Nonwoven Light Distribution Element for Uniform Luminance

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Solution Overview

Problem

Current light distribution elements, such as nonwoven fabrics, face challenges in achieving high luminance and uniform light transmittance while maintaining good diffusion properties, often requiring complex structures and costly process steps, which can lead to issues like delamination and reduced optical quality.

Innovation Solution

A nonwoven fabric with a composition of 1-50% matrix fibers, 50-99% thermally fused binding fibers, and 20-200% filler polymer, where the fibers and filler have specific refractive indices and porosity, resulting in a Gurley number greater than 250 seconds/100 ml, enhancing luminance and uniformity without compromising diffusion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If multiple layers of nonwoven fabric are combined to broaden the beam path and diffuse light, then light diffusion is improved, but light transmission is significantly reduced and the structure becomes more complex

Engineering Contradiction:
Improvelight diffusionVSAvoidlight transmission
Core Design Contradiction:
Illumination intensityVSQuantity of substance

Solution Approach 1:

The patent combines multiple functional components (matrix fibers for structural integrity, binder fibers for bonding, and filler polymer for light diffusion) into a single integrated nonwoven fabric layer, eliminating the need for multiple separate nonwoven layers while achieving both light diffusion and maintaining light transmission

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent uses a composite material system consisting of different fiber types (matrix and binder fibers) combined with filler polymer in specific ratios. This composite structure allows optimization of both light diffusion properties and light transmission by controlling the composition, where the filler polymer provides diffusion while the fiber matrix maintains structural integrity and transmission

Inventive Principle:
Principle #40Composite materials

2Illumination intensity

If special optical films are used to achieve high luminance and specific optical properties, then luminance is improved, but manufacturing complexity and cost increase due to multiple processing steps

Engineering Contradiction:
ImproveluminanceVSAvoidmanufacturing process complexity
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The patent combines multiple optical functions (light diffusion, luminance control, and structural support) into a single nonwoven fabric layer with integrated composite structure, eliminating the need for separate processing steps like laminating, surface treatment, or additive incorporation that are required for special optical films

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent optimizes optical properties by controlling material composition parameters (fiber types, filler polymer content, porosity, refractive indices) rather than requiring complex multilayer structures. By adjusting these parameters within the single-layer composite, the desired luminance and diffusion characteristics are achieved without additional manufacturing complexity

Inventive Principle:
Principle #35Parameter changes

3Illumination intensity

If multilayer special films are used to achieve specific optical properties, then optical performance is improved, but reliability decreases due to potential delamination and deformation from thermal expansion differences

Engineering Contradiction:
Improveoptical performanceVSAvoidstructural stability
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent combines multiple optical functions into a single integrated nonwoven fabric layer, eliminating the interfaces between multiple layers that cause delamination and thermal expansion problems. The single-layer composite structure with matrix fibers, binder fibers, and filler polymer maintains structural integrity and reliability while achieving the desired optical performance

Inventive Principle:
Principle #5Merging (Combining)

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 high luminance levels with improved light transmittance and uniformity, reducing luminance scatter and maintaining good mechanical properties, suitable for use in lighting applications like LEDs and LCD backlighting.

Implementation Method 1

50-99 wt.% at least partially thermally fused binding fibers

Methodology Applied
Scientific EffectThermal fusion: Melting

Implementation Method 2

20-200 wt.% at least one filler polymer... the difference between the refractive index of the matrix fiber polymer and the refractive index of the filler polymer and/or the difference between the refractive index of the binder fiber polymer and the refractive index of the filler polymer is 0.1 to 0.4

Methodology Applied
Scientific EffectLight scattering: Scattering

Implementation Method 3

the nonwoven fabric has a Gurley number > 250 sec./100 ml... achieving high luminance levels with improved light transmittance

Methodology Applied
Scientific EffectLight transmission: Refraction

Data Source

PatentEP3607122B1Element for manipulating light
Publication Date: 2021.03.17 CARL FREUDENBERG KG

AI summary

The invention relates to the use of a nonwoven, preferably a wet-laid nonwoven, as a light-distributing element, the nonwoven having a1) 1-50 wt% of matrix fibers, a2) 50-99 wt% of at least partially thermally fused binding fibers, and b) 20-200 wt% of at least one filling polymer, the weight proportions of matrix fibers, binding fibers and filling polymer each relating to the total weight of the nonwoven without filling polymer, and the matrix fibers containing at least one matrix fiber polymer and the binding fibers containing at least one binding fiber polymer, - matrix fiber polymer and/or binding fiber polymer having an index of refraction "n" of 1.3 to 1.7, preferably 1.5 to 1.65, independently of each other, the filling polymer having an index of refraction "n" of 1.2 to 1.7, the difference between the index of refraction of the matrix fiber polymer and the index of refraction of the filling polymer and/or the difference between the index of refraction of the binding fiber polymer and the index of refraction of the filling polymer being 0.1 to 0.4, the nonwoven having a Gurley number of > 250 seconds/100 milliliters.