Organic EL Panel Microcavity Segmentation Viewing Angle Dependence
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Solution Overview
Problem
Organic EL display devices with microcavities suffer from significant viewing angle dependence due to variations in optical length when viewed from different angles, affecting the wavelength of enhanced light.
Innovation Solution
Incorporating regions with no microcavity structure or varying the thickness of semi-transmissive films to adjust the microcavity effect based on color, allowing for differentiated cavity lengths for each pixel to reduce viewing angle dependence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a microcavity structure is used to enhance light of a specific wavelength, then the brightness and color purity are improved, but the viewing angle dependence increases significantly
Solution Approach 1:
The pixel is divided into multiple regions with different microcavity structures. Each region has a different cavity length optimized for specific viewing angles, allowing the pixel to maintain color purity across a wide viewing range by segmenting the enhancement function across multiple specialized zones
Solution Approach 2:
Different regions within the pixel are assigned different microcavity characteristics (different cavity lengths) tailored to their specific function. Regions are optimized for different viewing angles, with each local area having the quality needed for its intended purpose, thereby reducing overall viewing angle dependence
2Manufacturing precision
If the cavity length is increased to enhance specific wavelengths, then the color purity is improved, but the viewing angle dependence becomes larger
Solution Approach 1:
The pixel is divided into multiple regions with different microcavity structures. Each region has a different cavity length optimized for specific viewing angles, allowing the pixel to maintain color purity across a wide viewing range by segmenting the enhancement function across multiple specialized zones
Solution Approach 2:
The cavity length parameter is varied across different regions of the pixel rather than using a uniform length. By changing this critical parameter spatially, the system achieves broad viewing angle compatibility while maintaining color purity for each specific viewing direction
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 effectively enhances specific wavelengths while minimizing viewing angle dependence, maintaining color purity across different angles.
Implementation Method 1
an organic EL panel having, in each pixel, a micro-resonator (i.e., microcavity) capable of enhancing the light of a specific wavelength
Implementation Method 2
a region where the thickness of a semi-transmissive film is differentiated
Implementation Method 3
the optical length of the microcavity when seen from the vertical direction is different from an optical length seen from an oblique direction
Data Source
AI summary
Each pixel includes a region where a lower reflection film is not present. In each pixel, there is a region where a microcavity structure is formed between a counter electrode and a lower reflection film and another region where the microcavity structure is not formed. The regions differentiated in cavity length can differently enhance the peak wavelength so as to improve the viewing angle dependence. Furthermore, in each of R, G, and B light emitting pixels, the area ratio of a region where the microcavity structure is present and another region where the microcavity structure is not present can be adjusted so as to eliminate the differences caused by the microcavity structure.