METHOD OF CONTROLLING A MOTORIZED WINDOW TREATMENT

• US 20140156079A1
• Filed: 03/15/2013
• Published: 06/05/2014
• Est. Priority Date: 11/30/2012
• Status: Active Grant

• Current Assignee: Lutron Technology Company LLC
• Original Assignee: Lutron Electronics Company Incorporated (Lutron Electronics)
• Inventors: Courtney, Brian Michael, Gill, Timothy, Sarode, Shilpa
• Granted Patent: US 9,933,761 B2
• Time in Patent Office: Days
• US Class Current: 700/275
• CPC Class Codes: E06B 2009/6809 Control
• CPC Class Codes: E06B 2009/6827 sensing light
• CPC Class Codes: E06B 9/32 Operating, guiding, or securing devices therefor operation of tilting bars E06B9/307
• CPC Class Codes: E06B 9/68 Operating devices or mechanisms, e.g. with electric drive
• CPC Class Codes: G05B 15/02 electric
• CPC Class Codes: Y02A 30/24 Structural elements or technologies for improving thermal insulation
• CPC Class Codes: Y02B 80/00 Architectural or constructional elements improving the thermal performance of buildings

Abstract

A method comprises measuring a light intensity at a window; determining if the light intensity exceeds a cloudy-day threshold; operating in a sunlight penetration limiting mode to control the motorized window treatment to control the sunlight penetration distance in the space; enabling the sunlight penetration limiting mode if the light intensity is greater than the cloudy-day threshold; and disabling the sunlight penetration limiting mode if the total lighting intensity is less than the cloudy-day threshold. The cloudy-day threshold is maintained at a constant threshold if a calculated solar elevation angle is greater than a predetermined solar elevation angle, and the cloudy-day threshold varies with time if the calculated solar elevation angle is less than the predetermined solar elevation angle. The cloudy-day threshold is a function of the calculated solar elevation angle if the calculated solar elevation angle is less than the predetermined solar elevation angle.

Claims

1. A method of controlling a motorized window treatment positioned adjacent to a window on a wall of a building, the method comprising:

sampling a light intensity outside of the building;

computing a rate of change of the light intensity;

automatically controlling movement of the window treatment in a sunny operation mode if the absolute value of the computed rate of change is at least a first threshold value; and

automatically controlling movement of the window treatment in a cloudy operation mode if the absolute value of the computed rate of change is less than the first threshold value and the light intensity is less than a second threshold value.

2. The method of claim 1, further comprising automatically controlling movement of the window treatment in the sunny operation mode if the absolute value of the computed rate of change is less than the first threshold value and the light intensity is at least the second threshold value.

3. The method of claim 1 wherein the step of computing the rate of change includes:

summing or averaging the sampled light intensity over each of a plurality of intervals to provide a respective intensity value for each respective interval; and

calculating the rate of change as the difference between ones of the intensity values divided by a length of one of the intervals.

4. The method of claim 1 wherein the step of computing the rate of change includes:

calculating the rate of change as the difference between first and second sampled light intensities divided by a length of time between sampling the first light intensity and sampling the second light intensity.

5. The method of claim 1, wherein the step of controlling movement of the window treatment in the sunny operation mode includes:

moving the window treatment to a first position if the light intensity is at least a third threshold value; and

moving the window treatment to a second position if the light intensity is less than the third threshold value.

6. The method of claim 1, wherein the step of controlling movement of the window treatment in the sunny operation mode includes:

moving the window treatment to a position that is a function of the light intensity.

7. The method of claim 1, wherein the step of controlling movement of the window treatment in the sunny operation mode includes:

moving the window treatment to a position that is a linear function of the light intensity.

8. The method of claim 1, wherein the step of automatically controlling movement of the window treatment in a cloudy operation mode includes:

moving the window treatment to a visor position while the absolute value of the computed rate of change is less than the first threshold value.

9. The method of claim 7, wherein a third threshold value is lower than the first threshold value, and the rate of change of the light intensity is computed more frequently when the absolute value of the computed rate of change is between the first threshold value and the third threshold value than when the absolute value of the computed rate of change is between zero and the third threshold value.

17. The method of claim 1, wherein the method includes hysteresis, such that the automatically controlling steps transition between the sunny operation mode and the cloudy operation mode when the rate of change of the light intensity passes through a sunny threshold and a cloudy threshold, wherein the sunny threshold is higher than the cloudy threshold.

