Light source comprising light-emitting clusters

• US 7,731,389 B2
• Filed: 10/31/2007
• Issued: 06/08/2010
• Est. Priority Date: 10/31/2006
• Status: Active Grant

• Current Assignee: Signify Holding B.V. (Signify N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Salsbury, Marc, Draganov, Vladimir
• Primary Examiner(s): BRUCE, DAVID VERNON
• Application Number:
  US11/931,684
• Publication Number:
  US 20080101064A1
• Time in Patent Office: 951 Days
• Field of Search: 362/231, 362/544, 362/545, 362/230, 362/249.06, 362/249.14, 362/228
• US Class Current: 362/231
• CPC Class Codes: F21K 9/00 Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
• CPC Class Codes: F21Y 2113/17 forming a single encapsulated light source
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H05B 45/20 Controlling the colour of the light

Abstract

The present invention provides a light source for producing a substantially balanced output at a substantially optimised output intensity. In one embodiment, the light source comprises one or more light-emitting clusters of a first type and one or more light-emitting clusters of one or more other types, each one of which comprising one or more light-emitting elements, such that, when all light-emitting elements are driven to provide a substantially optimised output intensity, the spectral output of the one or more light-emitting clusters of the first type is substantially balanced by the spectral output of the one or more other light-emitting clusters.

Claims

1. A light source for producing a spectral output at an output intensity, the light source comprising:

one or more light-emitting clusters of a first type, each one of which comprising a first combination of one or more light-emitting elements in each of at least a first, a second and a third colour;

one or more light-emitting clusters of a second type, each one of which comprising a second combination of one or more light emitting elements in one or more of said first, said second and said third colour, and wherein each of said light-emitting clusters of said second type comprises one or more light-emitting elements in each of said first, said second and said third colour; and

a driving element for driving said light-emitting clusters;

wherein, when driven at the output intensity, the spectral output is provided by a combined spectral output of said one or more light-emitting clusters of said first type and said one or more light-emitting clusters of said second type.

2. The light source according to claim 1, wherein said driving element is configured to drive each of said light-emitting clusters via a substantially same drive current intensity.

3. The light source according to claim 1, further comprising a control element operatively coupled to said driving element, configured to adjust a drive signal to said first type relative to said second type in order to improve the spectral output.

4. The light source according to claim 3, wherein said control element is configured to improve said spectral output from being within a first tolerance of an ideal spectral output to being within a second tolerance of said ideal spectral output.

5. The light source according to claim 3, further comprising a sensing element operatively coupled to said control element for sensing an output of the light source and communicating a signal representative thereof to said control element for further controlling an output of said clusters in response thereto.

6. The light source according to claim 1, wherein the spectral output comprises white light having a colour rendering index above a pre-selected threshold value.

7. The light source according to claim 1, wherein a respective number of said light-emitting elements in each of said first, said second and said third colour is selected as a function of a respective colour-dependent output efficiency thereof.

8. The light source according to claim 7, wherein a ratio of said respective number of said light-emitting elements in a given colour to that of another colour is about equal to a ratio of said respective colour-dependent output efficiency of said light-emitting elements in said other colour to that of said given colour.

9. The light source according to claim 7, wherein a ratio of said respective number of said light-emitting elements in a given colour to that of another colour is proportional to a ratio of said respective colour-dependent output efficiency of said light-emitting elements in said other colour to that of said given colour.

10. The light source according to claim 1, wherein said first type comprises a different number of light-emitting elements than said second type.

11. The light source according to claim 1, wherein said first type comprises a same number of light-emitting elements as said second type.

12. The light source according to claim 1, wherein said second type comprises one or more light-emitting elements in a colour other than said first, said second and said third colour.

13. A light source for producing a spectral output at an output intensity, the light source comprising:

one or more light-emitting clusters of a first type, each one of which comprising a first combination of one or more light-emitting elements in each of at least a first, a second and a third colour;

one or more light-emitting clusters of a second type, each one of which comprising a second combination of one or more light emitting elements in one or more of said first, said second and said third colour,

one or more light-emitting clusters of a third type,

a driving element for driving said light-emitting clusters;

wherein, when driven at the output intensity, the spectral output is provided by a combined spectral output of said one or more light-emitting clusters of said first type and said one or more light-emitting clusters of said second type, and

wherein each one of said light-emitting clusters of said third type comprises a third combination of one or more light-emitting elements in one or more of said first, said second and said third colour.

14. The light source according to claim 13, wherein said first type comprises a different number of light-emitting elements than said second type.

15. The light source according to claim 13, wherein said first type comprises a same number of light-emitting elements as said second type.

16. The light source according to claim 13, wherein said second type comprises one or more light-emitting elements in a colour other than said first, said second and said third colour.

17. The light source according to claim 13, wherein said driving element is configured to drive each of said light-emitting clusters via a substantially same drive current intensity.

18. A light source for producing a spectral output at an output intensity, the light source comprising:

one or more light-emitting clusters of each of a first type and of one or more other types; and

a driving element for driving said one or more light-emitting clusters of said first type and of said one or more other types;

each cluster of said first type comprising one or more light-emitting elements in each of at least a first, a second and a third colour having respective output efficiencies, wherein one or more of said respective output efficiencies are lower than one or more others of said respective output efficiencies; and

each cluster of said one or more other types comprising one or more light-emitting elements selected to compensate for said one or more lower respective output efficiencies such that, when driven to provide the output intensity, a spectral output of said one or more light-emitting clusters of said first type is substantially balanced by a spectral output of said one or more light-emitting clusters of said one or more other types.

19. The light source according to claim 18, wherein a ratio of a number of said light-emitting elements of a given colour to a number of said light-emitting elements of another colour is inversely proportional to a ratio of said respective output efficiencies thereof.

20. The light source according to claim 18, wherein a ratio of a number of said light-emitting elements of a given colour to a number of said light-emitting elements of another colour is about equal to an inverse ratio of said respective output efficiencies thereof.

21. The light source according to claim 18, further comprising a control element operatively coupled to said drive element and configured to control an output intensity of said one or more clusters of said first type relative to that of said one or more other types in order to improve the spectral output.

22. The light source according to claim 18, further comprising a control element operatively coupled to said drive element and configured to control an output intensity of said light-emitting elements relative to one another in order to improve the spectral output.

23. The light source according to claim 22, wherein said control element provides a fine tuning of the spectral output a coarse tuning of which being provided by a combination of said one or more clusters of said first type with said one or more clusters of said one or more other types.

24. The light source according to claim 23, further comprising a sensing element operatively coupled to said control element for sensing an output of said light source and communicating a signal representative thereof to said control element for further controlling an output of said clusters in response thereto.

25. The light source according to claim 18, wherein said spectral output comprises white light.

26. The light source according to claim 25, wherein said white light is defined by a colour rendering index above a pre-selected threshold value.