Organic EL Device Series Pixel Architecture for Luminance Uniformity
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Solution Overview
Problem
As organic EL devices increase in size, the voltage drop across wiring leads to reduced luminance at the center of the light emitting region, and existing manufacturing methods do not effectively utilize the inkjet method to form light emitting films, limiting the device's performance and cost-effectiveness.
Innovation Solution
The organic EL device is designed with multiple light emitting elements connected in series within each pixel, using a droplet discharge method to form light emitting films and separating electrodes with reversed-tapered insulating members to reduce current and voltage drop, while also forming a hole transporting layer to improve hole injection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the organic EL device increases in size, then the display area is improved, but the voltage drop increases and luminance uniformity deteriorates
Solution Approach 1:
The patent divides each pixel into multiple light emitting elements connected in series (e.g., three elements per pixel). This segmentation reduces the current required for each element while maintaining overall luminance, thereby reducing voltage drop across the wiring in larger displays and improving luminance uniformity across the display area.
Solution Approach 2:
The patent applies different structures to different regions: insulating members with reversed-tapered shapes are formed at specific locations between adjacent light emitting elements to achieve electrical isolation where needed, while maintaining direct contact in other regions for current flow. This localized structural differentiation optimizes both electrical isolation and current distribution.
2Illumination intensity
If multiple light emitting elements are connected in series, then the voltage drop is reduced and luminance uniformity is improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple functions into single structures: the insulating members serve both as electrical isolation barriers between adjacent light emitting elements and as structural support elements. The reversed-tapered shape provides both the isolation function and facilitates the series connection architecture, reducing the need for additional separate components.
Solution Approach 2:
The patent uses a standardized configuration where multiple identical light emitting elements with the same structure are replicated within each pixel and across the display. This modular copying approach simplifies manufacturing and reduces design complexity compared to creating unique structures for each element.
3Ease of manufacture
If the inkjet method is used to form light emitting films, then the manufacturing cost is reduced and resource utilization is improved, but the manufacturing precision may be affected
Solution Approach 1:
The patent utilizes the inkjet method's ability to precisely control deposition parameters (droplet size, spacing, volume) to form light emitting films with controlled thickness and uniformity. By optimizing these parameters, the inkjet method achieves both cost reduction through direct writing without masks and acceptable manufacturing precision for the light emitting layers.
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 voltage drop and maintains luminance across the display region, allowing for thinner wiring and more precise display characteristics while conserving resources and reducing manufacturing costs.
Implementation Method 1
liquid material including a forming material of a light emitting film of an organic EL element is coated on a substrate by an inkjet method
Implementation Method 2
If a voltage is applied between the pair of electrodes opposite to each other, the injected electrons and holes are recombined within a light emitting film, so that the light emitting film emits light
Implementation Method 3
separating electrodes with reversed-tapered insulating members to reduce current and voltage drop
Data Source
AI summary
A light emitting device includes: a plurality of first electrodes; a plurality of second electrodes; and a plurality of light emitting films. Each of the plurality of light emitting films is disposed between one first electrode among the plurality of first electrodes and one second electrode among the plurality of second electrodes. The one first electrode is electrically connected to the second electrode that is adjacent to the one second electrode among the plurality of second electrodes.