Scattering Layer for OLED Microdisplay Color Cast Reduction
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Solution Overview
Problem
Silicon-based OLED microdisplays have relatively low brightness, limiting their application in Augmented Reality (AR) and Virtual Reality (VR) due to significant color cast issues at wider viewing angles caused by strong microcavity effects, which are not effectively corrected by traditional color filters.
Innovation Solution
Incorporating a scattering layer with randomly arranged protuberances on the microcavity adjustment layer of the white sub-pixel to reduce color cast to less than 0.025 across a viewing angle range of −50 to +50 degrees, thereby enhancing luminance and expanding the viewing angle without negative impact on light extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a strong microcavity effect is used to enhance luminance, then brightness is improved, but color cast increases at wider viewing angles
Solution Approach 1:
A scattering layer is introduced as an intermediary component between the microcavity adjustment layer and the emitting layer. This scattering layer mediates the interaction between the microcavity effect and the emitted light, allowing the strong microcavity effect to enhance luminance while the scattering layer simultaneously reduces color cast at wide viewing angles by scattering the light to minimize the microcavity effect's negative impact.
2Adaptability or versatility
If the viewing angle is expanded to −50 to +50 degrees, then the usable viewing range is improved, but color cast control becomes more difficult
Solution Approach 1:
The scattering layer serves as a mediator that enables the system to achieve a wide viewing angle range of −50 to +50 degrees while maintaining color cast control. The scattering layer's random protuberances scatter light in multiple directions, allowing viewers to see the display from wide angles without experiencing significant color cast, thus resolving the contradiction between viewing angle expansion and color cast control.
3Manufacturing precision
If traditional color filters are used to correct color cast, then color accuracy is improved, but brightness is reduced
Solution Approach 1:
Instead of using traditional color filters that block light to correct color cast, the invention converts the harmful microcavity effect into a beneficial tool by maintaining a strong microcavity effect for high brightness while using a scattering layer to mitigate color cast. This approach transforms the previously harmful wide-angle color cast issue into an opportunity to achieve both high brightness and acceptable color accuracy without light loss from filtering.
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
The solution significantly reduces color cast at large viewing angles, improving the luminance and brightness of silicon-based OLED displays while maintaining ultra-high brightness, enabling wider viewing angles under high microcavity conditions.
Implementation Method 1
a scattering layer, configured to reduce color cast of the first sub-pixel to be less than about 0.025 at viewing angles in a range of about −50 degree to +50 degree
Implementation Method 2
forming a first microcavity adjustment layer in a first sub-pixel configured to emit white light
Data Source
AI summary
A light emitting diode includes a pixel unit. The pixel unit may include a first sub-pixel configured to emit white light. The first sub-pixel may include a first microcavity adjustment layer, a scattering layer, a first transparent electrode layer, a first emitting layer, and a first semi-transparent electrode layer. The scattering layer includes a plurality of patterns formed on a surface of the scattering layer. The scattering layer may be configured to reduce color cast of the first sub-pixel to be less than about 0.025 at viewing angles in a range of about −50 degree to +50 degree.