Vehicle Interior Light Guide With Optical Coating

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Solution Overview

Problem

Existing vehicle interior illumination systems using light guides face issues with contamination and contact with surrounding materials, leading to fluctuations in brightness and increased costs for avoiding these contacts, especially in backlighting applications.

Innovation Solution

A flat light guide covered with an optical lacquer layer and connected to a first adhesive layer for secure attachment, which also features a surface structure for uniform light coupling and the use of LEDs or laser diodes for cost-effective implementation, allowing for homogeneous illumination and protection against contamination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a light guide is used for vehicle interior illumination, then homogeneous illumination of large areas is achieved, but the light guide becomes susceptible to contamination and contact with surrounding materials

Engineering Contradiction:
Improvehomogeneous illuminationVSAvoidcontamination
Core Design Contradiction:
Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

A planar diffuser is introduced as an intermediary element between the light guide and the surrounding environment. This diffuser serves as a protective barrier that prevents direct contact and contamination of the light guide while maintaining the homogeneous illumination function. The diffuser is optically coupled to the light guide, allowing light to pass through while providing mechanical protection.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If the light guide is protected from contact with surrounding materials, then contamination is prevented, but manufacturing costs increase

Engineering Contradiction:
Improvecontamination protectionVSAvoidmanufacturing cost
Core Design Contradiction:
Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The planar diffuser is designed to serve multiple functions simultaneously: it acts as a protective barrier against contamination, a structural element for mounting, and an optical component for light distribution. By combining these functions into a single element, the overall system complexity and manufacturing cost are reduced compared to using separate protective and optical components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Strength

If conventional adhesives are used to attach the light guide, then secure mechanical attachment is achieved, but the light guide surface becomes exposed to contamination

Engineering Contradiction:
Improvemechanical attachmentVSAvoidcontamination risk
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The planar diffuser serves as an intermediary mounting surface, allowing adhesives to be applied to its backside rather than directly to the light guide. This positioning strategy maintains the light guide's protected status while achieving secure mechanical attachment through the diffuser, which acts as a sacrificial interface between the bonding system and the optical component.

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 provides reliable, cost-effective, and homogeneous illumination with controlled light distribution, preventing contamination and ensuring mechanical stability, while allowing for a wide range of material choices for the cover element without affecting optical reflection behavior.

Implementation Method 1

The optical lacquer layer has a defined refractive index and thus controls the emergence of light rays on the surface of the light guide

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 2

total reflection takes place at the transition from the optically denser to the optically thinner medium, in this case the medium of air

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP2803531B1Laminar device for illuminating the interior of a vehicle
Publication Date: 2022.04.20 LISA DRAXLMAIER GMBH
  • EP2803531B1 patent drawingFigure 1~2
  • EP2803531B1 patent drawingFigure 3~5
  • EP2803531B1 patent drawingFigure 6~7

AI summary

The invention relates to a device for illuminating a component (2) in the interior (1) of a vehicle. The device includes a planar light guide (3) which is at least partially covered with an optical coating (4). The planar shape of the light guide allows for the more homogeneous illumination of larger areas. The optical coating protects the light guide, particularly in areas where contamination is a concern or where contact with other components is planned. The optical coating has a defined refractive index and thus controls the emission of light rays from the surface of the light guide. The coating is bonded to a cover element (6) made of spacer fabric and a lamination via an adhesive (5). This ensures a mechanically secure attachment of the light guide to the cover element to be backlit.