OLED Encapsulation Layer Layout for Front Visibility and Light Extraction
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Solution Overview
Problem
Organic light emitting display devices suffer from reduced light emission efficiency and display quality due to light reflection and total reflection at interfaces within their multi-layer structure, leading to degraded luminance and visibility.
Innovation Solution
The implementation of a specific layer structure comprising a substrate, electrodes, an organic light emitting layer, a thin film encapsulation layer, a sensing electrode, a low refractive index layer, and a high refractive index layer, where the gap between the edges of the openings defined by these layers is constant and the interface between the low and high refractive index layers forms an angle between 40° to 70°, optimizing light reflection and emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a multi-layer structure including OLED and touch portion is used, then touch functionality is achieved, but light reflection and total reflection occur at interfaces degrading light emission efficiency
Solution Approach 1:
The patent applies the principle of converting harm into benefit by utilizing the harmful light reflection and total reflection at layer interfaces to redirect light towards the front surface. The specific layer structure with low and high refractive index layers transforms the energy loss from reflection into useful light emission in the desired direction, improving front visibility while maintaining touch functionality.
2Loss of energy
If light reflection at interfaces is reduced, then light emission efficiency improves, but front visibility and directional light control may be compromised
Solution Approach 1:
The patent applies local quality by creating specific regions with different refractive indices at strategic locations within the display structure. The low refractive index layer and high refractive index layer are positioned to locally modify light reflection characteristics, directing light preferentially towards the front surface while maintaining overall light emission efficiency.
Solution Approach 2:
The patent utilizes parameter changes by varying the refractive index of specific layers to control light behavior. By introducing layers with low refractive index (1.3-1.6) and high refractive index (1.7-1.9), the patent modifies the optical parameters at layer interfaces to achieve desirable light directionality and front visibility without sacrificing emission efficiency.
3Manufacturing precision
If the gap between openings is reduced, then manufacturing precision is improved, but light reflection effects may be compromised
Solution Approach 1:
The patent applies composite materials by combining layers with different refractive indices (low refractive index layer with 1.3-1.6 and high refractive index layer with 1.7-1.9) to create a composite optical structure. This composite approach allows the system to maintain light reflection control effectiveness even with variations in gap dimensions, reducing sensitivity to manufacturing precision requirements.
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 enhances front visibility and light emission efficiency by directing light towards the front surface, improving display quality and maintaining consistent luminance across different viewing angles.
Implementation Method 1
a low refractive index layer on the sensing electrode, the low refractive index layer defining a second opening which overlaps the first opening; and a high refractive index layer on the thin film encapsulation layer
Implementation Method 2
When a light generated in the OLED is emitted to the outside, reflection, total reflection, or the like, of the light may occur at interfaces between layers
Data Source
AI summary
An organic light emitting display device includes: a substrate; a first electrode on the substrate; a pixel defining layer on the substrate, the pixel defining layer defining a first opening which exposes at least a part of the first electrode; an organic light emitting layer on the first electrode; a second electrode on the organic light emitting layer; a thin film encapsulation layer on the second electrode; a sensing electrode on the thin film encapsulation layer; a low refractive index layer on the sensing electrode, the low refractive index layer defining a second opening which overlaps the first opening; and a high refractive index layer on the thin film encapsulation layer. A gap between an edge of the first opening and an edge of the second opening is constant irrespective of direction.