Display Substrate Wiring Pattern for Thermal Transfer Color Purity
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Solution Overview
Problem
In active matrix display apparatuses with organic electroluminescent (EL) devices, the presence of numerous wiring lines causes surface unevenness, leading to color mixture during the thermal transfer process of light-emitting materials, which results in poor color reproducibility and sharpness in the displayed images.
Innovation Solution
The display apparatus features a substrate with a specific wiring pattern where recessed portions of the outer uneven zone are positioned behind raised portions of the inner uneven zone, creating distinct outer and inner regions along pixel boundaries. This pattern prevents light-emitting materials from leaking between pixels during the thermal transfer process by using a conductor film with a multilayer structure and strategically placed pads to compensate for level differences, ensuring precise deposition of colored materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If many wiring lines are formed on the substrate to enable active matrix display operation, then the display functionality is achieved, but surface unevenness occurs due to level differences in the conductor film
Solution Approach 1:
The patent applies the nesting principle by creating a multi-layer conductor structure where upper and lower conductor layers are stacked vertically. The upper conductor layer is positioned directly above the lower conductor layer, forming a nested configuration that compensates for surface unevenness. This vertical stacking allows the layers to interlock and fill in the level differences caused by the wiring lines, achieving a flatter overall surface suitable for thermal transfer processes.
2Manufacturing precision
If partition walls are formed to prevent color mixture during thermal transfer, then color purity is improved, but the unevenness on top of partition walls still causes gaps when donor substrate contacts, leading to material leakage
Solution Approach 1:
The patent applies local quality by creating different surface characteristics in different regions. The conductor film structure provides localized compensation for unevenness specifically at the pixel boundaries where partition walls are located. By having the upper and lower conductor layers positioned to compensate for level differences, the patent creates locally flat contact surfaces at critical areas without requiring the entire surface to be uniformly flat, thus preventing gaps and material leakage while maintaining color purity.
3Reliability
If the conductor film is made thicker to reduce resistance, then electrical performance is improved, but surface unevenness increases, worsening the thermal transfer process
Solution Approach 1:
The patent applies the dimensionality change principle by transitioning from a single-layer horizontal conductor structure to a multi-layer vertical structure. Instead of increasing the thickness of a single conductor layer (which would worsen unevenness), the patent stacks multiple thinner conductor layers vertically. This vertical arrangement maintains the necessary electrical conductivity through the stacked layers while the precise positioning of each layer compensates for surface unevenness, achieving both electrical performance and surface flatness.
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 effectively prevents color mixture, enabling the production of display panels with excellent color reproducibility and sharpness by ensuring that light-emitting materials for different colors are accurately deposited on their respective pixels, thereby improving the overall image quality.
Implementation Method 1
By heating the donor substrate placed opposite the pixel array substrate, with the partition walls interposed therebetween, the films of light-emitting material are evaporated from the donor substrate and transferred onto the corresponding pixels on the pixel array substrate.
Data Source
AI summary
In an example embodiment, a display apparatus includes a substrate having wiring lines formed by a conductor film including signal and scanning lines arranged in columns and rows, and a matrix of pixels, and includes a light-emitting material interposed between an anode and cathode electrode and a first and second uneven zone are between the anode electrode of the pixel and an adjacent pixel. The first uneven zone is formed on the substrate due to level differences resulting from the presence of the scanning lines. The second uneven zone is formed on the substrate also due to level differences resulting from the presence of the scanning lines. A pattern of the conductor film of which the wiring lines are made is formed so part of recessed portions of the first uneven zone are located behind their corresponding raised portions of the second uneven zone, as viewed from inside the pixel.