Bank Sidewall Inclination Angles for OLED Film Thickness Uniformity
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Solution Overview
Problem
Maintaining a uniform film thickness of the organic light emitting layer across the entire display device panel is challenging due to the difficulty in precisely forming convexities on the inner surface of the banks, leading to uneven luminance.
Innovation Solution
The display device features banks with varying inclination angles to control the pinning locations of the ink, where the inclination angle of the side walls is adjusted to achieve a uniform film thickness by increasing the angle for thinner layers and decreasing it for thicker layers, ensuring even luminance across the panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If convexities are formed on the inner surface of the bank to control pinning location, then film thickness uniformity is improved, but manufacturing precision deteriorates due to difficulty in forming minute convexities with high precision across the entire panel
Solution Approach 1:
The invention changes the geometric parameters of the bank structure by varying the inclination angles of side walls in different regions. Instead of forming minute convexities, the patent adjusts the inclination angle of bank side walls to control ink pinning locations, making the structure easier to manufacture while achieving uniform film thickness across the panel
Solution Approach 2:
The invention applies local quality by making different parts of the bank structure have different inclination angles. Banks in different regions (central vs. peripheral) have differently inclined side walls to compensate for position-dependent variations in film thickness, achieving uniformity without requiring high-precision convexity formation
2Manufacturing precision
If the same bank structure is used across the entire panel, then device complexity is reduced, but film thickness uniformity deteriorates due to position-dependent variations
Solution Approach 1:
The patent implements local quality by varying the inclination angles of bank side walls according to their position on the panel. Central regions have different inclination angles compared to peripheral regions, allowing each area to be optimized for its specific position while maintaining overall uniformity
Solution Approach 2:
The invention segments the bank structure into different regions with different inclination angle characteristics. By dividing the panel into central and peripheral regions and assigning different bank geometries to each, the patent achieves uniform film thickness without requiring complex convexity formation across the entire structure
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 approach results in a uniform film thickness and even luminance throughout the display device panel by varying the inclination angles of the bank side walls, addressing the issue of non-uniformity in existing technologies.
Implementation Method 1
progress has been made in the research and development of display devices that use the phenomenon of electroluminescence occurring in organic material
Implementation Method 2
The organic light emitting layer is formed by dripping ink that includes organic light emitting material into each region partitioned by the banks and drying the ink
Data Source
AI summary
A display device includes an array of light emitting cells. Banks define each of the light emitting cells. The light emitting cells include a first light emitting cell that is located in a central region of the array and a second light emitting cell that is located in a peripheral region of the array. First and third banks border the first light emitting cell with the first bank being closer to a periphery of the array than the second bank. Second and fourth banks border the second light emitting cell with the third bank being closer to the periphery of the array than the fourth bank. An inclination angle of an innermost sidewall of the third bank that is adjacent the second light emitting cell is different than an inclination angle of an innermost sidewall of the first bank that is adjacent the first light emitting cell.