Laminated Glass Wedge Angle Control for Double Image Reduction
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Solution Overview
Problem
Conventional laminated glass technologies face challenges in controlling the wedge angle, especially for interlayers, which affects the reduction of double images in transmission and reflection, due to material properties and environmental factors, leading to visibility issues in vehicle windshields.
Innovation Solution
The laminated glass design incorporates a first and second glass sheet with a wedge angle that satisfies a specific formula, where the wedge angle is determined by the sum of the glass sheets' wedge angles and the interlayer's wedge angle, ensuring optimal reduction of double images in transmission by managing the interlayer's wedge angle to be less than or equal to 0.5 mrad.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the interlayer is shaped to have a wedge angle, then double images in transmission can be reduced, but the film thickness is influenced by heating and press bonding, making it difficult to control the wedge angle
Solution Approach 1:
The patent divides the wedge angle control into two independent parts: the glass sheets provide a base wedge angle, and the interlayer provides a separate, minimal wedge angle (≤0.5 mrad). This segmentation allows each component to be manufactured and controlled independently, avoiding the difficulty of controlling a large wedge angle in the soft interlayer material alone.
Solution Approach 2:
The patent applies different wedge angle requirements to different components: the glass sheets are given a significant wedge angle for optical performance, while the interlayer is given a minimal wedge angle (≤0.5 mrad) to avoid deformation issues. This local differentiation of quality requirements resolves the manufacturing control problem.
2Manufacturing precision
If the wedge angle of the interlayer is increased, then double images in transmission are reduced, but the wedge angle changes depending on humidity, temperature, and press bonding conditions
Solution Approach 1:
Instead of relying on the interlayer to provide the full wedge angle needed for reducing double images, the patent uses the glass sheets to provide the majority of the wedge angle. The interlayer provides only a minimal wedge angle (≤0.5 mrad), which is sufficient to fine-tune the optical performance without being subject to environmental deformation.
3Ease of manufacture
If glass sheets are shaped to have a wedge angle, then wedge angle control is easier compared to interlayer, but conventional technologies have not sufficiently considered how to determine the wedge angle of glass sheets in laminated glass
Solution Approach 1:
The patent performs preliminary calculation and determination of the glass sheet wedge angle before manufacturing. By using the formula that relates wedge angle to double image reduction, the optimal glass sheet wedge angle is determined in advance, guiding the manufacturing process to achieve the desired optical performance.
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 approach effectively reduces double images in transmission, improving visibility by controlling the wedge angle of the interlayer and glass sheets, thereby minimizing distortion and visibility issues, especially in the non-HUD-display area of vehicle windshields.
Implementation Method 1
One or both of the first glass sheet and the second glass sheet are wedge-shaped glass. At one or more points in at least a part of an area of the second area, a wedge angle δg being a sum of a wedge angle of the first glass sheet and a wedge angle of the second glass sheet satisfies Formula (1) below: ... where n is a refractive index of the laminated glass; φ is a local incident angle of a ray of light incident on the laminated glass
Data Source
AI summary
Laminated glass includes a first glass sheet; a second glass sheet; and an interlayer positioned between the first and second glass sheets, to bond the first and second glass sheets together. The laminated glass has a first area used by a head-up display, and a second area adjacent to the first area and not used by the head-up display. One or both of the first and second glass sheets are wedge-shaped. At one or more points in at least a part of an area of the second area, a wedge angle δg being a sum of respective wedge angles of the first and second glass sheets satisfies Formula (1):δg=tRsinφcosφn2-sin2φ-ηcosφ2n2-sin2φ-δc-δi(1)where t, R, n, φ, η, δc, and δi are as specified in claim 1.