High efficiency lighting device including one or more solid state light emitters, and method of lighting

• US 9,441,793 B2
• Filed: 06/01/2009
• Issued: 09/13/2016
• Est. Priority Date: 12/01/2006
• Status: Active Grant

• Current Assignee: IDEAL Industries Lighting, LLC (Ideal Industries Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Van De Ven, Antony Paul, Negley, Gerald H.
• Primary Examiner(s): PAYNE, SHARON E
• Application Number:
  US12/475,850
• Publication Number:
  US 20090296384A1
• Time in Patent Office: 2,661 Days
• Field of Search: 362/231, 362/84
• US Class Current: 1/1
• CPC Class Codes: F21K 9/232 specially adapted for generating an essentially omnidirectional light distribution, e.g. with a glass bulb
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H01L 2224/45147 Copper (Cu) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H05B 45/00 Circuit arrangements for operating light-emitting diodes [LED]
• CPC Class Codes: H05B 45/22 using optical feedback

Abstract

There is provided a lighting device that comprises at least one 600-630 nm solid state light emitter and at least one light source emitting light within an area on a 1931 CIE Chromaticity Diagram defined by a first set of points having x, y coordinates of (0.32, 0.40), (0.36, 0.48), (0.43, 0.45), (0.42, 0.42), (0.36, 0.38), or a second set of points having x, y coordinates of (0.29, 0.36), (0.32, 0.35), (0.41, 0.43), (0.44, 0.49), (0.38, 0.53). Some embodiments further comprise at least a first power line. Also provided are methods that comprise illuminating at least one light source to emit light within one of the areas defined above, and illuminating at least one 600-630 nm emitter.

Claims

1. A lighting device comprising:

a plurality of light sources and at least a first group of solid state light emitters, each of the light sources comprising at least one of a second group of solid state light emitters,

at least one of the first group of solid state light emitters and at least one of the second group of solid state light emitters on a first string,

at least one of the first group of solid state light emitters and at least one of the second group of solid state light emitters on a second string,

the first string electrically parallel to the second string,

each light source, when illuminated, emits light which, in an absence of any additional light, has x, y color coordinates which define a point which is within a first area on a 1931 CIE Chromaticity Diagram enclosed by first, second, third, fourth and fifth line segments, the first line segment connecting a first point to a second point, the second line segment connecting the second point to a third point, the third line segment connecting the third point to a fourth point, the fourth line segment connecting the fourth point to a fifth point, and the fifth line segment connecting the fifth point to the first point, the first point having x, y coordinates of 0.32, 0.40, the second point having x, y coordinates of 0.36, 0.48, the third point having x, y coordinates of 0.43, 0.45, the fourth point having x, y coordinates of 0.42, 0.42, and the fifth point having x, y coordinates of 0.36, 0.38,

each of the first group of light emitters, when illuminated, emitting light having a dominant emission wavelength in the range of from about 602 nm to about 615 nm, wherein;

a first ratio differs from a second ratio,

said first ratio equal to (1) a number of solid state light emitters in said second group of solid state light emitters and in said first string, divided by (2) a number of solid state light emitters in said first group of solid state light emitters and in said first string;

said second ratio equal to (3) a number of solid state light emitters in said second group of solid state light emitters and in said second string, divided by (4) a number of solid state light emitters in said first group of solid state light emitters and in said second string.

2. A lighting device as recited in claim 1, wherein each of the first group of light emitters, when illuminated, emits light having a dominant emission wavelength in the range of from about 611 nm to about 615 nm.

3. A lighting device as recited in claim 1, wherein each of the first group of light emitters, when illuminated, emits light having a dominant emission wavelength in the range of from about 605 nm to about 615 nm.

4. A lighting device as recited in claim 1, wherein each of the first group of light emitters, when illuminated, emits light having a dominant emission wavelength in the range of from about 610 nm to about 615 nm.

5. A lighting device as recited in claim 1, wherein each of the first group of light emitters, when illuminated, emits light having a dominant emission wavelength in the range of from about 612 nm to about 615 nm.

6. A lighting device as recited in claim 1, wherein when each of the plurality of light sources is illuminated and the first group of solid state light emitters is illuminated,

a mixed illumination of (a) light exiting the lighting device which was emitted by the plurality of light sources and (b) light exiting the lighting device which was emitted by the first group of solid state light emitters has x, y coordinates on a 1931 CIE Chromaticity Diagram which define a point which is within 10 MacAdam ellipses of at least one point on the blackbody locus on a 1931 CIE Chromaticity Diagram.

