Backlight Reflector Wall Layout for Uniform HUD Illumination

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Solution Overview

Problem

Existing head-up display systems suffer from inefficiencies in backlighting devices due to light ray escape between the reflector and diffuser, leading to reduced efficiency and non-homogeneous illumination.

Innovation Solution

A reflector design with peripheral and internal walls forming cavities around light sources, where the internal walls extend further from the diffuser than the peripheral walls, confining light beams and ensuring homogeneous illumination while reducing light loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If the reflector is positioned at a distance from the diffuser to ensure even illumination, then the homogeneity of illumination is improved, but light ray escape increases and efficiency decreases

Engineering Contradiction:
Improvehomogeneity of illuminationVSAvoidlight ray escape
Core Design Contradiction:
Illumination intensityVSLoss of energy

Solution Approach 1:

The reflector is segmented into peripheral walls and internal walls with different heights. The peripheral walls extend to a confinement distance from the diffuser, while internal walls extend to a greater joint distance. This segmentation allows different regions of the reflector to perform different functions: peripheral walls confine light rays to prevent escape, while internal walls provide extended reflection paths for homogeneous illumination.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different parts of the reflector are given different local qualities through varying wall heights. The peripheral walls are taller (extending to confinement distance) to maximize light confinement at the edges, while internal walls are shorter (extending to joint distance) to allow light distribution. This local differentiation resolves the contradiction between light confinement and homogeneous illumination.

Inventive Principle:
Principle #3Local quality

2Loss of energy

If the reflector is positioned close to the diffuser to reduce light ray escape, then efficiency is improved, but illumination homogeneity deteriorates

Engineering Contradiction:
Improvelight ray escapeVSAvoidhomogeneity of illumination
Core Design Contradiction:
Loss of energyVSIllumination intensity

Solution Approach 1:

The reflector structure is divided into peripheral and internal wall segments with different extension distances from the diffuser. This segmentation enables the peripheral walls to confine light effectively while internal walls maintain illumination homogeneity, achieving both goals simultaneously rather than requiring a uniform reflector position.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The solution moves from a single-dimensional positioning problem (uniform distance) to a multi-dimensional structure where wall height varies spatially. By introducing vertical dimensionality variation in wall heights, the system achieves both light confinement and homogeneous illumination that cannot be achieved with uniform positioning.

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

3Loss of energy

If light source intensity is increased to compensate for light loss, then illumination efficiency is maintained, but heat loss increases

Engineering Contradiction:
Improvelight lossVSAvoidheat loss
Core Design Contradiction:
Loss of energyVSTemperature

Solution Approach 1:

The invention converts the potentially harmful effect of light ray escape into a beneficial structured reflection system. By designing peripheral and internal walls with specific geometries, escaped light rays are captured and redirected through multiple reflections, transforming light loss into useful illumination while maintaining lower light source intensity and reducing heat generation.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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 reflector design enhances lighting efficiency and homogeneity at the diffuser, allowing for reduced light source intensity and heat loss, while maintaining compactness and energy efficiency.

Implementation Method 1

a reflector comprising walls rising between the plurality of light sources and the diffuser, the walls forming cavities around the light sources so as to reflect at least part of the light beams towards the diffuser

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

a diffuser extending in front of the plurality of light sources

Methodology Applied
Scientific EffectDiffusion: Diffusion

Data Source

PatentEP4508488B1Backlighting device and image generator
Publication Date: 2026.03.18 VALEO COMFORT & DRIVING ASSISTANCE
  • EP4508488B1 patent drawingFigure 1~2
  • EP4508488B1 patent drawingFigure 3~4

AI summary

The invention relates to a backlighting device (3) for an image generator, comprising: - a plurality of light sources (10), designed to generate a light beam each; - a diffuser (20) extending so as to face the plurality of light sources; and - a reflector (30) comprising walls rising between the plurality of light sources and the diffuser, the walls forming cavities (31) around the light sources (10), wherein peripheral walls (32) extend at a containment distance (D1) from the diffuser, and wherein an inner wall (33) extends at a clearance distance (D2) from the diffuser, which clearance distance is greater than the containment distance. The invention also relates to an image generator.