Optical Fiber System with IR-Absorbing Intermediate Light Guide

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Solution Overview

Problem

Current light guide systems in motor vehicle headlights face challenges with thermal stability and self-heating issues due to infrared radiation, leading to reduced visual transmission and potential yellowing, especially when handling high radiation powers.

Innovation Solution

A light guide system comprising a first, temperature-compatible light guide intermediate piece with common absorption lines or behavior in the infrared range, which absorbs radiant energy and maintains high visible radiation permeability, is designed to keep the actual light guide at a distance from the heat source and prevent thermal damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If an infrared filter is placed in front of the light guide to reduce IR radiation, then self-heating is reduced, but visual transmission in the visible range is severely restricted

Engineering Contradiction:
Improvelight guide temperatureVSAvoidvisual transmission
Core Design Contradiction:
TemperatureVSIllumination intensity

Solution Approach 1:

The light guide system is divided into two separate components: a first light guide optimized for IR absorption and a second light guide optimized for visible light transmission. This segmentation allows each component to specialize in its respective function without compromising the other, resolving the contradiction between temperature control and visual transmission.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The first light guide acts as an intermediary component between the light source and the second light guide. It absorbs harmful IR radiation before it reaches the temperature-sensitive second light guide, while allowing visible light to pass through to illuminate the intended area.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a broadband absorption filter is used to absorb IR energy, then thermal damage is prevented, but excessive IR energy is absorbed that would not have heated the light guide

Engineering Contradiction:
Improvelight guide stabilityVSAvoidIR energy absorption efficiency
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The first light guide is specifically engineered with material properties that provide selective absorption characteristics - it absorbs IR radiation in the specific wavelength ranges that match its absorption lines while maintaining high transmission in the visible range. This localized optimization of absorption properties prevents unnecessary energy loss.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The system changes the absorption parameters by using materials with specific absorption line characteristics that match the IR radiation spectrum. This allows targeted absorption of only those IR wavelengths that would cause heating, rather than broad-spectrum absorption that wastes energy.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If the light guide is placed closer to the light source to improve illumination, then lighting efficiency is increased, but thermal damage and yellowing increase

Engineering Contradiction:
Improvelighting efficiencyVSAvoidthermal damage
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The first light guide serves as a protective intermediary positioned between the light source and the second light guide. It absorbs harmful IR radiation before it can reach and damage the second light guide, enabling the system to maintain high lighting efficiency without compromising the second light guide's longevity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The first light guide provides beforehand protection by absorbing thermal stress and IR radiation before it can affect the second light guide. This preliminary cushioning against thermal damage allows the second light guide to operate closer to the light source without risking yellowing or degradation.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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

This configuration ensures stable operation over long periods with high radiation power while minimizing heating and maintaining high optical transmission, allowing for increased luminous flux and reduced thermal stress on the light guide material.

Implementation Method 1

designed in such a way that in the infrared spectral range there is at least one common absorption line with the actual light guide

Methodology Applied
Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Implementation Method 2

absorbs at least a large part of the radiant energy in the frequency range of the common absorption line(s)

Methodology Applied
Scientific EffectAbsorption (physical): Absorption (physical)

Implementation Method 3

a rod-shaped light guide for the totally reflecting conduction of light

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP2047307B1Optical fiber system
Publication Date: 2011.11.30 BAYERISCHE MOTOREN WERKE AG
  • EP2047307B1 patent drawingFigure 1

AI summary

The invention relates to an optical fiber system having a first optical fiber (LL1 ) and a second optical fiber (LL2), wherein the second optical fiber (LL2) is disposed downstream to the first optical fiber (LL1 ) in the light propagation direction, wherein the first optical fiber (LL1 ) is more temperature tolerant than the second optical fiber (LL2), and wherein the first optical fiber (LL1 ) and the second optical fiber (LL2) have at least one mutual absorption line in the infrared spectral region.