LIGHT EMITTING DEVICE

• US 20160139328A1
• Filed: 06/19/2014
• Published: 05/19/2016
• Est. Priority Date: 06/20/2013
• Status: Active Grant

• Current Assignee: Lumencor, Inc.
• Original Assignee: Koninklijke Philips N.V.
• Inventors: HIKMET, Rifat Ata Mustafa, VAN BOMMEL, Ties
• Granted Patent: US 10,222,540 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: F21S 41/13 Ultraviolet light; Infrared light
• CPC Class Codes: F21S 41/14 characterised by the type of light source
• CPC Class Codes: F21S 41/153 arranged in a matrix
• CPC Class Codes: F21S 41/155 Surface emitters, e.g. organic light emitting diodes [OLED]
• CPC Class Codes: F21S 41/16 Laser light sources
• CPC Class Codes: F21S 41/176 Light sources where the light is generated by photoluminescent material spaced from a primary light generating element
• CPC Class Codes: F21S 41/24 Light guides
• CPC Class Codes: F21S 41/285 Refractors, transparent cover plates, light guides or filters not provided in groups F21S41/24 - F21S41/2805
• CPC Class Codes: F21S 43/14 Light emitting diodes [LED]
• CPC Class Codes: F21S 43/145 Surface emitters, e.g. organic light emitting diodes [OLED]
• CPC Class Codes: F21S 43/237 rod-shaped
• CPC Class Codes: F21S 43/239 plate-shaped
• CPC Class Codes: F21S 43/243 emitting light from one or more of its extremities
• CPC Class Codes: F21S 43/249 with two or more light sources being coupled into the light guide
• CPC Class Codes: F21S 43/255 Filters
• CPC Class Codes: F21S 45/47 Passive cooling, e.g. using fins, thermal conductive elements or openings
• CPC Class Codes: G02B 6/0003 the light guides being doped with fluorescent agents
• CPC Class Codes: G02B 6/0026 Wavelength selective element, sheet or layer, e.g. filter or grating
• CPC Class Codes: G02B 6/003 Lens or lenticular sheet or layer
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0035 : provided on the surface of the light guide or in the bulk of it
• 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 6/0065 : Manufacturing aspects; Material aspects
• 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: G02B 6/0085 : Means for removing heat created by the light source from the package heat extraction or cooling elements for semiconductor light sources in general H01L33/64
• CPC Class Codes: G03B 21/16 : Cooling; Preventing overheating
• CPC Class Codes: G03B 21/204 : using secondary light emission, e.g. luminescence or fluorescence using different colours G03B33/00; if related to video signals H04N9/3197

Abstract

A light emitting device (1) is provided comprising a light source (2) adapted for, in operation, emitting light (13) with a first spectral distribution, a first luminescent light guide (4) comprising a first light input surface (41) and a first light exit surface (42) extending at an angle different from zero to one another, and being adapted for receiving the light (13) with the first spectral distribution at the first light input surface (41), converting the light (13) with the first spectral distribution to light (14) with a second spectral distribution, guiding the light (14) with the second spectral distribution to the first light exit surface (42) and coupling the light (14) with the second spectral distribution out of the first light exit surface (42), and a first transparent heat sink element (3) arranged adjacent to at least one surface of the first luminescent light guide (4) and in the optical path between the light source (2) and the first luminescent light guide (4), the at least one surface being different from the light exit surface (42), wherein the first transparent heat sink element (3) is adapted for redirecting light by means of any one of refraction and diffraction.

Claims

1. A light emitting device comprising:

a light source adapted for, in operation, emitting light with a first spectral distribution,

a first luminescent light guide comprising a first light input surface and a first light exit surface extending at an angle different from zero to one another,

and the first luminescent light guide being adapted for receiving the light with the first spectral distribution at the first light input surface, converting at least a part of the light with the first spectral distribution to light with a second spectral distribution, guiding the light with the second spectral distribution to the first light exit surface and coupling the light with the second spectral distribution out of the first light exit surface, and

a first transparent heat sink element arranged adjacent to at least one surface of the first luminescent light guide and in the optical path between the light source and the first luminescent light guide, the at least one surface being different from the light exit surface, wherein the first transparent heat sink element is adapted for redirecting light by means of any one of refraction and diffraction.

2. The light emitting device according to claim 1, wherein the first transparent heat sink element is made of a material having a thermal conductivity being larger than 1 W/(K*m).

3. The light emitting device according to claim 1, wherein one or more surfaces of the first luminescent light guide other than the first light input surface and the first light exit surface are provided with a reflective layer.

4. The light emitting device according to claim 1, wherein the first luminescent light guide is made of a luminescent material chosen from a group comprising luminescent garnets, luminescent doped garnets, transparent luminescent materials, light concentrating luminescent materials and combinations thereof.

5. The light emitting device according to claim 1, wherein a gap is provided between the first transparent heat sink element and the first luminescent light guide.

6. The light emitting device according to claim 5, wherein the gap between the first transparent heat sink element and the first luminescent light guide comprises any one or more of air and an optical adhesive.

7. The light emitting device according to claim 1, wherein the first transparent heat sink element comprises any one or more of a coupling structure, which is arranged on or at a surface extending parallel to and opposite the first light exit surface, and a scattering material.

8. The light emitting device according to claim 1, wherein the first transparent heat sink element has a trapezoid cross-sectional shape having two oppositely tapered side surfaces.

9. The light emitting device according to claim 1, wherein the first transparent heat sink element extends adjacent to at least two surfaces of the first luminescent light guide.

10. The light emitting device according to claim 9, wherein the first transparent heat sink element is extending adjacent four sides of the first luminescent light guide and has a triangular cross-sectional shape and in which light sources are provided on all three sides of the first transparent heat sink element.

11. The light emitting device according to claim 1, wherein the transparent material of the first transparent heat sink element is chosen from the group comprising sapphire, undoped transparent garnets, such as YAG, LuAG, glass, quartz, ceramic materials such as alumina, luminescent materials, phosphors and combinations thereof.

12. The light emitting device according to claim 1, further comprising a second transparent heat sink element arranged adjacent a surface of the first luminescent light guide which is facing away from said first transparent heat sink element.

13. The light emitting device according to claim 1, wherein the light source is arranged on a base, the base being a non-transparent heat sink.

14. The light emitting device according claim 1, wherein a non-transparent heat sink is provided arranged in any one or more of physical and thermal contact with any one or more of the first transparent heat sink element and the first luminescent light guide.

15. A projector, a lamp or a luminaire comprising a light emitting device according to claim 1.