Yasuaki Hirano | Sharp: How did Sharp double the sRGB color gamut of their monolithic MicroLED displays?
09:11 - 10:11
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Summary of the clip:
How did Sharp double the sRGB color gamut of their monolithic MicroLED displays?
In monolithic MicroLED arrays, blue GaN LEDs are fabricated on a single wafer and paired with red and green quantum dot color conversion layers. However, at sub-24-micron pixel pitches, lateral light leakage causes severe optical crosstalk between sub-pixels.
To prevent this bleed, Sharp integrated reflective light-shielding walls (LSW) made of aluminum between individual sub-pixels. These micro-fabricated structures act as physical barriers, ensuring that blue excitation light does not inadvertently leak into adjacent red or green quantum dot channels.
The inclusion of these light-shielding walls dramatically reshaped the display's optical performance. Without these barriers, the sRGB color gamut is limited to a poor 60% due to color mixing, but with the walls, the gamut reaches an exceptional 120% sRGB.
In this short video, you can learn:
* The microfabrication of reflective aluminum light-shielding walls between sub-24μm pixels to prevent optical crosstalk.
* How lateral light leakage from blue GaN MicroLEDs degrades color purity in quantum dot conversion layers.
* The experimental comparison showing a doubling of color gamut from 60% to 120% sRGB using integrated micro-walls.
📋 **Clip Abstract** This clip demonstrates how Sharp resolved sub-pixel optical crosstalk in monolithic color-converted MicroLED displays. By incorporating micro-fabricated reflective light-shielding walls, they boosted the display's color gamut from 60% to 120% sRGB.
#MonolithicMicroLED, #QuantumDotColorConversion, #LightShieldingWalls, #OpticalCrosstalkMitigation, #MicroLEDDisplays, #AugmentedRealityDisplays
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03:50 - 05:15
Why does outdoor AR require a 1,000,000 nit light engine just to deliver 1,000 nits to your eye?
Why does outdoor AR require a 1,000,000 nit light engine just to deliver 1,000 nits to your eye?
Waveguide-based augmented reality glasses suffer from severe optical attenuation. Standard diffractive optical elements and holographic waveguides exhibit an internal coupling efficiency of only about 1%, meaning 99% of the incoupled light is lost before reaching the user's eye.
Furthermore, quantum-dot color-converted light engines exhibit a highly Lambertian emission profile. Due to the limited numerical aperture of coupling lenses, which typically have a restricted 30-degree acceptance angle, only about 13% of the generated light is successfully collected and directed into the waveguide.
To combat this combined system efficiency of under 0.13%, a microdisplay engine must output an astonishing 1 million nits (1 Mnit) to achieve a readable 1,300 nits at the eye. This immense brightness requirement disqualifies current microOLED technologies, making high-efficiency GaN MicroLEDs the primary candidate for outdoor AR.
In this short video, you can learn:
* How diffractive waveguide optics lose up to 99% of display luminance before reaching the user's eye.
* Why the Lambertian emission profile of quantum dots limits light collection to just 13% through standard coupling optics.
* The mathematical justification for why GaN-based MicroLEDs are required to hit outdoor AR brightness thresholds.
📋 **Clip Abstract** This clip breaks down the optical efficiency budget of diffractive waveguides and coupling lenses in AR systems. It explains why a 1,000,000 nit light source is required to achieve a functional 1,300 nits at the eye.
#GaNMicroLEDs, #DiffractiveWaveguides, #LambertianEmission, #MicroDisplayEngines, #AugmentedReality, #NearEyeDisplays
10:11 - 11:53
How do you scale full-color MicroLEDs to 3,600 PPI without losing quantum dot efficiency?
How do you scale full-color MicroLEDs to 3,600 PPI without losing quantum dot efficiency?
Scaling monolithic MicroLEDs to an ultra-dense 3,600 PPI pixel pitch poses extreme fabrication and material challenges. As the sub-pixel size shrinks, the available area for depositing cadmium-free quantum dots reduces, leading to low external quantum efficiency (EQE).
To maximize the active emission area, Sharp implemented a common cathode pixel architecture. This design eliminates the routing margins required for individual cathode contacts, allowing more physical space for quantum dot deposition and light emission.
To match this ultra-fine pitch, the reflective light shielding walls had to be scaled down to sub-micron widths. This co-design of common-cathode layouts and ultra-narrow optical isolation barriers enabled Sharp to demonstrate a fully functional 3,600 PPI full-color microdisplay.
In this short video, you can learn:
* The design shift to common cathode architectures to maximize active quantum dot emission area at sub-10μm sub-pixel pitches.
* The engineering of sub-micron light-shielding walls to suppress crosstalk without sacrificing pixel aperture ratio.
* Performance results of a prototype 3,600 PPI full-color display hitting 36,000 nits of luminance.
📋 **Clip Abstract** This clip explains the technical hurdles of scaling quantum-dot converted monolithic MicroLED displays to 3,600 PPI. It details how Sharp utilized common cathode layouts and sub-micron reflective walls to maintain high efficiency and color purity.
#MonolithicMicroLED, #QuantumDotColorConversion, #CommonCathodeArchitecture, #SubMicronOpticalIsolation, #ARMicrodisplays, #NearEyeDisplays