Electroluminescent Display Subpixel Leakage Prevention
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Solution Overview
Problem
Electroluminescent display apparatuses face challenges in preventing leakage current when emitting light of the same color in subpixels, leading to image quality degradation, and struggle with precise deposition of different light emitting layers in densely arranged subpixels when emitting different colors.
Innovation Solution
The apparatus includes a substrate with subpixels emitting different colors, each with a dedicated light emitting layer, and an additional light emitting layer on a bank between subpixels, allowing precise patterning and preventing leakage current by overlapping layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the light emitting layer emits light of the same color in each subpixel, then the manufacturing process is simpler, but leakage current occurs causing degradation in image quality
Solution Approach 1:
The patent divides the light emitting layer into different color segments (red, green, blue) corresponding to different subpixels. Each subpixel receives only its designated color light emitting layer material, preventing charge leakage between adjacent subpixels while maintaining manufacturing feasibility through sequential deposition processes.
Solution Approach 2:
The patent applies different light emitting layer materials locally to different subpixel regions. The first light emitting layer material is deposited only in first subpixels, the second material only in second subpixels, and so on. This local differentiation prevents leakage current while allowing each region to be optimized for its specific function.
2Reliability
If the light emitting layer emits lights of different colors in subpixels, then leakage current is prevented, but there is a limitation in precisely depositing different light emitting layers in densely arranged subpixels
Solution Approach 1:
The patent performs preliminary patterning by forming banks between adjacent subpixels before depositing the light emitting layers. These banks serve as physical barriers that pre-define the deposition regions, allowing subsequent light emitting layer materials to be deposited with higher precision and preventing cross-contamination between densely arranged subpixels.
Solution Approach 2:
The patent introduces banks as intermediary structures between adjacent subpixels. These banks act as mediators that physically separate the deposition zones of different light emitting layers, enabling precise deposition in densely arranged subpixels by preventing material diffusion and cross-contamination during the deposition process.
3Measurement precision
If subpixels are densely arranged to increase display resolution, then the display quality improves, but it becomes difficult to precisely deposit different light emitting layers without causing leakage current
Solution Approach 1:
The patent solves the deposition precision problem by transitioning from a two-dimensional planar deposition approach to a three-dimensional approach using vertical banks. These banks add a vertical dimension to the structure, creating physical walls that confine the light emitting layer materials to their respective subpixel regions even when subpixels are densely arranged in the horizontal plane.
Solution Approach 2:
The banks serve as intermediary structures that mediate between the densely arranged subpixels. By introducing these physical barriers, the patent enables high-resolution dense subpixel arrangements while maintaining precise light emitting layer deposition, as the banks prevent material diffusion between adjacent subpixels during the deposition process.
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 enables precise patterning of light emitting layers in densely arranged subpixels, preventing leakage current and enhancing image quality by ensuring accurate color emission without degrading the display.
Implementation Method 1
Electroluminescent display apparatuses are apparatuses where a light emitting layer is provided between two electrodes (i.e., an anode electrode and a cathode electrode) and emits light with an electric field generated between the two electrodes
Implementation Method 2
In the light emitting layer, an exciton is generated by a combination of an electron and a hole, and when the exciton is shifted from an excited state to a ground state, light is emitted
Data Source
AI summary
An electroluminescent display apparatus comprises a first subpixel, a second subpixel, and a third subpixel defined on a substrate; a first electrode disposed in each of the first subpixel, the second subpixel, and the third subpixel in the substrate; a bank provided between two adjacent subpixels among the first subpixel, the second subpixel, and the third subpixel to cover an edge of the first electrode; a first light emitting layer disposed on the first electrode of the first subpixel; a second light emitting layer disposed on the first electrode of the second subpixel; a third light emitting layer disposed on the first electrode of the third subpixel; and a second electrode disposed on the first to third light emitting layers, wherein the third light emitting layer is extended onto the bank between the first subpixel and the second subpixel.