Trilayer Bus Bar for Electroactive Window Electrical Connections
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Solution Overview
Problem
Existing electroactive devices face challenges in providing reliable electrical connections to transparent conductive layers while maintaining structural and functional integrity, particularly in applications like vehicle windshields, where extending conductive layers beyond the active area leads to electrical short-circuits, reduced current-carrying capability, and visible 'iris' effects.
Innovation Solution
A trilayer bus bar with electrically-conductive layers and an insulative layer is positioned between the overhang sections of transparent conductive layers, extending around more than half of the periphery to provide electrical connections and ensure electrical isolation, matching the thickness of the active film to avoid modifications to the conductive layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transparent conductive layers are extended beyond the active area to provide electrical connections, then electrical connection reliability is improved, but electrical short-circuits occur between opposing layers
Solution Approach 1:
An insulative layer is introduced as an intermediary between the opposing transparent conductive layers at their extended periphery regions. This insulative coating prevents electrical short-circuits while allowing the conductive layers to extend beyond the active area for reliable electrical connections, thus resolving the contradiction between connection reliability and short-circuit prevention.
2Area of stationary object
If transparent conductive layers are extended beyond the active area, then electrical connection area is increased, but current-carrying capability is reduced
Solution Approach 1:
The transparent conductive layers are designed with different functional regions: a central high-current-density region within the active area optimized for current carrying, and extended peripheral regions with lower current density requirements optimized for electrical connections. This local differentiation allows increased connection area without significantly reducing overall current-carrying capability.
3Ease of operation
If transparent conductive layers are extended beyond the active area, then electrical connection accessibility is improved, but visible 'iris' effects are introduced
Solution Approach 1:
The insulative layer acts as a visual and electrical barrier that masks the extended periphery regions of the transparent conductive layers from view, preventing the formation of visible 'iris' effects while still allowing electrical connections to be made at these extended locations, thus improving accessibility without the visual defect.
4Device complexity
If conventional electrical connections are made to transparent conductive layers, then device complexity is reduced, but structural integrity is compromised
Solution Approach 1:
The insulative layer is integrated directly onto the surface of the transparent conductive layers, merging the electrical connection function with the structural layer itself. This eliminates the need for separate connection structures that would compromise structural integrity, maintaining both low complexity and high strength.
Data Source
AI summary
An electroactive package is disclosed that includes an active film and a pair of transparent conductive layers positioned on opposite sides of the active film. The transparent conductive layers each include an overhang section that extends beyond an edge of the active film, with the overhang sections being located at a periphery of the electroactive package. A bus bar is disclosed that comprises a pair of electrically-conductive layers and an insulative layer positioned between the electrically-conductive layers. The bus bar extends along at least a portion of the periphery of the electroactive package and is positioned between the overhang sections of the transparent conductive layers. Also disclosed are electroactive windows, and methods of making them.