Back-lit Decorative Strip with Optical Waveguide and Light Gap

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Solution Overview

Problem

Existing decorative strips for motor vehicles with integrated lighting are complex, costly to manufacture, and do not allow for continuous, uniform illumination, often compromising visual appeal due to external structure visibility and material limitations.

Innovation Solution

A combination of a sealing profile and a backlit decorative strip using an optical waveguide that extends along the functional side of the profile strip, outside its cross-section, allowing indirect lighting that is evenly distributed and visually indistinguishable from non-illuminated strips, using non-transparent materials like metals and thermoplastics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If LEDs are embedded in the profile strip to illuminate the trim element, then illumination is achieved, but the design becomes complex and expensive to manufacture, and uniform illumination along the entire length is not possible

Engineering Contradiction:
ImproveilluminationVSAvoiddesign complexity
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The light source (LED) is extracted from the profile strip and placed in a separate lighting module positioned behind the trim strip. This separation allows the profile strip to remain simple while the lighting module handles illumination, enabling uniform lighting along the entire length without embedding complex components in the trim strip itself.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

A lighting module acts as an intermediary component between the light source and the trim strip. This module contains the LED and optical elements that distribute light uniformly along the trim strip's length, simplifying the overall design by consolidating lighting functionality in a dedicated module rather than integrating it directly into the profile strip.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Illumination intensity

If a lighting module is embedded as a separate component with a cutout, then illumination is achieved, but the design becomes complex and the visible surface is interrupted, diminishing visual appeal

Engineering Contradiction:
ImproveilluminationVSAvoidvisual appeal
Core Design Contradiction:
Illumination intensityVSShape

Solution Approach 1:

The lighting module is extracted and positioned behind the trim strip rather than creating a cutout in the visible surface. This allows the trim strip to maintain its continuous, uninterrupted visual appearance while the lighting module provides illumination from behind through the light gap.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The lighting module is positioned in a different spatial dimension (behind the trim strip) rather than integrating it into the visible surface plane. This creates a light gap that allows illumination to pass through while maintaining the continuous visual appearance of the trim strip's external surface.

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

3Illumination intensity

If light sources are glued to the inside of the functional side, then illumination is achieved, but the light source and components remain visible from the outside

Engineering Contradiction:
ImproveilluminationVSAvoidvisibility of components
Core Design Contradiction:
Illumination intensityVSObject-generated harmful factors

Solution Approach 1:

The lighting module is positioned in another dimension (behind the trim strip) creating a light gap that allows light to pass through while concealing the light source and components from external view. The trim strip acts as a mask that blocks the view of internal components while allowing light transmission.

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

Solution Approach 2:

The trim strip itself acts as an intermediary that blocks the direct line of sight to the light source and components while allowing light to pass through the light gap. This conceals the harmful factor (visible components) while maintaining the useful function (illumination).

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 a structurally simple, cost-effective, and visually superior decorative strip with uniform illumination, maintaining a flat structure and concealing assembly components, while allowing the use of non-transparent materials, ensuring the decorative strip appears unchanged from the outside.

Implementation Method 1

a light source in the form of an optical fiber is provided which, after proper installation, is arranged on the functional side in order to backlight at least a part of the profile strip

Methodology Applied
Scientific EffectOptical fiber light emission: Optical Fibre

Implementation Method 2

a light source is provided in the form of an optical waveguide which, when properly assembled, extends along at least a part of the profile strip on the functional side

Methodology Applied
Scientific EffectOptical waveguide: Waveguide (optics)

Data Source

PatentEP3245084B1Back-lit decorative strip
Publication Date: 2021.05.05 DURA AUTOMOTIVE HLDG U K LTD
  • EP3245084B1 patent drawingFigure 1~2

AI summary

The aim of the invention is to provide a back-lit decorative strip for a motor vehicle, in particular a decorative strip as a cover strip of a window weather strip of a vehicle door, which has a simple constructive design, can be produced at low cost and requires little space while producing a lighting effect that gives a refined impression. The exterior of said decorative strip should differ from non-back-lit decorative strips as little as possible. For this purpose, a light gap (S) is formed between a profile strip of the decorative strip (2) and the adjoining vehicle outer skin (12) through which light gap the light emitted by an optical waveguide (8) mounted on the back of the decorative strip can exit.