7. A lighting device as recited in claim 6, wherein the mixed illumination has a CRI of at least 70 and the lighting device has a wall plug efficiency of at least 70 lumens per watt.

8. A lighting device as recited in claim 1, wherein:

each of the plurality of light sources comprises a second group of solid state light emitters and at least a first luminescent material,

each of the second group of solid state light emitters, when illuminated, emits light having a peak emission wavelength in the range of from 400 nm to 480 nm; and

the first luminescent material, when excited, emits light having a dominant emission wavelength in the range of from about 555 nm to about 585 nm.

9. A lighting device as recited in claim 8, wherein:

if each of the second group of solid state light emitters is illuminated, a combination of (1) light exiting the lighting device which was emitted by the second group of solid state light emitters, and (2) light exiting the lighting device which was emitted by the first luminescent material would, in an absence of any additional light, produce a mixed illumination which defines a point which is within the first area.

10. A lighting device as recited in claim 8, wherein each of the second group of solid state light emitters, when illuminated, emits light having a peak emission wavelength in the range of from 430 nm to 480 nm.

11. A lighting device as recited in claim 1, wherein:

at least a first of the plurality of light sources comprises a white light source and a filter,

the white light source emits white light source light that has x, y coordinates on a 1931 CIE Chromaticity Diagram which define a point which is within 10 MacAdam ellipses of at least one point on the blackbody locus on a 1931 CIE Chromaticity Diagram, and

the filter removes at least some light from the white light source light to form light which, in an absence of any additional light, has x, y color coordinates which define a point which is within the first area on a 1931 CIE Chromaticity Diagram enclosed by the first, second, third, fourth and fifth line segments.

12. A lighting device as recited in claim 1, wherein:

at least a first of the plurality of light sources comprises at least a second light emitter and a third light emitter,

the second light emitter, when illuminated, emits light of a second color,

the third light emitter, when illuminated, emits light of a third color, and

the third color is different from the second color.

13. A light fixture comprising a housing and at least one lighting device as recited in claim 1.

14. A lighting device as recited in claim 1, wherein each light source, when illuminated, emits light which, in an absence of any additional light, has x, y color coordinates which define a point which is within a sub-area on a 1931 CIE Chromaticity Diagram enclosed by first, second, third and fourth line segments, the first line segment connecting a first point to a second point, the second line segment connecting the second point to a third point, the third line segment connecting the third point to a fourth point, the fourth line segment connecting the fourth point to the first point, the first point having x, y coordinates of 0.32, 0.40, the second point having x, y coordinates of 0.36, 0.48, the third point having x, y coordinates of 0.41, 0.455, and the fourth point having x, y coordinates of 0.36, 0.38.

15. A lighting device as recited in claim 1, wherein the plurality of light sources when illuminated, emits light which, in an absence of any additional light, has x, y color coordinates which define a point which is within a sub-area on a 1931 CIE Chromaticity Diagram in which x is between 0.36 and 0.37, and y is between 0.42 and 0.43.

16. A lighting device as recited in claim 1, wherein the plurality of light sources when illuminated, emits light which, in an absence of any additional light, has x, y color coordinates which define a point which is within a sub-area on a 1931 CIE Chromaticity Diagram in which x is between 0.36 and 0.37, and y is between 0.43 and 0.44.

17. A lighting device as recited in claim 1, wherein the plurality of light sources when illuminated, emits light which, in an absence of any additional light, has x, y color coordinates which define a point which is within a sub-area on a 1931 CIE Chromaticity Diagram in which x is between 0.37 and 0.38, and y is between 0.42 and 0.43.

18. A lighting device as recited in claim 1, wherein the plurality of light sources when illuminated, emits light which, in an absence of any additional light, has x, y color coordinates which define a point which is within a sub-area on a 1931 CIE Chromaticity Diagram in which x is between 0.37 and 0.38, and y is between 0.43 and 0.44.

19. A lighting device as recited in claim 1, wherein the plurality of light sources when illuminated, emits light which, in an absence of any additional light, has x, y color coordinates which define a point which is within a sub-area on a 1931 CIE Chromaticity Diagram in which x is between 0.37 and 0.38, and y is between 0.44 and 0.45.

