Methods for combining light emitting devices in a package and packages including combined light emitting devices

• US 7,967,652 B2
• Filed: 04/17/2009
• Issued: 06/28/2011
• 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: Emerson, David Todd
• Primary Examiner(s): Ton; Toan
• Assistant Examiner(s): Hanley; Britt D
• Application Number:
  US12/425,855
• Publication Number:
  US 20100140633A1
• Time in Patent Office: 802 Days
• Field of Search: None
• US Class Current: 445/24
• 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: F21K 9/90 Methods of manufacture
• 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

Abstract

Methods of forming a light emitting device package assembly include defining a chromaticity region in a two dimensional chromaticity space, 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 at least one of the defined chromaticity subregions, selecting at least three of the plurality of light emitting devices, each of the three light emitting devices emits light from a different one of the chromaticity subregions, and mounting the selected light emitting devices on a light emitting device package body.

Claims

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

providing a light emitting device package 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 point on the black body locus having a correlated color temperature between 2700K and 6500K, 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; and

mounting the selected light emitting devices on the light emitting device package body;

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; and

wherein selecting a pair of light emitting devices 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.

2. The method of claim 1, wherein each of the chromaticity subregions shares a boundary with at least two other chromaticity subregions.

3. The method of claim 1, wherein the chromaticity region encompasses a defined bin in the two dimensional chromaticity space.

4. The method of claim 3, wherein 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 3, wherein the defined bin comprises a bin defined in Table A1 of ANSI standard C78.377A.

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 the size of a 4-step MacAdam ellipse in the two dimensional chromaticity space.

9. The method of claim 3, wherein each of the at least three chromaticity subregions at least partially overlaps the defined bin.

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, 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;

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 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).

17. The light emitting device package assembly of claim 5, wherein the defined bin comprises a quadrangle on a two dimensional chromaticity space that has a width equal to a major axis a 7-step MacAdam ellipse in the two dimensional chromaticity space.

18. The light emitting device package assembly of claim 5, wherein the defined bin comprises a bin defined in Table A1 of ANSI standard C78.377A.

15. A light emitting device package assembly, comprising:

a light emitting device package body; and

at least three light emitting devices on the package 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 point on the black body locus having a correlated color temperature between 2700K and 6500K, the defined chromaticity space being larger than and encompassing a defined bin in the two dimensional chromaticity space and being subdivided into at least three subregions;

wherein each of the at least three light emitting devices emits light that falls within a different one of the at least three subregions of the defined chromaticity region, and wherein at least one of the light emitting devices emits light that falls outside the defined bin; and

wherein a first one of the at least three light emitting devices has 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 a second one of the at least three light emitting devices has 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.

16. The light emitting device package assembly of claim 15, wherein each of the chromaticity subregions shares a boundary with at least two other chromaticity subregions.

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

providing a light emitting device package 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 point on the black body locus having a correlated color temperature between 2700K and 6500K, 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; and

mounting the selected light emitting devices on the light emitting device package body;

wherein selecting the at least three light emitting devices 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.