Apparatus for producing a spectrally-shifted light output from a light emitting device utilizing thin-film luminescent layers

• US 20040173806A1
• Filed: 02/26/2003
• Published: 09/09/2004
• Est. Priority Date: 02/26/2003
• Status: Active Grant

• Current Assignee: Document Security Systems, Inc.
• Original Assignee: Avago Technologies ECBU IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Chua, Bee Yin Janet
• Granted Patent: US 7,423,296 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil

Abstract

A lighting device provides a spectrally-shifted light output from a light source. The lighting device includes a semiconductor light emitting device providing a source light and a first thin-film luminescent material layer coating a surface of the semiconductor light emitting device. The first thin-film luminescent material layer includes a luminescent material that emits an emitted light in response to the source light. The first thin-film luminescent material layer has a specific and consistent thickness and specific and consistent density of luminescent particles. The emitted light includes a first luminescent material emitted light when the luminescent material completely absorbs the source light. The emitted light includes a first composite light when the first luminescent material absorbs less than all of the source light. The device may further include a second thin-film luminescent layer coating the first thin-film luminescent layer.

Claims

1. A lighting device, comprising:

a semiconductor light emitting device providing a source light; and

a first thin-film luminescent material layer coating a surface of the semiconductor light emitting device, the first thin-film luminescent material layer including a luminescent material emitting an emitted light in response to the source light, the first thin-film luminescent material layer having a specific and consistent thickness and specific and consistent density of luminescent particles.

2. The lighting device of claim 1, wherein the emitted light comprises:

a first luminescent material emitted light when the luminescent material completely absorbs the source light; and

a first composite light when the luminescent material absorbs less than all of the source light.

3. The lighting device of claim 1, further comprising:

a second thin-film luminescent material layer coating a surface of the first thin-film luminescent material layer, the second thin-film luminescent material layer including luminescent material emitting an emitted light in response to the emitted light from the first thin film luminescent material layer, the second thin-film luminescent material layer having a specific and consistent thickness and specific and consistent density of luminescent particles.

4. The lighting device of claim 3, further comprising:

a third thin-film luminescent material layer coating a surface of the second thin-film luminescent material layer, the third thin-film luminescent material layer including a luminescent material emitting an emitted light in response to the emitted light emitted from the second thin-film luminescent material layer, the third thin-film luminescent material layer having a specific and consistent thickness and specific and consistent density of luminescent particles.

5. The lighting device of claim 1, additionally comprising a package in which the light emitting device is mounted.

6. The lighting device of claim 1, wherein the package is selected from the group consisting of:

a reflector cup package, a surface mountable package, and a through-hole package.

7. The lighting device of claim 1, wherein the luminescent material comprises:

at least one phosphor.

8. The lighting device of claim 1, wherein the thin-film luminescent material layer is deposited onto an exposed surface of the semiconductor light emitting device by a method selected from the group consisting of:

spraying, rolling, dipping, printing, fluidizing, and electrophoretic deposition.

9. A process for fabricating a lighting device, the process comprising:

providing a semiconductor light emitting device operable to provide a source light;

providing a first luminescent material; and

coating a surface of the semiconductor light emitting device with a thin layer of first luminescent material, the thin layer of first luminescent material having a specific and consistent thickness and specific and consistent density of luminescent particles.

10. The process of claim 9, further comprising:

providing a second luminescent material;

coating a surface of the thin layer of first luminescent material with a thin layer of second luminescent material, the thin layer of second luminescent material having a specific and consistent thickness and specific and consistent density of luminescent particles.

11. The process of claim 10, further comprising:

providing a third luminescent material;

coating a surface of the thin layer of second luminescent material with a thin layer of third luminescent material, the thin layer of third luminescent material having a specific and consistent thickness and specific and consistent density of luminescent particles.

12. The process of claim 9, wherein the luminescent material comprises:

at least one phosphor.

13. The process of claim 9, additionally comprising mounting the semiconductor light emitting device in a package.

14. The process of claim 13, wherein the package is selected from the group consisting of:

a reflector cup package, a surface mountable package, and a through-hole package.

15. A method for providing a spectrally-shifted light output, the method comprising:

providing a semiconductor light emitting device, the semiconductor light emitting device including a first thin-film luminescent material layer, the first thin-film luminescent material layer having a specific and consistent thickness and specific and consistent density of luminescent particles coating a surface of the light emitting device;

generating a source light using the semiconductor light emitting device;

absorbing at least part of the source light within the first thin-film luminescent material layer; and

emitting a first emitted light from the first thin-film luminescent material layer in response to the absorbed source light.

16. The method of claim 15, wherein the first light output comprises:

a first luminescent material emitted light when the thin-film luminescent layer completely absorbs the source light; and

a first composite light when the thin-film luminescent layer absorbs less than all of the source light.

17. The method of claim 15, wherein:

providing a semiconductor light emitting device, the semiconductor light emitting device additionally includes a second thin-film luminescent material layer coating the first thin-film luminescent material layer; and

the method additionally comprises;

absorbing at least part of the first emitted light within the second thin-film luminescent material layer, the second thin-film luminescent material layer having a specific and consistent thickness and density of luminescent particles; and

emitting a second emitted light from the second thin-film luminescent material layer in response to the absorbed first emitted light.

18. The method of claim 17, further comprising:

providing a semiconductor light emitting device, the semiconductor light emitting device additionally includes a third thin-film luminescent layer coating the second thin-film luminescent material layer; and

the method additionally comprises

absorbing at least part of the second emitted light within the third thin-film luminescent material layer, the third thin-film luminescent material layer having a specific and consistent thickness and density of luminescent particles; and

emitting a third emitted light from the third thin-film luminescent material layer in response to the absorbed second emitted light.

19. The method of claim 15, wherein producing the first emitted light includes the first luminescent material photoluminescing responsive to the absorbed source light.

20. The method of claim 15, wherein the luminescent material comprises:

at least one phosphor.