20. A lighting device as recited in claim 1, wherein the plurality of light sources when illuminated, emits light which, in an absence of any additional light, has x, y color coordinates which define a point which is within a sub-area on a 1931 CIE Chromaticity Diagram in which x is between 0.37 and 0.38, and y is between 0.45 and 0.46.

21. A lighting device as recited in claim 1, wherein the plurality of light sources when illuminated, emits light which, in an absence of any additional light, has x, y color coordinates which define a point which is within a sub-area on a 1931 CIE Chromaticity Diagram in which x is between 0.38 and 0.39, and y is between 0.43 and 0.44.

22. A lighting device as recited in claim 1, wherein the plurality of light sources when illuminated, emits light which, in an absence of any additional light, has x, y color coordinates which define a point which is within a sub-area on a 1931 CIE Chromaticity Diagram in which x is between 0.38 and 0.39, and y is between 0.44 and 0.45.

23. A lighting device as recited in claim 1, wherein the plurality of light sources when illuminated, emits light which, in an absence of any additional light, has x, y color coordinates which define a point which is within a sub-area on a 1931 CIE Chromaticity Diagram in which x is between 0.38 and 0.39, and y is between 0.45 and 0.46.

24. A lighting device as recited in claim 1, wherein:

the first string comprises a first number of solid state light emitters;

the second string comprises a second number of solid state light emitters;

a percentage of the first number of solid state light emitters in the first string that emit light having a dominant emission wavelength in the range of from about 602 nm to about 615 nm differs from a percentage of the second number of solid state light emitters in the second string that emit light having a dominant emission wavelength in the range of from about 602 nm to about 615 nm.

25. A lighting device comprising:

a plurality of light sources and at least a first group of solid state light emitters, each of the light sources comprising at least one of a second group of solid state light emitters,

at least one of the first group of solid state light emitters and at least one of the second group of solid state light emitters on a first string,

at least one of the first group of solid state light emitters and at least one of the second group of solid state light emitters on a second string,

the first string electrically parallel to the second string,

each light source, when illuminated, emits light which, in an absence of any additional light, has x, y color coordinates which define a point which is within a second area on a 1931 CIE Chromaticity Diagram enclosed by first, second, third, fourth and fifth line segments, the first line segment connecting a first point to a second point, the second line segment connecting the second point to a third point, the third line segment connecting the third point to a fourth point, the fourth line segment connecting the fourth point to a fifth point, and the fifth line segment connecting the fifth point to the first point, the first point having x, y coordinates of 0.29, 0.36, the second point having x, y coordinates of 0.32, 0.35, the third point having x, y coordinates of 0.41, 0.43, the fourth point having x, y coordinates of 0.44, 0.49, and the fifth point having x, y coordinates of 0.38, 0.53,

each of the first group of light emitters, when illuminated, emits light having a dominant emission wavelength in the range of from about 600 nm to about 630 nm, wherein;

a first ratio differs from a second ratio,

said first ratio equal to (1) a number of solid state light emitters in said second group of solid state light emitters and in said first string, divided by (2) a number of solid state light emitters in said first group of solid state light emitters and in said first string;

said second ratio equal to (3) a number of solid state light emitters in said second group of solid state light emitters and in said second string, divided by (4) a number of solid state light emitters in said first group of solid state light emitters and in said second string.

26. A lighting device as recited in claim 25, wherein each of the first group of light emitters, when illuminated, emits light having a dominant emission wavelength in the range of from about 602 nm to about 615 nm.

27. A lighting device as recited in claim 25, wherein each of the first group of light emitters, when illuminated, emits light having a dominant emission wavelength in the range of from about 611 nm to about 615 nm.

28. A lighting device as recited in claim 25, wherein each of the first group of light emitters, when illuminated, emits light having a dominant emission wavelength in the range of from about 605 nm to about 615 nm.

29. A lighting device as recited in claim 25, wherein each of the first group of light emitters, when illuminated, emits light having a dominant emission wavelength in the range of from about 610 nm to about 615 nm.

30. A lighting device as recited in claim 25, wherein each of the first group of light emitters, when illuminated, emits light having a dominant emission wavelength in the range of from about 612 nm to about 615 nm.

31. A lighting device as recited in claim 25, wherein when the plurality of light sources is illuminated and the first group of solid state light emitters is illuminated,

a mixed illumination of (a) light exiting the lighting device which was emitted by the plurality of light sources and (b) light exiting the lighting device which was emitted by the first group of solid state light emitters has x, y coordinates on a 1931 CIE Chromaticity Diagram which define a point which is within 10 MacAdam ellipses of at least one point on the blackbody locus on a 1931 CIE Chromaticity Diagram.

