Light emitting devices with phosphor wavelength conversion and methods of fabrication thereof

• US 20090117672A1
• Filed: 10/01/2007
• Published: 05/07/2009
• Est. Priority Date: 10/01/2007
• Status: Abandoned Application

• Current Assignee: Intematix Corporation
• Original Assignee: Intematix Corporation
• Inventors: Caruso, James, Edwards, Charles O.
• Application Number:
  US11/906,545
• Publication Number:
  US 20090117672A1
• Time in Patent Office: Days
• US Class Current: 438/7
• 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: H01L 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil

Abstract

A method of fabricating a light emitting device having a specific target color, CIE xy, of emitted light is described. The device comprises a light emitting diode that is operable to emit light of a first wavelength range and at least one phosphor material which converts at least a part of the light into light of a second wavelength range wherein light emitted by the device comprises the combined light of the first and second wavelength ranges. The method comprises: depositing a pre-selected quantity of the at least one phosphor material on a light emitting surface of the light emitting diode; operating the light emitting diode; measuring the color of light emitted by the device; comparing the measured color with the specific target color; and depositing and/or removing phosphor material to attain the desired target color.

Claims

1. A method of fabricating a light emitting device having a specific target color of emitted light, the device comprising at least one light emitting diode operable to emit light of a first wavelength range and at least one phosphor material which converts at least a part of the light into light of a second wavelength range wherein light emitted by the device comprises the combined light of the first and second wavelength ranges, the method comprising:

a) depositing a pre-selected quantity of the at least one phosphor material on a light emitting surface of the at least one light emitting diode;

b) operating the at least one light emitting diode;

c) measuring the color of light emitted by the device;

d) comparing the measured color with the specific target color; and

e) in dependence on the comparison depositing and/or removing a quantity of a phosphor material substantially to attain the specific target color.

2. The method according to claim 1, and comprising selecting the pre-selected quantity to ensure that the proportion of light of the second wavelength range is lower than is required in the specific target color.

3. The method according to claim 1, and comprising selecting the pre-selected quantity to ensure that the proportion of light of the second wavelength range is greater than in the specific target color.

4. The method according to claim 1, and comprising selecting the quantity of phosphor material to be deposited and/or removed using a look-up table.

5. The method according to claim 1, and further comprising operating the at least one light emitting diode a further time and measuring the color of light emitted by the device.

6. The method according to claim 4, and further comprising operating the at least one light emitting diode a further time;

measuring the color of light emitted by the device and updating the look-up table.

7. The method according to claim 1, and comprising removing the phosphor material using a method selected the group consisting of:

ablating;

slicing;

milling;

abrading;

drilling;

routing;

buffing and grinding.

8. The method according to claim 1, wherein when the light emitting device comprises a plurality of light emitting diodes including at least one phosphor material, the method comprising:

a) depositing a pre-selected quantity of the at least one phosphor material on a light emitting surface of each light emitting diode;

b) operating simultaneously each of the light emitting diodes;

c) measuring the color of light emitted by the device;

d) comparing the measured color with the specific target color; and

e) in dependence on the comparison depositing on, and/or removing from, a selected number of the light emitting diodes a fixed quantity of a phosphor material, the number being selected to substantially to attain the specific target color.

9. A method of fabricating a light emitting device having a specific target color of emitted light, the device comprising at least one light emitting diode operable to emit light of a first wavelength range and at least first and second phosphor materials which respectively convert at least a part of the light into light of second and third wavelength ranges wherein light emitted by the device comprises the combined light of the first, second and third wavelength ranges, the method comprising:

a) depositing pre-selected quantities of the first and second phosphor materials on a light emitting surface of the at least one light emitting diode;

b) operating the at least one light emitting diode;

c) measuring the color of light emitted by the device;

d) comparing the measured color with the specific target color; and

e) in dependence on the comparison depositing and/or removing selected quantities of the first and second phosphor materials substantially to attain the specific target color.

10. The method according to claim 9, and comprising selecting the pre-selected quantities to ensure that the proportion of light of the second and third wavelength ranges are lower than in the specific target color.

11. The method according to claim 9, and comprising selecting the pre-selected quantities to ensure that the proportion of light of the second and third wavelength ranges are greater than in the specific target color.

12. The method according to claim 9, and comprising selecting the quantities of phosphor materials to be deposited and/or removed using a look-up table.

13. The method according to claim 9, and further comprising operating the light emitting diode a further time and measuring the color of light emitted by the device.

