OLED Sub-Pixel Thickness Variation for Angle-Dependent Color Shift
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Solution Overview
Problem
OLED display panels experience significant color shift and brightness reduction when viewed from different angles due to changes in electroluminescence spectrum, leading to varying visual sensations for users.
Innovation Solution
The display panel incorporates sub-pixels with multiple light-emitting areas of varying thicknesses, where the first and second light-emitting layers are sequentially arranged perpendicular to the light-emitting direction, and manufactured using different masks to achieve distinct microcavity characteristics, ensuring the electroluminescence spectrum remains stable across viewing angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a uniform thickness light-emitting layer is used in OLED display panels, then the manufacturing process is simple, but the electroluminescence spectrum changes significantly at different viewing angles, causing color shift and brightness reduction
Solution Approach 1:
The light-emitting layer is segmented into multiple regions (first light-emitting area and second light-emitting area) with different thicknesses. The first light-emitting layer has a first thickness in the first light-emitting area, while the second light-emitting layer has a second thickness in the second light-emitting area. This segmentation allows different portions of the light-emitting layer to emit light at different wavelengths, compensating for the microcavity effect and reducing color shift at different viewing angles.
2Stability of the object's composition
If multiple light-emitting areas with different thicknesses are used, then the electroluminescence spectrum stability is improved, but the manufacturing process becomes more complex
Solution Approach 1:
Different regions of the light-emitting layer are given different local properties (thickness). The first light-emitting area has a first thickness optimized for certain wavelengths, while the second light-emitting area has a second thickness optimized for other wavelengths. This local quality variation allows the display panel to maintain consistent color output across different viewing angles by compensating for the angle-dependent microcavity effect in different regions.
3Stability of the object's composition
If multiple light-emitting areas with different thicknesses are used, then color shift is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The thickness parameter of the light-emitting layer is varied across different regions to achieve different optical effects. By controlling the thickness of the first light-emitting layer and second light-emitting layer to have different values, the patent modifies the optical path length and interference conditions in each region, thereby adjusting the emitted spectrum to compensate for viewing angle effects and maintain color consistency.
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 results in a wider peak range for the overall microcavity characteristic curve, reducing color shift and maintaining consistent color perception across different viewing angles, thereby enhancing user experience.
Implementation Method 1
a first light-emitting layer is disposed in the first light-emitting area, a second light-emitting layer is disposed in the second light-emitting area, and a thickness of the second light-emitting layer is greater than a thickness of the first light-emitting layer
Implementation Method 2
the electroluminescence spectrum changes less with change of viewing angles
Data Source
AI summary
The present disclosure provides a display panel. The light-emitting layers within a same sub-pixel have different thicknesses, and emit light that overlap with each other at the same time, resulting in that the peak of the overall microcavity characteristic curve has a wide range. Thus, the position of the peak of the overall microcavity characteristic curve produced by the sub-pixel can overlap with the position of the peak of the inherent brightness characteristic curve of the light-emitting layer within a wider range of angles, such that the electroluminescence spectrum changes less with change of viewing angles. Therefore, the color shift at different viewing angles is reduced, and there is no substantial difference for visual sensation for color when viewing the OLED display panel including such sub-pixels at different viewing angles.