Display Device Partition Wall Resistance for Chromaticity Control
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Solution Overview
Problem
In organic electroluminescence (EL) display devices, the non-uniform film formation caused by partition wall protrusions leads to variations in electric field and film thickness, resulting in conspicuous chromaticity changes during low luminance states due to differences in light emission between the organic layer on the electrode and the layer near the partition wall boundary.
Innovation Solution
A display device design featuring first electrodes arranged in a two-dimensional matrix with a partition wall having a decreasing cross-sectional width, an organic layer formed by laminating multiple material layers, and a second electrode on the entire surface, where the material layer closest to the second electrode has a higher resistance on the partition wall slope than on the electrode, ensuring uniform light emission and reduced chromaticity changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the organic layer is formed on the entire surface including the partition wall parts, then the film formation uniformity is impaired and chromaticity changes occur in low luminance state, but forming the organic layer on the partition wall parts is necessary for complete coverage and device structure
Solution Approach 1:
The patent applies local quality by creating different resistance characteristics in different regions of the organic layer. Specifically, the organic layer is designed to have higher resistance near the partition wall parts compared to the central regions of the electrodes. This localized resistance variation compensates for the non-uniform film thickness, ensuring uniform light emission and preventing chromaticity changes in low luminance states while maintaining complete surface coverage.
2Manufacturing precision
If the partition wall part protrudes more than the first electrode, then the film thickness becomes small near the boundary, but the partition wall structure is needed for electrode separation and device architecture
Solution Approach 1:
The patent employs parameter changes by modifying the resistance parameter of the organic layer in specific regions. By adjusting the resistance distribution within the organic layer (making it higher near partition walls), the patent compensates for the geometric irregularities caused by the protruding partition wall structure. This allows the partition wall to maintain its necessary separating function while the resistance variation ensures uniform electrical characteristics and light emission across the entire surface.
3Power
If the organic layer near the partition wall boundary emits light more easily in low luminance state, then light emission efficiency increases locally, but chromaticity changes become conspicuous
Solution Approach 1:
The patent applies local quality by creating spatially varying resistance characteristics within the organic layer. The resistance is designed to be higher in regions near the partition wall boundaries compared to the central electrode regions. This localized resistance increase balances the electrical field distribution, ensuring that all regions of the organic layer emit light with uniform chromaticity characteristics even in low luminance states, while maintaining overall emission efficiency.
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
The solution effectively reduces chromaticity changes in low luminance states by ensuring uniform film thickness and resistance across the organic layer, enhancing the display's luminous efficiency and color accuracy.
Implementation Method 1
a material layer arranged closest to the second electrode side is formed such that a resistance of a portion located on a slope of the partition wall part is higher than a resistance of a portion located on the first electrode
Data Source
AI summary
A display device includes: first electrodes formed to be arranged in a two-dimensional matrix on a substrate; a partition wall part provided between the first electrodes adjacent to each other and having a cross-sectional shape whose width decreases as it moves away from the substrate; an organic layer formed on an entire surface including surfaces of the first electrodes and the partition wall parts and formed by laminating a plurality of material layers; and a second electrode formed on an entire surface including a surface of the organic layer, in which among the plurality of material layers constituting the organic layer, a material layer arranged closest to the second electrode side is formed such that a resistance of a portion located on a slope of the partition wall part is higher than a resistance of a portion located on the first electrode.