Driving thin film switchable optical devices

• US 9,477,131 B2
• Filed: 06/09/2015
• Issued: 10/25/2016
• Est. Priority Date: 04/17/2012
• Status: Active Grant

• Current Assignee: View Incorporated
• Original Assignee: View Incorporated
• Inventors: Pradhan, Anshu A., Mehtani, Disha, Jack, Gordon
• Primary Examiner(s): Jones, James
• Application Number:
  US14/735,043
• Publication Number:
  US 20150293422A1
• Time in Patent Office: 504 Days
• Field of Search: 359/275
• US Class Current: 1/1
• CPC Class Codes: G02F 1/155 Electrodes
• CPC Class Codes: G02F 1/163 Operation of electrochromic cells, e.g. electrodeposition cells; Circuit arrangements therefor
• CPC Class Codes: G02F 2001/1555 Counter electrode

Abstract

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.

Claims

1. A method of transitioning an optically switchable device from a first optical state to a second optical state, the method comprising:

supplying an applied voltage (Vapp) to the optically switchable device,

the optically switchable device comprising transparent conductive layers and bus bars electrically connected with the transparent conductive layers, wherein the bus bars are separated by a distance of at least about 30 inches,

wherein the Vapp is supplied to the bus bars of the optically switchable device and results in a local effective voltage (Veff) between the transparent conductive layers,

wherein during the transition, the Veff remains above a minimum voltage threshold and below a maximum voltage threshold at locations between the bus bars.

2. The method of claim 1, wherein the maximum voltage threshold is a maximum safe operating voltage for local values of the Veff.

3. The method of claim 2, wherein the maximum voltage threshold is about 4V or below.

4. The method of claim 3, wherein the maximum voltage threshold is about 3V or below.

5. The method of claim 4, wherein the maximum voltage threshold is about 2.5 V or below, and wherein the minimum voltage threshold is about 1.2 V or higher.

6. The method of claim 3, wherein during the transition, the Veff remains between about 0.5-4 V at all locations between the bus bars.

7. The method of claim 6, wherein during the transition, the Veff remains between about 1-3 V at all locations between the bus bars.

8. The method of claim 1, wherein the maximum voltage threshold includes a maximum safe operating voltage for local values of the Veff and a buffer having a magnitude between about 0.2-0.6 V, such that during the transition, the Veff remains at least 0.2-0.6V below the maximum safe operating voltage for local values of Veff.

9. The method of claim 1, wherein the minimum voltage threshold has a magnitude that is sufficiently high to effect complete optical transition from the first optical state to the second optical state over the face of the optically switchable device in about 45 minutes or less.

10. The method of claim 9, wherein the magnitude of the minimum voltage threshold is sufficiently high to effect complete optical transition from the first optical state to the second optical state over the face of the optically switchable device in about 10 minutes or less.

11. The method of claim 9, wherein the minimum voltage threshold is at least about 1.2 V.

12. The method of claim 2, wherein the Vapp is supplied to the bus bars at a magnitude that is higher than a magnitude of the maximum safe operating voltage for local values of the Veff.

13. The method of claim 12, wherein the magnitude of the Vapp is about 0.5-2 V greater than the magnitude of the maximum safe operating voltage for local values of the Veff.

14. The method of claim 1, wherein the magnitude of the Vapp is between about 2.5-5 V.

15. The method of claim 1, wherein the magnitude of the Vapp is between about 2.3-6 V.

16. The method of claim 15, wherein the magnitude of the Vapp is between about 3.5-5 V.

17. The method of claim 1, wherein the distance between the bus bars is at least about 40 inches.

18. The method of claim 17, wherein the distance between the bus bars is at least about 50 inches.

19. The method of claim 18, wherein the distance between the bus bars is at least about 60 inches.

20. The method of claim 1, wherein supplying the Vapp comprises:

increasing a magnitude of the Vapp over a first time period during a ramp to drive phase,

applying the Vapp over a second time period during a drive phase, and

decreasing the magnitude of the Vapp over a third time period during a ramp to hold phase, wherein the first, second, and third phases occur in that order.

21. The method of claim 1, wherein the Vapp is supplied using a drive mechanism comprising applying a fixed voltage to the bus bars, applying a fixed polarity to the bus bars, and/or applying a reversing polarity to the bus bars.

22. A method of transitioning an optically switchable device from a first optical state to a second optical state, the method comprising:

supplying an applied voltage (Vapp) to the optically switchable device,

the optically switchable device comprising bus bars and conductive layers electrically connected with the bus bars,

wherein the Vapp is supplied to the bus bars of the optically switchable device,

wherein the Vapp is supplied such that Vmin<

(Vapp−

0.5RJL²)<

Vmax for all local positions on the optically switchable device, where

R is a sheet resistance of the conductive layers,

J is a local current density on the optically switchable device,

L is an effective separation distance between the bus bars,

Vmin is a minimum operating voltage to effect the transition from the first optical state to the second optical state on the optically switchable device, and

Vmax is a maximum safe operating voltage of the optically switchable device that will not damage the optically switchable device.

23. The method of claim 22, wherein the Vmax is about 4 V or less.

24. The method of claim 23, wherein the Vmax is about 3 V or less.

25. The method of claim 22, wherein the Vmin is about 0.5 V or greater.

26. The method of claim 25, wherein the Vmin is about 1.2 V or greater.

27. The method of claim 26, wherein the Vmax is about 2.5 V or less.

28. The method of claim 22, wherein the Vapp is supplied at a magnitude between about 2.3-6 V.

29. The method of claim 28, wherein the Vapp is supplied at a magnitude between about 2.5-5 V.

30. The method of claim 29, wherein the Vapp is supplied at a magnitude between about 3.5-5 V.

31. The method of claim 22, wherein the Vapp is supplied such that (Vapp−

0.5RJL²)<

Vmax−

Vbuffer, wherein the Vbuffer is between about 0.2-0.6 V.

32. The method of claim 22, wherein the Vapp is supplied such that Vapp−

0.5RJL² remains between about 0.5-4 V for all locations on the optically switchable device between the bus bars.

33. The method of claim 32, wherein the Vapp is supplied such that Vapp−

0.5RJL² remains between about 1-3 V for all locations on the optically switchable device between the bus bars.

34. The method of claim 22, wherein the Vmin is sufficiently high to effect the transition from the first optical state to the second optical state on the optically switchable device over a duration of about 45 minutes or less.

35. The method of claim 34, wherein the Vmin is sufficiently high to effect the transition from the first optical state to the second optical state on the optically switchable device over a duration of about 10 minutes or less.

36. The method of claim 22, wherein the bus bars of the optically switchable device are separated by a distance of at least about 30 inches.

37. The method of claim 36, wherein the bus bars of the optically switchable device are separated by a distance of at least about 40 inches.

38. The method of claim 37, wherein the bus bars of the optically switchable device are separated by a distance of at least about 50 inches.

39. The method of claim 38, wherein the bus bars of the optically switchable device are separated by a distance of at least about 60 inches.

40. The method of claim 22, wherein the Vapp is supplied at a magnitude that is greater than a magnitude of the Vmax.

41. The method of claim 40, wherein the magnitude of the Vapp is between about 0.5-2 V greater than the magnitude of the Vmax.

42. The method of claim 22, wherein supplying the Vapp comprises:

increasing a magnitude of the Vapp over a first time period during a ramp to drive phase,

applying the Vapp over a second time period during a drive phase, and

decreasing the magnitude of the Vapp over a third time period during a ramp to hold phase, wherein the first, second, and third phases occur in that order.