Auxiliary Wire Reduces Voltage Drop in Electrooptic Devices
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Solution Overview
Problem
In electrooptic devices like organic EL devices, the resistance of power supply wires leads to voltage drops and uneven brightness, particularly in large displays, making it difficult to achieve high-quality, high-resolution images due to limitations in wire thickness and material resistance.
Innovation Solution
The use of a second auxiliary wire with low resistance, formed on a separate substrate, supplies auxiliary power to the electrooptic elements, reducing voltage drops and allowing for high-quality image display by maintaining low resistance despite high sheet resistance of the second electrode, and incorporating a light-scattering layer for enhanced light extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the thickness of the power supply wire is increased to reduce resistance, then the voltage drop decreases, but the step differences increase making planarization difficult
Solution Approach 1:
The power supply wire is divided into multiple segments (first power supply wire and second power supply wire) that are arranged in different layers. The first power supply wire is formed in the insulating film layer, while the second power supply wire is formed on the opposite surface of the substrate. This segmentation allows each wire segment to have optimized thickness without creating excessive step differences, as the current path is distributed across multiple segments rather than requiring a single thick wire.
Solution Approach 2:
The solution transitions from a single-plane wire configuration to a three-dimensional multi-layer configuration. By forming power supply wires on both the front surface (in the insulating film) and the back surface (on the substrate opposite surface), the patent utilizes the third dimension (depth/layering) to reduce resistance without increasing the thickness of individual wires, thereby avoiding planarization issues.
2Productivity
If the width of the power supply wire is decreased to accommodate more pixels, then the resistance increases causing larger voltage drops
Solution Approach 1:
The power supply network is segmented into multiple parallel paths consisting of first power supply wires in the insulating film and second power supply wires on the substrate opposite surface. This segmentation creates multiple current channels, allowing narrower individual wires while maintaining low overall resistance through parallel conduction paths.
Solution Approach 2:
The patent employs a composite wiring structure combining conductive materials in different media (insulating film and substrate). The first power supply wire uses conductive material within the insulating film, while the second power supply wire uses conductive material on the substrate surface, creating a composite conduction system that achieves low resistance with reduced wire width.
3Loss of energy
If low-resistance metal materials are used for power supply wires, then the voltage drop decreases, but the manufacturing complexity increases
Solution Approach 1:
The first power supply wire formed in the insulating film serves dual functions: it acts as a power supply conductor and simultaneously functions as an electrode for electrooptic elements. This multi-functionality reduces the need for separate low-resistance metal layers, simplifying the manufacturing process while maintaining low voltage drop through the distributed wire configuration.
4Illumination intensity
If the power supply wire resistance is reduced to improve brightness uniformity, then the brightness variation decreases, but the manufacturing steps increase
Solution Approach 1:
The first power supply wire is formed within the insulating film during the insulating film formation process itself, before subsequent electrode and wiring layers are added. This preliminary action integrates the power supply function into an existing manufacturing step, avoiding additional high-complexity processes while achieving the brightness uniformity benefit of reduced wire resistance.
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 solution reduces brightness variation and enables high-quality, large-screen image displays with improved light extraction efficiency and reliability, while maintaining low wire resistance and preventing electrooptic element degradation.
Implementation Method 1
incorporating a light-scattering layer for enhanced light extraction
Data Source
AI summary
An electrooptic device includes a first substrate and a second substrate. The first substrate includes an electrooptic element in which an electrooptic substance is interposed between a first electrode and a second electrode, the electrooptic element being disposed on a surface of the first substrate that opposes the second substrate; an electronic element for driving the electrooptic element; and a power supply wire for supplying power to at least one of the electrooptic element and the electronic element. The second substrate includes a second auxiliary wire for supplying auxiliary power to at least one of the electrooptic element and the electronic element, the second auxiliary wire being disposed on a surface of the second substrate that opposes the first substrate, the second auxiliary wire having a planar shape that corresponds with a non-opening region of the electrooptic element.