Luminaire control system and method

• US 7,868,562 B2
• Filed: 12/11/2007
• Issued: 01/11/2011
• Est. Priority Date: 12/11/2006
• Status: Active Grant

• Current Assignee: Signify Holding B.V. (Signify N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Robinson, Shane P., Smith, Duncan L. B., Ashdown, Ian, Speier, Ingo, Salsbury, Marc
• Primary Examiner(s): Owens; Douglas W
• Assistant Examiner(s): Chen; Jianzi
• Application Number:
  US12/001,786
• Publication Number:
  US 20080215279A1
• Time in Patent Office: 1,127 Days
• Field of Search: 315/291, 315/294, 315/297, 315/299, 315/300, 315/301, 315/307, 315/312, 315/326
• US Class Current: 315/307
• CPC Class Codes: H05B 45/22 using optical feedback
• CPC Class Codes: H05B 45/28 using temperature feedback

Abstract

The present invention provides a system and method for controlling one or more light-emitting elements which are driven by forward currents to generate mixed light for use, for example, through a luminaire. The system has one or more light sensors for acquiring feedback optical sensor data and a user interface for providing reference data representative of a desired mixed light. The system also has a controller for transforming either the sensor data or the reference data into the coordinate space of the other and to determine a difference between the sensor and the reference data in that coordinate space. The controller is configured to adjust the forward currents during operating conditions so that the sensor data matches the setpoint data. The present invention also provides a system and method that can at least partially compensate certain temperature induced effects when transforming the optical sensor or the reference data.

Claims

1. A method for controlling one or more light-emitting elements (LEEs) driven by forward currents to generate a mixed light, said method comprising the steps of:

a) acquiring sensor data representative of the mixed light;

b) providing setpoint data representative of a desired mixed light;

c) transforming the sensor data into first data expressed in coordinates of a predetermined color coordinate system;

d) transforming the setpoint data into second data expressed in coordinates of said predetermined color coordinate system;

e) comparing the first and the second data and determining a difference between the first and the second data;

f) adjusting said forward currents in response to the difference between the first and the second data in order to decrease the difference between said first data and said second data; and

repeating steps a) through f) until an absolute value of said difference falls below a predetermined threshold.

2. The method according to claim 1 wherein the predetermined color coordinate system corresponds to the CIE xyY chromaticity coordinate system.

3. The method according to claim 1 wherein the predetermined color coordinate system corresponds to the CIE u′

v′

Y chromaticity coordinate system.

4. The method according to claim 1 wherein the sensor data is provided by one or more optical sensors each providing a responsivity at predetermined operating conditions of the corresponding sensor, each responsivity defining one basis function of the predetermined color coordinate system.

5. The method according to claim 1 wherein the sensor data comprises information representative of weighted averages of one or more response functions.

6. The method as described in claim 1 wherein the setpoint data is provided via a user interface.

7. The method according to claim 1 wherein linear variations of intensity of the light when expressed in the predetermined color coordinate system correspond to substantially linear perceived intensity variations of the emitted light.

8. The method according to claim 1, wherein the sensor data is provided by a predetermined number of sensors and the predetermined number corresponds with the number of different nominal colors of the one or more LEEs.

9. The method according to claim 8, wherein the predetermined number of sensors corresponds with the number of forward currents.

10. The method according to claim 1, wherein transforming the sensor data comprises performing a first linear transformation.

11. The method according to claim 1, wherein transforming the setpoint data comprises performing a second linear transformation.

12. The method according to any one of claim 1 to claim 11 for use in a feedback control system.

13. A system for controlling one or more light-emitting elements (LEEs) driven by forward currents to generate a mixed light, the system comprising:

a) one or more optical sensors for acquiring sensor data representative of the mixed light;

b) a user interface for providing setpoint data representative of a desired mixed light;

c) a controller, the controller transforming the sensor data into first data expressed in coordinates of a predetermined color coordinate system, the controller further transforming the setpoint data into second data expressed in coordinates of said predetermined color coordinate system, the controller further comparing the first and the second data and determining a difference between the first and the second data, the controller further adjusting said forward currents in response to the difference between the first and the second data;

wherein the controller is configured to decrease the difference between said first data and said second data until an absolute value of said difference falls below a predetermined threshold.

14. The system according to claim 13, wherein the predetermined color coordinate system corresponds to the CIE xyY chromaticity coordinate system.

15. The system according to claim 13, wherein the predetermined color coordinate system corresponds to the CIE u′

v′

Y chromaticity coordinate system.

16. The system according to claim 13, wherein each of said one or more optical sensors provides a responsivity at predetermined operating conditions and each responsivity defines one basis function of the predetermined color coordinate system.

17. The system according to claim 13, wherein the sensor data comprises information representative of weighted averages of one or more response functions.

18. The system according to claim 13, wherein linear variations of intensity of the light when expressed in the predetermined color coordinate system correspond to substantially linear perceived intensity variations of the emitted light.

19. The system according to claim 13, wherein the sensor data is provided by a predetermined number of sensors and the predetermined number corresponds with the number of different nominal colors of the one or more LEEs.

20. The system according to claim 13, wherein the predetermined number of sensors corresponds with the number of forward currents.

21. The system according to claim 13, wherein transforming the sensor data comprises performing a first linear transformation.

22. The system according to claim 14, wherein transforming the setpoint data comprises performing a second linear transformation.