32. A lighting device as recited in claim 31, wherein the mixed illumination has a CRI of at least 70 and the lighting device has a wall plug efficiency of at least 70 lumens per watt.

33. A lighting device as recited in claim 25, wherein:

each of the plurality of light sources comprises a second group of solid state light emitters and at least a first luminescent material,

each of the second group of solid state light emitters, when illuminated, emits light having a peak emission wavelength in the range of from 400 nm to 480 nm; and

the first luminescent material, when excited, emits light having a dominant emission wavelength in the range of from about 555 nm to about 585 nm.

34. A lighting device as recited in claim 33, wherein:

if each of the second group of solid state light emitters is illuminated, a combination of (1) light exiting the lighting device which was emitted by the second group of solid state light emitters, and (2) light exiting the lighting device which was emitted by the first luminescent material would, in an absence of any additional light, produce a mixed illumination which defines a point which is within the first area.

35. A lighting device as recited in claim 33, wherein each of the second group of solid state light emitters, when illuminated, emits light having a peak emission wavelength in the range of from 430 nm to 480 nm.

36. A lighting device as recited in claim 25, wherein:

at least a first of the plurality of light sources comprises a white light source and a filter,

the white light source emits white light source light that has x, y coordinates on a 1931 CIE Chromaticity Diagram which define a point which is within 10 MacAdam ellipses of at least one point on the blackbody locus on a 1931 CIE Chromaticity Diagram, and

the filter removes at least some light from the white light source light to form light which, in an absence of any additional light, has x, y color coordinates which define a point which is within the first area on a 1931 CIE Chromaticity Diagram enclosed by the first, second, third, fourth and fifth line segments.

37. A lighting device as recited in claim 25, wherein:

at least a first of the plurality of light sources comprises at least a second light emitter and a third light emitter,

the second light emitter, when illuminated, emits light of a second color,

the third light emitter, when illuminated, emits light of a third color, and

the third color is different from the second color.

38. A light fixture comprising a housing and at least one lighting device as recited in claim 25.

39. A lighting device as recited in claim 25, wherein each light source, when illuminated, emits light which, in an absence of any additional light, has x, y color coordinates which define a point which is within a sub-area on a 1931 CIE Chromaticity Diagram enclosed by first, second, third and fourth line segments, the first line segment connecting a first point to a second point, the second line segment connecting the second point to a third point, the third line segment connecting the third point to a fourth point, the fourth line segment connecting the fourth point to the first point, the first point having x, y coordinates of 0.32, 0.40, the second point having x, y coordinates of 0.36, 0.48, the third point having x, y coordinates of 0.41, 0.455, and the fourth point having x, y coordinates of 0.36, 0.38.

40. A lighting device as recited in claim 25, wherein:

the first string comprises a first number of solid state light emitters;

the second string comprises a second number of solid state light emitters;

a percentage of the first number of solid state light emitters in the first string that emit light having a dominant emission wavelength in the range of from about 600 nm to about 630 nm differs from a percentage of the second number of solid state light emitters in the second string that emit light having a dominant emission wavelength in the range of from about 600 nm to about 630 nm.

41. A lighting device comprising:

a plurality of light sources and at least a first group of solid state light emitters, each of the light sources comprising at least one of a second group of solid state light emitters,

at least one of the first group of solid state light emitters and at least one of the second group of solid state light emitters on a first string,

at least one of the first group of solid state light emitters and at least one of the second group of solid state light emitters on a second string,

the first string electrically parallel to the second string,

each light source, when illuminated, emits light which, in an absence of any additional light, has x, y color coordinates which define a point which is within a first area on a 1931 CIE Chromaticity Diagram enclosed by first, second, third, fourth and fifth line segments, the first line segment connecting a first point to a second point, the second line segment connecting the second point to a third point, the third line segment connecting the third point to a fourth point, the fourth line segment connecting the fourth point to a fifth point, and the fifth line segment connecting the fifth point to the first point, the first point having x, y coordinates of 0.32, 0.40, the second point having x, y coordinates of 0.36, 0.48, the third point having x, y coordinates of 0.43, 0.45, the fourth point having x, y coordinates of 0.42, 0.42, and the fifth point having x, y coordinates of 0.36, 0.38;

