Pixel Bank Structure for Ink Distribution in Display Manufacturing
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Solution Overview
Problem
Existing display devices face challenges in improving reliability due to non-ejected areas of ink containing light emitting elements, which can lead to defects.
Innovation Solution
The introduction of a display device with a pixel structure that includes a substrate, sub-light emitting areas, and a peripheral area with a bank and intermediate bank, where the intermediate bank is partially overlapping the electrodes and has a lyophilic side surface, and a liquid-repellent layer on its upper surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional pixel structure with a single bank is used, then the manufacturing process is simple, but ink distribution is poor leading to non-ejected areas and defects
Solution Approach 1:
The pixel structure is segmented by dividing the single bank into multiple components: a main bank and an intermediate bank. The intermediate bank is positioned between sub-light emitting areas and partially overlaps with electrodes, creating distinct zones for ink ejection control. This segmentation allows separate control of ink distribution in different regions, eliminating non-ejected areas and improving reliability without excessive complexity
Solution Approach 2:
The intermediate bank acts as an intermediary structure between the main bank and the light emitting elements. It mediates ink flow by providing a lyophilic side surface that guides ink ejection, while its liquid-repellent upper surface prevents ink overflow. This intermediary structure resolves the contradiction by improving ink distribution control without requiring complete redesign of the entire pixel structure
2Manufacturing precision
If the bank structure is simplified, then manufacturing is easier, but ink ejection control is insufficient causing non-ejected areas
Solution Approach 1:
The bank structure applies local quality by having different surface properties in different regions. The side surface of the intermediate bank is treated to be lyophilic (liquid-attracting) to guide ink ejection, while the upper surface is made liquid-repellent to prevent overflow. This localized differentiation of surface properties enables precise ink ejection control without complicating the overall manufacturing process
Solution Approach 2:
The invention changes the surface energy parameters of the bank structure by applying different surface treatments to different regions. The lyophilic treatment on the side surface increases liquid affinity for controlled ejection, while the liquid-repellent treatment on the upper surface decreases affinity to prevent overflow. These parameter changes achieve precise ink control with manageable manufacturing complexity
3Reliability
If no intermediate bank is provided, then the structure is simpler, but light emitting elements may misalign causing defects
Solution Approach 1:
The intermediate bank performs preliminary action by pre-establishing the correct positioning for light emitting elements during the ink ejection process. Its lyophilic side surface guides the ink flow to the precise location where light emitting elements should be placed, ensuring proper alignment before the elements are fully deposited. This preliminary positioning action improves placement accuracy without requiring complex post-processing alignment mechanisms
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 configuration enhances the control of ink distribution, reduces non-ejected areas, and prevents defects by ensuring proper alignment and placement of light emitting elements.
Implementation Method 1
At least one of at least one surface of the bank and at least one surface of the intermediate bank may include a liquid-repellent layer that is liquid-repellent-treated
Implementation Method 2
each of a side surface of the bank and a side surface of the intermediate bank may not liquid-repellent-treated and may have a lyophilic characteristic
Data Source
AI summary
A display device includes: a substrate including a pixel area; and a pixel in the pixel area, the pixel including a first sub-light emitting area, a second sub-light emitting area, and a peripheral area surrounding the first and second sub-light emitting areas. The pixel may include: a first electrode, a second electrode, a third electrode, and a fourth electrode that are spaced from each other; a plurality of light emitting elements in the first and second sub-light emitting areas; a bank in the peripheral area and including a first opening corresponding to the first sub-light emitting area and a second opening corresponding to the second sub-light emitting area; and an intermediate bank between the first sub-light emitting area and the second sub-light emitting area and partially overlapping the second and third electrodes in a plan view.