Solid state white light emitter and display using same

• US 6,600,175 B1
• Filed: 03/26/1996
• Issued: 07/29/2003
• Est. Priority Date: 03/26/1996
• Status: Expired due to Term

• Current Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Original Assignee: Advanced Technology Materials, Inc. (Entegris Incorporated)
• Inventors: Baretz, Bruce, Tischler, Michael A.
• Primary Examiner(s): JACKSON JR, JEROME
• Application Number:
  US08/621,937
• Time in Patent Office: 2,681 Days
• Field of Search: 257/88, 257/98, 257/99, 257/100
• US Class Current: 257/100
• 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 emitting device, comprising:

at least one single-die semiconductor light-emitting diode (LED) coupleable with a power supply to emit a primary radiation which is the same for each single-die semiconductor LED present in the device, said primary radiation being a relatively shorter wavelength radiation outside the visible white light spectrum; and

a down-converting luminophoric medium arranged in receiving relationship to said primary radiation, and which in exposure to said primary radiation responsively emits radiation at a multiplicity of wavelengths and in the visible white light spectrum, with said radiation of said multiplicity of wavelengths mixing to produce a white light output.

2. A light-emitting device according to claim 1, comprising a two-lead array of single-die semiconductor LEDs.

3. A light-emitting device, comprising:

a semiconductor laser coupleable with a power supply to emit a primary radiation having a relatively shorter wavelength outside the visible light spectrum; and

a down-converting luminophoric medium arranged in receiving relationship to said primary radiation, and which in exposure to said primary radiation responsively emits polychromatic radiation in the visible light spectrum, with different wavelengths of said polychromatic radiation mixing to produce a white light output.

4. A light-emitting device according to claim 3, wherein said semiconductor laser includes an active material selected from the group consisting of III-V alloys and II-VI alloys.

5. A light-emitting device, comprising:

at least one single-die semiconductor light-emitting diode (LED) coupleable with a power supply to emit a primary radiation which is the same for each single-die LED present in the device, said primary radiation being a relatively shorter wavelength radiation; and

a down-converting luminophoric medium arranged in receiving relationship to said primary radiation, and which in exposure to said primary radiation, is excited to responsively emit a secondary, relatively longer wavelength, polychromatic radiation, with separate wavelengths of said polychromatic radiation mixing to produce a white light output.

6. A light-emitting device according to claim 5, wherein said at least one single-die semiconductor LED and said down-converting luminophoric medium are associated with one another in a unitary structure.

7. A light-emitting device according to claim 5, further comprising a housing member formed of a light-transmissive material, said housing member defining therewithin an interior volume, with said at least one single-die semiconductor LED and said down-converting luminophoric medium being disposed in said interior volume.

8. A light-emitting device according to claim 7, further comprising first and second electrical contacts extending through said housing member and coupleable to a power supply which is constructed and arranged for imposing a voltage on said at least one single-die semiconductor LED, to induce emission of said primary radiation.

9. A light-emitting device according to claim 8, wherein said down-converting luminophoric medium is contiguously arranged in said interior volume of said housing in relation to said at least one single-die semiconductor LED.

10. A light-emitting device according to claim 8, wherein. said down-converting luminophoric medium is arranged in spaced relation to said at least one single-die semiconductor LED in said interior volume of said housing.

11. A light-emitting device according to claim 5, wherein each single-die semiconductor LED present in the device includes a substrate and a multilayer device structure, and wherein said substrate comprises silicon carbide.

12. A light-emitting device according to claim 5, wherein each single-die semiconductor LED present in the device includes a substrate and a multilayer device structure, and wherein said substrate comprises a material selected from the group consisting of sapphire, SiC, and InGaAIN.

13. A light-emitting device according to claim 12, wherein said multilayer device structure includes layers selected from the group consisting of silicon carbide, aluminum nitride, gallium nitride, gallium phosphide, germanium carbide, indium nitride, and their mixtures and alloys.

14. A light-emitting device according to claim 5, wherein said primary radiation emitted by said at least one single-die semiconductor LED comprises ultraviolet light and said down-converting luminophoric medium comprises a material selected from the group consisting of:

perylene tetracarboxylic diimide fluorescent dye;

napthalene tetracarboxylic diimide fluorescent dye;

9,10-bis(phenylethynyl)anthracene fluorescent dye;

substituted 9,10-diphenylanthracene dyes; and

tetraphenylbutadiene (TPB) fluorescent dye.

