Transparent Roof Panel Light Coupling for Thermal Expansion Alignment

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Solution Overview

Problem

Existing transparent roof panel assemblies for vehicles lack efficient and precise integration of light sources and in-coupling elements, leading to suboptimal light transmission and assembly challenges due to thermal expansion differences.

Innovation Solution

The integration of an in-coupling element with a cover that allows light to pass through a selected area, combined with a pre-assembled light module and adjustable attachment methods, such as spacers and gluing chambers, to ensure precise positioning and efficient light distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If light sources and in-coupling elements are integrated in transparent roof panel assemblies, then light transmission efficiency is improved, but assembly precision and positioning accuracy deteriorate due to thermal expansion differences

Engineering Contradiction:
Improvelight transmission efficiencyVSAvoidassembly precision
Core Design Contradiction:
Use of energy by moving objectVSManufacturing precision

Solution Approach 1:

The in-coupling element is divided into multiple segments that can move independently relative to each other. This segmentation allows each segment to accommodate thermal expansion independently while maintaining overall functionality, thus preserving assembly precision despite temperature variations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The in-coupling element incorporates movable segments that can dynamically adjust their positions to accommodate thermal expansion differences between the glass panel and the in-coupling element. This dynamic adaptation maintains optimal light coupling efficiency while preventing assembly distortion.

Inventive Principle:
Principle #15Dynamics

2Object-affected harmful factors

If in-coupling element is fully covered for protection, then protection from moisture and view is improved, but light transmission capability deteriorates

Engineering Contradiction:
Improveprotection from moistureVSAvoidlight transmission capability
Core Design Contradiction:
Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The in-coupling element features selective transparency with different optical properties in different regions. The first region is transparent to allow light transmission, while the second region is opaque or translucent to provide protection and control visibility. This local differentiation enables simultaneous achievement of light transmission and protection functions.

Inventive Principle:
Principle #3Local quality

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

Facilitates efficient light transmission and improved assembly by allowing precise alignment of light sources, protecting them from view and moisture, and accommodating thermal expansion differences.

Implementation Method 1

an in-coupling element to in-couple light into the panel from the interior side of the panel and redirecting light from the light source into the panel

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 2

an out-coupling pattern arranged on the surface of the transparent area of the panel, the out-coupling pattern is adapted to out-couple light propagating in the panel

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 3

the in-coupling element is provided with a cover on its side facing the interior of the vehicle, the cover being attached, clipped or taped to the in-coupling element and/or to the interior side of the panel such that also the light source is covered to protect it from view from the interior of the vehicle and/or against moisture

Methodology Applied
Scientific EffectPhysical containment: Physical Containment

Implementation Method 4

the in-coupling element is divided in its length direction in segments positioned side-by-side such that they are able to move with respect to each other when the panel expands or shrinks in a different manner relative to the in-coupling element due to different thermal expansion coefficients

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP4344951B1A transparent roof panel assembly for a vehicle roof
Publication Date: 2025.11.12 INALFA ROOF SYST GROUP
  • EP4344951B1 patent drawingFigure 1~2
  • EP4344951B1 patent drawingFigure 3(a)~3(c)
  • EP4344951B1 patent drawingFigure 4~5(b)

AI summary

A transparent roof panel assembly for a vehicle roof comprises a panel (3) having a transparent area. The panel is configured to be arranged over an opening (1) in the vehicle roof (2) to allow visible light to pass through the transparent area between an exterior of the vehicle and an interior (11) of the vehicle. A light source (8) is arranged to provide light in the panel. An in-coupling element (13) couples light into the panel from the interior side of the panel, the in-coupling element being attached to the interior side of the panel and redirecting light from the light source into the panel. The in-coupling element (13) may be partly covered towards the interior of the vehicle, with the exception of a selected area (16), such that light is able to pass from the in-coupling element towards the interior (11) through the selected area. The in-coupling element (13) is attached to the interior side of the panel (3) by means of an adhering material accommodated in a chamber (4) formed between the in-coupling element and the panel. The invention includes many more aspects.