OLED White Pixel Optical Path Control Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current organic light emitting display (OLED) technologies face challenges in achieving excellent viewing angle characteristics, low power consumption, and long lifetime, particularly due to issues with color change and brightness variation when using a combination of resonance and non-resonance pixels, which affects the display's applicability in actual displays.
Innovation Solution
The solution involves an OLED display apparatus with red, green, and blue pixels having semi-transparent electrodes and reflection electrodes, along with a white pixel featuring a transparent electrode and an optical path control layer between the transparent electrode and the white color filter, which controls the optical path and refractive index to minimize color change and maximize viewing angle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If an RGBW pixel structure with resonance RGB pixel and non-resonance white pixel is used to maximize optical efficiency, then optical transmittance is improved, but color change according to viewing angle increases severely
Solution Approach 1:
The patent applies local quality by introducing an optical path control layer specifically in the white pixel region with a refractive index matching the transparent electrode (1.7-2.2), while maintaining different electrode structures (semi-transparent for RGB, transparent for white) in different pixel types. This localized intervention corrects viewing angle characteristics in the white pixel without affecting the resonance characteristics of RGB pixels, thereby maintaining color consistency across viewing angles while preserving high optical transmittance.
2Ease of manufacture
If a white OLED-color filter method is used to improve processability and yield, then manufacturing ease is improved, but optical transmittance decreases due to color filter absorption
Solution Approach 1:
The patent applies parameter changes by optimizing the refractive index of the optical path control layer to match the transparent electrode (1.7-2.2) and controlling its thickness (50-200 nm) to minimize optical absorption while maintaining viewing angle correction functionality. This allows the white pixel to achieve high optical transmittance (greater than 90% in visible region) while still using the manufacturable WOLED-CF approach with color filters.
3Illumination intensity
If resonance structure is used in WOLED-CF method to increase optical transmittance by 30-50%, then illumination intensity is improved, but color reproducibility becomes unstable due to brightness change difference between resonance and non-resonance pixels
Solution Approach 1:
The patent introduces an optical path control layer as an intermediary element between the transparent electrode and color filter in the white pixel. This layer acts as a mediator that corrects the viewing angle characteristics by controlling light propagation paths, thereby stabilizing the brightness and color across different viewing angles while allowing the resonance structure to maintain its high optical transmittance advantage.
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 viewing angle characteristics, reduces color change, and improves power consumption while maintaining high optical transmittance, thereby addressing the limitations of existing OLED technologies.
Implementation Method 1
an optical path control layer disposed at least between the transparent electrode and the white color filter in the white pixel
Implementation Method 2
generates light by recombining electrons injected from the cathode and holes injected from the anode in the organic light emitting layer
Implementation Method 3
When a resonance structure is used in the WOLED-CF method, the optical transmittance in a frontal direction can be increased approximately 30 to 50%
Data Source
AI summary
An organic light emitting display apparatus has a hybrid structure in which resonance red, green and blue pixels and a non-resonance white pixel are combined. An optical path control layer and a white color filter which selectively absorbs light having a specific wavelength are included in the white pixel. Thus, the organic light emitting display apparatus has a large viewing angle, low power consumption, and long lifetime.