10. A method of controlling a motorized window treatment positioned adjacent to a window on a wall of a building, the method comprising:

(a) sampling a light intensity outside of the building;

(b) computing a rate of change of the light intensity;

(c) automatically controlling movement of the window treatment based on the light intensity if the absolute value of the light intensity is at least a first threshold value; and

(d) automatically controlling movement of the window treatment based at least partially on a rate of change of the light intensity if the absolute value of the light intensity is less than the first threshold value.

11. The method of claim 10, wherein step (d) includes moving the window treatment to a first position if the absolute value of the rate of change of the light intensity is at least a second threshold value.

12. The method of claim 11, wherein step (d) includes moving the window treatment to a second position if the absolute value of rate of change of the light intensity is less than the second threshold value.

13. The method of claim 10, wherein step (d) includes moving the window treatment to a position that varies as a function of the light intensity if the absolute value of the rate of change of the light intensity is less than a second threshold value.

14. The method of claim 10, wherein step (d) includes:

controlling the window treatment in a sunny day mode if the absolute value of the rate of change of the light intensity is greater than or equal to a second threshold value; and

controlling the window treatment in a cloudy day mode if the absolute value of the rate of change of the light intensity is less than a threshold value.

15. The method of claim 14, wherein the step of controlling the window treatment in a sunny day mode includes causing the window treatment to remain in a sunny day position for at least a predetermined minimum time period before transitioning to a cloudy day position.

16. The method of claim 14, wherein the step of controlling the window treatment in the cloudy day mode includes transitioning to control the window treatment in the sunny day mode immediately upon determining that the absolute value of the rate of change of the light intensity has increased to at least the first threshold value.

18. A method of controlling a motorized window treatment for adjusting the amount of sunlight entering a space of a building through a window to control a sunlight penetration distance in the space, the method comprising:

measuring a total light intensity at the window;

calculating a solar elevation angle;

calculating a cloudy-day threshold as a function of the calculated solar elevation angle;

determining if the total light intensity exceeds the cloudy-day threshold;

operating in a sunlight penetration limiting mode to control the motorized window treatment to thus control the sunlight penetration distance in the space;

enabling the sunlight penetration limiting mode if the total light intensity is greater than the cloudy-day threshold; and

disabling the sunlight penetration limiting mode if the total lighting intensity is less than the cloudy-day threshold.

19. The method of claim 18, wherein the cloudy-day threshold is maintained at a constant threshold if the calculated solar elevation angle is greater than a predetermined solar elevation angle, and the cloudy-day threshold is a function of the calculated solar elevation angle if the calculated solar elevation angle is less than the predetermined solar elevation angle.

20. The method of claim 19, wherein the cloudy-day threshold is a linear function of the calculated solar elevation angle if the calculated solar elevation angle is less than the predetermined solar elevation angle.

21. The method of claim 18, further comprising:

controlling the motorized window treatment to a predetermined position when the sunlight penetration limiting mode is disabled.

22. A method of controlling a motorized window treatment for adjusting the amount of sunlight entering a space of a building through a window to control a sunlight penetration distance in the space, the method comprising:

measuring a total light intensity at the window;

determining if the total light intensity exceeds a cloudy-day threshold;

operating in a sunlight penetration limiting mode to control the motorized window treatment to thus control the sunlight penetration distance in the space;

enabling the sunlight penetration limiting mode if the total light intensity is greater than the cloudy-day threshold; and

disabling the sunlight penetration limiting mode if the total lighting intensity is less than the cloudy-day threshold;

wherein the cloudy-day threshold varies with time around sunrise and sunset, and is maintained at a constant threshold near midday.

23. The method of claim 22, wherein the cloudy-day threshold varies with time if a calculated solar elevation angle is less than a predetermined solar elevation angle, and is maintained at the constant threshold if the calculated solar elevation angle is greater than the predetermined solar elevation angle.

24. The method of claim 23, wherein the cloudy-day threshold is a function of the calculated solar elevation angle if the calculated solar elevation angle is less than the predetermined solar elevation angle.

25. The method of claim 24, wherein the cloudy-day threshold is a linear function of the calculated solar elevation angle if the calculated solar elevation angle is less than the predetermined solar elevation angle.

26. The method of claim 22, wherein the cloudy-day threshold varies with time for a first predetermined time period after sunrise and a second predetermined time period before sunset.

27. The method of claim 22, further comprising:

controlling the motorized window treatment to a predetermined position when the sunlight penetration limiting mode is disabled.

28. A system comprising:

a motorized window treatment adapted to be positioned adjacent to a window on a wall of a building;

a sensor for sampling a light intensity outside of the building; and

a processor configured to;

compute a rate of change of the light intensity,

automatically control movement of the window treatment in a sunny operation mode if the absolute value of the computed rate of change is at least a first threshold value, and

automatically control movement of the window treatment in a cloudy operation mode if the absolute value of the computed rate of change is less than the first threshold value and the light intensity is less than a second threshold value.

