Controlling transitions in optically switchable devices

摘要

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.

主权项

1. A method of controlling an optical transition of an electrochromic device from a starting optical state to an ending optical state, the method comprising:
(a) applying a drive voltage for driving the electrochromic device to transition from the starting optical state to the ending optical state, wherein the drive voltage is applied to bus bars of the electrochromic device; (b) before the transition is complete, reducing the magnitude of the voltage applied to the bus bars to a magnitude less than the drive voltage; (c) after reducing the magnitude of voltage applied to the bus bars, waiting a defined period of time, then detecting current or open circuit voltage in the electrochromic device; (d) determining whether the current or open circuit voltage detected in (c) has a characteristic indicating that the optical transition is nearly complete; and (e) if it is determined in (d) that the optical transition is nearly complete, applying a hold voltage for holding the ending optical state, wherein the magnitude of the hold voltage is lower than the magnitude of the drive voltage.