods using Fine Metal Masks (FMMs) are limited by the thickness of the mask, which restricts the reduction of sub-pixel size and hence the improvement of Pixels Per Inch (PPI), leading to a trade-off between PPI and manufacturing difficulty and cost.
Innovation Solution
A mask design with alternately arranged shielding and opening regions, where the width of the opening region exposes two sub-pixels and the shielding region covers four sub-pixels, allowing for a thinner mask while maintaining or increasing the mask thickness, thereby reducing sub-pixel width and improving PPI without increasing manufacturing difficulty.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the mask thickness is reduced to decrease sub-pixel width and increase PPI, then the sub-pixel size is reduced and PPI is improved, but the manufacturing difficulty and cost increase significantly
Solution Approach 1:
The mask is divided into multiple thickness regions: a first thickness region (thicker) for the shielding portion and a second thickness region (thinner) for the opening portion. This segmentation allows the mask to maintain structural integrity where needed while enabling smaller sub-pixel formation where required, resolving the contradiction between manufacturing difficulty and sub-pixel size reduction.
Solution Approach 2:
Different portions of the mask are given different thickness properties locally. The shielding portion has greater thickness to maintain structural strength and blocking capability, while the opening portion has reduced thickness to enable precise sub-pixel formation. This local differentiation allows the mask to simultaneously achieve manufacturability and high PPI.
2Manufacturing precision
If the mask thickness is reduced to increase PPI, then the image delicacy is improved, but the manufacturing cost increases
Solution Approach 1:
The mask structure is segmented into different thickness zones, allowing the opening portion to be thinner for high PPI while the shielding portion remains thicker for manufacturability. This reduces overall manufacturing complexity and cost compared to making the entire mask uniformly thin.
Solution Approach 2:
The mask exhibits local quality variations in thickness to optimize both PPI and manufacturing cost. The opening region has reduced thickness to enable small sub-pixel formation, while the shielding region maintains sufficient thickness for cost-effective manufacturing, achieving a balance between image delicacy and production cost.
3Manufacturing precision
If the side wall inclined angle is decreased to improve evaporation quality, then the sub-pixel shape accuracy is improved, but the mask thickness must be reduced which increases manufacturing difficulty
Solution Approach 1:
The mask is segmented into different thickness regions that can have optimized side wall angles independently. The opening portion with reduced thickness can achieve the ideal small side wall angle for precise sub-pixel formation, while the shielding portion maintains greater thickness and can have a more practical side wall angle, reducing overall device complexity.
Solution Approach 2:
Different portions of the mask are designed with different side wall inclined angles according to local requirements. The opening portion has a smaller side wall angle to ensure precise sub-pixel shape, while the shielding portion has a larger angle for manufacturing feasibility, resolving the contradiction between shape accuracy and structural complexity.
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 design achieves a significant reduction in sub-pixel width, enhancing PPI and image delicacy while reducing manufacturing difficulty and cost by optimizing the trade-off between mask thickness and sub-pixel width.
Implementation Method 1
pixels of the OLED display device are formed by a vacuum evaporation process with a Fine Metal Mask (FMM)
Data Source
Figure 1
Figure 2
Figure 3(a)~3(c)
AI summary
Embodiments of the disclosure provide a mask, a mask group, a manufacturing method of pixels and a pixel structure. The mask comprises a shielding region (202) and an opening region (201) which are alternately arranged. A width of the opening region (201) is twice of a width of one sub pixel, and a width of the shielding region (202) between two adjacent opening regions (201) is four times of the width of one sub pixel.