LED Illumination with Scattering Particle PMMA Cover

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Solution Overview

Problem

Luminous devices incorporating high-luminous flux LEDs require an adapted plastic cover to address the directional illumination and unique emission spectrum issues, as existing solutions do not effectively handle LEDs with luminous flux exceeding 5 lumens.

Innovation Solution

A luminous device featuring a transparent PMMA cover with 5-30% scattering particles by weight, specifically BaSO4, dispersed within the plastic to scatter light and provide uniform illumination, reducing directional effects and halo phenomena.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If conventional light sources (incandescent lamps, neon tubes) are used, then omnidirectional illumination (0 to 360°) is achieved, but high energy consumption and short lifetime result

Engineering Contradiction:

Improveenergy consumptionVSAvoidillumination directionality

Core Design Contradiction:

Use of energy by moving objectVSIllumination intensity

Solution Approach 1:

The patent applies local quality by incorporating scattering particles specifically in the regions where light needs to be redirected. The particles are dispersed throughout the transparent plastic cover, creating localized scattering zones that convert directional LED light into omnidirectional illumination without requiring the entire structure to be complex

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The transparent plastic cover with scattering particles acts as an intermediary between the LED light source and the surrounding environment. It receives directional light from the LED and transforms it into omnidirectional illumination, mediating between the energy-efficient but directional LED and the requirement for omnidirectional lighting

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If LED with high luminous flux (>3 Lm) is used, then energy efficiency and compactness are improved, but directional illumination and halo effects worsen

Engineering Contradiction:

Improveluminous fluxVSAvoidillumination uniformity

Core Design Contradiction:

ProductivityVSIllumination intensity

Solution Approach 1:

The patent changes the optical parameters of the light transmission medium by incorporating scattering particles with specific properties (size, concentration, material composition). This modifies how light propagates through the cover, scattering the directional high-intensity LED light into more uniform omnidirectional illumination and reducing halo effects

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The transparent plastic cover is formulated as a composite material combining the base transparent plastic with dispersed scattering particles. This composite structure maintains the transparency and protective functions of the plastic while adding light-scattering capabilities to address the directional illumination and halo effects of high-flux LEDs

Inventive Principle:

Principle #40Composite materials

3Illumination intensity

If scattering particles are added to transparent plastic, then light scattering and uniform illumination are improved, but light transmission and manufacturing complexity worsen

Engineering Contradiction:

Improveillumination uniformityVSAvoidmanufacturing process

Core Design Contradiction:

Illumination intensityVSEase of manufacture

Solution Approach 1:

The patent utilizes a particle-dispersed composite structure where scattering particles are distributed throughout the transparent plastic matrix. This approach is analogous to porous material techniques, where the particles create scattering centers without fundamentally changing the manufacturing process, allowing standard injection molding or extrusion methods to be used

Inventive Principle:

Principle #31Porous materials

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 achieves uniform and non-dazzling illumination, effectively addressing the directional lighting issues of high-luminous flux LEDs, while maintaining high transparency and thermal stability, and reducing the number of LEDs required for a given illumination.

Implementation Method 1

particles that scatter the light emitted by the light-emitting diode are dispersed

Methodology Applied

Scientific EffectLight scattering: Scattering

Implementation Method 2

a cover made of a transparent plastic in which particles that scatter the light emitted by the light-emitting diode are dispersed

Methodology Applied

Scientific EffectLight transmission: Refraction

Data Source

PatentEP1864274B1Illuminating device combining a LED and a diffusing sheet

Publication Date: 2019.04.24 ARKEMA FRANCE SA

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AI summary

The invention relates to a luminous device comprising at least one LED having a luminous flux of greater than 3 Lm, advantageously greater than 5 Lm, preferably greater than 10 Lm and even more preferably greater than 50 Lm, and to a cover made of a transparent plastic in which scattering particles with a content of 3 to 30% are dispersed. The scattering particles may be of organic nature. In which case they may be polyamide or PTFE particles, methyl-methacrylate-based crosslinked particles, crosslinked styrene-based particles or silicone particles. The scattering particles may be of mineral nature. In this case they may be BaSO4, TiO2, ZnO, CaCO3, MgO or AI2O3 particles or hollow glass microspheres. The LED may be a colour LED or a white LED.