Solid state white light emitter and display using same

• US 7,943,945 B2
• Filed: 11/01/2005
• Issued: 05/17/2011
• Est. Priority Date: 03/26/1996
• Status: Expired due to Fees

• Current Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Baretz, Bruce, Tischler, Michael A.
• Primary Examiner(s): Fahmy, Wael M
• Assistant Examiner(s): Kalam, Abul
• Application Number:
  US11/264,124
• Publication Number:
  US 20060049416A1
• Time in Patent Office: 2,023 Days
• Field of Search: 257/79, 257 81- 82, 257 94- 95, 257/88, 257 98-100, 257/E33.059, 257/E33.061
• US Class Current: 257/98
• CPC Class Codes: G09F 13/04 Signs, boards or panels, illuminated from behind the insignia
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2224/48139 with an intermediate bond, e.g. continuous wire daisy chain
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• 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 2924/00014 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 33/50 Wavelength conversion elements
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials
• CPC Class Codes: Y02E 10/52 PV systems with concentrators

Abstract

A light emitting assembly comprising a solid state device coupleable with a power supply constructed and arranged to power the solid state device to emit from the solid state device a first, relatively shorter wavelength radiation, and a down-converting luminophoric medium arranged in receiving relationship to said first, relatively shorter wavelength radiation, and which in exposure to said first, relatively shorter wavelength radiation, is excited to responsively emit second, relatively longer wavelength radiation. In a specific embodiment, monochromatic blue or UV light output from a light-emitting diode is down-converted to white light by packaging the diode with fluorescent organic and/or inorganic fluorescers and phosphors in a polymeric matrix.

Claims

1. A light emission assembly, comprising at least one light emission device including an LED emitting radiation with an emission maximum in a spectral range of the blue to ultraviolet spectrum, and a luminophoric medium impinged by radiation emitted from the LED and responsively emitting radiation in a range of wavelengths, which combine to produce a white light output from the light emission device, wherein said light emission device comprises at least one of the characteristics of:

(i) the luminophoric medium being coated on and/or dispersed in light-transmissive material enclosing the LED; and

(ii) the luminophoric medium being in contact with an emitting face of the LED.

2. The light emission assembly of claim 1, comprising a circuit including a power supply coupled to said at least one light emission device.

3. The light emission assembly of claim 1, comprising a multiplicity of said light emission devices.

4. The light emission assembly of claim 3, wherein said light emission devices are arranged in an array.

5. The light emission assembly of claim 3, comprising a display in which each of said light emission devices constitutes a pixel element of the display.

6. The light emission assembly of claim 5, wherein each of said light emission devices is adapted to be selectively illuminated so that the display produces messages.

7. The light emission assembly of claim 5, wherein each of said light emission devices is adapted to be selectively illuminated so that the display produces designs.

8. The light emission assembly of claim 3, wherein each of said light emission devices are connected to electrical circuitry.

9. The light emission assembly of claim 8, further comprising a controller adapted to selectively illuminate individual ones of the multiplicity of said light emission devices, in response to input to the controller.

10. The light emission assembly of claim 3, comprising a back lighting assembly including said multiplicity of said light emission devices.

11. The light emission assembly of claim 10, further comprising a display adapted to be back lit by said back lighting assembly.

12. The light emission assembly of claim 11, wherein said display comprises a liquid crystal display.

13. The light emission assembly of claim 1, comprising an enclosure in which said at least one light emission device is disposed.

14. The light emission assembly of claim 13, wherein said enclosure includes a light-transmissive structure.

15. The light emission assembly of claim 13, including a multiplicity of said LEDs.

16. The light emission assembly of claim 15, wherein said LEDs comprise LEDs mounted on a conductive substrate in said enclosure, in series relationship to one another.

17. The light emission assembly of claim 1, wherein the luminophoric medium comprises phosphor material.

18. The light emission assembly of claim 1, wherein the luminophoric medium comprises a material responsively emitting radiation in at least one of the green spectrum and the yellow spectrum.

