Electrochromic Device Clearing via Temperature-Adaptive PWM
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Solution Overview
Problem
Existing electrochromic devices struggle to rapidly clear without reverse coloring, especially under varying temperature conditions, which affects the diffusion rate of electrochromic species.
Innovation Solution
A controller system that includes an electro-optic device with substrates and an electro-optic medium, and a controller capable of supplying electrical power in pulse width modulation signals, including a reverse potential for a measured time interval followed by no power for another measured time interval, while also determining the temperature of the device to optimize clearing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If reverse bias pulse is applied to accelerate clearing, then clearing speed is improved, but reverse coloring occurs at extreme temperatures
Solution Approach 1:
The system dynamically adjusts the reverse bias pulse width based on real-time temperature measurements. At low temperatures, the pulse width is reduced to prevent reverse coloring, while at high temperatures, it is optimized for maximum clearing speed. This dynamic adaptation allows the system to maintain both fast clearing performance and reliability across varying temperature conditions.
Solution Approach 2:
The system changes the temporal parameter (pulse width) of the reverse bias signal based on temperature conditions. By modifying this parameter according to environmental conditions, the system achieves optimal clearing performance without causing reverse coloring, resolving the contradiction between speed and reliability.
2Speed
If reverse bias pulse width is increased to clear species at electrode surfaces, then clearing speed is improved, but reverse coloring occurs
Solution Approach 1:
The system applies a preliminary reverse bias pulse of controlled duration to clear electrochromic species from electrode surfaces before the main coloring process. By limiting the pulse width based on temperature, it prevents the accumulation of excess species that would cause reverse coloring, while still achieving effective surface clearing and maintaining fast response.
Solution Approach 2:
The system applies a partial reverse bias pulse that is sufficient to clear species at electrode surfaces but deliberately limited in duration to avoid excessive action that would cause reverse coloring. This partial action approach optimizes the balance between clearing effectiveness and preventing harmful side effects.
3Loss of time
If diffusion distance is reduced by shorting electrodes, then clearing time is reduced, but temperature-dependent diffusion rates cause inconsistent performance
Solution Approach 1:
The system incorporates temperature sensing and uses this feedback to adjust the reverse bias pulse width accordingly. This closed-loop control ensures that the clearing process remains effective and consistent across varying temperature conditions, adapting the pulse parameters to compensate for temperature-dependent diffusion rate changes.
Solution Approach 2:
The system dynamically adapts its clearing parameters based on real-time temperature measurements, transforming a static clearing approach into a dynamic one that responds to environmental conditions. This allows consistent performance across different temperatures while maintaining reduced clearing time through electrode shorting.
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 system achieves faster clearing of electrochromic devices with minimal reverse coloring by optimizing the pulse width modulation signals based on temperature, thereby improving the control of transmissivity levels.
Implementation Method 1
The redox potential of the anodic and cathodic chemical species at the two electrodes is sufficient to drive electron transfer across the electrodes to revert the oxidized anodic and reduced cathodic EC species to their original oxidation states.
Implementation Method 2
The concentration gradient of reduced cathodic and oxidized anodic species at their respective electrodes drives diffusion away from the electrode surfaces into the cell.
Implementation Method 3
A complication of the reverse biased clearing approach is that the diffusion rate of the EC species, like other chemical species, changes with temperature.
Data Source
Figure 1~2
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AI summary
A controller system configured to clear an electro-optic device may include an electro-optic device having a first substrate having a first surface and a second surface, the second surface having a first layer of electrically conductive material disposed thereon; a second substrate having a first surface having a second layer of electrically conductive material disposed thereon, and a second surface, the second substrate being approximately parallel to the first substrate such that a chamber is defined by the first and second substrates; and an electro-optic medium disposed in the chamber defined by the first and second substrates and in contact with the first and second layers of electrically conductive material; a controller in communication with the electro-optic device, wherein the controller is configured to control electrical power supplied to the electro-optic device and a potentiometer in communication with the electro-optic device and with the controller.