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 optically switchable device from a starting optical state to an ending optical state, the method comprising:
(a) applying a drive voltage for driving the optically switchable device to transition from the starting optical state to the ending optical state, wherein the drive voltage is applied to bus bars of the optically switchable device; (b) before the transition is complete, periodically determining an open circuit voltage between the bus bars of the optically switchable device, and periodically determining a total delivered charge density supplied to the optically switchable device during the transition; (c) determining whether the open circuit voltage determined in (b) has a magnitude greater than or equal to a magnitude of a target open circuit voltage, and determining whether a magnitude of the total delivered charge density determined in (b) is greater than or equal to a magnitude of a threshold charge density; and (d) if it is determined in (c) that both (i) the magnitude of the open circuit voltage determined in (b) is greater than or equal to the magnitude of the target open circuit voltage, and (ii) the magnitude of the total delivered charge density determined in (b) is greater than or equal to the magnitude of the threshold charge density, applying a hold voltage for holding the ending optical state.