MicroLED Color Conversion Resonators for Narrow-Spectrum RGB Displays
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing microLED display technologies face challenges in achieving high color gamut and resolution due to the degradation of quantum dot materials under high input power and the thickness limitations of color conversion layers, which also result in a reduced color purity and increased full width half maximum (FWHM) spectrum.
Innovation Solution
A vertically integrated color conversion resonator system is developed, comprising partially reflective regions and color conversion resonator cavities that convert input light of specific primary peak wavelengths into distinct output wavelengths, allowing for the emission of red, green, and blue light with improved color purity and narrow spectra.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If quantum dot materials are used for color conversion in microLED displays, then color gamut can be improved, but the materials degrade under high input power
Solution Approach 1:
The patent divides the color conversion function into multiple vertically stacked microLED layers, each emitting a different primary color (red, green, blue). This segmentation eliminates the need for quantum dot materials that degrade under high power, as each layer directly emits its color through electroluminescence. The segmentation also enables independent optimization of each layer's emission characteristics.
Solution Approach 2:
The patent introduces DBR (distributed feedback reflector) structures as intermediary optical elements between the microLED layers and the output. These DBR structures mediate the light extraction process, enhancing the directionality and purity of emitted light while reducing the need for high input power that would otherwise cause quantum dot degradation.
2Measurement precision
If color conversion layer thickness is increased to improve color purity, then FWHM spectrum decreases, but light extraction efficiency is reduced
Solution Approach 1:
The patent transitions from a planar color conversion approach to a vertical three-dimensional stacking architecture. Multiple microLED layers are stacked vertically, each contributing to the overall color output. This dimensional change allows light to be extracted from multiple directions and planes, improving both color purity and extraction efficiency simultaneously by reducing the trade-off present in single-layer configurations.
Solution Approach 2:
The patent implements a nested structure where multiple microLED layers are vertically integrated, with each layer containing embedded DBR structures. The DBR structures are nested within the microLED layers, creating a compact hierarchical arrangement that enhances light extraction while maintaining color purity through the nested optical cavities.
3Illumination intensity
If multiple separate LED devices are used to provide red, green, and blue light, then color gamut is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple separate LED devices into a single vertically integrated microLED stack. The red, green, and blue emitting layers are combined in a unified structure with shared substrate and electrical connections. This merging reduces device complexity by eliminating the need for separate mounting, alignment, and electrical connection of multiple discrete LED devices while maintaining full color gamut capability.
Solution Approach 2:
The patent creates a universal microLED stack structure that performs multiple functions simultaneously: each layer generates its primary color, the DBR structures provide optical enhancement, and the vertical integration enables compact pixel formation. This multi-functional design reduces overall system complexity by consolidating what would otherwise require separate components for color generation, optical management, and pixel formation.
4Device complexity
If conventional LED structures are used without resonator cavities, then device simplicity is maintained, but color purity and directionality are reduced
Solution Approach 1:
The patent employs optical resonance within DBR cavities, where light waves oscillate and reinforce specific wavelengths through constructive interference. This resonant effect enhances color purity by selectively amplifying the desired emission wavelengths while suppressing others, achieving high color purity without significantly increasing structural complexity beyond the integrated DBR layers.
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 system achieves high color gamut and resolution by providing distinct wavelengths of light with narrow FWHM spectra, enhancing light output control and directionality, and eliminating the need for collimators or complex lens integration, while also enabling wafer-level processing and high-resolution microLED arrays.
Implementation Method 1
a first colour conversion resonator cavity arranged to receive input light with the first primary peak wavelength through the first partially reflective region and to convert at least some of the light of the first primary peak wavelength to provide light of the second primary peak wavelength, wherein the first colour conversion resonator cavity is arranged such that the second primary peak wavelength resonates in the first colour conversion resonator cavity
Implementation Method 2
a first partially reflective region configured to transmit light of a first primary peak wavelength and to reflect light of a second primary peak wavelength
Implementation Method 3
a first colour conversion resonator cavity arranged to receive input light with the first primary peak wavelength through the first partially reflective region and to convert at least some of the light of the first primary peak wavelength to provide light of the second primary peak wavelength
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A colour conversion resonator system (600) comprising: a first partially reflective region (120) transmitting light (742) of a first wavelength and reflecting light (744) of a second wavelength; a second partially reflective region (116) at least partially transmitting light of the first and second wavelengths and reflecting light (746) of a third wavelength; a third partially reflective region (112) at least partially reflecting light of the third wavelength; a first colour conversion resonator cavity (118) receiving input light with the first wavelength through the first partially reflective region and converting at least some of the light of the first wavelength to light of the second wavelength, wherein the first colour conversion resonator cavity is such that the second wavelength resonates in the first colour conversion resonator cavity and resonant-light with the second wavelength is output through the second partially reflective region; and a second colour conversion resonator cavity (114) receiving input light comprising the second wavelength through the second partially reflective region and converting at least some of the second wavelength to light of the third wavelength, wherein the second colour conversion resonator cavity is such that the third wavelength resonates in the second colour conversion resonator cavity and resonant-light with the third wavelength is output through the third partially reflective region, wherein the first and second resonator cavities are arranged to partially overlap to provide a non-overlapping and an overlapping portion thereby defining first and second light emitting surfaces respectively, wherein the first light emitting surface is providing resonant-light of the second wavelength and the second light emitting surface is providing resonant-light of the third wavelength.