Organic EL Bank Recess for Ink Overflow Control
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Solution Overview
Problem
Existing organic EL display panels face challenges in preventing color mixture of inks during the application step, particularly due to ink overflow beyond banks, which leads to contamination between adjacent element formation regions, despite conventional methods like thermal shrinkage-based recess formation being insufficient.
Innovation Solution
The organic EL display panel incorporates a substrate with an interlayer insulating layer and banks that have a buried part filling the interval between electrodes, along with a recess on the bank's main part, allowing for a deeper and accurately adjusted recess to hold overflowed ink, and the banks are formed to be tightly integrated with the substrate, enhancing adhesion and preventing ink overflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thermal shrinkage-based recess formation is used in the burning step, then the bank structure is formed, but the recess depth is insufficient to prevent ink overflow
Solution Approach 1:
The bank structure is segmented into two functional parts: a buried part that fills the interval between electrodes and provides structural support, and a main part that forms the visible bank with a recess on its top surface. This segmentation allows the recess to be formed with sufficient depth to hold overflowed ink while maintaining overall structural integrity.
Solution Approach 2:
The recess is formed in advance on the top of the main part of the bank before the ink application step. This preliminary formation of the recess ensures that when ink is applied and potentially overflows due to vibration or acceleration, the overflowed ink is already contained within the pre-formed recess, preventing color mixture between adjacent element formation regions.
2Productivity
If ink is applied by inkjet method, then mass production and large screen size are achieved, but ink overflows beyond banks due to vibration or acceleration
Solution Approach 1:
The recess on the top of the bank main part serves as a cushioning structure formed beforehand to accommodate and hold overflowed ink. This prior cushioning capacity ensures that even when vibration or acceleration occurs during substrate conveyance in mass production, the ink overflow is contained within the recess and does not cause color mixture between adjacent elements.
3Manufacturing precision
If the bank material is shrunk thermally, then the bank structure is formed, but the recess depth cannot be accurately adjusted
Solution Approach 1:
The recess depth is controlled by changing the parameters of the burning step, specifically by adjusting the irradiation dose of ultraviolet light or the exposure time. This allows accurate adjustment of the recess depth to match the interval between adjacent first electrodes, ensuring proper ink containment while maintaining ease of manufacture through a simple parameter adjustment rather than complex structural changes.
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 solution effectively prevents color mixture of inks by holding overflowed ink within the recessed area, improving the manufacturing of organic EL display panels with enhanced image display capabilities and operational reliability.
Implementation Method 1
a recess is formed on the top of a bank by taking advantage of thermal shrinkage of the bank material
Implementation Method 2
the inkjet head is driven by a drive system such as a piezo system
Data Source
AI summary
An organic EL display panel includes a substrate; an interlayer insulating layer on the substrate; first electrodes on the interlayer insulating layer to correspond to element formation regions in rows and columns; banks extending in columns to partition the regions in rows; organic light-emitting layers above the first electrodes, and each containing organic light-emitting material having light-emitting color differing between each two adjacent regions in rows; and second electrodes above the light-emitting layers, and being opposite in polarity to the first electrodes, wherein the interlayer insulating layer has first opening corresponding to interval between each two adjacent first electrodes in rows, the banks each have integrally formed buried part and main part, the buried part fills the interval and the first opening, and the main part is protrusion of the buried part and has recess on top thereof along with shapes of the interval and the first opening.