Pre-shaped Interlayer Wedge for HUD Optical Clarity
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Solution Overview
Problem
Laminated vehicle glazings with curvature suffer from secondary image distortions due to thickness variations and wedge angles, which can be disconcerting and pose safety concerns, especially in head-up display regions, where image clarity and driver focus are compromised.
Innovation Solution
A method of pre-shaping a ply of interlayer material with a wedged cross-section by controlled heating and stretching, using multiple rotating drums to minimize the standard deviation of the wedge angle, allowing precise control of the wedge angle across the glazing, particularly in the HUD region, to enhance optical quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a ply of interlayer material with a wedged cross-section is used to reduce secondary images in HUD regions, then the clarity of projected images is improved, but the manufacturing precision of the wedge angle is difficult to control
Solution Approach 1:
The interlayer material is pre-shaped with the desired wedged cross-section before lamination. This preliminary shaping ensures that the wedge angle is controlled during manufacturing, and the pre-shaped material maintains this geometry through the lamination process, resulting in consistent optical performance across all laminated glazings.
Solution Approach 2:
The patent controls the wedge angle parameter of the interlayer material by adjusting the stretching process parameters. By changing the stretching ratio, temperature, and humidity during manufacturing, the wedge angle can be precisely controlled to achieve the desired optical quality while maintaining manufacturing feasibility.
2Measurement precision
If the wedge angle is increased to eliminate secondary images, then the optical quality in HUD regions is improved, but the standard deviation of the wedge angle increases
Solution Approach 1:
The patent applies a localized wedged cross-section to the interlayer material specifically in the HUD viewing region, while maintaining uniform thickness in other areas. This local quality approach improves optical quality where needed without requiring extreme wedge angles across the entire material, thereby reducing manufacturing variability.
3Object-affected harmful factors
If a fully wedged cross-section is used across the entire glazing, then secondary images are reduced, but the complexity of the manufacturing process increases
Solution Approach 1:
Instead of applying a wedged cross-section across the entire interlayer material, the patent applies the wedge only in the specific HUD viewing region. This local quality approach eliminates secondary images in the critical viewing area while keeping the manufacturing process simpler than producing a fully wedged cross-section across the entire glazing surface.
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 method achieves a significant reduction in the standard deviation of the wedge angle and ghosting distance, improving the clarity and consistency of images projected onto the HUD area, thereby enhancing the overall optical quality and reducing driver fatigue.
Implementation Method 1
providing heat and moisture to a first surface of the ply of interlayer material to perform a first heating stage; providing heat and moisture to a second surface of the ply of interlayer material, opposite the first surface, to perform a second heating stage
Implementation Method 2
stretching the ply of interlayer material into a desired shape; the rate at which the heat and moisture are supplied is controlled such that the shaping of the ply of interlayer material is uniform
Data Source
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AI summary
A laminated vehicle glazing comprising a first ply of a glazing material and a second ply of a glazing material having a substantially co-extensive ply of an interlayer material laminated therebetween, at least a portion of the ply of interlayer material having a wedged cross-section, wherein the ply of interlayer material is pre-shaped by stretching such that either: (a) when the wedge angle is calculated at a plurality of points across the glazing, by taking measurements of a deflection of a laser beam as it passes through the glazing, the standard deviation in the magnitude of the wedge angle of the wedged portion is less than 0.05m rad;or (b) when a grid pattern is projected onto the glazing, the standard deviation in the displacement between observed primary and secondary images of portions of the grid is less than 0.85 mm.