each of the first group of light emitters, when illuminated, emitting light having a dominant emission wavelength in the range of from about 602 nm to about 615 nm; and

at least a first power line, each of the plurality of light sources and each of the first group of solid state light emitters electrically connected to the first power line,

the first and second strings electrically parallel to each other and in series relative to the first power line,

wherein;

a first ratio differs from a second ratio,

said first ratio equal to (1) a number of solid state light emitters in said second group of solid state light emitters and in said first string, divided by (2) a number of solid state light emitters in said first group of solid state light emitters and in said first string;

said second ratio equal to (3) a number of solid state light emitters in said second group of solid state light emitters and in said second string, divided by (4) a number of solid state light emitters in said first group of solid state light emitters and in said second string, and

if current is supplied to the first power line, a combination of (1) light exiting the lighting device which was emitted by the plurality of light sources and (2) light exiting the lighting device which was emitted by the first group of solid state light emitters would, in an absence of any additional light, produce a mixed illumination which defines a point which is within 10 MacAdam ellipses of at least one point on the blackbody locus on a 1931 CIE Chromaticity Diagram.

42. A lighting device as recited in claim 41, wherein:

the first string comprises a first number of solid state light emitters;

the second string comprises a second number of solid state light emitters;

a percentage of the first number of solid state light emitters in the first string that emit light having a dominant emission wavelength in the range of from about 602 nm to about 615 nm differs from a percentage of the second number of solid state light emitters in the second string that emit light having a dominant emission wavelength in the range of from about 602 nm to about 615 nm.

43. A lighting device comprising:

a plurality of light sources and at least a first group of solid state light emitters, each of the light sources comprising at least one of a second group of solid state light emitters,

at least one of the first group of solid state light emitters and at least one of the second group of solid state light emitters on a first string,

at least one of the first group of solid state light emitters and at least one of the second group of solid state light emitters on a second string,

the first string electrically parallel to the second string,

each light source, when illuminated, emits light which, in an absence of any additional light, has x, y color coordinates which define a point which is within a second area on a 1931 CIE Chromaticity Diagram enclosed by first, second, third, fourth and fifth line segments, the first line segment connecting a first point to a second point, the second line segment connecting the second point to a third point, the third line segment connecting the third point to a fourth point, the fourth line segment connecting the fourth point to a fifth point, and the fifth line segment connecting the fifth point to the first point, the first point having x, y coordinates of 0.29, 0.36, the second point having x, y coordinates of 0.32, 0.35, the third point having x, y coordinates of 0.41, 0.43, the fourth point having x, y coordinates of 0.44, 0.49, and the fifth point having x, y coordinates of 0.38, 0.53;

each of the first group of light emitters, when illuminated, emitting light having a dominant emission wavelength in the range of from about 600 nm to about 630 nm; and

at least a first power line, each of the plurality of light sources and each of the first group of solid state light emitters electrically connected to the first power line,

the first and second strings electrically parallel to each other and in series relative to the first power line,

wherein;

a first ratio differs from a second ratio,

said first ratio equal to (1) a number of solid state light emitters in said second group of solid state light emitters and in said first string, divided by (2) a number of solid state light emitters in said first group of solid state light emitters and in said first string;

said second ratio equal to (3) a number of solid state light emitters in said second group of solid state light emitters and in said second string, divided by (4) a number of solid state light emitters in said first group of solid state light emitters and in said second string, and

if current is supplied to the first power line, a combination of (1) light exiting the lighting device which was emitted by the plurality of light sources and (2) light exiting the lighting device which was emitted by the first group of solid state light emitters would, in an absence of any additional light, produce a mixed illumination which defines a point which is within 10 MacAdam ellipses of at least one point on the blackbody locus on a 1931 CIE Chromaticity Diagram.

44. A lighting device as recited in claim 43, wherein:

the first string comprises a first number of solid state light emitters;

the second string comprises a second number of solid state light emitters;

a percentage of the first number of solid state light emitters in the first string that emit light having a dominant emission wavelength in the range of from about 600 nm to about 630 nm differs from a percentage of the second number of solid state light emitters in the second string that emit light having a dominant emission wavelength in the range of from about 600 nm to about 630 nm.

