Laminated Glass Wedge Interlayer for HUD Double Image Reduction
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Solution Overview
Problem
Existing laminated glass technologies for head-up displays in vehicles face challenges in controlling the wedge angle precisely, leading to inconspicuous reflected images due to errors in the wedge angle, which results in noticeable double images for drivers.
Innovation Solution
A laminated glass design featuring a first glass plate inside the vehicle, a second glass plate outside, and an interlayer with a wedge shape in the cross-section, where the thickness difference between the thickest and thinnest portions satisfies ΔTv ≥ 2.2Δt, ensuring reduced visible light transmittance and minimizing reflected double images even with wedge angle errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a wedge-shaped interlayer is used to reduce reflected double images, then the reflected double image is reduced, but manufacturing precision deteriorates due to difficulty in controlling the wedge angle precisely
Solution Approach 1:
The invention changes the parameter from wedge angle to thickness difference. Instead of controlling the wedge angle α, the patent specifies a thickness difference Δt between the thickest and thinnest portions of the wedge-shaped interlayer. This parameter substitution makes manufacturing more controllable while achieving the same optical effect of reducing reflected double images.
Solution Approach 2:
The invention replaces the optical-mechanical wedge angle parameter with a simple thickness measurement parameter. By using thickness difference Δt instead of wedge angle α, the patent simplifies the measurement and control process, replacing complex angular measurement with straightforward thickness measurement at two points.
2Object-affected harmful factors
If the wedge angle is increased to reduce transmitted double images, then the transmitted double image is reduced, but the reflected double image control deteriorates due to angle errors
Solution Approach 1:
The invention changes the controlling parameter from wedge angle to thickness difference, which provides more reliable control over both transmitted and reflected double images. The thickness difference parameter Δt directly controls the optical path difference without the compounding errors associated with angular measurements.
3Object-affected harmful factors
If a variable wedge angle region is provided on the front windshield, then both transmitted and reflected double images are reduced, but device complexity increases
Solution Approach 1:
The invention applies local quality by providing the wedge shape only in the necessary regions (HUD display area and/or transparent area) rather than uniformly across the entire windshield. This localized application reduces double images where needed while minimizing overall complexity and material usage.
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 design effectively reduces the conspicuousness of reflected double images by adjusting the visible light transmittance, maintaining the clarity of the primary image while minimizing the visibility of the reflected double image, even when the wedge angle has errors.
Implementation Method 1
a laminated glass obtained by holding with two glass plates an interlayer having a wedge shape in a cross section and a wedge angle of the interlayer being changed depending on a site on the front windshield
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3~4
AI summary
A laminated glass includes first and second glass plates to be arranged on the inside and the outside of a vehicle, respectively; an interlayer located between the first and second glass plates and bonded to the first and second glass plates; and a display area used for a head up display, including a region having a wedge shape in a cross section, a thickness at an upper end of the region in a vertical direction being greater than a thickness at a lower end of the region. A difference, Δt [mm], between a thickness of the laminated glass at a thickest portion in the display area and a thickness at a thinnest portion, and a difference, 22ΔTv [%], between a visible light transmittance of the laminated glass at the thickest portion in the display area and a visible light transmittance at the thinnest portion, satisfy a relation of ΔTv≥2.2Δt.