NIR-Transparent Obscuration Pigments for Laminated Windscreen Sensors
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Solution Overview
Problem
Current polyvinyl butyral (PVB) interlayer films in laminated glazing, particularly in windscreens, absorb near-infrared (NIR) and infrared (IR) radiation, which interferes with sensors used in vehicles for rain detection and autonomous navigation, posing a safety hazard and being costly to rectify.
Innovation Solution
A laminated glass configuration using two glass sheets bonded with an adhesive film comprising a polyvinyl acetal film A with low plasticizer content and a polyvinyl acetal film B with high plasticizer content, where film A has a printed or coated obscuration area with specific transmission properties to allow NIR and IR transparency while maintaining visibility, utilizing NIR-transparent pigments like perylene for improved sensor functionality and aesthetic appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If carbon black or typical dyes/pigments are used to create obscuration areas in PVB films, then visibility is improved (obscuration achieved), but NIR and IR transmission deteriorates (absorption increases)
Solution Approach 1:
The patent applies local quality by using different pigment compositions in different areas of the film. NIR-transparent pigments (like perylene) are used specifically in the obscuration areas where sensor functionality is needed, while conventional carbon black can be used in non-obscuration areas. This allows each local region to have the optimal properties for its specific function.
Solution Approach 2:
The patent changes the chemical composition parameter of the pigments from conventional carbon black to NIR-transparent organic pigments (such as perylene, isoindoline, or indigo carmine) in the obscuration areas. This parameter change maintains the visible obscuration function while fundamentally improving NIR and IR transmission properties for sensor operation.
2Reliability
If NIR-transparent pigments are used throughout the entire tinted area, then sensor functionality is improved, but manufacturing cost increases
Solution Approach 1:
The patent applies local quality by using different pigment compositions in different areas of the film. NIR-transparent pigments (like perylene) are used specifically in the obscuration areas where sensor functionality is needed, while conventional carbon black can be used in non-obscuration areas. This allows each local region to have the optimal properties for its specific function.
Solution Approach 2:
Instead of applying the expensive NIR-transparent pigments throughout the entire film, the patent applies them only partially - specifically in the obscuration areas where they are critically needed for sensor functionality. This partial application achieves the necessary sensor performance while minimizing the quantity of expensive pigment required, thereby reducing manufacturing costs.
3Reliability
If cut-outs are made in the ribbon and filled with clear PVB, then sensor transparency is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent changes the chemical composition parameter of the pigments from conventional carbon black to NIR-transparent organic pigments (such as perylene, isoindoline, or indigo carmine) in the obscuration areas. This parameter change maintains the visible obscuration function while fundamentally improving NIR and IR transmission properties for sensor operation.
Solution Approach 2:
The patent merges the obscuration function with the sensor transparency function by using NIR-transparent pigments that simultaneously provide visible light blocking while allowing NIR and IR transmission. This eliminates the need for separate clear PVB inserts or cut-outs, combining multiple functions into a single integrated film structure.
4Ease of manufacture
If conventional pigments are used in the colored ribbon, then manufacturing simplicity is maintained, but sensor detection accuracy deteriorates
Solution Approach 1:
The patent applies local quality by using different pigment compositions in different areas of the film. NIR-transparent pigments (like perylene) are used specifically in the obscuration areas where sensor functionality is needed, while conventional carbon black can be used in non-obscuration areas. This allows each local region to have the optimal properties for its specific function.
Solution Approach 2:
The patent changes the chemical composition parameter of the pigments from conventional carbon black to NIR-transparent organic pigments (such as perylene, isoindoline, or indigo carmine) in the obscuration areas. This parameter change maintains the visible obscuration function while fundamentally improving NIR and IR transmission properties for sensor operation.
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 solution ensures better processability, lower manufacturing costs, and higher optical quality for detection areas, enabling effective operation of sensors in the NIR and IR range without visible obstruction, thus enhancing safety and appearance of windscreens.
Implementation Method 1
The dyes or pigments used must have sufficient solubility or dispersibility in the plasticized PVB resin and, at the same time, have sufficient UV stability. As an excellent light-stable pigment, colored carbon black is used for the colored ribbon of the PVB film. The disadvantage of carbon black and other typically used dyes and pigments is that they absorb far into the NIR or IR range.
Implementation Method 2
wherein the at least one area (2) has a transmission for infrared radiation from 850 nm to 1200 nm of more than 50%
Data Source
Figure 1~2
AI summary
The present invention relates to interlayer films for laminated glazing, in particular windscreens, which have a printed, non-transparent region highly transparent for NIR and/or IR radiation.