Switchable Glass Laminate Circuit Layout for Low-Resistance Connections
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Solution Overview
Problem
In switchable glass assemblies for automotive applications, the electrical connections between conductive coatings result in poor connectivity due to significant resistance, primarily caused by the molecular composition or structure of the coated surfaces, leading to inefficient power supply connections for multiple segments.
Innovation Solution
A laminated stack design is implemented with a conductive bridge connecting the second conductive coating of a single segment directly to the busbar, and a printed circuit with busbars in conductive contact with each segment, allowing for improved electrical connectivity by extending the first thermoplastic film beyond the perimeter of the switchable film to define a print zone and facilitate external connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical connections are made through conductive coatings on thermoplastic films, then the assembly structure is maintained, but significant resistance results in poor connectivity
Solution Approach 1:
A conductive adhesive layer is introduced as an intermediary between the conductive coating and the busbar/printed circuit. This adhesive layer has superior electrical conductivity compared to the conductive coating alone, acting as a mediator that reduces overall electrical resistance and improves connectivity reliability while maintaining the layered assembly structure.
Solution Approach 2:
The electrical conductivity parameter of the connection interface is improved by changing the material properties of the adhesive layer. The conductive adhesive is specifically formulated with higher electrical conductivity than the transparent conductive coating, thereby reducing resistance without requiring changes to the existing conductive coating or busbar materials.
2Ease of manufacture
If the first thermoplastic film is extended beyond the perimeter of the switchable film to define a print zone, then external connections are facilitated, but the device complexity increases
Solution Approach 1:
The first thermoplastic film is segmented into two functional zones: a central region that bonds to the switchable film and an extended peripheral region that forms the print zone. This segmentation allows the same film to serve dual purposes - structural bonding and electrical connection facilitation - thereby reducing overall device complexity despite the extended perimeter.
Solution Approach 2:
The extended first thermoplastic film performs multiple functions: it provides structural support, maintains lamination integrity, and creates the print zone for electrical connections. This multi-functionality reduces the need for separate components, thereby simplifying the overall device structure despite the extended perimeter.
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 enhances connectivity by reducing resistance and ensuring reliable power supply to each segment, improving the assembly and functionality of switchable glass assemblies in vehicles.
Implementation Method 1
a first transparent conductive coating, the first thermoplastic film including at least two segments separated by at least one cut line running through the first conductive coating
Implementation Method 2
providing a conductive bridge connecting the second conductive coating of a single first segment of the at least two segments directly to the busbar of the single segment
Data Source
Figure 1~2
Figure 3A~4
Figure 5A~6C
AI summary
The invention relates to a laminated stack for a switchable glass assembly and a method for providing such. The laminated stack includes first and second thermoplastic film each having a surface coated with a transparent conductive coating, a switchable film located between the first and second thermoplastic film, facing each of the first and second coated surfaces. The first thermoplastic film extends in surface beyond a perimeter of the switchable film and the second thermoplastic film, defining a print zone and includes two segments. A printed circuit in the print zone includes for each segment a busbar and a track running from the busbar to an external connection zone (46) of the print zone, wherein a single first segment includes a conductive bridge connecting the second conductive coating directly to the busbar of the single segment.