Curved Light Guide Reflecting Element for Vehicle Rear Lighting

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Solution Overview

Problem

Vehicle rear lights with curved light guides often suffer from light loss and uneven brightness due to refracted light beams, and existing solutions like using two separate light sources are cost-sensitive and space-unfeasible.

Innovation Solution

A lighting device with a reflecting element at the end of the light guide opposite the light inlet, combined with prismatic surfaces and a light guide support, optimally directs light beams for improved outcoupling, even in curved configurations, reducing manufacturing costs and enhancing efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a curved light guide is used to accommodate vehicle shape and curvature, then the lighting device can adapt to geometric limitations, but light beams are refracted instead of reflected causing light loss and uneven brightness

Engineering Contradiction:
Improveadaptability to curved geometriesVSAvoidlight loss due to refraction
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent applies local quality by creating a specific geometric configuration at the light outlet surface where the angle between the outlet surface and the first direction exceeds 90 degrees. This localized geometric feature ensures that light beams undergo total internal reflection rather than refraction, maintaining brightness consistency in curved light guides without requiring the entire light guide to have special geometry.

Inventive Principle:
Principle #3Local quality

2Illumination intensity

If two light sources are used at separate ends of the light guide, then lighting efficiency is improved and brightness is more uniform, but device complexity and cost increase due to separate PCBs

Engineering Contradiction:
Improvelighting efficiency and brightness uniformityVSAvoidcomplexity of having separate PCBs
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The patent extracts the light reflection function from the light source assembly and implements it through the geometric configuration of the light guide itself. By designing the light outlet surface with an angle greater than 90 degrees relative to the first direction, the light guide structure itself performs the reflection function, eliminating the need for separate reflection components or dual light source PCBs.

Inventive Principle:
Principle #2Taking out (Extraction)

3Volume of moving object

If the light source is located at an end of the light guide opposite to the optimal light emission end, then space requirements are met, but lighting efficiency decreases

Engineering Contradiction:
Improvespace utilization in lighting deviceVSAvoidlighting efficiency
Core Design Contradiction:
Volume of moving objectVSIllumination intensity

Solution Approach 1:

The patent inverts the conventional light guide geometry by configuring the light outlet surface angle to exceed 90 degrees relative to the first direction. This inverted geometric approach allows light beams to be reflected back toward the optimal emission direction even when the light source is positioned at the opposite end, effectively reversing the usual light propagation issues caused by suboptimal source placement.

Inventive Principle:
Principle #13The other way round (Inversion)

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 increases lighting efficiency by reflecting and refracting light beams to ensure consistent brightness and reduced visual gaps between vehicle sections, accommodating curved geometries without additional light sources.

Implementation Method 1

The light guide then transports light from the light inlet surface to some light outlet surface by means of total refraction of light at the boundary of the light guide with the surrounding medium

Methodology Applied
Scientific EffectTotal internal refraction: Refraction

Implementation Method 2

a reflecting element for reflecting light beams emitted by the light source, the reflecting element being located at an end of the at least one light guide opposite the light inlet surface

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 3

a portion of the light guide comprises some prisms for reflecting rays of light towards the light outlet surface

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP3413105B1Lighting device
Publication Date: 2021.09.08 VALEO ILUMINACION SA
  • EP3413105B1 patent drawingFigure 1
  • EP3413105B1 patent drawingFigure 2
  • EP3413105B1 patent drawingFigure 3

AI summary

The present invention relates to a lighting device comprising: - at least one light guide (20); - a light source (10) coupled to a light inlet surface (21) of the at least one light guide (20); the lighting device further comprising a reflecting element (30) for reflecting light beams (a) emitted by the light source (10), the reflecting element (30) being located at an end (22) of the at least one light guide (20) opposite the light inlet surface (21).