Organic EL Display Optical Path Length Adjusting Insulating Layer
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Solution Overview
Problem
Organic EL display devices suffer from variations in luminance and color due to interference effects caused by differences in refractive indices between functional thin layers, leading to poor viewing angle characteristics and display quality.
Innovation Solution
A light emitting display with a plurality of pixels, each featuring an emitting element layer between electrodes, an insulating layer with convexity/concavity to adjust optical path lengths, and a wavelength adjusting layer to control interference conditions, thereby averaging interference effects and stabilizing color and luminance across viewing angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a stacked layer structure with multiple functional thin layers is used in the emitting element, then the display can achieve high luminance and various colors, but reflection occurs at interfaces between layers with different refractive indices, causing interference and variation in luminance and color
Solution Approach 1:
The patent divides the pixel region into multiple regions with different optical path lengths by forming convexities and concavities in the insulating layer. This segmentation creates multiple interference conditions that average out the interference effects, reducing color variation and improving color uniformity across the display.
Solution Approach 2:
The patent applies local quality changes by creating specific convex and concave portions in the insulating layer at different locations within the pixel region. These local structural variations adjust the optical path length locally, ensuring that interference conditions vary across different regions, thereby averaging the overall interference effect and improving color consistency.
2Device complexity
If light directly emits from the emitting layer, then the display structure remains simple, but reflected light interferes with direct light causing phase differences and luminance variation
Solution Approach 1:
The patent introduces a new dimension to the insulating layer structure by forming three-dimensional convexities and concavities. This dimensional change creates multiple optical path lengths without adding complex additional layers, effectively managing interference while maintaining relatively simple device structure.
3Device complexity
If a single optical path length is used from the emitting layer to the display surface, then the device structure is simple, but interference conditions are fixed leading to color variation with viewing angle
Solution Approach 1:
The patent creates dynamic interference conditions by forming multiple optical path lengths within the pixel region. This allows the interference pattern to vary with viewing angle, effectively averaging out color variations and improving viewing angle characteristics without requiring complex dynamic adjustment mechanisms.
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 effectively reduces color and luminance variations, improving display quality by averaging interference conditions across the viewing angle, resulting in more consistent and accurate color representation.
Implementation Method 1
light directly emitting from an emitting layer has a different phase from light reflected midway before emission, causing interference on the observation surface side
Implementation Method 2
different materials are used depending on the function of each layer, resulting in different refractive indices in different layers
Data Source
AI summary
Disclosed is a light-emitting display having a plurality of pixels wherein each pixel comprises a light-emitting device (100) having a light-emitting element layer which is formed between a first electrode and a second electrode and contains at least a light-emitting layer. An insulating layer (30) is formed between the light-emitting device (100) and a surface of a first or second substrate on the viewing side of the display, and the insulating layer (30) is provided with recesses and projections in at least one or more pixel regions, thereby forming an optical path length adjusting portion (32). By forming such an optical path length adjusting portion (32) in a pixel region, there is an increase in the interference conditions for the light emitted from the light-emitting device (100) to the outside, thereby averaging the interference.