METHOD AND APPARATUS FOR ADJUSTING AN AMBIENT LIGHT THRESHOLD

• US 20150271897A1
• Filed: 06/08/2015
• Published: 09/24/2015
• Est. Priority Date: 06/10/2011
• Status: Active Grant

• Current Assignee: Lutron Technology Company LLC
• Original Assignee: Lutron Electronics Company Incorporated (Lutron Electronics)
• Inventors: Steiner, James P., BEDELL, RYAN S.
• Granted Patent: US 10,159,137 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H05B 47/105 in response to determined parameters
• CPC Class Codes: H05B 47/11 by determining the brightness or colour temperature of ambient light
• CPC Class Codes: H05B 47/115 by determining the presence or movement of objects or living beings
• CPC Class Codes: H05B 47/13 by using passive infrared detectors
• CPC Class Codes: H05B 47/16 by timing means
• CPC Class Codes: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

A load control device adapted to be coupled between an AC power source and an electrical load for controlling the power delivered to the load includes a controller, an actuator for turning the electrical load on and off, an occupancy detection circuit, and an ambient light detector. The load control device automatically turns on the electrical load in response to the presence of an occupant only if the detected ambient light is below a predetermined ambient light level threshold. After first detecting the presence of an occupant, the load control device monitors actuations of the actuator to determine whether a user has changed the state of the load. The load control device automatically adjusts the predetermined ambient light level threshold in response to the user actuations that change the state of the load.

Claims

1. A load control device for controlling power delivered from an AC power source to an electrical load in a space, the load control device comprising:

an actuator;

an occupancy detection circuit for detecting the presence or absence of an occupant in the space;

an ambient light detector for measuring an ambient light level in the space; and

a controller operatively coupled to the actuator, the occupancy detection circuit, and the ambient light detector, the controller configured to turn the electrical load on and off in response to actuations of the actuator, the controller configured to compare a measured ambient light level from the ambient light detector to an ambient light level threshold, the controller further configured to turn the electrical load on and off in response to the occupancy detection circuit and the comparison between the measured ambient light level and the ambient light level threshold,

wherein the controller is further configured to automatically adjust the ambient light level threshold in response to detecting an actuation of the actuator that occurs after detecting the presence of an occupant.

2. The load control device of claim 1, wherein the controller is configured to calculate a difference between the measured ambient light level and a first value of the ambient light level threshold, and use the calculated difference to adjust the ambient light level threshold from the first value to a second value.

3. The load control device of claim 2, wherein the controller is configured to multiply the calculated difference by a scaling factor, and adjust a value of the measured ambient light level by the product of the calculated difference and the scaling factor to generate an adjusted value of the ambient light level threshold, the controller further configured to use the adjusted value of the ambient light level threshold to adjust the ambient light level threshold from the first value to the second value.

4. The load control device of claim 3, wherein the adjusted value of the ambient light level threshold is the second value of the ambient light level threshold.

5. The load control device of claim 3, wherein the controller is configured to digitally filter the adjusted value of the ambient light level threshold to generate the second value of the ambient light level threshold.

6. The load control device of claim 1, wherein, if the measured ambient light level is less than the ambient light level threshold, the controller is configured to turn the electrical load on in response to the occupancy detection circuit detecting the presence of an occupant.

7. The load control device of claim 6, wherein, in response to receiving an actuation to turn the electrical load off after turning the electrical load on in response to the occupancy detection circuit detecting the presence of an occupant, the controller is configured to decrease the ambient light level threshold to a second value less than the first value.

8. The load control device of claim 1, wherein, if the measured ambient light level is greater than the ambient light level threshold, the controller is configured to maintain the electrical load off in response to detecting the presence of an occupant.

9. The load control device of claim 8, wherein, in response to receiving an actuation to turn the electrical load on after maintaining the electrical load off in response to the occupancy detection circuit detecting the presence of an occupant, the controller is configured to increase the ambient light level threshold to a second value greater than the first value.

10. The load control device of claim 1, further comprising:

a controllably conductive device adapted to be coupled between the AC power source and the electrical load for controlling the power delivered to the electrical load,

wherein the controller is operatively coupled to the controllably conductive device and is configured to render the controllably conductive device conductive and non-conductive to turn the electrical load on and off, respectively.

11. The load control device of claim 1, wherein the controller is further configured to detect a second occupancy condition, and compare the measured ambient light level to the second value of the ambient light level threshold.

12. The load control device of claim 1, wherein the controller is further configured to automatically adjust the ambient light level threshold in response to detecting an actuation of the actuator that occurs within a predetermined time window after detecting the presence of an occupant.

13. A method for controlling power delivered from an AC power source to an electrical load, the method comprising:

detecting an occupancy condition;

comparing a measured ambient light level to a first value of an ambient light level threshold;

turning the electrical load on in response to detecting the occupancy condition if the measured ambient light level is less than the ambient light level threshold;

maintaining the electrical load off in response to detecting the occupancy condition if the measured ambient light level is greater than the ambient light level threshold;

subsequently receiving an actuation to adjust the power delivered to the electrical load; and

adjusting the ambient light level threshold to a second value in response to receiving the actuation.

14. The method of claim 13, wherein adjusting the ambient light level threshold further comprises:

calculating a difference between the measured ambient light level and the first value of the ambient light level threshold; and

using the calculated difference to adjust the ambient light level threshold from the first value to the second value.

15. The method of claim 14, wherein adjusting the ambient light level threshold further comprises:

multiplying the calculated difference by a scaling factor; and

adjusting a value of the measured ambient light level by the product of the calculated difference and the scaling factor to generate an adjusted value of the ambient light level threshold,

wherein the adjusted value of the ambient light level threshold is used to adjust the ambient light level threshold from the first value to the second value.

16. The method of claim 15, wherein the adjusted value of the ambient light level threshold is the second value of the ambient light level threshold.

17. The method of claim 15, wherein adjusting the ambient light level threshold further comprises digitally filtering the adjusted value of the ambient light level threshold to generate the second value of the ambient light level threshold.

18. The method of claim 13, wherein receiving an actuation further comprises receiving an actuation to turn the electrical load on after maintaining the electrical load off in response to detecting the occupancy condition if the measured ambient light level is greater than the ambient light level threshold.

19. The method of claim 18, wherein adjusting the ambient light level threshold further comprises increasing the ambient light level threshold from the first value to the second value.

20. The method of claim 13, wherein receiving an actuation further comprises receiving an actuation to turn the electrical load off after turning the electrical load on in response to detecting the occupancy condition if the measured ambient light level is less than the ambient light level threshold.

21. The method of claim 20, wherein adjusting the ambient light level threshold further comprises decreasing the ambient light level threshold from the first value to the second value.

22. The method of claim 13, further comprising:

detecting a second occupancy condition; and

comparing the measured ambient light level to the second value of the ambient light level threshold.

23. The method of claim 13, wherein adjusting the ambient light level threshold further comprises adjusting the ambient light level threshold to a second value in response to receiving the actuation within a predetermined time window after detecting the occupancy condition.