Light Diffusing Fiber with Color Conversion Layer

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Solution Overview

Problem

Conventional light diffusing devices using low wavelength light sources, such as red laser diodes, have limited color flexibility, shorter lifespan, and higher operating temperatures, leading to inefficiencies and speckle patterns in illumination systems.

Innovation Solution

A light diffusing optical fiber with a silica-based glass core, a scattering layer, and a color converting layer comprising a polymer matrix and luminophores that emit light in the 580 nm to 680 nm range, optically coupled to a low wavelength light source, allowing for broader color output and improved reliability by converting input light to higher wavelengths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If low wavelength light sources (e.g., red laser diodes) are used in conventional light diffusing devices, then the device structure is simpler, but the color flexibility is limited, lifespan is shorter, and operating temperature is higher

Engineering Contradiction:
Improvecolor flexibilityVSAvoiddevice structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

A wavelength conversion layer is introduced as an intermediary between the blue light source and the output medium. This layer contains luminophores that absorb blue light (430-480 nm) and convert it to longer wavelengths (580-680 nm), enabling color flexibility without requiring multiple light sources. The intermediary layer resolves the contradiction by allowing a simple blue light source to produce variable colors through material composition control.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the parameters of the wavelength conversion layer, specifically the thickness (150-450 μm) and luminophore concentration (2.5-15 wt%), to control the output color characteristics. By adjusting these parameters, the system achieves broad color output range while maintaining a simple blue light source structure, thus resolving the contradiction between color flexibility and device complexity.

Inventive Principle:
Principle #35Parameter changes

2Duration of action of moving object

If low wavelength light sources are used, then the initial setup is simpler, but the lifespan is shorter and reliability is reduced

Engineering Contradiction:
ImprovelifespanVSAvoiddevice structure
Core Design Contradiction:
Duration of action of moving objectVSDevice complexity

Solution Approach 1:

The wavelength conversion layer acts as a protective intermediary that enables the use of durable blue light sources instead of fragile red laser diodes. Blue LED and laser diode technology has superior lifespan and reliability characteristics. The conversion layer maintains system simplicity while extending component lifespan, resolving the contradiction between lifespan improvement and device complexity.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Use of energy by moving object

If low wavelength light sources are used, then the system is simpler, but operating temperature is higher and energy efficiency is lower

Engineering Contradiction:
Improveenergy efficiencyVSAvoiddevice structure
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The invention optimizes the parameters of the wavelength conversion layer, including thickness (150-450 μm) and luminophore concentration (2.5-15 wt%), to maximize energy conversion efficiency. The scattering layer with specific refractive index (1.3-1.6) further optimizes light extraction. These parameter optimizations enable efficient energy utilization with a simple blue light source structure, resolving the contradiction between energy efficiency and device complexity.

Inventive Principle:
Principle #35Parameter changes

4Object-affected harmful factors

If low wavelength light sources are used, then the initial design is simpler, but speckle patterns are more prominent

Engineering Contradiction:
Improvespeckle patternsVSAvoiddevice structure
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The wavelength conversion layer serves as an intermediary that spatially distributes and randomizes the coherent blue light before it exits the device. This conversion process inherently reduces speckle pattern formation by converting coherent light to incoherent emission from multiple luminophore centers. The scattering layer further enhances this effect, resolving the contradiction between speckle reduction and device complexity.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 provides a more reliable, energy-efficient, and flexible lighting system with reduced speckle patterns, enabling a wider range of output colors and longer lifespan compared to traditional systems, while allowing for passive cooling and broader access to color spaces.

Implementation Method 1

The luminophore is configured to emit light in response to absorption of an input light, and the emitted light has a peak wavelength greater than the peak wavelength of the input light

Methodology Applied
Scientific EffectPhotoluminescence: Photoluminescence

Implementation Method 2

a scattering layer surrounding the core

Methodology Applied
Scientific EffectLight scattering: Scattering

Data Source

PatentEP3775681B1Light diffusing device with color conversion and related light system
Publication Date: 2024.03.06 CORNING INC
  • EP3775681B1 patent drawingFigure 1~2
  • EP3775681B1 patent drawingFigure 3~4A
  • EP3775681B1 patent drawingFigure 4B~5B

AI summary

Embodiments of a light diffusing device with a color conversion layer are disclosed. Specifically the color conversion layer includes a luminophore that converts light from a higher wavelength to a lower wavelength.