Controlling transitions in optically switchable devices

Patent metadata

Field	Value
Publication number	US-9412290-B2
Application number	US-201313931459-A
Country	US
Kind code	B2
Filing date	Jun 28, 2013
Priority date	Jun 28, 2013
Publication date	Aug 9, 2016
Grant date	Aug 9, 2016

Abstract

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.

First claim

What is claimed is:

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.

2. The method of claim 1 , wherein the voltage is reduced in (b) at a defined time after applying the drive voltage in (a).

3. The method of claim 2 , wherein the defined time between applying the drive voltage in (a) and reducing the voltage in (b) is at most about 30 minutes.

4. The method of claim 1 , wherein the voltage is reduced in (b) from the drive voltage to the hold voltage.

5. The method of claim 1 , wherein determining whether the current or open circuit voltage detected in (c) has the characteristic indicating that the optical transition is nearly complete comprises determining whether the current in a particular direction drops below a threshold level.

6. The method of claim 5 , wherein the threshold level is 0 amps.

7. The method of claim 1 , further comprising after (d) and before (e)
(i) increasing the magnitude of voltage applied to the bus bars to the drive voltage as a result of determining in (d) that the detected current does not have the characteristic indicating that the optical transition is nearly complete; and
(ii) repeating (b)-(d).

8. The method of claim 7 , wherein (b)-(d) are repeated at a frequency of between about 5 seconds and five minutes.

9. The method of claim 1 , wherein the bus bars are separated from one another by at least about 10 inches.

10. The method of claim 1 , wherein the magnitude of voltage applied to the bus bars in (c) is reduced for a duration between about 0.1-20 seconds.

11. The method of claim 10 , wherein the magnitude of voltage applied to the bus bars in (c) is reduced for a duration between about 0.5-5 seconds.

12. An apparatus for controlling an optical transition of an electrochromic device from a starting optical state to an ending optical state, the apparatus comprising:
a processor designed or configured to
(a) apply 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, reduce 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, wait a defined period of time, then detect current or open circuit voltage in the electrochromic device,
(d) determine 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, apply 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; and

a power supply for providing voltage and/or current at defined magnitudes to the electrochromic device to control the optical transition.

13. The apparatus of claim 12 , wherein the processor is further designed or configured to reduce the voltage in (b) at a defined time after applying the drive voltage in (a).

14. The apparatus of claim 13 , wherein the defined time between applying the drive voltage in (a) and reducing the voltage in (b) is at most about 30 minutes.

15. The apparatus of claim 12 , wherein the processor is further designed or configured reduce the voltage in (b) from the drive voltage to the hold voltage.

16. The apparatus of claim 12 , wherein the processor is further designed or configured such that determining whether the current detected in (c) has the characteristic indicating that the optical transition is nearly complete comprises determining whether the current in a particular direction drops below a threshold level.

17. The apparatus of claim 16 , wherein the threshold level is 0 amps.

18. The apparatus of claim 12 , wherein the processor is further designed or configured to, after (d) and before (e)
(i) increase the magnitude of voltage applied to the bus bars to the drive voltage as a result of determining in (d) that the detected current does not have the characteristic indicating that the optical transition is nearly complete; and
(ii) repeat (b)-(d).

19. The apparatus of claim 18 , wherein the processor is further designed or configured to repeat (b)-(d) at a frequency of between about 5 seconds and five minutes.

20. The apparatus of claim 12 , wherein the bus bars are separated from one another by at least about 10 inches.

21. 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 or drive current for driving the electrochromic device to transition from the starting optical state to the ending optical state, wherein the drive voltage or drive current is applied to bus bars of the electrochromic device;
(b) detecting current or open circuit voltage in the electrochromic device;
(c) determining whether the current or open circuit voltage detected in (b) has a characteristic indicating that the optical transition will complete within a target timeframe; and
(d) if it is determined in (c) that the optical transition will complete within the target timeframe, applying the drive voltage or drive current.

22. The method of claim 21 , wherein (b) comprises reducing the magnitude of the voltage or current applied to the bus bars to a magnitude less than the drive voltage or drive current.

23. The method of claim 22 , wherein reducing the magnitude of the voltage or current applied to the bus bars is performed at a defined time after applying the drive voltage or drive current in (a).

24. The method of claim 23 , wherein the defined time is at most about 30 minutes.

25. The method of claim 21 , wherein determining whether the current or open circuit voltage detected in (c) has a characteristic indicating that the optical transition will complete within a target timeframe comprises determining whether the current or open circuit voltage is within a defined range.

26. The method of claim 21 , further comprising repeating (b)-(d).

27. The method of claim 21 , wherein the bus bars are separated from one another by at least about 10 inches.

28. The method of claim 21 , wherein if it is determined in (c) that the optical

Assignees

• View Inc

Inventors

• Jack Gordon
• Pradhan Anshu

Classifications

• G02F1/15165

  Polymers · CPC title

• G02F1/1533

  structural features not otherwise provided for · CPC title

• G02F1/163 Primary

  Operation of electrochromic cells, e.g. electrodeposition cells; Circuit arrangements therefor · CPC title

• G02F1/155

  Electrodes · CPC title

• G02F1/157

  Structural association of cells with optical devices, e.g. reflectors or illuminating devices · CPC title