Stacked Optical Waveguides for Motor Vehicle Headlight Illuminance

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Solution Overview

Problem

Existing motor vehicle lighting devices with flat, elongated light exit surfaces struggle to achieve a desired illuminance profile from the center to the edges, failing to conform to regulatory light distribution standards for low-beam and high-beam lighting.

Innovation Solution

A motor vehicle headlight design featuring multiple light guides with strategically arranged light exit surfaces and imaging optics to concentrate light, ensuring maximum brightness at the center and creating a uniform, large-area exit surface, with the light exit surfaces positioned near the object-side focal surface of the imaging optics to achieve a rule-compliant light distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a flat, elongated light exit surface is used in existing lighting devices, then the device structure is simple and manufacturing is easier, but the illuminance profile from center to edges cannot achieve the desired shape and regulatory compliance

Engineering Contradiction:
Improveease of manufactureVSAvoidilluminance profile
Core Design Contradiction:
Ease of manufactureVSIllumination intensity

Solution Approach 1:

The patent divides the lighting system into multiple separate light guides (first light guide, second light guide, etc.) arranged in a stack, each contributing to different portions of the light distribution. This segmentation allows independent optimization of each light guide's illuminance profile while maintaining overall manufacturing simplicity through modular assembly.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from a single-plane light exit surface to a three-dimensional stacked arrangement of multiple light guides. By positioning light guides at different heights and orientations, the system achieves complex illuminance profiles in multiple dimensions, enabling regulatory compliance while maintaining structural simplicity.

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

2Area of stationary object

If multiple light guides are stacked to form a large exit surface, then a uniformly illuminated area is achieved, but the device complexity increases

Engineering Contradiction:
Improveexit surface areaVSAvoiddevice complexity
Core Design Contradiction:
Area of stationary objectVSDevice complexity

Solution Approach 1:

The patent combines multiple light guides into a unified stacked structure that functions as a single large-area exit surface. The light guides are positioned and oriented to work together, creating a homogeneous illuminance profile across the entire exit surface while maintaining individual component simplicity for ease of manufacturing and assembly.

Inventive Principle:
Principle #5Merging (Combining)

3Illumination intensity

If light exit surfaces are positioned near the object-side focal surface of imaging optics, then a light distribution with maximum brightness at the center is achieved, but the positioning precision requirements increase

Engineering Contradiction:
Improvebrightness distributionVSAvoidpositioning precision
Core Design Contradiction:
Illumination intensityVSManufacturing precision

Solution Approach 1:

The patent positions different light guides at specific locations relative to the imaging optics' focal surface, with each light guide optimized for its local function. The first light guide, second light guide, and other light guides are strategically positioned to achieve maximum brightness at the center while maintaining appropriate illumination at edges, reducing overall positioning precision requirements through localized optimization.

Inventive Principle:
Principle #3Local quality

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 enables the generation of a light distribution with maximum brightness at the center, providing a uniformly illuminated area that conforms to regulatory standards, enhancing both low-beam and high-beam lighting performance.

Implementation Method 1

The light guide (10) has a first light-guiding surface (12), a second light-guiding surface (14) opposite the first light-guiding surface (12), and narrow sides (20) connecting between an edge (16) of the first light-guiding surface (12) and an edge (18) of the second light-guiding surface (14) and the first light-guiding surface (12) with the second light-guiding surface (14)

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

The light guide (10) has a reflection surface (24), the reflection surface (24) being a depression in one of the two light-guiding surfaces (12, 14) that extends to a specific depth into the light guide (10). A light source (34) is arranged in such a way that light emanating from it illuminates the reflection surface (24) and is radially reflected by it

Methodology Applied
Scientific EffectRadial reflection: Reflection

Implementation Method 3

Light incident on the reflector (26) from this radially reflected light is deflected twice there. The direction of the incident light is reversed during the deflection in such a way that the further path of the deflected light leads between the reflection surface (24) and the opposite light-guiding surface (12, 14)

Methodology Applied
Scientific EffectLight deflection: Reflection

Data Source

PatentEP3080513B1Motor-vehicle lighting device
Publication Date: 2020.10.21 MARELLI GERMANY GMBH
  • EP3080513B1 patent drawingFigure 1~2
  • EP3080513B1 patent drawingFigure 3~4
  • EP3080513B1 patent drawingFigure 5~6

AI summary

The invention relates to a motor-vehicle lighting device, comprising at least one plate-shaped, flat optical waveguide, which has a first light-conducting surface, a second light-conducting surface, and narrow sides, wherein a first region of the narrow sides is designed as a light outlet surface and a second region of the narrow sides is designed as a reflector, wherein the reflector is designed to direct part of the light coupled into the optical waveguide by a light source in the direction of the light outlet surface. According to the invention the lighting device has a plurality of such optical waveguides, which are arranged in the manner of a stack in such a way that the light-conducting surfaces of adjacent optical waveguides contact each other in a passage region and that the optical waveguide of the plurality of optical waveguides whose light outlet surface is arranged near a reference axis characterizing the lighting device is designed to concentrate the light coupled into said optical waveguide in such a way that a light distribution has a brightness maximum lying in the area in front of the lighting device.