Controlling transitions in optically switchable devices

• US 10,401,702 B2
• Filed: 10/17/2017
• Issued: 09/03/2019
• Est. Priority Date: 06/28/2013
• Status: Active Grant

• Current Assignee: View Incorporated
• Original Assignee: View Incorporated
• Inventors: Jack, Gordon, Kailasam, Sridhar K., Brown, Stephen C., Pradhan, Anshu A.
• Primary Examiner(s): Thomas, Brandi N
• Application Number:
  US15/786,488
• Publication Number:
  US 20180039149A1
• Time in Patent Office: 686 Days
• Field of Search: 359 27, 359242, 359265-267, 359269, 359275, 359290-292, 359295, 359298
• CPC Class Codes: G02F 1/163 Operation of electrochromic cells, e.g. electrodeposition cells; Circuit arrangements therefor
• CPC Class Codes: G09G 3/19 using electrochromic devices

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.

Claims

1. An apparatus for controlling an optical transition of an optically switchable 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 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 determine an open circuit voltage between the bus bars of the optically switchable device, and periodically determine a total delivered charge density supplied to the optically switchable device during the transition,

(c) determine 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 determine whether the total delivered charge density determined in (b) has a magnitude 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, apply a hold voltage for holding the ending optical state; and

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

2. The apparatus of claim 1, wherein the processor is further designed or configured to determine the open circuit voltage and total delivered charge density in (b) at a defined time after applying the drive voltage in (a).

3. The apparatus of claim 2, wherein the defined time is at most about 120 minutes.

4. The apparatus of claim 1, wherein the magnitude of the target open circuit voltage is between about 0-1V greater than the magnitude of the hold voltage.

5. The apparatus of claim 4, wherein the magnitude of the target open circuit voltage is at least about 0.025V greater than the magnitude of the hold voltage.

6. The apparatus of claim 1, wherein the magnitude of the threshold charge density is between about 1×

10<sup>−

5</sup> C/cm² and about 5 C/cm².

7. The apparatus of claim 1, wherein the processor is further designed or configured to, after (c) and before (d)

(i) increase the magnitude of voltage applied to the bus bars to the drive voltage as a result of determining in (c) that either the magnitude of the open circuit voltage determined in (b) is less than the magnitude of the target open circuit voltage, or that the magnitude of the total delivered charge density determined in (b) is less than the magnitude of the threshold charge density;

and

(ii) repeat (b)-(c).

8. The apparatus of claim 7, wherein the processor is further designed or configured to repeat (b)-(c) at a frequency of between about 5 seconds and 5 minutes.

9. The apparatus of claim 1, wherein the optical switchable device is an electrochromic device.

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

11. An apparatus for controlling an optical transition of an optically switchable 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 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 reduce the magnitude of the voltage applied to the bus bars of the optically switchable device to a probe voltage and detect a current response, and periodically determine a total delivered charge density supplied to the optically switchable device during the transition;

(c) determine whether the current response detected in (b) reaches a target current, and determine 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 current response detected in (b) reaches the target current, 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, apply a hold voltage for holding the ending optical state; and

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