Display Device Insulating Layer Leakage Current Prevention
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Solution Overview
Problem
Current display devices face challenges in achieving high resolution, high definition, and high reliability, particularly in manufacturing processes where leakage current and crosstalk between subpixels can decrease display quality and yield.
Innovation Solution
A display device design featuring island-shaped EL layers separated between light-emitting devices, with an insulating layer forming openings to prevent leakage current, and a manufacturing method that includes forming a common electrode over EL layers without using a shadow mask, allowing for higher temperature processing to enhance reliability and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a shadow mask is used to form common electrode, then manufacturing precision can be improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent removes the shadow mask from the manufacturing process entirely. The common electrode is formed by directly depositing conductive material over the entire surface, and the insulating layer with openings is used to prevent leakage current instead of the shadow mask pattern. This extraction of the shadow mask simplifies the manufacturing process while maintaining precision through the insulating layer structure.
Solution Approach 2:
The patent segments the common electrode formation process into two parts: (1) a continuous common electrode layer deposited over the entire surface, and (2) an insulating layer with openings that selectively exposes regions where leakage current prevention is needed. This segmentation allows the common electrode to be formed without shadow mask while still achieving precise control over current paths.
2Reliability
If lower temperature processing is used to protect EL layers, then reliability can be improved, but productivity decreases due to process constraints
Solution Approach 1:
The patent applies a low-melting-point glass layer beforehand as a protective cushioning layer during higher temperature processing steps. This protective layer prevents damage to the EL layers during temperature annealing or firing processes, enabling higher temperature processing that improves productivity without compromising the reliability of the light-emitting layers.
3Reliability
If insulating layer openings are made smaller to reduce leakage current, then reliability improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality by creating openings in the insulating layer only in specific regions where leakage current paths exist between adjacent light-emitting devices. The openings are strategically positioned at the boundaries between devices rather than uniformly across the entire structure. This localized approach prevents leakage current while minimizing the total number and size of openings required, thereby reducing manufacturing precision requirements compared to a uniform opening pattern.
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
The solution enables high-resolution, high-definition display devices with reduced leakage current and crosstalk, improving display quality and manufacturing efficiency by preventing horizontal leakage current and allowing for higher temperature processing to protect the light-emitting layers.
Implementation Method 1
an insulating layer which includes an opening... The insulating layer includes a first surface in contact with a side surface of the first pixel electrode... a third surface in contact with a bottom surface of the first EL layer
Implementation Method 2
Light-emitting devices utilizing an electroluminescence (hereinafter referred to as EL) phenomenon (also referred to as EL devices or EL elements)
Data Source
AI summary
A display device with high display quality is provided. The display device includes a first light-emitting device, a second light-emitting device, and an insulating layer. The first light-emitting device includes a first pixel electrode, a first EL layer, and a common electrode. The second light-emitting device includes a second pixel electrode, a second EL layer, and the common electrode. The insulating layer includes an opening, and includes a first surface in contact with a side surface of the first pixel electrode, a second surface facing the first surface, and a third surface in contact with a bottom surface of the first EL layer. The insulating layer includes a region where the third surface and the top surface of the first pixel electrode are level or substantially level with each other. In a cross-sectional view, an angle formed between the second surface and the third surface is greater than or equal to 80° and less than or equal to 110°. The first EL layer contains the same material as the second EL layer. The first EL layer is separated from the second EL layer.