Electroluminescent Display Electrode Layout for Uniform Luminance
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Solution Overview
Problem
Electroluminescent display devices suffer from non-uniform luminance due to resistance differences in the second electrode, which affects the display's performance and image quality.
Innovation Solution
Incorporating an auxiliary electrode with an inclined surface and an undercut structure in the contact area, connected to the power line and the second electrode, to ensure uniform contact and reduce resistance variations across the display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the second electrode is provided commonly for all sub-pixels in a relatively large area, then the device structure is simplified and manufacturing is easier, but the resistance of the second electrode increases depending on position, causing non-uniform luminance
Solution Approach 1:
The second electrode is divided into multiple segments, each connected to the power line through separate contact holes. This segmentation reduces the resistance variation across the electrode by creating multiple independent electrical pathways, thereby improving luminance uniformity while maintaining the simplified common electrode structure.
Solution Approach 2:
The patent introduces an auxiliary electrode as an intermediary component between the power line and the second electrode. This auxiliary electrode helps distribute electrical potential more evenly across the large-area second electrode, reducing resistance differences and improving luminance uniformity without complicating the overall device structure.
2Reliability
If the second electrode is formed in a relatively large area to cover the entire display area, then the electrode provides comprehensive electrical connection, but the resistance difference increases causing non-uniform luminance
Solution Approach 1:
The second electrode is segmented into multiple regions with separate contact holes to the power line. This segmentation maintains comprehensive electrical connection across the entire display area while reducing resistance differences, thereby ensuring both reliability of electrical connection and uniformity of luminance.
Solution Approach 2:
The patent applies local quality by creating multiple contact holes at different positions across the large-area second electrode. Each local region has its own direct connection to the power line, ensuring uniform electrical potential and luminance across different areas of the electrode.
3Manufacturing precision
If multiple contact holes are formed in the insulation layer to connect the auxiliary electrode, then the resistance uniformity is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The insulation layer is segmented into multiple regions with contact holes at different positions. This segmentation improves resistance uniformity by providing multiple access points to the auxiliary electrode, while the contact holes are formed using standard manufacturing processes that minimize added complexity.
Solution Approach 2:
The patent addresses the resistance uniformity issue by adding vertical dimensionality through multiple contact holes at different depths and positions. This three-dimensional approach to electrode connection improves electrical uniformity without significantly increasing planar device complexity.
Data Source
AI summary
An electroluminescent display device includes a substrate including an emission area and a contact area; a power line over the substrate; a light-emitting diode in the emission area and including a first electrode, a light-emitting layer, and a second electrode; at least one structure in the contact rea; an auxiliary electrode in the contact area, connected to the power line and the second electrode, and having an inclined surface over the structure; and an insulation layer between the auxiliary electrode and the light-emitting diode and having a contact hole exposing the auxiliary electrode, wherein an undercut structure is on at least one side of the contact hole, and the light-emitting layer and the second electrode are cut off by the undercut structure and are in contact with the inclined surface of the auxiliary electrode under the undercut structure.