Organic EL Display Panel with Aperiodic Emitter Width
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Solution Overview
Problem
Organic electroluminescence (EL) display panels face issues with luminance unevenness due to variations in film thickness of functional layers, particularly noticeable when viewed from low angles, caused by factors like ink droplet size variations during the inkjet process.
Innovation Solution
The display panel design features pixel electrodes and column insulating layers arranged in a matrix, with organic light emitting layers continuous in the column direction and positioned between column insulating layers, where the width of these layers changes irregularly or aperiodically in the row direction, with minimum intervals equal to or less than the pixel electrode pitch, to minimize luminance unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the inkjet process is used to form functional layers, then the manufacturing efficiency and scalability are improved, but luminance unevenness occurs due to variations in film thickness
Solution Approach 1:
The patent applies local quality by varying the width of organic light emitting layers in the row direction at different column positions. Specifically, the width changes irregularly or aperiodically with minimum intervals equal to or less than the pixel electrode pitch, creating local variations that counteract the systematic film thickness variations caused by inkjet droplet size variations. This local modulation makes luminance unevenness less conspicuous while maintaining the efficiency of the inkjet manufacturing process.
2Illumination intensity
If the film thickness is increased to improve luminance, then the brightness is improved, but the luminance unevenness becomes more noticeable
Solution Approach 1:
The patent applies parameter changes by modulating the width parameter of organic light emitting layers rather than uniformly increasing film thickness. By changing the width parameter locally across different columns and rows, the patent achieves luminance enhancement while simultaneously compensating for film thickness variations. The irregular or aperiodic width changes with appropriate minimum intervals create a compensation effect that reduces luminance unevenness visibility.
3Manufacturing precision
If the column insulating layers are made wider to define the organic light emitting layers, then the manufacturing precision is improved, but the area for light emission is reduced
Solution Approach 1:
The patent applies dynamics by making the width of organic light emitting layers variable rather than fixed. The width changes at different positions in the row direction, with minimum intervals equal to or less than the pixel electrode pitch. This dynamic width adjustment allows the patent to maintain adequate pattern definition through column insulating layers while compensating for area loss by strategically varying the emitting area across different regions of the display panel.
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 reduces the visibility of luminance unevenness by modulating the luminance distribution, making streaks caused by film thickness variations less conspicuous, especially when viewed from low angles, and improves luminance uniformity across the display.
Implementation Method 1
organic electroluminescence (EL) display panels that use electroluminescence of organic materials
Data Source
AI summary
An organic EL display panel including pixel electrodes above a substrate in a matrix, column banks above the substrate at least between edges of the pixel electrodes in a row direction, extending in a column direction and side-by-side in the row direction, organic light emitting layers continuous in the column direction in gaps between the column banks, and a counter electrode layer above the organic light emitting layers. Width in the row direction of the organic light emitting layers, which is defined by width of the gaps between the column banks, changes at intervals in the column direction. For each of the light emitting layers, a minimum interval is equal to or less than a pitch in the column direction of the pixel electrodes and the changes are different from others of the light emitting layers.