Light Guide with Reflector for Obstruction-Free Visibility

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Solution Overview

Problem

Motor vehicle lighting devices face challenges in meeting visibility criteria due to design specifications that result in the light guide being covered by components, limiting visibility in certain viewing directions while maintaining rule-compliant signal light distributions and brand recognition.

Innovation Solution

Incorporating a reflector in the light path of the light emitted via second partial surfaces to direct light past obstacles, and using a convexly curved front side of the light guide to enhance visibility without altering the light guide's shape or obstruction, thereby meeting visibility criteria for covered viewing angles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the light guide is covered by components to meet design specifications, then the design freedom is improved, but the visibility in certain viewing directions deteriorates

Engineering Contradiction:
Improvedesign freedomVSAvoidvisibility criteria
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

A reflector is introduced as an intermediary component between the light guide and the external environment. The reflector redirects light that would otherwise be blocked by covering components, directing it around the obstacles to reach viewing areas. This mediator enables the system to maintain both design freedom (covering components) and visibility criteria (redirected light paths).

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The solution transitions from a two-dimensional light exit problem (front surface only) to a three-dimensional light distribution system by utilizing side surfaces and introducing a reflector that creates additional light paths in spatial dimensions. This allows light to reach viewing angles that would otherwise be blocked, maintaining visibility while preserving design freedom.

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

2Manufacturing precision

If the front side is used as the primary light exit surface, then the light distribution control is improved, but the visibility range is limited when covered by components

Engineering Contradiction:
Improvelight distribution controlVSAvoidvisibility range
Core Design Contradiction:
Manufacturing precisionVSArea of stationary object

Solution Approach 1:

The light exit function is segmented from being concentrated solely on the front surface to being distributed across multiple surfaces including the front side and side surfaces. Second partial surfaces are created on side surfaces to provide additional light exit points, thereby expanding the effective visibility range while maintaining controlled light distribution through structured surface arrangements.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The reflector serves as an intermediary that takes light from the segmented side surfaces and redirects it to enhance visibility in covered viewing directions, effectively expanding the visibility range without compromising the controlled light distribution from the front surface.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Illumination intensity

If second partial surfaces are arranged with a larger angle of incidence, then the light exit from side surfaces is improved, but the total internal reflection is reduced

Engineering Contradiction:
Improvelight exit intensityVSAvoidtotal internal reflection
Core Design Contradiction:
Illumination intensityVSLoss of energy

Solution Approach 1:

Different regions of the light guide are assigned different optical functions: the front surface maintains high reflectivity for controlled light distribution, while specific second partial surfaces on side surfaces are designed with larger angles of incidence to optimize local light exit intensity. This local differentiation allows simultaneous optimization of both light exit and energy retention in different areas.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The reflector acts as an intermediary that compensates for the energy loss from reduced total internal reflection by capturing and redirecting light that would otherwise be lost, thereby maintaining overall system efficiency while enabling improved light exit from side surfaces.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 improves visibility values by directing light around obstructions, ensuring compliance with visibility criteria without changing the light guide's shape or design, providing greater design freedom for motor vehicle lighting devices.

Implementation Method 1

light incident from the interior of the light guide onto the first partial areas, which is incident from the same direction as light incident from inside the light guide onto the first partial areas, still causes total internal reflections there

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

light incident from the interior of the light guide onto the second partial areas, which is incident from the same direction as light incident from inside the light guide onto the first partial areas, still causes total internal reflections there exits directly from the respective second partial area

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 3

the lighting module has a reflector which is arranged in the light path of the light emitted directly via the second partial surface and to it is set up to direct this light through the light guide or past the light guide

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP3301353B1Motor vehicle lighting device with a light guide
Publication Date: 2021.05.05 MARELLI GERMANY GMBH
  • EP3301353B1 patent drawingFigure 1
  • EP3301353B1 patent drawingFigure 2
  • EP3301353B1 patent drawingFigure 3

AI summary

A vehicle lighting device (26) is presented, comprising an elongated light guide (10) having a front surface (12) extending along its length, a back surface (14), and side surfaces (15, 18). The back surface (14) has first partial surfaces (20) arranged in it, which are tilted at a first angle relative to the longitudinal extent of the light guide (10), and a component (34) that covers the front surface for a viewing angle range. The lighting device (26) is further characterized in that the light guide has second partial surfaces (24) that define a light-guiding projection (22) extending from a side surface and are tilted at a second angle relative to a longitudinal direction of the light guide, the second angle being greater than the first angle.