Aspherical Light Guide Ring for Vehicle Headlight Luminance

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing vehicle headlight designs with light guide rings suffer from undefined scattering optics, which inefficiently widen the light distribution and fail to meet recent legal requirements for daytime running lights, particularly in terms of luminance and energy efficiency.

Innovation Solution

The front side of the light guide ring is designed aspherical to correct spherical aberration, with prisms on the rear side decoupling light in a defined manner, allowing at least 30-90% of light intensity to be emitted in the main emission direction, using a toroidal shape and Fresnel prism structures for efficient light collimation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a light guide ring with undefined scattering optics is used, then the light distribution is widened, but the luminance in the main emission direction is insufficient and legal requirements cannot be met

Engineering Contradiction:
Improveluminance in main emission directionVSAvoidenergy efficiency
Core Design Contradiction:
Illumination intensityVSLoss of energy

Solution Approach 1:

The light guide ring is segmented into different functional zones: a first region with a specific refractive index for light guidance, a second region with a different refractive index for light extraction, and a third region for additional light management. This segmentation allows optimized light control in each zone, achieving high luminance in the main emission direction while improving overall energy efficiency

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the light guide ring are assigned different optical properties (refractive indices) to perform different functions. The first region is optimized for light guidance, the second region for light extraction, and the third region for additional light management, allowing each local area to contribute optimally to the overall performance

Inventive Principle:
Principle #3Local quality

2Illumination intensity

If a spherical light guide ring is used, then the structure is simple, but spherical aberration occurs and light cannot be efficiently emitted in the main direction

Engineering Contradiction:
Improvelight intensity in main emission directionVSAvoidstructural complexity
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The light guide ring transitions from a spherical shape to an aspherical shape to eliminate spherical aberration. The aspherical design allows light rays to be focused more precisely in the main emission direction, significantly improving light intensity while maintaining manufacturability through modern molding techniques

Inventive Principle:
Principle #4Asymmetry

3Illumination intensity

If the aperture of the light bundle is increased, then the light distribution is broadened, but the light intensity in the main direction is reduced

Engineering Contradiction:
Improvelight intensity in main directionVSAvoidlight distribution area
Core Design Contradiction:
Illumination intensityVSArea of stationary object

Solution Approach 1:

The refractive index is changed as a key parameter to control light behavior. By using regions with different refractive indices, the patent achieves both broad light distribution and high intensity in the main direction, as the refractive index differences enable precise control over light extraction and direction

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

This design enables compliance with legal requirements in an economical and efficient manner, providing high luminance in the main emission direction while minimizing aberrations, thus enhancing the vehicle headlight's performance and appearance.

Implementation Method 1

The front side, in particular the optical front surface, of the light guide ring is designed aspherically in such a way that the spherical aberration of the light deflected by the prisms and coupled out of the light guide ring is corrected

Methodology Applied
Scientific EffectSpherical aberration correction: Lens

Implementation Method 2

A large number of prisms, which are arranged in particular circumferentially on the rear side of the light guide ring, causes the light to emerge from the light guide ring

Methodology Applied
Scientific EffectLight refraction: Refraction

Implementation Method 3

The prisms are preferably formed by corresponding recesses or corresponding cantilevered structures running around the back of the light guide ring

Methodology Applied
Scientific EffectFresnel prism: Fresnel Lens

Implementation Method 4

Light from a light source is coupled into the cross section of a light guide at the focal point of a reflector

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP2052283B1Vehicle headlight
Publication Date: 2014.08.20 BAYERISCHE MOTOREN WERKE AG
  • EP2052283B1 patent drawingFigure 1
  • EP2052283B1 patent drawingFigure 2~3
  • EP2052283B1 patent drawingFigure 4

AI summary

The invention relates to a vehicle headlight (1) comprising a light source (7), an optical wave guide ring (4) into which light enters from the light source (7), and a plurality of prisms (46) which are arranged on the rear side (45) of the optical wave guide ring (4) in order to generate the emergence of the light from the optical wave guide ring (4), the front side of the optical wave guide ring being aspherical.