Vehicle Windshield Laminated Glass HUD Optical Distortion
Solution Overview
Problem
High-functional windshields with multi-layer interlayers for vehicles face challenges in preventing double images and optical distortion in HUD devices, especially when a wedge-shaped thickness profile is employed, which complicates the control of layer thickness and refractive index differences, leading to deteriorated display quality.
Innovation Solution
A laminated glass design with a multi-layer interlayer where the first resin layer has a thickness of at least 0.3 mm in the display region and a wedge-shaped thickness profile, supported by layers with higher hardness, which prevents optical distortion and allows for easier expansion and control of the interlayer's shape, reducing the influence of refractive index differences and minimizing the thickness of the sound insulation layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multi-layer interlayer with wedge-shaped thickness profile is employed to prevent double images in HUD devices, then the display quality is improved, but the control of layer thickness and refractive index becomes complicated, leading to optical distortion
Solution Approach 1:
The interlayer is divided into multiple resin layers with different functions. The first resin layer (0.3-1.0mm thick) provides structural support and maintains wedge shape, while the second resin layer (0.05-0.5mm thick) provides sound insulation. This segmentation allows each layer to be optimized independently, simplifying thickness control while preventing double images and reducing optical distortion.
Solution Approach 2:
Different regions of the interlayer are assigned different thicknesses and materials based on local requirements. The first resin layer has varying thickness (0.3-1.0mm) to maintain the wedge shape for HUD functionality, while the second resin layer is positioned specifically for sound insulation. This local optimization resolves the contradiction between wedge shape requirements and thickness control complexity.
2Reliability
If the thickness of the multi-layer interlayer is reduced to minimize optical distortion in the wedge-shaped region, then the display quality is improved, but the sound insulation ability is deteriorated
Solution Approach 1:
The interlayer is segmented into a first resin layer optimized for optical properties (0.3-1.0mm thick wedge shape) and a second resin layer optimized for sound insulation (0.05-0.5mm thick). This segmentation allows the sound insulation layer to maintain sufficient thickness for acoustic performance while the overall interlayer structure maintains the wedge shape needed for HUD display quality, preventing both double images and excessive optical distortion.
Solution Approach 2:
The interlayer uses composite material structure with at least two different resin layers having different properties. The first resin layer provides structural integrity and optical clarity for the wedge shape, while the second resin layer provides sound insulation. This composite approach resolves the contradiction between minimizing optical distortion and maintaining sound insulation ability.
3Device complexity
If a single-layer interlayer with wedge shape is used, then the construction is simple and light utilization efficiency is high, but the optical distortion occurs in the thin portion
Solution Approach 1:
The interlayer is segmented into multiple resin layers where the first resin layer (0.3-1.0mm thick) maintains the wedge shape for structural simplicity and light utilization, while the second resin layer provides additional support to prevent excessive thinning and optical distortion in the wedge's thin portion. This segmentation maintains construction simplicity while eliminating optical distortion issues.
4Reliability
If the thickness of the first resin layer is increased to prevent optical distortion, then the display quality is improved, but the weight and cost of the laminated glass are increased
Solution Approach 1:
The interlayer is segmented into a first resin layer (0.3-1.0mm thick) that provides the minimum necessary thickness for preventing optical distortion and maintaining wedge shape, and a second resin layer (0.05-0.5mm thick) that provides sound insulation. This segmentation optimizes the first resin layer thickness to the minimum required for display quality, reducing weight compared to a single thick layer, while adding only the necessary thickness for sound insulation functionality.
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
This design effectively prevents double images and optical distortion, enhances visibility, and allows for efficient production and design flexibility, reducing the weight and cost of the laminated glass while maintaining high display quality.
Implementation Method 1
another light beam 53 of display information is incident at a point B on the 1st face in a car-interior side of the windshield, refracted and reaches to a point C on 1st face of the windshield
Implementation Method 2
due to optical distortion caused by the multi-layer interlayer in the display area, the display quality is deteriorated
Data Source
Figure 1~2
Figure 3~4
Figure 5~6(B)
AI summary
It is an object of the present invention to provide, in a HUD device employing a high-functional windshield such as a sound-insulation glass having a multi-layer interlayer, a windshield for a vehicle which does not produce double images and has excellent visibility without deteriorating functionality of the windshield. In a laminated glass having a multi-layer interlayer having a wedge-shaped thickness profile sandwiched by glass sheets, the multi-layer interlayer has layers having different hardness, the thickness of first resin layers having high hardness is at least 0.3 mm in a region within 400 mm from a lower side, which prevents generation of optical distortion of the laminated glass and efficiently prevents double images of display.