Driving thin film switchable optical devices

• US 9,454,056 B2
• Filed: 08/10/2015
• Issued: 09/27/2016
• 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:
  US14/822,781
• Publication Number:
  US 20150346576A1
• Time in Patent Office: 414 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 changing an optical state of an electrochromic window, the method comprising:

(a) applying an analog signal of between 0-10 V to a controller used for controlling the optical state of the electrochromic window;

(b) interpreting the analog signal with the controller'"'"'s logic, and, in response, producing a first voltage; and

(c) generating a second voltage based on the first voltage, and applying the second voltage to bus bars on the electrochromic window to thereby cause the electrochromic window to change its optical state in a manner specified by the analog signal.

2. The method of claim 1, wherein the analog signal is a tint command signal (V_TC) that indicates a desired optical state for the electrochromic window, the desired optical state being specified by a user.

3. The method of claim 2, wherein the electrochromic window is configured to achieve at least a first optical state and a second optical state, and wherein the tint command signal (V_TC) comprises at least a first range and a second range, the first range of the tint command signal (V_TC) corresponding to a command for changing the electrochromic window to the first optical state, and the second range of the tint command signal (V_TC) corresponding to a command for changing the electrochromic window to the second optical state.

4. The method of claim 1, wherein the controller comprises a signal conditioner configured to receive the analog signal.

5. The method of claim 4, wherein the controller comprises a microcontroller;

further comprising using the signal conditioner to generate a conditioning signal (V_CON) based on the received analog signal, wherein the conditioning signal (V_CON) is the first voltage; and

using the microcontroller to generate a command signal (V_COMMAND) based on the conditioning signal (V_CON).

6. The method of claim 5, wherein the controller further comprises a pulse width modulator, wherein the pulse width modulator receives the command signal (V_COMMAND) and generates the second voltage based on the received command signal (V_COMMAND).

7. The method of claim 6, wherein the pulse width modulator generates a current feedback signal (I_FB) and/or a voltage feedback signal (V_FB), and wherein the microcontroller uses the current feedback signal (I_FB) and/or the voltage feedback signal (V_FB) to generate the command signal (V_COMMAND).

8. The method of claim 4, wherein the signal conditioner is also configured to receive feedback from one or more sensors.

9. The method of claim 8, wherein at least one of the sensors is selected from the group consisting of an exterior photosensor or photodetector, an interior photosensor or photodetector, and a thermal or temperature sensor.

10. The method of claim 1, wherein the second voltage comprises a positive component (V_PW1) and a negative component (V_PW2).

11. The method of claim 10, wherein the positive component (V_PW1) and negative component (V_PW2) of the second voltage are supplied in pulses having unequal durations.

12. The method of claim 10, wherein the controller further comprises a pulse width modulator, and wherein the pulse width modulator is configured to modify a magnitude of the positive component (V_PW1) and the negative component (V_PW2) of the second voltage.

13. The method of claim 1, wherein the controller further comprises a pulse width modulator, wherein the pulse width modulator generates the second voltage.

14. The method of claim 1, wherein the analog voltage signal is transferred over a communication bus.

15. The method of claim 1, wherein the first voltage is transferred over a communication bus.

16. The method of claim 15, wherein the communication bus is an Inter-Integrated Circuit (I²C) multi-master serial single-ended computer bus.

17. The method of claim 1, wherein the window controller communicates with a network controller via a communication bus, wherein the network controller controls a plurality of electrochromic windows.

18. The method of claim 1, wherein the electrochromic window comprises at least a first pane with an electrochromic device positioned thereon, and wherein the second voltage applied to the bus bars has a magnitude such that an area of the electrochromic device between the bus bars experiences an effective voltage between a maximum effective voltage that avoids damaging the electrochromic device and a minimum effective voltage that drives the change in optical state of the electrochromic window, wherein the second voltage is greater than the maximum effective voltage.

19. The method of claim 18, wherein the second voltage has a magnitude that is between about 2.3-6V.

20. The method of claim 18, wherein a distance between the bus bars is at least about 40 inches.

21. A controller for controlling the optical state of a thin film electrochromic device, the controller comprising:

circuitry for applying voltage or providing instructions to apply voltage between bus bars on the thin film electrochromic device;

a processing component designed or configured to perform the following operations;

(a) receive an analog signal of between 0-10 V, the analog signal indicating a target optical state of the thin film electrochromic device;

(b) interpret the analog signal using logic, and, in response, produce a first voltage; and

(c) generate a second voltage based on the first voltage, and apply the second voltage to bus bars in electrical communication with the thin film electrochromic device to thereby cause the thin film electrochromic device to change to the target optical state in a manner specified by the analog signal.

22. The controller of claim 21, wherein the analog signal is a tint command signal (V_TC) that indicates the target optical state of the thin film electrochromic device, the target optical state being specified by a user.

23. The controller of claim 21, further comprising a signal conditioner configured to receive the analog signal.

24. The controller of claim 23, further comprising a microcontroller, wherein the signal conditioner is configured to generate a conditioning signal (V_CON) based on the received analog signal, wherein the conditioning signal (V_CON) is the first voltage, and wherein the microcontroller is configured to generate a command signal (V_COMMAND) based on the conditioning signal (V_CON).

25. The controller of claim 24, further comprising a pulse width modulator, wherein the pulse width modulator is configured to receive the command signal (V_COMMAND) and to generate the second voltage based on the received command signal (V_COMMAND).

26. The controller of claim 25, wherein the pulse width modulator generates a current feedback signal (I_FB) and/or a voltage feedback signal (V_FB), and wherein the microcontroller is configured to use the current feedback signal (I_FB) and/or the voltage feedback signal (V_FB) to generate the command signal (V_COMMAND).

27. The controller of claim 24, wherein the signal conditioner is also configured to receive feedback from one or more sensors selected from the group consisting of:

an exterior photosensor or photodetector, an interior photosensor or photodetector, and a thermal or temperature sensor.

28. The controller of claim 21, wherein the second voltage comprises a positive component (V_PW1) and a negative component (V_PW2).

29. The controller of claim 28, wherein the positive component (V_PW1) and negative component (V_PW2) of the second voltage are supplied in pulses having unequal durations.

30. The controller of claim 28, further comprising a pulse width modulator, wherein the pulse width modulator is configured to modify a magnitude of the positive component (V_PW1) and the negative component (V_PW2) of the second voltage.

31. The controller of claim 21, wherein the second voltage applied to the bus bars has a magnitude such that an area of the thin film electrochromic device between the bus bars experiences an effective voltage between a maximum effective voltage that avoids damaging the thin film electrochromic device and a minimum effective voltage that drives the change in optical state of the thin film electrochromic device, wherein the second voltage is greater than the maximum effective voltage.

32. The controller of claim 31, wherein the second voltage has a magnitude that is between about 2.3-6V.