CONTROLLING TRANSITIONS IN OPTICALLY SWITCHABLE DEVICES

• US 20190324342A1
• Filed: 07/01/2019
• Published: 10/24/2019
• Est. Priority Date: 06/28/2013
• Status: Active Grant

• Current Assignee: View Incorporated
• Original Assignee: View Incorporated
• Inventors: Jack, Gordon E., Kailasam, Sridhar Karthik, Brown, Stephen Clark, Pradhan, Anshu A.
• Granted Patent: US 10,969,646 B2
• Time in Patent Office: Days
• CPC Class Codes: G02F 1/13306 Circuit arrangements or driving methods for the control of single liquid crystal cells G02F1/132, G02F1/133382 take precedence
• CPC Class Codes: G02F 1/13318 Circuits comprising a photodetector
• CPC Class Codes: G02F 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making
• CPC Class Codes: G02F 1/15165 Polymers
• CPC Class Codes: G02F 1/153 Constructional details
• CPC Class Codes: G02F 1/1533 structural features not otherwise provided for
• CPC Class Codes: G02F 1/155 Electrodes
• CPC Class Codes: G02F 1/157 Structural association of cells with optical devices, e.g. reflectors or illuminating devices
• 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
• CPC Class Codes: G09G 3/38 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 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

apply a voltage to a first bus bar of the optically switchable device,

at one or more times, determine an open circuit voltage between the first bus bar and a second bus bar of the optically switchable device, and, at one or more times, determine a charge supplied to the optically switchable device,

determine whether the open circuit voltage has a magnitude greater than or equal to a magnitude of a target open circuit voltage, and determine whether the supplied charge gives rise to a total delivered charge density greater than or equal to a threshold charge density, and

if the magnitude of the determined open circuit voltage is greater than or equal to the magnitude of the target open circuit voltage, and if the magnitude of the total delivered charge density is determined to be greater than or equal to the magnitude of the threshold charge density, apply a hold voltage to the first bus bar of the optically switchable device.

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 at a defined time after applying the voltage.

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, prior to application of the hold voltage to the first bus bar of the optically switchable device

increase the magnitude of the voltage applied to the first bus bar in response to determining that either the magnitude of the open circuit voltage is less than the magnitude of the target open circuit voltage, or determining that the magnitude of the total delivered charge density is less than the magnitude of the threshold charge density;

and

repeat the determining the open circuit voltage between the first bus bar and the second bus bar and the determining whether the open circuit voltage has a magnitude greater than or equal to the magnitude of the target open circuit voltage.

8. The apparatus of claim 7, wherein the processor is further designed or configured to repeat the determining the open circuit voltage between the first bus bar and the second bus bar and determining whether the open circuit voltage has a magnitude greater than or equal to the magnitude of the target open circuit voltage at an interval of between about 5 seconds and 5 minutes.

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

10. The apparatus of claim 1, wherein the first bus bar is separated from the second bus bar by at least about 10 inches.

11. An apparatus for controlling a 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

apply a voltage to a first bus bar of the optically switchable device;

at one or more times, reduce the magnitude of the voltage applied to the first bus bar of the optically switchable device to a probe voltage and detect a current response, and periodically determine a charge supplied to the optically switchable device;

determine whether the detected current response reaches a target current, and determine whether a magnitude of the supplied charge is greater than or equal to a threshold charge; and

if it is determined the detected current response reaches the target current, and that the magnitude of the supplied charge is greater than or equal to the magnitude of the threshold charge density, apply a hold voltage.

12. The apparatus of claim 11, wherein the reducing of the magnitude of the voltage applied to the first bus bar of the optically switchable device is performed periodically during the transition.

13. The apparatus of claim 11, wherein the magnitude of the supplied charge gives rise to a charge density having at least a predetermined threshold value.

14. The apparatus of claim 13, wherein the predetermined threshold value of the charge density comprises a value between about 1×

10<sup>−

5</sup> C/cm² and about 5 C/cm².

15. A method for controlling a transition of an optically switchable device from a starting optical state to an ending optical state, comprising:

applying a voltage to a first bus bar of the optically switchable device,

determining, at one or more times during the transition, whether an open circuit voltage between the first bus bar and a second bus bar of the optically switchable device comprises a magnitude greater than or equal to a magnitude of a target open circuit voltage, and determining whether a charge supplied to the optically switchable device gives rise to a total delivered charge density greater than or equal to a threshold charge density, and

if the magnitude of the determined open circuit voltage is greater than or equal to the magnitude of the target open circuit voltage, and if the magnitude of the total delivered charge density determined is greater than or equal to the magnitude of the threshold charge density, applying a hold voltage to the first bus bar of the optically switchable device.

16. The method of claim 15, wherein determining, at the one or more times during the transition, the open circuit voltage comprises periodically determining the open circuit voltage.

17. The method of claim 15, wherein the threshold charge density comprises a value of between about 1×

10<sup>−

5</sup> C/cm² and about 5 C/cm².

18. The method of claim 15, wherein the optically switchable device comprises an electrochromic device.

19. The method of claim 15, wherein the magnitude of the target open circuit voltage is between about 0 V and 1 V greater than the magnitude of the hold voltage.

20. The method of claim 15, wherein the magnitude of the target open circuit voltage is at least about 0.025 volt greater than the magnitude of the hold voltage.