Yasuaki Hirano | Sharp: Why does outdoor AR require a 1,000,000 nit light engine just to deliver 1,000 nits to your eye?
03:50 - 05:15
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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.
ð **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
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09:11 - 10:11
How did Sharp double the sRGB color gamut of their monolithic MicroLED displays?
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-24Ξm 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.
ð **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
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-10Ξm 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.
ð **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