OLED Cathode Thickness Control for Viewing Angle Color Shift
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Solution Overview
Problem
State-of-the-art OLED displays face challenges with viewing angle color shift, off-angle emission intensity, and color point drift due to the angular intensity distributions of RGB OLEDs, which affect the display's color accuracy and efficiency.
Innovation Solution
The implementation of polarization sensitive diffusers, subpixel cathode thickness control, various filtermask configurations, touch detection layers, and color filters to control reflection performance and angular performance, including the use of a polarization sensitive diffuser layer with a quarterwave film and linear polarization film, and independent cathode layer thickness for each subpixel to match luminance distributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If top emission OLED architecture with optical microcavity effect is used to enhance optical efficiency, then optical efficiency is improved, but viewing angle color shift occurs due to different angular intensity distributions of RGB OLEDs
Solution Approach 1:
The patent applies local quality by implementing different cathode layer thicknesses for different subpixels (red, green, blue). Each subpixel's cathode thickness is specifically optimized to compensate for its unique angular intensity distribution characteristics, thereby reducing viewing angle color shift while maintaining the optical microcavity effect's efficiency benefits.
Solution Approach 2:
The patent changes physical parameters by varying the cathode layer thickness for each subpixel. This parameter adjustment modifies the optical cavity resonance conditions differently for each color, allowing compensation of angular intensity variations and reduction of color shift at different viewing angles.
2Ease of manufacture
If different cathode layer thicknesses are used for each subpixel to match luminance distributions, then viewing angle performance is improved, but device complexity increases
Solution Approach 1:
The patent segments the cathode layer into different thickness regions corresponding to different subpixels. This segmentation allows independent optimization of each subpixel's optical characteristics while maintaining a unified display structure, thereby improving viewing angle performance without requiring completely separate cathode structures for each color.
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 reduces white off-angle color shift, improves viewing angle performance, and increases on-axis efficiency while lowering panel power consumption by adjusting cathode thickness and using filtermasks to match luminance distributions across subpixels.
Implementation Method 1
polarization sensitive diffuser layer with a quarterwave film and linear polarization film
Implementation Method 2
polarization sensitive diffuser layer
Implementation Method 3
liquid crystal polymer film includes a top surface characterized by a higher average surface roughness
Implementation Method 4
emissive light emitting diode (LED)
Implementation Method 5
filtermask over the passivation layer, the filtermask including an aperture over the first LED
Data Source
AI summary
Display structures for controlling viewing angle color shift are described. In various embodiments, polarization sensitive diffusers, independent controlled cathode thicknesses, filtermasks, touch detection layers, and color filters are described.