45. A method comprising:

illuminating a plurality of light sources to emit light which, in an absence of any additional light, has x, y color coordinates which define a point which is within a first area on a 1931 CIE Chromaticity Diagram enclosed by first, second, third, fourth and fifth line segments, the first line segment connecting a first point to a second point, the second line segment connecting the second point to a third point, the third line segment connecting the third point to a fourth point, the fourth line segment connecting the fourth point to a fifth point, and the fifth line segment connecting the fifth point to the first point, the first point having x, y coordinates of 0.32, 0.40, the second point having x, y coordinates of 0.36, 0.48, the third point having x, y coordinates of 0.43, 0.45, the fourth point having x, y coordinates of 0.42, 0.42, and the fifth point having x, y coordinates of 0.36, 0.38; and

illuminating a first group of solid state light emitters, the first group of solid state light emitters comprising at least one solid state light emitter, to emit light having a wavelength in the range of from about 602 nm to about 615 nm,

each said light source comprising at least one of a second group of solid state light emitters,

at least one of the first group of solid state light emitters and at least one of the second group of solid state light emitters on a first string,

at least one of the first group of solid state light emitters and at least one of the second group of solid state light emitters on a second string,

the first string electrically parallel to the second string,

a first ratio differing from a second ratio,

said first ratio equal to (1) a number of solid state light emitters in said second group of solid state light emitters and in said first string, divided by (2) a number of solid state light emitters in said first group of solid state light emitters and in said first string;

said second ratio equal to (3) a number of solid state light emitters in said second group of solid state light emitters and in said second string, divided by (4) a number of solid state light emitters in said first group of solid state light emitters and in said second string.

46. A method as recited in claim 45, wherein a mixed illumination of (a) light emitted by the plurality of light sources and (b) light emitted by the first group of solid state light emitters has x, y coordinates on a 1931 CIE Chromaticity Diagram which define a point which is within 10 MacAdam ellipses of at least one point on the blackbody locus on a 1931 CIE Chromaticity Diagram.

47. A method as recited in claim 46, wherein the mixed illumination has a correlated color temperature of not greater than 5000 K.

48. A method as recited in claim 46, wherein the mixed illumination has a CRI of at least 70 and the mixed illumination is emitted at a wall plug efficiency of at least 70 lumens per watt.

49. A method comprising:

illuminating a plurality of light sources to emit light which, in an absence of any additional light, has x, y color coordinates which define a point which is within a second area on a 1931 CIE Chromaticity Diagram enclosed by first, second, third, fourth and fifth line segments, the first line segment connecting a first point to a second point, the second line segment connecting the second point to a third point, the third line segment connecting the third point to a fourth point, the fourth line segment connecting the fourth point to a fifth point, and the fifth line segment connecting the fifth point to the first point, the first point having x, y coordinates of 0.29, 0.36, the second point having x, y coordinates of 0.32, 0.35, the third point having x, y coordinates of 0.41, 0.43, the fourth point having x, y coordinates of 0.44, 0.49, and the fifth point having x, y coordinates of 0.38, 0.53; and

illuminating a first group of solid state light emitters, the first group of solid state light emitters comprising at least one solid state light emitter, to emit light having a wavelength in the range of from about 600 nm to about 630 nm,

each said light source comprising at least one of a second group of solid state light emitters,

at least one of the first group of solid state light emitters and at least one of the second group of solid state light emitters on a first string,

at least one of the first group of solid state light emitters and at least one of the second group of solid state light emitters on a second string,

the first string electrically parallel to the second string,

a first ratio differing from a second ratio,

said first ratio equal to (1) a number of solid state light emitters in said second group of solid state light emitters and in said first string, divided by (2) a number of solid state light emitters in said first group of solid state light emitters and in said first sting;

said second ratio equal to (3) a number of solid state light emitters in said second group of solid state light emitters and in said second string, divided by (4) a number of solid state light emitters in said first group of solid state light emitters and in said second string.

50. A method as recited in claim 49, wherein a mixed illumination of (a) light emitted by the plurality of light sources and (b) light emitted by the first group of solid state light emitters has x, y coordinates on a 1931 CIE Chromaticity Diagram which define a point which is within 10 MacAdam ellipses of at least one point on the blackbody locus on a 1931 CIE Chromaticity Diagram.

51. A method as recited in claim 50, wherein the mixed illumination has a correlated color temperature of not greater than 5000 K.

52. A method as recited in claim 50, wherein the mixed illumination has a CRI of at least 70 and the mixed illumination is emitted at a wall plug efficiency of at least 70 lumens per watt.