Headlight Light Guide Layout for Uniform Surface Illumination

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Solution Overview

Problem

Existing lighting devices for motor vehicle headlights require multiple light sources to uniformly illuminate the light-entry surface, leading to increased manufacturing costs, energy consumption, and reduced homogeneity of the lighting effect due to space constraints.

Innovation Solution

A lighting device with a second optical element arranged between the light guide and the first optical element to deflect light uniformly across the entire light-entry surface, utilizing a rod-shaped light guide with deflecting elements and total internal reflection, and a retaining element for secure attachment, without the need for additional light sources.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If multiple light sources are used to illuminate the entire light-entry surface, then uniform illumination is achieved, but manufacturing costs and energy consumption increase

Engineering Contradiction:
Improveuniformity of illuminationVSAvoidenergy consumption
Core Design Contradiction:
Illumination intensityVSUse of energy by moving object

Solution Approach 1:

The patent combines the functions of multiple light sources into a single light guide that distributes light across the entire light-entry surface through total internal reflection and controlled light extraction, eliminating the need for multiple separate light sources while maintaining uniform illumination

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The light guide acts as an intermediary between the single light source and the light-entry surface, distributing light uniformly across the surface through its optical properties and structural design, including deflecting surfaces and controlled coupling sections

Inventive Principle:
Principle #24Intermediary (Mediator)

2Illumination intensity

If multiple light sources are used to illuminate the entire light-entry surface, then uniform illumination is achieved, but manufacturing costs increase

Engineering Contradiction:
Improveuniformity of illuminationVSAvoidmanufacturing cost
Core Design Contradiction:
Illumination intensityVSEase of manufacture

Solution Approach 1:

The patent combines the functions of multiple light sources into a single light guide that distributes light across the entire light-entry surface through total internal reflection and controlled light extraction, eliminating the need for multiple separate light sources while maintaining uniform illumination

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The light guide provides a cost-effective solution by replacing expensive multiple light sources and their associated control systems with a single, simple optical component that achieves the same illumination uniformity

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Illumination intensity

If the light guide is made longer to illuminate the second section of the light-entry surface, then complete illumination is achieved, but space constraints are violated

Engineering Contradiction:
Improvecoverage areaVSAvoidspace occupation
Core Design Contradiction:
Illumination intensityVSVolume of moving object

Solution Approach 1:

The patent uses the third dimension (vertical depth) by incorporating deflecting surfaces and layered optical structures within the light guide, allowing light to reach the second section of the light-entry surface without increasing the horizontal length of the light guide

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The light guide is integrated within the headlight assembly with the second optical element and light-entry surface in a nested configuration, maximizing space utilization and achieving complete illumination within the available volume

Inventive Principle:
Principle #7Nested doll (Nesting)

4Illumination intensity

If multiple light sources are used to illuminate different areas, then complete coverage is achieved, but the homogeneity of the lighting effect is reduced

Engineering Contradiction:
Improvecoverage areaVSAvoidhomogeneity of lighting effect
Core Design Contradiction:
Illumination intensityVSStability of the object's composition

Solution Approach 1:

The light guide is designed with uniform optical properties and a consistent structure along its length, ensuring that light is distributed evenly across the entire light-entry surface, including both the first and second sections, achieving homogeneous illumination without the variations introduced by multiple separate light sources

Inventive Principle:
Principle #33Homogeneity

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

Uniform illumination of the light-entry surface is achieved without additional light sources, reducing manufacturing costs and energy consumption while maintaining homogeneous lighting, and allowing for a compact design within vehicle headlight constraints.

Implementation Method 1

The deflecting surface can incorporate deflecting elements that redirect the light propagating within the light guide towards the front surface. These deflecting elements can, for example, have prismatic structures and utilize total internal reflection for light redirection.

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

a light guide, wherein the light from the light source is coupled into the light guide via an input coupling surface of the light guide

Methodology Applied
Scientific EffectOptical coupling: Refraction

Implementation Method 3

a second optical element which is arranged between the output section of the light guide and the light-entry surface of the first optical element and is configured to deflect light coupled out of the output section of the light guide

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP4419835B1Lighting device for a motor vehicle
Publication Date: 2026.02.25 ZKW GRP GMBH
  • EP4419835B1 patent drawingFigure 1~2

AI summary

The invention relates to an illumination device (1) for a motor vehicle headlight, comprising: a lamp (2); an optical fibre (3), the light from the lamp (2) being coupled into the optical fibre optic (3) and coupled out via an outcoupling portion (3a); a first optical element (4) having a light entry surface and a light exit surface associated with the light entry surface, wherein light from the optical fibre (3) can be coupled into the first optical element (4) via the light entry surface and can be coupled out via the light exit surface, and the light entry surface has a first portion (4a) and at least one second portion (4b) adjoining the first portion. Between the outcoupling portion (3a) and the light entry surface (4a, 4b) the illuminating device (1) has a second optical element (5) which is designed to redirect the light which is outcoupled from the optical fibre (3), so that the light, after passing through the second optical element (5), strikes the entire first portion (4a) and the entire second portion (4b) of the light entry surface of the first optical element (4).