Thin Inner Pane Laminated Glass for HUD Ghosting

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Solution Overview

Problem

Conventional laminated glasses for head-up displays in vehicles are expensive and complex to produce due to the need for thermoplastic films with large wedge angles, which result in ghosting and double image issues, affecting visibility and safety.

Innovation Solution

A laminated glass with a thin inner pane (0.5 mm to 0.9 mm) and a thermoplastic intermediate layer with a variable thickness and small wedge angle (≤0.15 mrad), produced by stretching a film with constant thickness, reducing production costs and eliminating ghosting and double image problems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a thermoplastic film with a large wedge angle is used to reduce ghosting, then the ghost image is less noticeable, but the manufacturing cost and complexity increase significantly

Engineering Contradiction:

ImproveghostingVSAvoidmanufacturing complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent changes the wedge angle parameter from the conventional large value (around 0.5 mrad) to a small value (less than or equal to 0.15 mrad). This parameter change fundamentally alters the approach to ghosting reduction, allowing the use of simpler, more cost-effective manufacturing processes while still achieving acceptable ghosting suppression through the combination of thin panes and small wedge angle

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Instead of using a large wedge angle to separate the ghost image from the main image (conventional approach), the patent inverts the approach by using a small wedge angle combined with thin panes to bring the reflective surfaces closer together. This inversion of the conventional wisdom allows for simpler manufacturing while still addressing the ghosting problem

Inventive Principle:

Principle #13The other way round (Inversion)

2Object-affected harmful factors

If a thermoplastic film with a large wedge angle is used to reduce ghosting, then the ghost image is less noticeable, but the production cost increases

Engineering Contradiction:

ImproveghostingVSAvoidproduction cost

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a thermoplastic film with a small wedge angle that can be manufactured using simpler, more cost-effective methods. This approach replaces the expensive, complex wedge films with a more economical solution that achieves the required functional performance through the combination of thin panes and small wedge angle

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Manufacturing precision

If the inner pane thickness is reduced to 0.5 mm to 0.9 mm, then the reflective surfaces are closer together enabling smaller wedge angles, but the structural strength may be compromised

Engineering Contradiction:

Improvewedge angle precisionVSAvoidpane strength

Core Design Contradiction:

Manufacturing precisionVSStrength

Solution Approach 1:

The patent uses a composite structure consisting of two glass panes (with the inner pane being thin at 0.5 mm to 0.9 mm) bonded together with a thermoplastic intermediate layer. This composite construction allows the thin inner pane to achieve the required precision for small wedge angles while the overall laminated structure maintains sufficient strength through the combination of layers

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent employs a thermoplastic intermediate layer between the two glass panes to provide structural support and cushioning. This intermediate layer compensates for the reduced strength of the thin inner pane, allowing it to be used without compromising the overall structural integrity of the laminated glass

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 and stable laminated glass with reduced ghosting and double image issues, enhancing visibility and safety in head-up displays while maintaining structural integrity and reducing vehicle weight, thus contributing to lower fuel consumption.

Implementation Method 1

The thickness of the intermediate layer is variable in the vertical course between the lower edge and the upper edge of the laminated glass, at least in sections, with a maximum wedge angle α of less than or equal to 0.15 mrad

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

images are projected onto the windshield, reflected there and perceived by the driver as a virtual image

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentEP3230058B1Laminated glass with low thickness for a head-up display (HUD)

Publication Date: 2022.02.23 SAINT GOBAIN VITRAGE SA

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AI summary

The invention relates to a laminated glass (10) for a head-up display having an upper edge (O) and a lower edge (U), at least comprising an outer pane (1) made of glass and an inner pane (2) made of glass, which are connected to one another via a thermoplastic intermediate layer (3), wherein the inner pane (1) has a thickness of less than 1.2 mm, and wherein the thickness of at least some sections of the intermediate layer (3), in the vertical course between the lower edge (U) and the upper edge (O), is variable, with a maximum wedge angle (α) of less than or equal to 0.3 mrad.