Inkjet Organic EL Panel Bank Offset Nozzle Switching
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Solution Overview
Problem
Conventional organic EL display panels experience stripe unevenness due to variations in nozzle precision and ink flow within the inkjet head, leading to inconsistent film thickness and decreased image quality.
Innovation Solution
The method involves forming organic light-emission layers using an inkjet head with nozzles that are switched between two groups to ensure that each column-direction array of openings receives a different ink volume, with the bank layer offset by no more than 50% of the predetermined pitch, preventing continuous erroneous ink ejection and maintaining uniform film thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the same nozzles are used continuously to eject ink liquid droplets for each row of openings, then the manufacturing process is simple, but stripe unevenness occurs due to variations in nozzle precision and ink flow
Solution Approach 1:
The nozzles are divided into two groups (first group and second group) that are switched alternately for different row-direction arrays of openings. This segmentation allows the system to avoid continuous use of the same nozzles, thereby preventing stripe unevenness caused by nozzle precision variations and ink flow inconsistencies while maintaining a relatively simple overall structure.
2Manufacturing precision
If the openings are arranged in aligned column-direction arrays, then the bank layer structure is simple, but stripe unevenness occurs due to consistent ink ejection patterns
Solution Approach 1:
The bank layer is designed with an offset structure where the first row-direction array of openings and the second row-direction array of openings are positioned at different locations in the column direction. This asymmetric arrangement ensures that when nozzles are switched between groups, the ink ejection patterns vary between arrays, preventing stripe unevenness while maintaining a relatively simple bank layer structure.
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 effectively reduces the occurrence of stripe unevenness, enhancing image display quality by ensuring consistent ink volume distribution across the panel.
Implementation Method 1
When an inkjet head is driven according to the piezo method, ink ejection is controlled by using piezoelectric elements.
Data Source
AI summary
An organic EL display panel including organic light-emission layers formed according to an inkjet method and suppressing decrease in image display quality caused by stripe unevennesses, and a method of manufacturing the same. In a bank layer forming process, openings belonging to a first array and openings belonging to a second array that is adjacent to the first in a row direction are offset with respect to one another in the column direction. In an organic light-emission layer forming process, a head unit is caused to move in a row direction, and nozzles used are switched between the first and second arrays. When a nozzle ejecting an erroneous ink volume is switched between being used and not being used, continuous forming of organic light-emission layers having a same, erroneous film thickness in the row direction is prevented. Thus, unevenness in luminance is suppressed.