Light emitting device with phosphor wavelength conversion

• US 8,686,449 B2
• Filed: 05/25/2012
• Issued: 04/01/2014
• Est. Priority Date: 10/17/2007
• Status: Expired due to Fees

• Current Assignee: Intematix Corporation
• Original Assignee: Intematix Corporation
• Inventors: Li, Yi-Qun
• Primary Examiner(s): Toledo, Fernando L
• Assistant Examiner(s): KUSUMAKAR, KAREN M
• Application Number:
  US13/481,565
• Publication Number:
  US 20120299032A1
• Time in Patent Office: 676 Days
• Field of Search: 438 28- 30, 257/89
• US Class Current: 257/89
• CPC Class Codes: F21K 9/232 specially adapted for generating an essentially omnidirectional light distribution, e.g. with a glass bulb
• CPC Class Codes: F21K 9/64 using wavelength conversion means distinct or spaced from the light-generating element, e.g. a remote phosphor layer
• CPC Class Codes: F21V 13/14 the elements being filters or photoluminescent elements, reflectors and refractors
• CPC Class Codes: F21V 3/062 the material being plastics
• CPC Class Codes: F21V 3/12 the coatings comprising photoluminescent substances
• CPC Class Codes: F21V 9/32 characterised by the arrangement of the photoluminescent material
• CPC Class Codes: F21V 9/38 Combination of two or more photoluminescent elements of different materials
• CPC Class Codes: F21Y 2103/10 comprising a linear array of point-like light-generating elements
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: G02B 6/005 provided by one optical element, or plurality thereof, placed on the light output side of the light guide
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02B 6/0073 Light emitting diode [LED]
• CPC Class Codes: H01L 33/50 Wavelength conversion elements

Abstract

A light emitting device comprises a substantially planar light transmissive substrate having a light emitting surface and an opposite surface. The substrate is configured as a light guiding medium. The light emitting device also comprises at least one phosphor material disposed as a layer on the light emitting surface with a plurality of window areas and at least one source of excitation radiation of a first wavelength positioned adjacent to at least one peripheral edge of the substrate. The source is configured to couple excitation radiation into the substrate such that it is waveguided within the substrate by total internal reflection. Additionally, the light emitted by the device from the light emitting surface comprises first wavelength radiation and second, longer wavelength photoluminescent light emitted by the phosphor layer as a result of excitation by the source.

Claims

1. A light emitting device comprising:

a substantially planar light transmissive substrate having a light emitting surface and an opposite surface and wherein the substrate is configured as a light guiding medium;

at least one phosphor material disposed as a layer adjacent to the light emitting surface with a plurality of window areas; and

at least one source of excitation radiation of a first wavelength positioned adjacent to at least one peripheral edge of the substrate,

wherein the source is configured to couple excitation radiation into the substrate such that it is waveguided within the substrate by total internal reflection;

wherein the light emitted by the device from the light emitting surface comprises first wavelength radiation and second, longer wavelength photoluminescent light emitted by the phosphor layer as a result of excitation by the source, and

wherein light of the first wavelength and light of the second wavelength are emitted through the plurality of window areas.

2. The light emitting device of claim 1, wherein excitation radiation is coupled into at least a part of one edge of the substrate.

3. The light emitting device of claim 1, wherein the layer of phosphor material comprises a pattern of regions and wherein the window areas are defined by the gaps between the phosphor material regions.

4. The light emitting device of claim 3, wherein the phosphor material regions are selected from the group consisting of being:

substantially square, substantially circular, substantially elliptical, substantially triangular, substantially rectangular, substantially polygonal and combinations thereof

5. The light emitting device of claim 1, wherein the window areas are selected from the group consisting of being:

substantially square, substantially circular, substantially elliptical, substantially triangular, substantially rectangular, substantially polygonal and combinations thereof.

6. The light emitting device of claim 1, further including a reflecting layer positioned adjacent to at least a portion of the surface of the substrate opposite the light emitting surface.

7. The light emitting device of claim 1, wherein the light emitting surface of the substrate further includes a surface topology configured to promote the emission of light from the light emitting surface.

8. The light emitting device of claim 1, wherein the layer of phosphor material comprises a pattern of at least two different phosphor materials.

9. The light emitting device of claim 1, wherein the second, longer wavelength photoluminescent light emitted by the phosphor layer is selected from the group consisting of green, yellow, orange, and red light.

10. The light emitting device of claim 1, wherein the substrate is selected from the group consisting of an acrylic, a polycarbonate, a polythene and a glass.

11. The light emitting device of claim 1, wherein the at least one excitation source comprises an array of blue light emitting LEDs.

12. The light emitting device of claim 1, and further comprising at least one source of red light that is configured to couple red light into the substrate.

13. The light emitting device of claim 1, wherein the at least one phosphor material is disposed as the layer on the light emitting surface.