Auxiliary Wire Segmentation for OLED Voltage Drop
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Solution Overview
Problem
Existing display devices with top emission type organic electroluminescent elements face issues with brightness nonuniformity due to voltage drops across the display panel, leading to variations in pixel brightness, especially as screen size increases, which complicates the production process with the need for accurate film forming masks and complex processes.
Innovation Solution
A display device configuration where an auxiliary wire is spaced apart from the first electrode, with an intermediate layer between the first and second electrodes, ensuring the resistance value of the intermediate layer satisfies a specific relationship between the second electrode and auxiliary wire resistances, reducing voltage drops and simplifying the production process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the display panel area is increased to create larger screens, then the display size is improved, but voltage drop increases causing brightness nonuniformity
Solution Approach 1:
The patent segments the power supply function by introducing auxiliary wires that are spaced apart from the first electrode. These auxiliary wires divide the large display panel into multiple smaller electrical zones, each with its own power supply path. This segmentation reduces the effective current path length and minimizes voltage drop across the entire panel, thereby maintaining brightness uniformity even in large-format displays.
Solution Approach 2:
The patent applies local quality by positioning auxiliary wires at specific locations across the display panel. The auxiliary wires are strategically placed to provide localized power supply to different regions of the panel. This creates non-uniform electrical characteristics in different areas, with each region receiving optimized power delivery according to its specific distance from the power supply source, thus compensating for the increased voltage drop in larger panels.
2Illumination intensity
If transparent conductive material with high resistivity is used for the second electrode, then light transmittance is improved, but voltage drop increases causing brightness variation
Solution Approach 1:
The patent segments the electrical path by introducing auxiliary wires that work in conjunction with the transparent conductive second electrode. Instead of relying on a single continuous transparent electrode to carry current across the entire panel, the auxiliary wires create multiple parallel current paths. This segmentation reduces the current density through the high-resistivity transparent material, minimizing voltage drop and maintaining brightness consistency.
Solution Approach 2:
The auxiliary wires act as intermediary conductive elements between the power supply and the transparent conductive second electrode. These auxiliary wires provide low-resistance alternative paths for current flow, mediating the electrical connection and reducing the burden on the high-resistivity transparent material. This intermediary structure allows the use of highly transparent materials without sacrificing brightness uniformity.
3Reliability
If auxiliary wire is directly connected to second electrode through opening in partition wall, then electrical connection is improved, but production process complexity increases
Solution Approach 1:
The patent extracts the connection requirement from the partition wall structure. Instead of forming openings through the partition wall to connect auxiliary wires to the second electrode, the invention removes this complex connection requirement entirely. The auxiliary wires are positioned and connected in a manner that eliminates the need for penetrating the partition wall, thereby simplifying the production process while maintaining reliable electrical connections.
Solution Approach 2:
The patent inverts the conventional approach by not connecting the auxiliary wire through the partition wall opening. Instead, the auxiliary wire is positioned such that it connects to the second electrode through the intermediate layer without requiring an opening in the partition wall. This inversion of the connection methodology simplifies the manufacturing process by eliminating a complex step while maintaining the electrical connection function.
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 significantly reduces brightness variations between pixels by minimizing voltage drops, even in large-format panels, while simplifying the production process and improving productivity without requiring highly accurate film forming masks.
Implementation Method 1
an intermediate layer provided between the first electrode and the second electrode, the intermediate layer and the second electrode extend from above the first electrode to above the auxiliary wire
Implementation Method 2
a light emitting layer formed above the first electrode, the light emitting layer containing a light emitting substance
Data Source
AI summary
A display device includes: a display unit in which a plurality of pixels are arranged; and a power supply unit configured to feed a power supply voltage to the pixels through a power feeding line disposed on an outer periphery of the display unit. The pixels each include: an anode formed on a drive circuit layer; an auxiliary wire formed on the drive circuit layer to be spaced apart from the anode; an organic light emitting layer and an electron transport layer that are formed above the anode; and a transparent cathode formed above the electron transport layer. The electron transport layer and the transparent cathode extend from above the anode to above the auxiliary wire. The electron transport layer has a resistance value Rip that satisfies the following relationship: Rip≤(R2p−Rbp)×M×(M+1)/2.