OLED Display Panel White Sub-pixel Mask Aperture Optimization
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Solution Overview
Problem
The low aperture ratio of Fine Metal Mask (FMM) in OLED display panel fabrication leads to blocked apertures and line defects, resulting in poor quality OLED displays due to the need for multiple evaporation processes and limited resolution.
Innovation Solution
The OLED display panel employs a light-emitting layer with white sub-pixels sized equal to the sum of two color sub-pixels, allowing for a larger mask aperture and reducing the risk of blockages, and uses a mask evaporation process that requires fewer iterations, improving productivity and reducing color mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the aperture ratio of FMM MASK is reduced to improve resolution, then the resolution of OLED display panel is improved, but the aperture is easily blocked during evaporation process leading to line defects
Solution Approach 1:
The patent segments the light-emitting layer fabrication into two distinct parts: color sub-pixels (R, G, B) evaporated through FMM MASK and white sub-pixels evaporated through a separate mask with larger aperture. This segmentation allows each part to use an aperture size appropriate for its function, resolving the contradiction between resolution and aperture blockage resistance.
Solution Approach 2:
The patent introduces a new dimension to the pixel structure by adding white sub-pixels alongside color sub-pixels. This dimensional change in pixel composition enables the use of different aperture sizes for different pixel types, allowing large apertures for white sub-pixels without compromising the resolution achieved by precise color sub-pixel placement.
2Measurement precision
If the aperture ratio of FMM MASK is reduced to improve resolution, then the resolution of OLED display panel is improved, but color mixing occurs on the display panel
Solution Approach 1:
The patent segments the evaporation process into two separate operations: first evaporating color sub-pixels through FMM MASK with small aperture for precise placement, then evaporating white sub-pixels through a different mask. This segmentation prevents color mixing by ensuring color materials are deposited only in their designated small aperture regions before the white sub-pixel layer is added.
Solution Approach 2:
The patent performs preliminary action by first completing the color sub-pixel evaporation through FMM MASK with precise small apertures, establishing the color pattern before introducing white sub-pixels. This preliminary placement of color materials prevents subsequent color mixing while maintaining high resolution.
3Manufacturing precision
If FMM MASK evaporation process is performed three times for R, G and B respectively, then the color accuracy is improved, but the productivity is reduced due to multiple processes
Solution Approach 1:
The patent merges the white sub-pixel evaporation process with the color sub-pixel evaporation process by using two masks simultaneously or in sequence, rather than requiring three separate evaporation processes for R, G, and B. This merging reduces the total number of evaporation steps while maintaining color accuracy through the precise FMM MASK for color sub-pixels.
Solution Approach 2:
The patent applies multi-functionality to the mask system by designing masks that handle both color sub-pixel patterning and white sub-pixel patterning in a unified process flow. The FMM MASK serves the universal function of precise patterning for color sub-pixels, while the white sub-pixel mask complements it, together achieving both color accuracy and improved productivity.
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 approach enhances the quality of OLED displays by minimizing line defects and color mixing while increasing production efficiency and economic benefits by reducing the risk of mask misalignment and aperture blockages.
Implementation Method 1
it requires the use of Fine Metal Mask (hereinafter referred to FMM MASK) evaporation process three times to evaporate R, G and B respectively
Data Source
Figure 1a~1c
Figure 1d~2c
Figure 2d~2f
AI summary
The present invention provides an OLED display panel and a method for fabricating the same and an OLED display apparatus. The OLED display panel includes a light-emitting layer, the light-emitting layer comprises white sub-pixels and color sub-pixels, the size of the white sub-pixel is equal to the sum of size of at least two of the color sub-pixels, and the number of the color sub-pixels is less than the number of color-forming primary colors; the OLED display panel further comprises a color film, the color film comprising color blocks matching the color sub-pixels, the color blocks being disposed on a side of the light-emitting layer toward the display side and at positions corresponding to the positions where the white sub-pixels are located. The OLED display apparatus according to the present invention not only can improve the quality of the OLED display panel and display apparatus, but also may even reduce a mask evaporation process once, improve production efficiency, and thus improve economic benefits.