Manufacturing method for LED emitter with high color consistency

• US 9,234,801 B2
• Filed: 03/14/2014
• Issued: 01/12/2016
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Ledengin, Inc. (Ams-Osram AG)
• Original Assignee: Ledengin, Inc. (Ams-Osram AG)
• Inventors: Mei, Zequn, Gonzales, Danny, Yan, Xiantao, Armstrong, William E.
• Primary Examiner(s): Nikmanesh, Seahvosh
• Application Number:
  US14/214,479
• Publication Number:
  US 20140268153A1
• Time in Patent Office: 669 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G01J 3/463 Colour matching

Abstract

A method is provided for forming multiple-LED (light-emitting-diode) light emitters from a plurality of LEDs, wherein the number of LEDs in each emitter is an integer M. The method includes providing a plurality of LEDs, each of the LEDs characterized by a first parameter and a second parameter, which are related to color coordinates CIEx and CIEy in a chromaticity diagram. The method also includes determining first and second parameter X₀ and Y₀ for a target color. The method further includes, for all possible combinations of M LEDs out of the plurality of LEDs, determining a first group parameter and a second group parameter based on the first and second parameters for all of the M LEDs, and selecting a group of M LEDs whose first group parameter and second group parameter are closest to X₀ and Y₀ as a candidate for forming a light emitter of M LEDs.

Claims

1. A method for forming light emitters with multiple LEDs (light-emitting-diodes), wherein the number of LEDs in each emitter is an integer M, the method comprising:

determining color coordinates CIEx and CIEy and intensity for each of a plurality of LEDs, wherein CIEx and CIEy are color coordinates in a CIE chromaticity diagram, and wherein N is the number of LEDs in the plurality of LEDs;

determining a first parameter X₀ and a second parameter Y₀ for a target light color, wherein X₀ and Y₀ are related to CIEx and CIEy of each of the N LEDs and a weighting factor related to the intensity of each of the N LEDs;

for each possible group of M LEDs out of the N LEDs in the plurality of LEDs;

determining a first group parameter X and a second group parameter Y, wherein X and Y are related to CIEx and CIEy of each of the M LEDs and a weighting factor related to the intensity of each of the M LEDs; and

determining a difference between the first and second group parameters X and Y of each LED in the group of M LEDs and X₀ and Y₀;

selecting a first group of M LEDs whose first group parameter X and second group parameter Y are closest to X₀ and Y₀ as a first candidate for forming a light emitter with M LEDs;

removing the selected first group of M LEDs from the plurality of LEDs; and

for the LEDs remaining in the plurality of LEDs, repeating the above processes to select a group of M LEDs as the next candidate for forming a light emitter.

2. The method of claim 1, wherein the weighting factor is related to the lumen of the LEDs.

3. The method of claim 2, wherein the weighting factor is related to a ratio of lumen over CIE-y of each LED.

4. The method of claim 1, wherein the weighting factor is related to radiant power of the LEDs.

5. The method of claim 4, wherein the first parameter X₀ of the target light color is related to a sum of the CIEx of each of N LEDs multiplied by a ratio of the radiant power of each of the N LEDs divided by a sum of the radiant power of all N LEDs, and the second parameter Y₀ of the target light color is related to a sum of the CIEy of each of N LEDs multiplied by a ratio of the radiant power of each of the N LEDs divided by a sum of the radiant power of all N LEDs.

6. The method of claim 4, wherein the first group parameter X of each of the possible groups of M LEDs is related to a sum of the CIEx of each of M LEDs multiplied by a ratio of the radiant power of each of the M LEDs divided by a sum of the radiant power of all M LEDs in that group, and the second group parameter Y of each of the possible groups of M LEDs is related to a sum of the CIEy of each of M LEDs multiplied by a ratio of the radiant power of each of the M LEDs divided by a sum of the radiant power of all M LEDs in that group.

7. The method of claim 1, wherein selecting the first group of M LEDs comprises:

calculating a root mean square difference between (X, Y) and (X₀, Y₀), wherein X and Y are the first and the second group parameters for each of the possible groups of M LEDs, and X₀ and Y₀ are first and the second parameters of the target light color, and

selecting a group with the minimum root mean square difference.

8. The method of claim 1, wherein each of the LEDs comprises an LED chip having a phosphor-containing material disposed thereon.

9. The method of claim 8, wherein each of the LEDs comprises a blue LED having a phosphor-containing material including a green phosphor and a red phosphor disposed thereon.

10. The method of claim 8, wherein each of the LEDs comprises a blue LED having a phosphor-containing material including a yellow phosphor and a red phosphor disposed thereon.

11. A method for forming multiple-LED (light-emitting-diode) light emitters from a plurality of LEDs, the method comprising:

characterizing the plurality of LEDs according to first and second parameters of each LED, the first and second parameters being related to color coordinates CIEx and CIEy, respectively;

determining a target color, which is characterized by a first and second parameters, X₀ and Y₀, that are related to color coordinates CIEx and CIEy in a chromaticity diagram;

for all possible combinations of M LEDs out of the LEDs in the plurality of LEDs;

determining a first group parameter X and a second group parameter Y based on the first and second parameters for each of the M LEDs in the group; and

determining a difference between the first and second parameters of each group and X₀ and Y₀;

selecting a group of M LEDs that has the smallest difference as a candidate for forming a light emitter of M LEDs.

12. The method of claim 11, further comprising:

removing the selected group of M LEDs from the plurality of LEDs; and

for the remaining LEDs, repeating the process of selecting a group of M LEDs for forming a multiple-LED emitter.

13. The method of claim 11, wherein the first parameter X₀ and the second parameter Y₀ for the target light color is further related to a weighting factor related to the intensity of each of the plurality of LEDs.

14. The method of claim 13, wherein the weighting factor is related to the lumen of the LEDs.

15. The method of claim 13, wherein each of the weighting factor is related to a ratio of lumen over CIE-y of each LED.

16. The method of claim 13, wherein the weighting factor is related to the radiant power of the LEDs.

17. The method of claim 11, wherein the first group parameter X and the second group parameter Y for the group of M LEDs is further related to a weighting factor related to the intensity of each of the M LEDs.

18. The method of claim 17, wherein the weighting factors are related to the lumen of the LEDs.

19. The method of claim 17, wherein the weighting factors are related to the radiant power of the LEDs.

20. The method of claim 11, wherein each of the LEDs comprises an LED chip having a phosphor-containing material disposed thereon.