29. The system of claim 28, wherein the processor is further configured to automatically control movement of the window treatment in the sunny operation mode if the absolute value of the computed rate of change is less than the first threshold value and the light intensity is at least the second threshold value.

30. The system of claim 28, wherein controlling movement of the window treatment in the sunny operation mode includes:

moving the window treatment to a first position if the light intensity is at least a third threshold value; and

moving the window treatment to a second position if the light intensity is less than the third threshold value.

31. A system comprising:

a motorized window treatment adapted to be positioned adjacent to a window on a wall of a building, comprising;

a sensor for sampling a light intensity outside of the building; and

a processor configured for;

computing a rate of change of the light intensity;

automatically controlling movement of the window treatment based on the light intensity if the absolute value of the light intensity is at least a first threshold value; and

automatically controlling movement of the window treatment based at least partially on a rate of change of the light intensity if the absolute value of the light intensity is less than the first threshold value.

32. The system of claim 31, wherein the processor is configured for moving the window treatment to a first position if the absolute value of the rate of change of the light intensity is at least a second threshold value.

33. The system of claim 32, wherein the processor is configured for moving the window treatment to a second position if the absolute value of rate of change of the light intensity is less than the second threshold value.

34. The system of claim 31, wherein the processor is configured for:

controlling the window treatment in a sunny day mode if the absolute value of the rate of change of the light intensity is greater than or equal to a second threshold value; and

controlling the window treatment in a cloudy day mode if the absolute value of the rate of change of the light intensity is less than a threshold value.

35. The system of claim 34, wherein the step of controlling the window treatment in a sunny day mode includes causing the window treatment to remain in a sunny day position for at least a predetermined minimum time period before transitioning to a cloudy day position.

36. The system of claim 31, wherein the method includes hysteresis, such that the automatically controlling steps transition between the sunny operation mode and the cloudy operation mode when the rate of change of the light intensity passes through a sunny threshold and a cloudy threshold, wherein the sunny threshold is higher than the cloudy threshold.

37. A system for controlling a motorized window treatment for adjusting the amount of sunlight entering a space of a building through a window to control a sunlight penetration distance in the space, comprising:

a sensor for measuring a total light intensity at the window; and

a processor configured for;

calculating a solar elevation angle;

calculating a cloudy-day threshold as a function of the calculated solar elevation angle;

determining if the total light intensity exceeds the cloudy-day threshold;

operating in a sunlight penetration limiting mode to control the motorized window treatment to thus control the sunlight penetration distance in the space;

enabling the sunlight penetration limiting mode if the total light intensity is greater than the cloudy-day threshold; and

disabling the sunlight penetration limiting mode if the total lighting intensity is less than the cloudy-day threshold.

38. The system of claim 37, wherein the cloudy-day threshold is maintained at a constant threshold if the calculated solar elevation angle is greater than a predetermined solar elevation angle, and the cloudy-day threshold is a function of the calculated solar elevation angle if the calculated solar elevation angle is less than the predetermined solar elevation angle.

39. The system of claim 37, wherein the processor is configured to control the motorized window treatment to a predetermined position when the sunlight penetration limiting mode is disabled.

40. A system for controlling a motorized window treatment for adjusting the amount of sunlight entering a space of a building through a window to control a sunlight penetration distance in the space, comprising:

a sensor for measuring a total light intensity at the window; and

a processor configured for;

determining if the total light intensity exceeds a cloudy-day threshold;

operating in a sunlight penetration limiting mode to control the motorized window treatment to thus control the sunlight penetration distance in the space;

enabling the sunlight penetration limiting mode if the total light intensity is greater than the cloudy-day threshold; and

disabling the sunlight penetration limiting mode if the total lighting intensity is less than the cloudy-day threshold;

wherein the cloudy-day threshold varies with time around sunrise and sunset, and is maintained at a constant threshold near midday.

41. The system of claim 40, wherein the cloudy-day threshold varies with time if a calculated solar elevation angle is less than a predetermined solar elevation angle, and is maintained at the constant threshold if the calculated solar elevation angle is greater than the predetermined solar elevation angle.

42. The system of claim 41, wherein the cloudy-day threshold is a function of the calculated solar elevation angle if the calculated solar elevation angle is less than the predetermined solar elevation angle.

43. The system of claim 40, wherein the cloudy-day threshold varies with time for a first predetermined time period after sunrise and a second predetermined time period before sunset.