OLED Array Substrate Layout for Uniform Inkjet Pixel Film Formation
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Solution Overview
Problem
Inkjet printing for OLED display manufacturing faces challenges in achieving uniform film formation due to uneven ink diffusion in pixel openings with unequal side lengths, leading to uneven pixel brightness and display effects.
Innovation Solution
The array substrate design includes first and second pixel defining portions that jointly define pixel openings with specific size ratios and arrangements, allowing for improved ink diffusion and uniform light emitting layer formation by setting the size ratio of adjacent pixel openings to 0.8 to 1.2, enhancing film formation uniformity and display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pixel openings have unequal side lengths to accommodate electrode layouts, then electrode arrangement flexibility is improved, but ink diffusion uniformity deteriorates
Solution Approach 1:
The patent introduces different types of pixel defining portions (first pixel defining portions and second pixel defining portions) with different heights to create locally varied structures. The first pixel defining portions have a first height and the second pixel defining portions have a second height, allowing different regions to serve different functions: some regions prioritize electrode accommodation while others prioritize uniform ink diffusion
Solution Approach 2:
The patent employs asymmetric pixel defining portions with different heights rather than uniform symmetric structures. This asymmetry allows the pixel openings to have unequal side lengths in plan view while the vertical height variation compensates for the asymmetric diffusion paths, achieving uniform film thickness despite the asymmetric footprint
2Ease of manufacture
If pixel openings are made rectangular with unequal sides to match electrode spacing, then electrode integration is improved, but light emitting layer uniformity deteriorates
Solution Approach 1:
The patent transitions from a two-dimensional uniform opening design to a three-dimensional structure by introducing height variations through different pixel defining portions. The pixel openings maintain their rectangular footprint for electrode matching, but the added vertical dimension with varying heights creates controlled diffusion pathways that ensure uniform ink distribution regardless of the rectangular aspect ratio
3Device complexity
If all pixel defining portions have the same height for simplicity, then manufacturing complexity is reduced, but film formation uniformity deteriorates in rectangular openings
Solution Approach 1:
The patent segments the pixel defining portions into two distinct types with different heights rather than using a single uniform structure. This segmentation allows the system to handle the complexity of uniform film formation in rectangular openings by dividing the defining portions into functional groups: first pixel defining portions for one orientation and second pixel defining portions for the perpendicular orientation, each optimized for their specific diffusion path
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 improves the uniformity of the light emitting layer, leading to better display effects and extended lifetime of the OLED display device by optimizing the diffusion range of luminescent materials between adjacent pixel openings.
Implementation Method 1
optimizing the diffusion range of luminescent materials between adjacent pixel openings
Data Source
AI summary
An array substrate, including: a plurality of first pixel defining portions and a plurality of second pixel defining portions arranged on a base substrate and jointly define a plurality of pixel openings; and a light emitting functional layer arranged on the base substrate and includes a first light emitting portion and a second light emitting portion that emit different colors of light, at least a part of the first light emitting portion and the second light emitting portion is respectively located in a first pixel opening and a second pixel opening. An orthographic projection of a combination of two adjacent pixel openings separated by the second pixel defining portion on a base substrate has a first size in a first direction and a second size in a second direction, and a ratio of the first size to the second size is within a range of 0.8 to 1.2.