Tilting Optical Waveguide for HUD Sunlight Reflection Avoidance

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Solution Overview

Problem

Existing head-up displays in vehicles suffer from safety-critical reflections of sunlight into the driver's eye, which can cause irritation, and common attenuation strategies like louver films and polarizers are costly and inefficient.

Innovation Solution

An optical system with a radiation detection unit to measure solar radiation and a control unit that tilts the optical waveguide to avoid direct reflections by adjusting its angle, using an actuator system to rapidly switch between positions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the optical waveguide is tilted to redirect sunlight reflections away from the driver's eye, then harmful reflections are reduced, but the alignment and positioning precision of the optical system becomes more complex

Engineering Contradiction:
Improvesunlight reflection into driver's eyeVSAvoidalignment precision of optical waveguide
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The optical waveguide is made tiltable relative to the windshield, allowing dynamic adjustment of its angle. The control unit activates an actuator to tilt the optical waveguide when sunlight reflection is detected, redirecting harmful reflections away from the driver's eye while maintaining proper alignment through controlled movement.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The radiation detection unit continuously monitors for sunlight hitting the optical waveguide and sends signals to the control unit. This feedback loop enables the system to detect harmful radiation angles and automatically adjust the optical waveguide's tilt angle to eliminate reflections into the driver's eye.

Inventive Principle:
Principle #23Feedback

2Object-affected harmful factors

If the optical waveguide is tilted to avoid reflections, then harmful factors are reduced, but the device complexity increases due to additional actuation mechanisms

Engineering Contradiction:
Improvestray light reflectionVSAvoidactuator and control system
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The system uses the detected sunlight information to automatically control its own adjustment. The radiation detection unit detects harmful radiation, the control unit processes this information, and the actuator automatically tilts the optical waveguide to eliminate reflections, enabling the system to self-regulate without manual intervention.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system replaces complex optical filtering mechanisms (such as polarizers or louver films) with a simpler mechanical tilting mechanism. Instead of using expensive optical materials to block reflections, the patent uses an actuator to physically tilt the optical waveguide, redirecting reflections away from the driver's eye through geometric adjustment.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Loss of time

If rapid tilting of the optical waveguide is implemented, then response time to harmful radiation is reduced, but the mechanical stress and durability requirements increase

Engineering Contradiction:
Improveresponse time to sunlight reflectionVSAvoidmechanical durability of optical waveguide
Core Design Contradiction:
Loss of timeVSStrength

Solution Approach 1:

The system operates in periodic cycles: the radiation detection unit continuously monitors for sunlight, detects when harmful radiation is present, triggers the actuator to tilt the optical waveguide, and maintains the tilted position until the sunlight angle changes. This periodic activation reduces mechanical stress compared to continuous adjustment while maintaining rapid response when needed.

Inventive Principle:
Principle #19Periodic action

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

Effectively prevents sunlight reflections from entering the driver's eye by geometrically redirecting them away, ensuring rapid adjustment without significant loss of useful light, thus enhancing safety and reducing manufacturing costs.

Implementation Method 1

a radiation detection unit is provided for detecting an angle of incidence range of radiation incident on the optical waveguide

Methodology Applied
Scientific EffectRadiation detection: Absorption (EM radiation)

Implementation Method 2

an optical waveguide which is designed to project the image information in at least one direction

Methodology Applied
Scientific EffectOptical transmission: Refraction

Implementation Method 3

a disc inclined with respect to the optical waveguide for reflecting the projected image information of the optical waveguide

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP3835849B1Optical system for generating a two or three-dimensional image
Publication Date: 2025.09.24 CONTINENTAL AUTOMOTIVE TECHNOLOGIES GMBH
  • EP3835849B1 patent drawingFigure 1~2
  • EP3835849B1 patent drawingFigure 3
  • EP3835849B1 patent drawingFigure 4~5

AI summary

The invention relates to an optical system (1) for generating a two- or three-dimensional image, comprising an imaging unit (8) for optical transmission and/or generation of image information, and an optical waveguide (7) configured to project the image information in at least one direction, and a disk inclined relative to the optical waveguide (7) for reflecting the projected image information of the optical waveguide (7), so that the viewer perceives the image information as a virtual image in a display area (9) on one of the user-away sides of the disk, wherein a radiation detection unit (14, 14a) is provided for detecting an angle of incidence range (α1, α2) of radiation incident on the optical waveguide (7), and a control unit (12) is provided which is connected to the radiation detection unit (14, 14a) for data transmission.and which accomplishes a tilting of the optical waveguide (7) for a given angle of incidence range.