Multilayer Cathode Electrode Layout for Uniform Display Luminance
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Solution Overview
Problem
The conventional method of providing a contact electrode on the outer peripheral portion of the effective pixel area to connect the cathode electrode results in increased sheet resistance, leading to decreased luminance in the central portion of the display device, especially with larger angles of view and higher current application.
Innovation Solution
The implementation of multilayer cathode electrodes with a protective film interposed between them, where the cathode electrodes of subsequent layers are electrically connected to a potential supply wire at the bottom of a contact hole, reducing sheet resistance and allowing for cathode contact portions within the effective pixel area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a contact electrode is provided on the outer peripheral portion of the effective pixel area to connect the cathode electrode, then the cathode electrode can be electrically connected, but the sheet resistance of the cathode electrode increases
Solution Approach 1:
The patent transitions from a planar contact electrode configuration to a three-dimensional multilayer cathode electrode structure. By stacking multiple cathode electrode layers with protective films and creating contact holes through the layers, the invention provides multiple electrical connection paths vertically, reducing sheet resistance while maintaining reliable electrical connection.
Solution Approach 2:
The cathode electrode is divided into multiple layers (first cathode electrode layer, second cathode electrode layer, etc.), each separated by protective films. Contact holes are created through these layers to establish electrical connection, segmenting the single-plane connection into multiple staged connections that reduce overall resistance.
2Reliability
If the sheet resistance of the cathode electrode increases, then the electrical connection is maintained, but the luminance decreases in the central portion of the effective pixel area
Solution Approach 1:
By creating a multilayer cathode electrode structure with vertical stacking and contact holes, the invention reduces sheet resistance through multiple parallel electrical paths. This reduction in resistance directly improves luminance in the central portion of the effective pixel area while maintaining stable electrical connection through the layered architecture.
3Object-affected harmful factors
If multilayer cathode electrodes are stacked with protective film interposed, then sheet resistance is reduced, but the device structure becomes more complex
Solution Approach 1:
The cathode electrode system is segmented into multiple functional layers (first cathode electrode layer, protective film, second cathode electrode layer, etc.), where each layer serves a specific purpose. This segmentation reduces sheet resistance through multiple connection paths while the modular structure makes the complexity manageable and systematic.
Solution Approach 2:
The invention creates a composite structure combining conductive cathode electrode layers with insulating protective films. This composite multilayer architecture achieves reduced sheet resistance through the conductive paths while the protective films provide necessary insulation, balancing performance improvement with structural complexity.
Data Source
AI summary
A display device of the present disclosure includes a light emitting unit, multilayer cathode electrodes stacked on the light emitting unit in two or more layers with a protective film interposed between the cathode electrodes and electrically connected to each other, and a potential supply wire that applies predetermined potential to the multilayer cathode electrodes. Then, the cathode electrodes of second and subsequent layers out of the multilayer cathode electrodes are electrically connected to the potential supply wire via a first contact hole.