OLED Pixel Electrode Flatness for Stable Color and Luminance
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Solution Overview
Problem
In organic light-emitting display apparatuses, the luminance ratio of pixels emitting different colors can deviate from preset ratios, affecting image quality, particularly due to variations in the flatness of pixel electrode surfaces and emission layer thicknesses, which impact luminance and color coordinates.
Innovation Solution
The apparatus includes multiple pixel electrodes with specific flatness and emission layers emitting light within distinct wavelength bands, where the flatness of the pixel electrodes' surfaces is controlled to optimize the root mean square of stepped portions, ensuring consistent luminance and color coordinates across different viewing angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If pixel electrodes have uniform flatness, then manufacturing process is simplified, but luminance ratio and color coordinates cannot be precisely controlled across different viewing angles
Solution Approach 1:
The patent applies local quality by assigning different flatness characteristics to different pixel electrodes based on their specific color emission requirements. Blue pixel electrodes have RMS of 14-33nm, green pixel electrodes have RMS of 11-22nm, and red pixel electrodes have RMS of 2-11nm. This localized differentiation allows each color to achieve optimal luminance ratio and color coordinates while maintaining overall manufacturing feasibility.
2Manufacturing precision
If pixel electrodes have varying flatness for precise luminance control, then image quality improves, but manufacturing complexity increases
Solution Approach 1:
The patent implements parameter changes by systematically varying the RMS values of pixel electrode surfaces according to color type. By establishing specific RMS ranges for each color (blue: 14-33nm, green: 11-22nm, red: 2-11nm), the patent transforms a complex control problem into a manageable parameter specification system that can be integrated into existing manufacturing processes.
3Illumination intensity
If emission layer thickness is increased to improve luminance, then brightness increases, but color coordinates and luminance ratio precision deteriorates
Solution Approach 1:
The patent applies local quality by optimizing emission layer thickness specifically for each pixel electrode based on its color and flatness characteristics. Rather than using a uniform thickness across all pixels, the emission layer thickness is locally adjusted to compensate for variations in pixel electrode flatness, ensuring that each color maintains precise color coordinates and luminance ratio while achieving sufficient brightness.
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 the display's ability to maintain high-quality image rendering by stabilizing luminance ratios and color coordinates, even at varying viewing angles, by precisely managing the flatness and emission layer thicknesses of the pixel electrodes.
Implementation Method 1
a first color emission layer on the first pixel electrode, and a second color emission layer on the second pixel electrode and configured to emit light having a wavelength longer than a wavelength of light emitted by the first color emission layer
Data Source
AI summary
An organic light-emitting display apparatus includes: a first pixel electrode; a second pixel electrode spaced apart from the first pixel electrode and comprising a top surface that is flatter than a top surface of the first pixel electrode; a first color emission layer on the first pixel electrode; and a second color emission layer on the second pixel electrode and configured to emit light having a wavelength longer than a wavelength of light emitted by the first color emission layer.