OLED Encapsulation Bank Structure for Low-Reflection Mask Alignment
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Solution Overview
Problem
Display devices face challenges in reducing external light reflection and minimizing defects due to residual films, while also requiring easy mask alignment during manufacturing.
Innovation Solution
The display device incorporates a substrate with an emission layer, an encapsulation layer comprising inorganic and organic films, and a dam structure with sub-dams and banks, including light-blocking materials to manage the encapsulation layer and prevent film overflow, facilitating alignment and reducing reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a thin-film encapsulation layer is applied to make the OLED display thinner and flexible, then the display device becomes thinner and more flexible, but external light reflection increases and defects due to residual films occur
Solution Approach 1:
The encapsulation layer is segmented into multiple thin films (first encapsulation layer, second encapsulation layer, third encapsulation layer) with different materials and functions. Each layer addresses specific issues: the first layer provides base encapsulation, the second layer reduces light reflection, and the third layer prevents residual film defects, thereby solving the harmful effects while maintaining thinness.
Solution Approach 2:
The encapsulation structure uses composite materials consisting of organic and inorganic layers. The first encapsulation layer uses an organic material, the second layer uses an inorganic material with low refractive index for anti-reflection, and the third layer uses an organic material to prevent residual films. This composite structure addresses multiple issues simultaneously.
2Manufacturing precision
If a dam structure is formed to prevent overflow of organic film and support mask, then the encapsulation layer is properly contained, but mask alignment becomes difficult and manufacturing complexity increases
Solution Approach 1:
The bank structure incorporates a light-blocking layer in specific regions to create local visual references. This light-blocking layer is positioned at the outer side of the bank to provide a clear alignment reference for mask placement, making mask alignment easier without compromising the dam's containment function.
Solution Approach 2:
The light-blocking layer acts as an intermediary element between the bank structure and the mask. It provides a visual reference that facilitates mask alignment while the bank itself maintains the structural support and containment functions. This intermediary layer solves the alignment difficulty without affecting the primary containment purpose.
3Object-affected harmful factors
If multiple encapsulation layers are used to reduce reflection and prevent defects, then external light reflection is reduced and residual film defects are minimized, but device structure becomes more complex
Solution Approach 1:
The encapsulation problem is segmented into three distinct layers, each with a specific function: the first layer for base encapsulation, the second layer for light reflection reduction, and the third layer for preventing residual film defects. This segmentation allows each layer to be optimized for its specific purpose while collectively solving multiple harmful effects.
Solution Approach 2:
The bank structure serves multiple functions: it acts as a dam to prevent organic film overflow, provides mechanical support for the mask during manufacturing, and includes a light-blocking layer that serves as both a structural component and an alignment reference. This multi-functionality reduces the need for additional separate components, thereby managing complexity.
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 effectively reduces external light reflection, minimizes defects from residual films, and simplifies mask alignment during the manufacturing process.
Implementation Method 1
The pixel defining layer is disposed between the plurality of emission areas and includes a light blocking material... The third bank layer includes the light blocking material
Data Source
AI summary
A display device includes a substrate; an emission layer disposed on the substrate, and including emission areas and a pixel defining layer disposed between the emission areas and including a light blocking material; an encapsulation layer disposed on the emission layer, and including a first inorganic encapsulation film, an organic encapsulation film on the first inorganic encapsulation film, and a second inorganic encapsulation film on the organic encapsulation film; a dam surrounding the organic encapsulation film, comprising an organic material, and including a plurality of sub-dams; and a bank disposed to surround at least a portion of the dam, and including a first bank layer, a second bank layer on the first bank layer, a third bank layer on the second bank layer, and a fourth bank layer on the third bank layer, wherein the third bank layer includes the light blocking material.