METHODS FOR COMBINING LIGHT EMITTING DEVICES IN A PACKAGE AND PACKAGES INCLUDING COMBINED LIGHT EMITTING DEVICES

• US 20110037080A1
• Filed: 07/19/2010
• Published: 02/17/2011
• Est. Priority Date: 02/19/2009
• Status: Active Grant

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Keller, Bernd P., McOlear, Mark, Emerson, David Todd, Andrews, Peter S.
• Granted Patent: US 8,333,631 B2
• Time in Patent Office: Days
• US Class Current: 257/88
• 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 2105/10 comprising a two-dimensional array of point-like light-generating elements
• CPC Class Codes: F21Y 2105/12 characterised by the geometrical disposition of the light-generating elements, e.g. arranging light-generating elements in differing patterns or densities
• CPC Class Codes: F21Y 2113/13 comprising an assembly of point-like light sources
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H05B 45/20 Controlling the colour of the light

Abstract

Methods of forming a light emitting device package assembly include defining a chromaticity region in a two dimensional chromaticity space within a 10-step MacAdam ellipse of a target chromaticity point, and subdividing the defined chromaticity region into at least three chromaticity subregions, providing a plurality of light emitting devices that emit light having a chromaticity that falls within the defined chromaticity region, selecting at least three of the plurality of light emitting devices, wherein each of the three light emitting devices emits light from a different one of the chromaticity subregions. The at least three light emitting devices are selected from chromaticity subregions that are complementary relative to the target chromaticity point to at least one other chromaticity subregion from which a light emitting device is selected.

Claims

1. A method of forming a light emitting device assembly, comprising:

providing a light emitting device assembly body;

defining a chromaticity region in a two dimensional chromaticity space wherein the chromaticity region is defined within a 10-step MacAdam ellipse of a target chromaticity point, and subdividing the defined chromaticity region into at least three chromaticity subregions;

providing a plurality of light emitting devices that emit light having a chromaticity that falls within the defined chromaticity region;

selecting at least three of the plurality of light emitting devices, wherein each of the three light emitting devices has a chromaticity point in a different one of the chromaticity subregions and wherein the at least three light emitting devices are selected from chromaticity subregions that are complementary relative to the target chromaticity point to at least one other chromaticity subregion from which a light emitting device is selected; and

mounting the selected light emitting devices on the light emitting device assembly body.

2. The method of claim 1, wherein the target chromaticity point is on the black body locus and has a correlated color temperature between 2600K and 6600K.

3. The method of claim 1, wherein selecting the at least three light emitting devices comprises selecting at least two sets of light emitting devices, wherein each set of light emitting devices comprises at least two light emitting devices selected from chromaticity subregions that are complementary relative to the target chromaticity point.

4. The method of claim 3, wherein the chromaticity region encompasses a defined bin in the two dimensional chromaticity space, and the defined bin comprises a quadrangle on a two dimensional chromaticity space that has a width equal to a major axis of a 7-step MacAdam ellipse in the two dimensional chromaticity space.

5. The method of claim 4, wherein each of the at least three chromaticity subregions at least partially overlaps the defined bin.

6. The method of claim 3, wherein combined light from the at least three light emitting devices falls within a target chromaticity region that is a subset of the defined bin.

7. The method of claim 6, wherein the defined chromaticity region is larger than and encompasses the defined bin, and wherein the target chromaticity region touches an edge of the defined bin.

8. The method of claim 6, wherein the target chromaticity region has an area on a two dimensional chromaticity space that is about the size of a 2-step MacAdam ellipse in the two dimensional chromaticity space.

9. The method of claim 6, wherein the target chromaticity region has an area on a two dimensional chromaticity space that is smaller than a 2-step MacAdam ellipse in the two dimensional chromaticity space.

10. The method of claim 1, wherein the light emitting devices comprise phosphor-coated blue light emitting device chips.

11. The method of claim 1, wherein the chromaticity region comprises a first chromaticity region, and the plurality of light emitting devices comprises a first plurality of light emitting devices, the method further comprising:

defining a second chromaticity region in a two dimensional chromaticity space wherein the second chromaticity region is defined within a 10-step MacAdam ellipse of a second target chromaticity point and wherein the second chromaticity region does not overlap with the first chromaticity region, and subdividing the second chromaticity region into at least three second chromaticity subregions;

providing a second plurality of light emitting devices that emit light having a chromaticity that falls within at least one of the second chromaticity subregions;

selecting at least three of the second plurality of light emitting devices, wherein each of the three light emitting devices of the second plurality of light emitting devices emits light from a different one of the second chromaticity subregions; and

mounting the selected light emitting devices of the second plurality of light emitting devices on the light emitting device package body.

12. The method of claim 11, wherein the second chromaticity region comprises light having a dominant wavelength greater than about 600 nm.

13. The method of claim 11, further comprising:

defining a third chromaticity region in a two dimensional chromaticity space, and subdividing the third chromaticity region into at least three third chromaticity subregions wherein the third chromaticity region does not overlap with the first and/or second chromaticity regions;

providing a third plurality of light emitting devices that emit light having a chromaticity that falls within at least one of the third chromaticity subregions;

selecting at least three of the third plurality of light emitting devices, wherein each of the three light emitting devices of the third plurality of light emitting devices emits light from a different one of the third chromaticity subregions; and

mounting the selected light emitting devices of the third plurality of light emitting devices on the light emitting device package body.

14. The method of claim 13, wherein the first chromaticity region comprises light having a chromaticity point that is within a 10-step MacAdam ellipse of a point on the black body locus having a correlated color temperature between 2600K and 6600K, the second chromaticity region comprises light having a dominant wavelength greater than about 600 nm, and the third chromaticity region comprises light having x, y color coordinates within an area on a 1931 CIE Chromaticity Diagram defined by points having coordinates (0.32, 0.40), (0.36, 0.48), (0.43, 0.45), (0.42, 0.42), (0.36, 0.38).

15. The method of claim 1, wherein the defined subregions comprise a plurality of pairs of complementary subregions, wherein respective subregions in a pair of complementary subregions are arranged opposite a center point of the chromaticity region from one another, wherein selecting the at least three of the plurality of light emitting devices comprises selecting at least four of the plurality of light emitting devices from at least four chromaticity subregions in pairs from respective pairs of complementary subregions.

16. The method of claim 15, wherein selecting a pair of light emitting device from one pair of complementary subregions comprises selecting a first light emitting device having a first luminous flux from a first subregion that has a center point that is located a first distance from a center point of the chromaticity region, and selecting a second light emitting device having a second luminous flux from a second subregion that is complementary to the first subregion and that has a center point that is located a second distance from a center point of the chromaticity region, wherein the first distance is smaller than the second distance and wherein the first luminous flux is larger than the second luminous flux.

17. The method of claim 1, wherein the at least three light emitting devices are selected from at least three chromaticity subregions that are complementary relative to the target chromaticity point.

18. A light emitting device assembly, comprising:

a light emitting device assembly body; and

at least three light emitting devices on the assembly body, wherein each of the at least three light emitting devices emits light having a chromaticity that falls within a defined chromaticity region in a two dimensional chromaticity space wherein the chromaticity region is defined within a 10-step MacAdam ellipse of a target chromaticity point that is on the black body locus and that has a correlated color temperature between 2600K and 6600K, the defined chromaticity region being subdivided into at least three chromaticity subregions, wherein the at least three light emitting devices emit light when energized that falls within chromaticity subregions that are complementary relative to the target chromaticity point to at least one other chromaticity subregion in which a light emitting device in the light emitting device assembly emits light.