Vehicle Interior Light Box for Uniform Planar Illumination

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Solution Overview

Problem

Existing vehicle interior lighting devices are complex, heavy, and expensive due to the use of special beam-shaping optics or solid translucent bodies, which complicates their manufacture and affects luminance distribution homogeneity.

Innovation Solution

A lighting device with a housing featuring a light-reflecting or light-scattering rear wall and a translucent cover, utilizing a light source to illuminate the rear wall for uniform illumination of the cover, with a diffusely scattering surface to avoid sharp brightness contrasts and edges, allowing for smooth transitions and high luminance homogeneity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If special beam-shaping optics or solid translucent bodies are used to ensure luminance distribution homogeneity, then luminance homogeneity is improved, but device complexity increases, weight increases, and manufacturing cost increases

Engineering Contradiction:
Improveluminance homogeneityVSAvoiddevice complexity
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The patent extracts the complex beam-shaping optics and solid translucent bodies from the lighting device, replacing them with a simple housing that has a light-reflecting or light-scattering rear wall. The housing itself becomes the light-distributing element, eliminating the need for separate complex optical components while achieving uniform luminance distribution through the reflective/scattering properties of the rear wall.

Inventive Principle:
Principle #2Taking out (Extraction)

2Illumination intensity

If special beam-shaping optics or solid translucent bodies are used to ensure luminance distribution homogeneity, then luminance homogeneity is improved, but manufacturing cost increases

Engineering Contradiction:
Improveluminance homogeneityVSAvoidmanufacturing cost
Core Design Contradiction:
Illumination intensityVSEase of manufacture

Solution Approach 1:

The patent employs a housing with a light-reflecting or light-scattering rear wall that is simpler and cheaper to manufacture than complex optical systems. The housing structure serves multiple functions including structural support and light distribution, reducing the need for expensive specialized components and simplifying the manufacturing process.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Illumination intensity

If special beam-shaping optics or solid translucent bodies are used to ensure luminance distribution homogeneity, then luminance homogeneity is improved, but weight increases

Engineering Contradiction:
Improveluminance homogeneityVSAvoidweight
Core Design Contradiction:
Illumination intensityVSWeight of stationary object

Solution Approach 1:

The housing in the patent serves multiple functions: it provides structural support for the lighting device and simultaneously acts as the light-distributing element through its light-reflecting or light-scattering rear wall. This multi-functionality eliminates the need for separate heavy optical components, achieving uniform luminance distribution without increasing weight.

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

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 cost-effective, easily manufacturable, and reusable lighting device with high luminance homogeneity and smooth transitions, achieving visually appealing and harmonious illumination without abrupt brightness jumps.

Implementation Method 1

The rear wall of the housing can be designed as a freeform surface... the rear wall of the housing forms a type of light box, in which the rear wall of the housing can function as a projection surface for the at least one light source

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 2

The rear wall of the housing can have an at least partially diffuse light-scattering inner surface. By means of the diffuse light-scattering inner surface, the diffusivity of the light reflected from the inner surface of the rear wall can be increased

Methodology Applied
Scientific EffectLight scattering: Scattering

Implementation Method 3

The translucent cover can, in particular, have a substantially diffusely light-scattering optical body with a front side that is at least partially substantially flat and can be configured such that, when the rear side is illuminated, a diffuse glow from the front side can be visually perceived

Methodology Applied
Scientific EffectDiffuse light scattering: Scattering

Data Source

PatentEP4592141A1Lighting device for an interior of a vehicle and vehicle comprising the lighting device
Publication Date: 2025.07.30 STELLANTIS AUTO SAS
  • EP4592141A1 patent drawingFigure 1
  • EP4592141A1 patent drawingFigure 2
  • EP4592141A1 patent drawingFigure 3

AI summary

A lighting device (2) for the interior of a vehicle is proposed. The lighting device comprises a housing (4) with an at least partially light-reflecting rear wall (5) and with a flat, translucent cover (3). The cover has a rear side facing the rear wall (5) of the housing (5) and a front side opposite the rear side. The lighting device also comprises at least one light source (6) for illuminating the rear wall (5) of the housing (4), such that the rear side of the cover (3) can be illuminated by light reflected from the rear wall (5) of the housing (5) to generate a substantially uniform, planar illumination of the front side of the cover (3) at least in some regions. Furthermore, a vehicle with an interior is proposed, wherein at least one lighting device (2) is implemented in the interior.