Angled Bus Bar Layout for Uniform Electrochromic Switching
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Solution Overview
Problem
Existing electrochromic devices face issues with non-uniform transition between optical states due to high sheet resistance and terminal effects, leading to hot spots, curtain effects, and slow switching rates, particularly in large devices.
Innovation Solution
The use of angled bus bars that follow the shape of the device's perimeter corners, allowing for symmetrical and rapid switching without overdriving, and minimizing hot spots and curtain effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional bus bars are used in electrochromic devices, then the device can be manufactured with standard configurations, but non-uniform transition between optical states occurs due to high sheet resistance and terminal effects
Solution Approach 1:
The bus bar configuration transitions from conventional symmetric placements to asymmetric angled placements that specifically target corner regions. The first bus bar is positioned at a first angle to the first edge and a second angle to the second edge, while the second bus bar is positioned at a third angle to the first edge and a fourth angle to the second edge. This asymmetric positioning optimizes current distribution to eliminate non-uniform optical transitions and prevent hot spots.
2Area of stationary object
If larger electrochromic devices are manufactured to increase energy savings, then more surface area is covered, but switching speed decreases and curtain effects increase
Solution Approach 1:
The bus bar system segments the current distribution by placing separate angled bus bars at different corners and edges of the device. The first bus bar targets current delivery to corner regions while the second bus bar targets opposite corners and edges, creating multiple current pathways that reduce the curtain effect and maintain fast switching speeds across large device areas.
3Speed
If higher current is applied to speed up switching, then transition time decreases, but hot spots are generated that can damage the device
Solution Approach 1:
The angled bus bar configuration provides localized current distribution tailored to specific device regions. By positioning bus bars at optimized angles relative to edges and corners, current is distributed more evenly across the electrochromic material, preventing localized overheating while maintaining fast switching speeds throughout the entire device.
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
Enables uniform and fast transitions between optical states in electrochromic devices, reducing the risk of damage and improving switching speed and uniformity across the entire device surface.
Implementation Method 1
Tungsten oxide is a cathodic electrochromic material in which a coloration transition, transparent to blue, occurs by electrochemical reduction
Implementation Method 2
Electrochromism is a phenomenon in which a material exhibits a reversible electrochemically-mediated change in an optical property when placed in a different electronic state, typically by being subjected to a voltage change
Data Source
AI summary
This disclosure provides configurations, methods of use, and methods of fabrication for a bus bar of an optically switchable device. In one aspect, an apparatus includes a substrate and an optically switchable device disposed on a surface of the substrate. The optically switchable device has a perimeter with at least one corner including a first side, a second side, and a first vertex joining the first side and the second side. A first bus bar and a second bus bar are affixed to the optically switchable device and configured to deliver current and/or voltage for driving switching of the device. The first bus bar is proximate to the corner and includes a first arm and a second arm having a configuration that substantially follows the shape of the first side, the first vertex, and the second side of the corner.