CONTROLLING TRANSITIONS IN OPTICALLY SWITCHABLE DEVICES

• US 20180067372A1
• Filed: 09/14/2017
• Published: 03/08/2018
• 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.
• Granted Patent: US 10,514,582 B2
• Time in Patent Office: Days
• CPC Class Codes: E06B 2009/2464 featuring transparency control by applying voltage, e.g. LCD, electrochromic panels
• CPC Class Codes: E06B 3/6722 with adjustable passage of light
• CPC Class Codes: E06B 9/24 Screens or other constructions affording protection against light, especially against sunshine; Similar screens for privacy or appearance; Slat blindsoperating, guiding or securing devices or arrangements for roll-type closures E06B9/56; free-hanging flexible screens A47H23/00
• CPC Class Codes: G02F 1/0121 Operation of devices; Circuit arrangements, not otherwise provided for in this subclass
• CPC Class Codes: G02F 1/163 Operation of electrochromic cells, e.g. electrodeposition cells; Circuit arrangements therefor
• CPC Class Codes: G02F 2201/58 Arrangements comprising a monitoring photodetector

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. In some cases, feedback may be used to monitor an optical transition. In these or other cases, a group of optically switchable devices may transition together over a particular duration to achieve approximately uniform tint states over time during the transition.

Claims

1. (canceled)

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

(a) ramping a voltage applied to bus bars of the optically switchable device, wherein the voltage is ramped from a first voltage to a second voltage during (a), the second voltage having a larger magnitude than the first voltage;

(b) during (a);

periodically measuring an open circuit voltage between the bus bars of the optically switchable device;

(c) after (a) and (b), applying a third voltage to the bus bars of the optically switchable device to transition the optically switchable device toward the ending optical state.

3. The method of claim 2, further comprising ceasing to apply the third voltage when the optically switchable device approaches the ending optical state.

4. The method of claim 3, further comprising determining when the optically switchable device approaches the ending optical state by, during (c):

(i) periodically measuring the open circuit voltage between the bus bars of the optically switchable device, and

(ii) determining that the optically switchable device approaches the ending optical state when the open circuit voltage measured in (c)(i) has a magnitude greater than or equal to a magnitude of a target open circuit voltage.

5. The method of claim 3, further comprising determining when the optically switchable device approaches the ending optical state by, during (c):

(i) periodically measuring the open circuit voltage between the bus bars of the optically switchable device,

(ii) periodically determining an amount of charge delivered to the optically switchable device during the optical transition,

(iii) determining that the optically switchable device approaches the ending optical state when (A) the open circuit voltage measured in (c)(i) has a magnitude greater than or equal to a magnitude of a target open circuit voltage, and (B) the amount of charge delivered to the optically switchable device determined in (c)(ii) has a magnitude greater than or equal to a magnitude of a target charge.

6. The method of claim 2, wherein the second voltage and third voltage have the same magnitude.

7. The method of claim 2, further comprising ceasing to apply open circuit conditions during (b) in response to a determination that the open circuit voltage has reached a target open circuit voltage.

8. The method of claim 2, wherein the third voltage is selected based on the open circuit voltage determined prior to (c).

9. The method of claim 8, wherein the third voltage is selected based on an amount of charge delivered to the optically switchable device prior to (c) in addition to the open circuit voltage determined prior to (c).

10. The method of claim 3, further comprising after ceasing to apply the third voltage, applying a fourth voltage to the bus bars of the optically switchable device, wherein the fourth voltage has a magnitude less than a magnitude of the third voltage.