Auxiliary Electrode Structure for EL Display Signal Delay Reduction
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Solution Overview
Problem
Large display devices face challenges with signal delay due to signal line resistance and nonuniform potential distribution caused by high film resistance in conductive films used for top emission EL display devices, leading to issues like luminance variations in light-emitting elements.
Innovation Solution
A structure is introduced with an auxiliary electrode in contact with the conductive film, using a MgAg film with a thickness of 15-20 nm, and a second partition with a specific angle to reduce contact resistance and improve light transmission, along with an oxide semiconductor transistor for high field-effect mobility, enabling high-definition and large-area displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conductive film with light-transmitting property (such as ITO or indium zinc oxide) is used for the second electrode in a top emission EL display device, then light transmission is improved, but film resistance increases causing nonuniform potential distribution and luminance variations
Solution Approach 1:
The second electrode is divided into a first electrode and a second electrode. The first electrode has a larger area and is positioned closer to the layer containing an organic compound, while the second electrode has a smaller area and is positioned closer to the substrate. This segmentation allows the first electrode to provide better electrical contact and lower resistance, while the second electrode maintains light transmission properties.
Solution Approach 2:
The invention introduces a vertical dimension to the electrode structure by stacking the first and second electrodes at different heights and positions. The first electrode is closer to the organic compound layer in the vertical direction, while the second electrode is closer to the substrate, creating a three-dimensional electrode configuration that addresses both electrical and optical requirements.
2Area of stationary object
If the display area is increased to manufacture large display devices, then the utility of the device is improved, but signal delay due to signal line resistance increases
Solution Approach 1:
The second electrode is segmented into multiple auxiliary electrodes arranged in a matrix pattern across the display area. Each auxiliary electrode is electrically connected to the first electrode through contact portions, creating multiple parallel electrical pathways that reduce overall resistance and signal delay across large display areas.
Solution Approach 2:
The first electrode acts as an intermediary between the transistor and the multiple auxiliary electrodes. It receives electrical signals from the transistor and distributes them to numerous auxiliary electrodes through contact portions, enabling efficient signal distribution across large display areas with reduced resistance and delay.
3Manufacturing precision
If the number of pixels is increased to achieve high definition displays, then the display quality is improved, but the number of signal lines increases causing more signal delay
Solution Approach 1:
Multiple auxiliary electrodes are electrically connected to a single first electrode through contact portions. This merging approach allows numerous electrodes to share common electrical connection points, reducing the total number of independent signal lines needed while maintaining high pixel density and display definition.
Solution Approach 2:
The first electrode serves multiple functions: it acts as an electrode for light emission, a distribution network for electrical signals, and a connection point for multiple auxiliary electrodes. This multi-functionality reduces the need for separate dedicated signal lines for each pixel, simplifying the overall signal routing in high-definition displays.
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 signal delay and potential variations, enabling high-definition and large-area displays with improved aperture ratio and manufacturing efficiency, using the same material for the auxiliary and second electrodes to minimize contact resistance.
Implementation Method 1
an auxiliary electrode in contact with the conductive film, using a MgAg film with a thickness of 15-20 nm
Implementation Method 2
a transistor using an oxide semiconductor and applying such a transistor to an electronic appliance or an optical device
Data Source
AI summary
A structure of an EL display device which has an increased display area is provided. Further, a structure of an EL display device which has a high definition display is provided. An auxiliary electrode is formed over a first partition and side surfaces of the auxiliary electrode are covered with a second partition. A top surface of the auxiliary electrode is in contact with the conductive film which is one electrode of a light-emitting element and has a light-transmitting property, which enables a large-area display. Further, even the distance between the adjacent light-emitting elements is shortened, the auxiliary electrode can be provided between the adjacent light-emitting elements, which enables a high definition display.