Curved Automotive Glazing with Optical Coupling Layer
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Solution Overview
Problem
The integration of pressure-sensitive functional films, such as liquid crystal films, into complexly curved automotive glazings is challenging due to sensitivity to pressure and temperature during the lamination process, leading to aesthetic issues like black spots and non-standard, heavier product structures.
Innovation Solution
A laminated glazing design featuring a first and second glass sheet with an electrically powered functional film, separated by an optical coupling material that maintains a distance between the film and the glass sheets, allowing for the integration of functional films into curved shapes while managing thermal expansion and pressure sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a functional film is integrated into a curved laminated glazing using conventional lamination processes, then the glazing achieves the desired curvature and structural integrity, but the functional film is damaged by pressure and temperature leading to aesthetic defects like black spots
Solution Approach 1:
The patent segments the lamination process into two distinct stages: first, curving the glass sheets independently; second, laminating the functional film to the pre-curved glass. This segmentation allows the glass to be shaped without exposing the functional film to damaging high pressure and temperature conditions, thereby preventing aesthetic defects while achieving the desired curvature.
Solution Approach 2:
The glass sheets are pre-curved to the desired shape before the functional film is applied. This preliminary action of curving the glass independently allows subsequent lamination to occur at lower, non-damaging pressures and temperatures, preserving the functional film's aesthetic quality while achieving the required glazing curvature.
2Ease of manufacture
If thicker glass sheets or pre-laminated structures are used to facilitate functional film integration, then the assembly process becomes easier, but the product structure becomes non-standard and heavier
Solution Approach 1:
Instead of the conventional approach of laminating the functional film to flat glass and then curving the entire assembly (which requires thick glass or pre-lamination for ease of handling), the patent inverts the sequence: glass sheets are curving first, then the functional film is applied to the pre-curved surface. This inversion eliminates the need for thicker glass or pre-laminated structures, maintaining standard lightweight construction while simplifying the assembly process.
3Device complexity
If the functional film is placed in direct contact with the glass sheets, then the structure is simplified, but thickness variations cause inhomogeneous pressure leading to black spots during assembly
Solution Approach 1:
The patent introduces an optical coupling material as an intermediary layer between the functional film and the glass sheets. This intermediary layer compensates for thickness variations in the glass, ensuring homogeneous pressure distribution during assembly and preventing the formation of black spots, while maintaining optical clarity and structural integrity.
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 solution enables the successful integration of pressure-sensitive functional films into curved automotive glazings with good aesthetic quality and reduced thickness, avoiding the issues of pressure-induced defects and non-standard structures.
Implementation Method 1
an optical coupling material being a layer of polymer that is polymerized or cured from a liquid resin
Data Source
AI summary
The present invention relates to an automotive curved laminated glazing (1) comprising (i) a first glass sheet (11) having an outer (P1) and an inner (P2) faces, (ii) an electrically powered functional film (13), (iii) a second glass sheet (12) having an outer (P3) and an inner (P4) faces. (iv) at least one optical coupling material (14) being a layer of polymer that is polymerized or cured from a liquid resin and provided between the said functional film and the at least first (11) and/or the second (12) glass sheets. According to the present invention, the curved laminated glazing has at least 50% of the total surface area of the outer face (P1) of the first glass sheet (11) and the inner face (P4) of the second glass sheet (12), having a minimum radius of curvature (R min) comprised between 75-8500 mm.