Electrochromic Device Voltage Control for Uniform Transition
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Solution Overview
Problem
Electrochromic devices face challenges in uniformly transitioning between optical states due to variations in effective voltage across their surface, leading to non-uniform coloration and slow switching times, especially in larger devices where the center experiences lower effective voltage.
Innovation Solution
A controller system that applies a drive voltage to bus bars, monitoring the open circuit voltage and charge density to determine when to transition from a drive voltage to a hold voltage, ensuring uniform optical transitions across the device by harnessing the non-uniform voltage distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a constant drive voltage is applied across the electrochromic device, then the device can be driven to transition between optical states, but the transition is non-uniform with regions near bus bars experiencing higher effective voltage and transitioning faster than center regions
Solution Approach 1:
The patent applies a dynamic drive voltage that varies over time during the optical transition. The controller adjusts the voltage magnitude based on the progression of the transition, using higher initial voltage to drive the transition and then reducing voltage as the transition approaches completion. This dynamic approach compensates for the non-uniform voltage distribution across the device surface, allowing uniform coloration while maintaining fast switching times.
Solution Approach 2:
The patent employs feedback control where the controller monitors the optical state of the device (through optical sensors or electrical characteristics) and adjusts the drive voltage accordingly. This feedback mechanism allows the system to detect when the transition is complete and terminate or reduce the voltage application, ensuring uniform coloration across the entire device surface while optimizing switching speed and energy consumption.
2Manufacturing precision
If the drive voltage is applied for a long duration to ensure complete transition across the entire device surface, then uniform coloration is achieved, but the switching time increases and energy consumption rises
Solution Approach 1:
The patent uses periodic or pulsed voltage application rather than continuous voltage. The controller applies voltage in controlled intervals or pulses, allowing the optical transition to progress during voltage application and then pausing or reducing voltage. This periodic approach ensures complete and uniform transition across the device while significantly reducing the total switching time and energy consumption compared to continuous voltage application.
Solution Approach 2:
The patent implements dynamic voltage adjustment where the magnitude and duration of the drive voltage are optimized based on real-time monitoring of the transition progress. The controller increases voltage during phases requiring faster transition and reduces or terminates voltage when the transition is complete, achieving uniform coloration with minimized switching time and energy usage.
3Loss of time
If higher drive voltage is applied to speed up the transition in center regions with lower effective voltage, then switching time is reduced, but regions near bus bars may experience over-driving and damage
Solution Approach 1:
The patent applies different voltage magnitudes to different regions of the device or applies voltage in a controlled manner that accounts for local variations in effective voltage. By recognizing that regions near bus bars experience higher effective voltage while center regions experience lower effective voltage, the controller adjusts the overall drive voltage to ensure uniform transition without over-driving any specific region, thereby maintaining device reliability and durability while achieving fast switching times.
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 approach allows for efficient and uniform optical transitions, reducing the need for custom characterization and pre-programmed algorithms, and enables faster switching times by terminating the drive voltage when the transition is complete, thus maintaining the desired optical state.
Implementation Method 1
at least one layer of electrochromic material, that changes its optical properties in response to the application of an electrical potential
Implementation Method 2
an ion conductor (IC) layer that allows ions, such as lithium ions, to move through it, into and out from the electrochromic material to cause the optical property change
Data Source
AI summary
Aspects of this disclosure concern controllers and control methods for applying a drive voltage to bus bars of optically switchable devices such as electrochromic devices. Such devices are often provided on windows such as architectural glass. In certain embodiments, the applied drive voltage is controlled in a manner that efficiently drives an optical transition over the entire surface of the electrochromic device. The drive voltage is controlled to account for differences in effective voltage experienced in regions between the bus bars and regions proximate the bus bars. Regions near the bus bars experience the highest effective voltage.