Kinematic Mechanism for Head-Up Display Cover and Combiner

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Solution Overview

Problem

Existing kinematic mechanisms for combiner head-up display (C-HUD) systems in automotive applications face issues with noise levels, complexity, and cost due to the use of stepper motors and planetary gearing, which also limit angular adjustment and increase the risk of blockages and image distortions.

Innovation Solution

A kinematic mechanism using a single DC motor to simultaneously move the combiner and protective cover, with a synchronized movement ensured by a pin on the cover gear and a Geneva gear slot, allowing for angular adjustment and fine-tuning of the combiner position, and utilizing a modular chassis design for structural stiffness and ease of assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If stepper motors and planetary gearing are used to move the combiner and protective cover, then the movement control is improved, but the noise level increases and the system complexity increases

Engineering Contradiction:
Improvemovement control precisionVSAvoidnoise level
Core Design Contradiction:
Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the stepper motor and planetary gearing mechanical system with a DC motor coupled to a gearbox. This substitution maintains the required movement control precision while significantly reducing noise levels and system complexity, as the simpler mechanical transmission system generates less operational noise and has fewer components that could fail or require maintenance.

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

2Measurement precision

If stepper motors and planetary gearing are used to move the combiner and protective cover, then the movement control is improved, but the device complexity increases

Engineering Contradiction:
Improvemovement control precisionVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the complex stepper motor and planetary gearing system with a simpler DC motor coupled to a gearbox. This substitution maintains the required movement control precision while significantly reducing system complexity by eliminating the need for stepper motor control electronics and planetary gear assemblies, resulting in fewer parts and simpler maintenance requirements.

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

Solution Approach 2:

The single DC motor with gearbox serves multiple functions: it controls both the combiner movement and the protective cover operation. This multi-functionality reduces the overall system complexity by consolidating control functions into a single motor assembly rather than requiring separate actuators for each component.

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

3Measurement precision

If cam-wheels with pins are used to guide combiner movement, then the trajectory control is improved, but the risk of blockage increases and noise level increases

Engineering Contradiction:
Improvetrajectory control precisionVSAvoidrisk of blockage
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent replaces the cam-wheel and pin mechanical guidance system with a bar linkage mechanism. This substitution maintains precise trajectory control for the combiner movement while eliminating the pin-and-cam interface that is prone to blockages. The bar linkage provides continuous contact and guidance without the risk of pins becoming dislodged or cam surfaces becoming worn or blocked.

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

4Object-generated harmful factors

If a single DC motor with gearbox is used to move the combiner and protective cover, then the noise level is reduced and complexity is reduced, but the synchronized movement control becomes more challenging

Engineering Contradiction:
Improvenoise levelVSAvoidsynchronized movement control
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges the control of the combiner and protective cover into a single integrated mechanism driven by one DC motor. The bar linkage and cover gear are designed to translate the motor's rotational output into coordinated movement of both components. This merging eliminates the need for complex synchronized control of separate motors, as the mechanical linkage inherently coordinates the movement timing and sequence.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces a bar linkage as an intermediary mechanical element that mediates between the DC motor output and the combiner/protective cover components. This bar linkage acts as a kinematic mediator that automatically coordinates the movement of both components, simplifying the control architecture by using passive mechanical coordination rather than active electronic synchronization.

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 enables fast and precise movement of the combiner between retracted and display positions, reduces noise and complexity, and enhances positional accuracy, while being cost-effective and adaptable to different driver heights, thus improving the overall robustness and usability of the C-HUD system.

Implementation Method 1

a Geneva gear arranged in cooperation with the combiner gear such that continuous rotary motion of the cover gear is translated into an intermittent rotary motion of the Geneva gear

Methodology Applied
Scientific EffectGeneva Drive: Geneva Drive

Data Source

PatentEP3307590B1Kinematic mechanism for a head-up display
Publication Date: 2019.08.07 BOSCH CAR MULTIMEDIA PORTUGAL SA
  • EP3307590B1 patent drawingFigure 1
  • EP3307590B1 patent drawingFigure 2(a)~2(b)
  • EP3307590B1 patent drawingFigure 3(a)~3(b)

AI summary

Head-up display comprising an image-combiner (1), a protective cover (2), and a kinematic mechanism comprising a cover-gear (6.1) for opening and closing the head-up display's protective cover (2), a combiner-gear (5.1) for moving the image-combiner (1) between a retracted position and an image-display position, a motor (9) for driving the cover-gear (6.1) and a Geneva-gear (7.1) arranged in cooperation with the combiner-gear (5.1) such that continuous rotary motion of the cover-gear (6.1) is translated into an intermittent rotary motion of the Geneva-gear, said Geneva-gear (7.1) and said combiner-gear (5.1) being either the same gear or are intermeshing gears.