19. The light emission assembly of claim 1, wherein said LED comprises a blue light LED.

20. The light emission assembly of claim 1, wherein said LED comprises a GaN LED energizable to emit blue light having an emission maximum at approximately 450 nm.

21. The light emission assembly of claim 1, wherein said white light output comprises primary radiation emission from the LED and secondary radiation emission from the luminophoric medium.

22. The light emission assembly of claim 1, wherein said at least one light emission device comprises an LED including a material selected from the group consisting of:

gallium nitride;

indium gallium nitride;

aluminum gallium indium nitride;

aluminum gallium nitride;

silicon carbide; and

zinc selenide.

23. The light emission assembly of claim 1, wherein the luminophoric medium comprises a material responsively emitting radiation in at least red, yellow and green spectral regions.

24. The light emission assembly of claim 1, wherein the luminophoric medium is coated on and/or dispersed in light-transmissive material enclosing the LED.

25. The light emission assembly of claim 1, wherein the luminophoric medium is coated on an interior surface of the light-transmissive material enclosing the LED.

26. The light emission assembly of claim 1, wherein the luminophoric medium is coated on an exterior surface of the light-transmissive material enclosing the LED.

27. The light emission assembly of claim 1, wherein the luminophoric medium is dispersed in the light-transmissive material enclosing the LED.

28. The light emission assembly of claim 1, wherein a layer of the luminophoric medium is in contact with an emitting face of the LED.

29. A light emission assembly, comprising at least one light emission device including an LED emitting radiation with an emission maximum in a spectral range of the blue to ultraviolet spectrum, and a luminophoric medium impinged by radiation emitted from the LED and responsively emitting radiation in a range of wavelengths, which combine to produce a white light output from the light emission device, wherein said light emission device comprises the luminophoric medium being coated on and/or dispersed in light-transmissive material forming a wall of an enclosure in which the LED is disposed.

30. A light emission assembly, comprising at least one light emission device including a GaN-based LED die emitting blue light, and a luminophoric medium impinged by blue light emitted from the LED die and responsively emitting radiation in a range of wavelengths, which combine to produce a white light output from the light emission device, wherein the luminophoric medium comprises phosphor material, and wherein (i) a layer of the phosphor material is on an interior or exterior surface of a light-transmissive enclosure defining an interior volume in which the LED die is mounted, and/or (ii) the phosphor material is contiguously arranged about an emitting surface of the LED die, and/or (iii) the phosphor material is in a polymeric matrix overlying the LED die.

31. The light emission assembly of claim 30, wherein a layer of the phosphor material is on an interior surface of a light-transmissive enclosure defining an interior volume in which the LED die is mounted.

32. The light emission assembly of claim 30, wherein a layer of the phosphor material is on an exterior surface of a light-transmissive enclosure defining an interior volume in which the LED die is mounted.

33. The light emission assembly of claim 30, wherein the phosphor material is contiguously arranged about an emitting surface of the LED die.

34. The light emission assembly of claim 30, wherein the phosphor material is in a polymeric matrix overlying the LED die.

35. The light emission assembly of claim 30, wherein the phosphor material comprises inorganic phosphor material.

36. The light emission assembly of claim 30, wherein the phosphor material comprises a mixture of phosphors.

37. The light emission assembly of claim 30, wherein the phosphor material has a spectral overlap with said blue light.

38. The light emission assembly of claim 30, wherein said LED die comprises an emitting surface in spaced-apart relationship to the phosphor material, without intervening structure between the emitting surface and the phosphor material.

39. The light emission assembly of claim 30, wherein each light emission device comprises circuit-forming elements cooperative with said LED die.

40. The light emission assembly of claim 30, comprising a light-transmissive wall bounding an enclosed interior volume in which the LED die is mounted.

41. The light emission assembly of claim 40, wherein the light-transmissive wall comprises a cylindrical sidewall portion and a hemispherical top portion.