OLED Pixel Structure with Staggered Sub-pixel Groups for High PPI
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Solution Overview
Problem
The traditional RGB pixel structure in OLED displays faces challenges in achieving high Pixel Per Inch (PPI) due to limitations in the Fine Metal Mask (FMM) process, making it difficult to produce high PPI displays effectively.
Innovation Solution
A pixel structure comprising adjacent pixel groups with misaligned sub-groups of three different colors each, where each sub-group consists of four identical sub-pixels, arranged in a staggered manner to optimize the evaporation process and increase PPI, along with a mask design that includes staggered evaporation openings to facilitate the production of small-sized sub-pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a traditional side-by-side RGB pixel structure is used, then the manufacturing process is simple, but the PPI cannot exceed 300 PPI due to FMM opening limitations
Solution Approach 1:
The pixel structure is divided into multiple pixel groups, each containing first and second pixel sub-groups with different color arrangements. This segmentation allows the mask to have corresponding sub-groups of evaporation openings that can be staggered, enabling higher PPI by reducing the minimum opening size requirement while maintaining manufacturability.
Solution Approach 2:
The patent introduces asymmetric arrangements where the first pixel sub-group and second pixel sub-group have different color compositions (e.g., different ratios of red, green, blue sub-pixels). The mask accordingly has asymmetric evaporation opening arrangements, allowing optimization of the evaporation process for high PPI displays while compensating for the complexity through systematic design.
2Manufacturing precision
If the FMM opening size is reduced to achieve higher PPI, then the PPI increases, but the manufacturing precision and evaporation process control become more difficult
Solution Approach 1:
The patent transitions from a single-row evaporation opening arrangement to a multi-dimensional staggered arrangement across multiple pixel groups. By distributing evaporation openings across first and second pixel sub-groups with different color compositions, the mask can maintain larger effective opening sizes while achieving higher PPI through the staggered geometric arrangement, thus easing manufacturing requirements.
3Manufacturing precision
If sub-pixels are made smaller to increase PPI, then the PPI improves, but the display uniformity and color consistency become harder to maintain
Solution Approach 1:
The patent applies local quality by creating different color compositions in different pixel groups. Specifically, the first pixel sub-group and second pixel sub-group have different ratios of red, green, and blue sub-pixels. This local variation in color quality, when combined with the staggered arrangement, ensures that each local region contributes appropriately to the overall color balance, maintaining display uniformity even as sub-pixel size decreases for higher PPI.
Data Source
AI summary
The present disclosure provides a pixel structure, a mask and a display device. The pixel structure includes a number of pixel groups arranged in an array. Each of the pixel groups includes a first pixel sub-group and a second pixel sub-group disposed adjacent to each other in a first direction and misaligned with each other in a second direction perpendicular to the first direction. The first pixel sub-group and the second pixel sub-group include sub-pixel groups of three different colors including a first sub-pixel group, a second sub-pixel group, and a third sub-pixel group. Each sub-pixel group includes four sub-pixels of a same color, and the sub-pixel groups of a same color are alternately arranged in a regular manner.