Electrochromic Device Voltage Control for Uniform Switching
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Solution Overview
Problem
Conventional methods for driving electrochromic devices are inadequate for large-scale applications, as they either slow down switching speed or lead to premature device degradation due to voltage limitations, resulting in poor performance across the entire surface of the device.
Innovation Solution
A controller system that applies a defined drive voltage to bus bars of electrochromic devices, ensuring all locations experience an effective voltage within a safe range that avoids damage while maintaining rapid optical state transitions, by adjusting the voltage magnitude and ramp rate to account for sheet resistance and distance between bus bars.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional driving profiles are used with low voltages to avoid device damage, then device reliability is maintained, but switching speed deteriorates
Solution Approach 1:
The patent applies different voltage levels to different regions of the electrochromic device. High voltage is applied near the bus bars to ensure rapid switching, while the center region receives lower voltage to avoid degradation. This spatial differentiation of voltage quality resolves the contradiction between switching speed and device reliability.
Solution Approach 2:
The patent dynamically adjusts the driving voltage during the switching process. Initially, high voltage is applied to rapidly initiate the optical transition, then the voltage is reduced to a lower maintenance level to complete the transition without causing degradation. This temporal dynamics allows both fast switching and device protection.
2Speed
If higher voltages are applied to increase switching speed, then switching speed is improved, but device degradation accelerates
Solution Approach 1:
The patent applies different voltage levels to different regions of the electrochromic device. High voltage is applied near the bus bars to ensure rapid switching, while the center region receives lower voltage to avoid degradation. This spatial differentiation of voltage quality resolves the contradiction between switching speed and device reliability.
Solution Approach 2:
The patent dynamically adjusts the driving voltage during the switching process. Initially, high voltage is applied to rapidly initiate the optical transition, then the voltage is reduced to a lower maintenance level to complete the transition without causing degradation. This temporal dynamics allows both fast switching and device protection.
3Area of stationary object
If the device size is increased for architectural applications, then area is improved, but voltage distribution uniformity deteriorates
Solution Approach 1:
The patent recognizes that different regions of a large electrochromic device require different voltage levels. The bus bar regions receive higher voltage to overcome the increased distance and resistance, while the center region receives lower voltage to maintain uniform optical transition without over-driving. This local quality approach enables large device area while maintaining voltage distribution control.
Solution Approach 2:
The patent introduces a spatial dimension to the voltage control strategy by considering the two-dimensional distribution of voltage across the device surface. By mapping voltage requirements across the device area and applying differentiated voltage levels to different zones, the patent achieves uniform optical transition across large areas despite varying distance from bus bars.
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 enables efficient and rapid optical state transitions across large electrochromic devices without causing degradation, ensuring consistent performance and extending the lifespan of the device.
Implementation Method 1
Electrochromic (EC) devices typically comprise a multilayer stack including (a) at least one electrochromic material, that changes its optical properties, such as visible light transmitted through the layer, in response to the application of an electrical potential
Implementation Method 2
an ion conductor (IC), which allows ions (e.g. Li+) to move through the stack
Data Source
Figure 1A
Figure 1B~1C
Figure 2
AI summary
Controllers and control methods apply a drive voltage to bus bars of a thin film optically switchable device. The applied drive voltage is provided at a level that drives a transition over the entire surface of the optically switchable device but does not damage or degrade the device. This applied voltage produces an effective voltage at all locations on the face of the device that is within a bracketed range. The upper bound of this range is associated with a voltage safely below the level at which the device may experience damage or degradation impacting its performance in the short term or the long term. At the lower boundary of this range is an effective voltage at which the transition between optical states of the device occurs relatively rapidly. The level of voltage applied between the bus bars is significantly greater than the maximum value of the effective voltage within the bracketed range.