15. A light-emitting device according to claim 5, wherein said primary radiation emitted by said at least one single-die semiconductor LED comprises ultraviolet light and said down-converting luminophoric medium comprises a napthalene tetracarboxylic diimide fluorescent dye, to provide blue light emission, and substituted perylene tetracarboxylic diimide dyes to provide green (or green-yellow) and red light emissions.

16. A light-emitting device according to claim 5, wherein said primary radiation emitted by said at least one single-die semiconductor LED comprises blue light and said down-converting luminophoric medium comprises a material selected from the group consisting of:

a napthalene tetracarboxylic diimide fluorescent dye, to provide greater luminosity of the color hue blue;

a 9,10-diphenylanthracence, to provide greater luminosity of the color hue blue;

a substituted 9,10-diphenylanthracence, to provide greater luminosity of the color hue blue;

1,1,4,4-tetraphenylbutadiene (TPB) to provide greater luminosity of the color hue blue;

a perylenetetracarboxylic diimide to provide greater luminosity of the color hues green and red;

a perylenetetracarboxylic diimide to provide greater luminosity of the color hue red, and 9,10-bis(phenylethynyl)athracence to provide greater luminosity of the color hue green;

a perylenetetracarboxylic diimide to provide greater luminosity of the color hue red[,] ; and

halogen-substituted 9,10-bis(phenylethynyl)athracence to provide greater luminosity of the color hue green.

17. A light-emitting device according to claim 5, wherein said down-converting luminophoric medium comprises a perylenetetracarboxylic diimide and a napthalenetetracarboxylic diimide, and wherein each perylenetetracarboxylic diimide is formulated with a concentration between 10⁻

3 and 5 mole percent, and wherein each napthalenetetracarboxylic diimide is formulated with a concentration between 10<sup>−

2</sup> and 10 mole percent.

18. A light-emitting device according to claim 5, wherein said primary radiation is down-converted to at least two distinct and separable regions of red and/or green and/or blue light, with said at least two regions of red and/or green and/or blue light mixing to produce a different colored output.

19. A light-emitting device according to claim 5, wherein said primary radiation is down-converted to between 2 and 10 distinct and separable regions of white light and light of the color hue red, green or blue light.

20. A display according to claim 18, further comprising a user-responsive controller for selectively illuminating specific ones of said light-emitting devices.

21. A light-emitting device according to claim 5, wherein each single-die semiconductor LED present in the device comprises a single:

die, two-lead semiconductor LED.

22. A light-emitting device according to claim 5, wherein each single-die semiconductor LED present in the device comprises a single-die two-lead semiconductor LED.

23. A light-emitting device according to claim 5, comprising a two-lead array of single-die semiconductor LEDs.

24. A liquid crystal display, including:

a backlight member including a multiplicity of light-emitting devices, each light-emitting device comprising;

at least one single-die semiconductor light-emitting diode (LED) coupleable with a power supply to emit a primary radiation which is the same for each single-die LED present in the device, said primary radiation being a relatively shorter wavelength radiation, and

a down-converting luminophoric medium arranged in receiving relationship to said primary radiation, and which in exposure to said primary radiation responsively emits a secondary, relatively longer wavelength, polychromatic radiation, with separate wavelengths of said polychromatic radiation mixing to produce a white light output.

25. A display, including:

a viewable panel including a multiplicity of light-emitting devices, each light-emitting device comprising;

at least one single-die semiconductor light-emitting diode (LED) coupleable with a power supply to emit a primary radiation which is the same for each single-die semiconductor LED present in the device, said primary radiation being a relatively shorter wavelength radiation, and

a down-converting luminophoric medium arranged in receiving relationship to said primary radiation, and which in exposure to said primary radiation responsively emits a secondary, relatively longer wavelength, polychromatic radiation, with separate wavelengths of said polychromatic radiation mixing to produce a white light output.

26. A light-emission device, comprising

a single-die, two-lead semiconductor light-emitting diode emitting radiation;

and

a recipient down-converting luminophoric medium for down-converting the radiation emitted by the light-emitting diode, to a polychromatic white light.