Vehicle Light Mixing Unit With Diffusive Reflection in Compact Space

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Solution Overview

Problem

Existing illumination devices for vehicles require significant construction space due to long mixing units with specular reflection surfaces, limiting their application and leading to light intensity loss.

Innovation Solution

A mixing unit with a reflection surface having both Lambertian and specular reflections, allowing for efficient light mixing in a compact design, coupled with a light guide via a ferrule for reduced space usage and improved light homogeneity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a long mixing unit with specular reflection surface is used, then light homogeneity is improved, but construction space increases

Engineering Contradiction:
Improvelight homogeneityVSAvoidconstruction space
Core Design Contradiction:
Illumination intensityVSVolume of stationary object

Solution Approach 1:

The reflection surface is changed from a specular (mirror-like) surface to a diffusive (Lambertian) surface. This parameter change in surface properties allows the mixing unit to achieve effective light mixing in a shorter length, thereby reducing construction space while maintaining light homogeneity.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The reflection surface is designed with locally varying properties - it has diffusive characteristics that scatter light in multiple directions. This local quality change enables more uniform light distribution throughout the mixing unit, achieving homogeneous output light with a compact design.

Inventive Principle:
Principle #3Local quality

2Illumination intensity

If a long mixing unit is used, then light mixing effectiveness is improved, but light intensity loss increases

Engineering Contradiction:
Improvelight mixing effectivenessVSAvoidlight intensity loss
Core Design Contradiction:
Illumination intensityVSLoss of energy

Solution Approach 1:

Changing the reflection surface from specular to diffusive reduces the number of reflections needed for effective mixing. The diffusive surface scatters light more uniformly, achieving effective mixing in fewer reflections and a shorter path length, thereby reducing light intensity loss.

Inventive Principle:
Principle #35Parameter changes

3Volume of stationary object

If the light guide is positioned far from the passenger compartment, then installation space is reduced, but light intensity loss increases

Engineering Contradiction:
Improveinstallation spaceVSAvoidlight intensity loss
Core Design Contradiction:
Volume of stationary objectVSLoss of energy

Solution Approach 1:

The compact mixing unit design with diffusive reflection surface reduces the overall length of the illumination device. This allows the light guide to be positioned closer to the passenger compartment while maintaining sufficient installation space, thereby reducing light intensity loss over the transmission path.

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 compact design maintains light homogeneity while reducing construction space, enabling more applications within vehicles without compromising light quality.

Implementation Method 1

the reflection surface has diffusive properties such that the light coupled into the mixing unit is diffusively reflected

Methodology Applied
Scientific EffectDiffusive reflection (Lambertian reflection): Reflection

Data Source

PatentEP4382800B1Illumination device for a vehicle and vehicle comprising such an illumination device
Publication Date: 2025.12.10 HELLA GMBH & CO KGAA
  • EP4382800B1 patent drawingFigure 1A~2B
  • EP4382800B1 patent drawingFigure 3~4

AI summary

The present invention is directed to an illumination device (24) for a vehicle (46), comprising a light generating unit (12), comprising at least a first light source (141) providing light of a first color, and a second light source (142) providing light of a second color, and a mixing unit (16) having a first end (18) and a second end (20), wherein the light provided by the first light source (141) and the second light source (142) is coupled into the mixing unit (16) at the first end (18), the mixed light is leaving the mixing unit (16) at the second end (20), and a reflection surface (22) extending between the first end (18) and the second end (20) on which the light coupled into the mixing unit (16) is reflected, wherein the reflection surface (22) has diffusive properties (D) such that the light coupled into the mixing unit (16) is diffusively reflected. Moreover, the present invention relates to a vehicle (46) comprising such an illumination device (24).