Method of adjusting multiple light sources to compensate for variation in light output that occurs with time

• US 20060049332A1
• Filed: 09/08/2004
• Published: 03/09/2006
• Est. Priority Date: 09/08/2004
• Status: Active Grant

• Current Assignee: Hubbell Lighting Incorporated (Hubbell, Inc.)
• Original Assignee: Emteq Lighting & Cabin Systems, Inc.
• Inventors: Hamilton, Douglas M., Vornsand, Steven J.
• Granted Patent: US 7,135,664 B2
• Time in Patent Office: Days
• US Class Current: 250/205
• CPC Class Codes: H05B 45/22 using optical feedback

Abstract

A feedback method on occasion independently senses a characteristic of light produced by each of several light sources in a lighting apparatus. The sensed value of that characteristic is compared to a reference value for the respective light source and that light source'"'"'s operation is adjusted accordingly. This method has particular application in a lighting apparatus that produces different lighting effects by varying the intensity of different colors of light produced by the various light sources. The feedback method compensates for light emission variation as the sources age, thus ensuring that the lighting apparatus continues to produce the desired lighting effects. This enables multiple lighting apparatus in an area to be calibrated to the same standard so that uniform illumination is provided.

Claims

1. A method for calibrating a light emission apparatus that has a plurality of light sources each producing different colored light, said method comprising:

defining a separate reference value for a characteristic of light produced by each light source;

sensing the characteristic of the light produced by each light source and thereby producing a sensed value for each light source;

for each light source, comparing the respective sensed value to the respective reference value;

adjusting operation of each light source as necessary based on the comparing.

2. The method as recited in claim 1 wherein the characteristic of the light is light intensity.

3. The method as recited in claim 1 wherein operation of each light source is adjusted until the respective sensed value substantially equals the respective reference value.

4. The method as recited in claim 1 wherein adjusting operation of each light source comprises altering an amount of electric current that flows to the respective light source.

5. The method as recited in claim 1 wherein defining a separate reference value for a characteristic of the light produced by each light source comprises:

adjusting operation of the plurality of light sources until a combination of the light produced by the plurality of light sources has a predefined correlated color temperature; and

sensing the characteristic of the light produced by each light source and thereby producing a reference value for each light source.

6. The method as recited in claim 1 wherein a first light source of the plurality of light sources produces white light, and wherein defining a separate reference value for a characteristic of the light produced by each light source comprises:

setting luminance of the first light source to a predefine level;

adjusting operation of the plurality of light sources other than the first light source until a correlated color temperature of a combination of light produced by the plurality of light sources has a predefined value; and

sensing the characteristic of the light produced by each light source and thereby producing a reference value for each light source.

7. A method for calibrating light system having a first light source and a second light source each producing light of having a different color which combine during an operating mode of the light system, said method comprising:

(a) defining a first reference value for a characteristic of the light produced by the first light source;

(b) defining a second reference value for a characteristic of the light produced by the second light source;

(c) defining the first light source as a selected light source;

(d) operating only the selected light source;

(e) sensing the characteristic of the light produced by the selected light source and thereby producing a sensed value;

(f) selecting either the first reference value as a selected reference value when the first light is the selected light source or the second reference value as a selected reference value when the second light is the selected light source;

(g) comparing the sensed value to the selected reference value;

(h) adjusting operation of the selected light source until the sensed value has a predefined relationship to the selected reference value;

(i) defining the second light source as a selected light source; and

(j) repeating steps (d) through (h).

8. The method as recited in claim 7 wherein the characteristic of the light produced by the first light source and second light source is light intensity.

9. The method as recited in claim 7 wherein adjusting operation of the selected light source comprises altering a magnitude of electric current that flows to the selected light source.

10. The method as recited in claim 7 wherein defining a first reference value and defining a second reference value each comprises:

adjusting operation of the first and second light sources until a correlated color temperature of a combination of light produced by both light sources has a predefined value;

sensing the characteristic of the light produced by the first light source, thereby producing the first reference value; and

sensing the characteristic of the light produced by the second light source, thereby producing a second reference value.

11. A method for calibrating light emission apparatus having a first light source that produces white light, a second light source that produces a first color of light, and a third light source that produces a third color of light, said method comprising:

operating the first light source to produce light at defined luminance level which is a first reference level;

adjusting operation of the second light sources and the third light source until a correlated color temperature of a combination of light produced by all light sources has a predefined value;

sensing a first characteristic of light produced by the second light source, thereby producing a second reference value;

sensing a second characteristic of light produced by the third light source, thereby producing a third reference value;

thereafter;

sensing luminance of light produced by the first light source, thereby producing a first sensed value;

comparing the first sensed value to the first reference value;

adjusting operation of the first light source in response to comparing the first sensed value;

sensing the second characteristic of light produced by the second light source, thereby producing a second sensed value;

comparing the second sensed value to the second reference value;

adjusting operation of the second light source in response to comparing the second sensed value;

sensing the third characteristic of light produced by the third light source, thereby producing a third sensed value;

comparing the third sensed value to the third reference value; and

adjusting operation of the third light source in response to comparing the third sensed value.

12. The method as recited in claim 11 wherein the second and third characteristics are light intensity.

13. The method as recited in claim 11 wherein operation of each light source is adjusted until the respective sensed value substantially equals the respective reference value.

14. The method as recited in claim 11 wherein adjusting operation of each light source comprises altering an amount of electric current that flows to the respective light source.

15. The method as recited in claim 11 wherein the second light source emits monochromatic light.

16. The method as recited in claim 11 wherein the second light source emits red light.

17. The method as recited in claim 11 wherein the second light source emits polychromatic light.

18. The method as recited in claim 11 wherein the second light source emits amber-green light.