ELECTROCHROMIC SYSTEM AND METHOD FOR CONTROLLING PHOTOCHROMIC DARKENING

• US 20170219904A1
• Filed: 01/27/2017
• Published: 08/03/2017
• Est. Priority Date: 02/01/2016
• Status: Active Grant

• Current Assignee: Hivisq Technologies Sociedad Limitada
• Original Assignee: Heliotrope Technologies, Inc.
• Inventors: BASU, Sourav, GARCIA, Guillermo, HOLT, Jason
• Granted Patent: US 10,156,764 B2
• Time in Patent Office: Days
• CPC Class Codes: B32B 17/10477 thermochromic
• CPC Class Codes: B32B 17/10486 photochromic
• CPC Class Codes: B32B 17/10513 Electrochromic layer
• CPC Class Codes: E06B 2009/2464 featuring transparency control by applying voltage, e.g. LCD, electrochromic panels
• CPC Class Codes: E06B 3/6715 specially adapted for increased thermal insulation or for controlled passage of light E06B3/66323 takes precedence; coating of glass pains C03C17/00; devices or arrangements for controlling the intensity, colour, phase, polarisation or direction of light G02F1/00
• 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: G02B 5/23 Photochromic filters
• CPC Class Codes: G02F 1/1508 using a solid electrolyte
• CPC Class Codes: G02F 1/1524 Transition metal compounds
• CPC Class Codes: G02F 1/1533 structural features not otherwise provided for
• 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
• CPC Class Codes: G02F 2001/164 the electrolyte is made of polymers
• CPC Class Codes: G02F 2201/086 UV absorbing
• CPC Class Codes: G02F 2201/346 distributed (Bragg) reflector
• CPC Class Codes: G02F 2202/36 Micro- or nanomaterials
• CPC Class Codes: G09G 3/38 using electrochromic devices

Abstract

An electrochromic system and method for controlling photochromic darkening of an electrochromic device, the system including an EC device, a control unit, a voltage detector, and a power supply. The EC device includes a working electrode, a counter electrode, and a solid-state polymer electrolyte disposed therebetween. The control unit is configured to control a sweep voltage applied between the working and counter electrodes, such that the sweep voltage is applied when an open circuit voltage (OCV) between the working and counter electrodes is less than a threshold voltage.

Claims

1. An electrochromic (EC) system, comprising:

an EC device comprising;

a working electrode;

a counter electrode;

a solid state electrolyte layer disposed between the counter and working electrodes; and

a control unit configured to selectively apply a sweep voltage between the working and counter electrodes, such that the sweep voltage is applied when an open circuit voltage (OCV) between the working and counter electrodes is less than a threshold voltage.

2. The EC system of claim 1, further comprising a voltage detector configured to detect the OCV,

wherein the control unit is configured to apply the sweep voltage when the voltage detector detects that the OCV is below the threshold voltage.

3. The EC system of claim 1, wherein the threshold voltage is between 0V and −

2V, and the sweep voltage is a positive voltage.

4. The EC system of claim 1, wherein the control unit is configured to:

determine an amount of time since a voltage was applied to the EC device to change a transmissivity thereof; and

apply the sweep voltage to the EC device, if determined amount of time exceeds a threshold time period.

5. The EC system of claim 1, wherein the control unit is configured to periodically apply the sweep voltage between the working and counter electrodes, such that a open circuit voltage between the working and counter electrodes is changed from a negative voltage below the threshold voltage to a positive voltage.

6. The EC system of claim 1, wherein the control unit is configured to:

control the sweep voltage, such that the magnitude of the sweep voltage is greater than the magnitude of the OCV;

control the sweep voltage, such that the sweep voltage applies a saturation current ranging from about 10 to 30 μ

A/cm² between the working and counter electrodes; and

control the sweep voltage, such that the sweep voltage is applied at a frequency ranging from about 1 day to about 3 days.

7. The EC system of claim 1, wherein the control unit is configured to control the sweep voltage, such that the sweep voltage is applied only at night.

8. The EC system of claim 1, wherein the control unit is configured to control the sweep voltage, such that the sweep voltage is applied only on weekends, on holidays, or on weekends and holidays.

9. The EC system of claim 1, further comprising a power source electrically connected to the EC device and configured to generate the sweep voltage,

wherein the control unit is configured to control the power source to control the application of the sweep voltage.

10. The EC system of claim 1, wherein the control unit is configured to control the sweep voltage, such that the sweep voltage ranges from about 0.5 volts to about 5 volts.

11. A method of controlling photochromic darkening of an EC device comprising a working electrode, a counter electrode, and a solid-state electrolyte disposed between the working and counter electrodes, the method comprising:

detecting an open circuit voltage (OCV) between the working and counter electrodes of the EC device; and

applying a sweep voltage between the working and counter electrodes, when the OCV is more negative than a threshold voltage.

12. The method of claim 11, wherein the threshold voltage ranges from 0 volts to about 2 volts.

13. The method of claim 11, wherein the sweep voltage ranges from about 0.5 volts to about 5 volts.

14. The method of claim 11, wherein a magnitude of the sweep voltage is greater than or equal to the magnitude of the OCV.

15. The method of claim 11, wherein the sweep voltage is configured to remove a UV photogenerated charge that causes photochromic darkening of the EC device.

16. The method of claim 11, wherein the sweep voltage is applied only at night.

17. A method of controlling photochromic darkening of an EC device comprising a working electrode, a counter electrode, and a solid-state electrolyte disposed between the working and counter electrodes, the method comprising:

determining an amount of time since a voltage was applied to the EC device to change the transmissivity thereof; and

applying a sweep voltage to the EC device, if determined amount of time exceeds a threshold time period.

18. The method of claim 17, wherein the threshold time period ranges from about 6 hours to about 4 days.

19. The method of claim 17, wherein a magnitude of the sweep voltage is greater than or equal to a magnitude of an open circuit voltage between the working and counter electrodes.

20. The method of claim 17, wherein the determining an amount of time comprises determining an amount of time since a positive voltage was applied to the EC device.

21. A method of controlling photochromic darkening of an EC device comprising a working electrode, a counter electrode, and a solid-state electrolyte disposed between the working and counter electrodes, the method comprising:

periodically applying a sweep voltage between the working and counter electrodes, such that an open circuit voltage between the working and counter electrodes is changed from a negative voltage to a positive voltage.

22. The method of claim 21, wherein the periodically applying a sweep voltage comprises applying the sweep voltage at night during every 24 hour period.

23. The method of claim 21, wherein the periodically applying a sweep voltage comprises applying the sweep voltage on weekends, holidays, or on weekends and holidays.

24. The method of claim 21, wherein the periodically applying a sweep voltage comprises applying the sweep voltage at a predetermined time that is independent of applying a bright mode voltage to the EC device by a user or a control system.