14. The method according to claim 12, and further comprising operating the at least one light emitting diode a further time;

measuring the color of light emitted by the device and updating the look-up table.

15. The method according to claim 9, wherein when the light emitting device comprises a plurality of light emitting diodes including at least first and second phosphor materials, the method comprising in dependence on the comparison depositing on, and/or removing from, a selected number of the light emitting diodes fixed quantities of the phosphor materials, the number being selected to substantially to attain the specific target color.

16. Apparatus for fabricating a light emitting device having a specific target color of emitted light, the device comprising at least one light emitting diode operable to emit light of a first wavelength range and at least one phosphor material which converts at least a part of the light into light of a second wavelength range wherein light emitted by the device comprises the combined light of the first and second wavelength ranges, the apparatus comprising:

a dispenser for depositing a pre-selected quantity of the at least one phosphor material on a light emitting surface of the at least one light emitting diode;

a controller operable to operate the at least one light emitting diode;

light measuring means for measuring the color of light emitted by the device;

wherein the controller is operable to compare the measured color with the specific target color and in dependence on the comparison to deposit a further selected quantity of a phosphor material substantially to attain the specific target color.

17. The apparatus according to claim 16, and comprising selecting the pre-selected quantity to ensure that the proportion of light of the second wavelength range is lower than in the specific target color.

18. The apparatus according to claim 16, and further comprising a look-up table for selecting the quantity of further phosphor material to be deposited.

19. The apparatus according to claim 18, and further comprising operating the at least one light emitting diode a further time;

measuring the color of light emitted by the device and updating the look-up table.

20. The apparatus according to claim 16, wherein the dispenser comprises a plunger type dispenser head.

21. The apparatus according to claim 16, wherein when the light emitting device comprises a plurality of light emitting diodes including at least one phosphor material, the controller is operable in dependence on the comparison to deposit on a selected number the light emitting diodes a fixed quantity of the phosphor material, the number being selected to substantially to attain the specific target color.

22. Apparatus for fabricating a light emitting device having a specific target color of emitted light, the device comprising at least one light emitting diode operable to emit light of a first wavelength range and at least one phosphor material which converts at least a part of the light into light of a second wavelength range wherein light emitted by the device comprises the combined light of the first and second wavelength ranges, the apparatus comprising:

a dispenser operable to deposit a pre-selected quantity of the at least one phosphor material on a light emitting surface of the at least one light emitting diode;

a controller operable to operate the at least one light emitting diode;

light measuring means for measuring the color of light emitted by the device; and

phosphor removing means operable to remove a quantity of phosphor material to attain the specific target color, wherein the controller is operable to compare the measured color with the specific target color and in dependence on the comparison to select the quantity of phosphor material to be removed substantially to attain the specific target color.

23. The apparatus according to claim 22, and comprising selecting the pre-selected quantity to ensure that the proportion of light of the second wavelength range is greater than in the specific target color.

24. The apparatus according to claim 22, and further comprising a look-up table for selecting the quantity of phosphor material to be removed.

25. The apparatus according to claim 24, and further comprising operating the at least one light emitting diode a further time;

measuring the color of light emitted by the device and updating the look-up table.

26. The apparatus according to claim 22, wherein the phosphor removing means comprises a laser operable to ablate the selected quantity of phosphor material.

27. The apparatus according to claim 22, wherein when the light emitting device comprises a plurality of light emitting diodes including at least one phosphor material, the controller is operable in dependence on the comparison to remove from a selected number the light emitting diodes a fixed quantity of the phosphor material, the number being selected to substantially to attain the specific target color.

28. Apparatus for fabricating a light emitting device having a specific target color of emitted light, the device comprising at least one light emitting diode operable to emit light of a first wavelength range and first and second phosphor materials which respectively convert at least a part of the light into light of second and third wavelength ranges wherein light emitted by the device comprises the combined light of the first, second and third wavelength ranges, the apparatus comprising:

a first dispenser for depositing a pre-selected quantity of a mixture of the first and second phosphor materials on a light emitting surface of the at least one light emitting diode;

a second dispenser for depositing the first phosphor material;

a third dispenser for depositing the second;

a controller operable to operate the at least one light emitting diode;

light measuring means for measuring the color of light emitted by the device;

wherein the controller is operable to compare the measured color with the specific target color and in dependence on the comparison to deposit using the second and third dispensers selected quantities of the first and second phosphor materials substantially to attain the specific target color.