Metal Nanostructure Diffuser for Isotropic LED Light

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Solution Overview

Problem

Conventional dielectric diffusion films fail to achieve isotropic light diffusion for pixelized light sources, such as LEDs, leading to uneven luminance and directional issues in display screens, particularly for sources smaller than 15 μm, where the averaging effect is not obtained, resulting in anisotropic refraction and luminance variations.

Innovation Solution

A diffuser comprising a transmission layer and a diffusion layer with metal nanostructures, where the nanostructures have dimensions less than 650 nm and are randomly distributed to ensure effective and isotropic light diffusion, utilizing their higher refractive index to scatter light in multiple directions, thereby improving the diffusion efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a dielectric diffusion film with random corrugations is used to diffuse light from pixelized light sources, then the light diffusion coverage is improved, but the isotropy of diffusion deteriorates for sources smaller than 15 μm

Engineering Contradiction:

Improvelight diffusion coverageVSAvoidisotropy of diffusion

Core Design Contradiction:

Illumination intensityVSStability of the object's composition

Solution Approach 1:

The patent changes the fundamental parameter of the diffusion mechanism from refraction-based (dielectric) to scattering-based (metallic). By using metal nanostructures with dimensions smaller than the light wavelength and high refractive index contrast, the system achieves true isotropic scattering that is independent of source size, resolving the contradiction between diffusion coverage and diffusion isotropy.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite structure combining dielectric substrate with metallic nanostructures. The dielectric provides mechanical support and optical transparency, while the metal nanostructures (such as aluminum, silver, or gold) provide the high refractive index contrast necessary for isotropic light scattering, achieving both diffusion coverage and isotropy simultaneously.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If a refractive diffusion film is used for pixelized light sources, then the manufacturing process is simplified, but the luminance uniformity deteriorates due to anisotropic refraction

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidluminance uniformity

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent substitutes the refraction mechanism (optical path bending through dielectric interfaces) with a scattering mechanism (random redirection of light by metal nanostructures). This substitution maintains manufacturing simplicity through standard nanofabrication techniques while achieving superior luminance uniformity through isotropic scattering that eliminates directional bias.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Illumination intensity

If the dimensions of metal nanostructures are reduced below 650 nm, then the light scattering efficiency is improved, but the manufacturing precision requirements increase

Engineering Contradiction:

Improvelight scattering efficiencyVSAvoidnanostructure dimension control

Core Design Contradiction:

Illumination intensityVSManufacturing precision

Solution Approach 1:

The patent identifies and exploits the critical parameter threshold of 650 nm (matching the red light wavelength) as the optimal size for metal nanostructures. At this scale, the nanostructures achieve maximum scattering efficiency while remaining compatible with standard nanofabrication processes, balancing optical performance with manufacturing feasibility.

Inventive Principle:

Principle #35Parameter changes

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 effectively diffuses light from pixelized sources, enhancing the isotropy of light distribution and reducing luminance variations across the screen, ensuring a more uniform and directive light output for improved display performance.

Implementation Method 1

utilizing their higher refractive index to scatter light in multiple directions

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

a diffusion layer intended to diffuse the light transmitted by the light source

Methodology Applied

Scientific EffectLight diffusion: Scattering

Data Source

PatentUS11592601B2Diffusive structure for light source

Publication Date: 2023.02.28 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES

AI summary

The invention relates to a diffuser 3 intended to be facing a light source 1 comprising a transmission layer 10 and a diffusion layer 22, 23 intended to diffuse a light transmitted by the light source, the diffuser being characterised in that the diffusion layer comprises a plurality of metal structures 200, 200a, 200b, called metal nanostructures, having dimensions less than a wavelength of the light transmitted, said metal nanostructures having varied sizes and being distributed within the diffusion layer such that adjacent metal nanostructures have between them, varied distances and preferably less than the wavelength of the light transmitted.The invention also relates to a method for manufacturing such a diffuser, and a display system comprising such a diffuser.