Solid state light emitting devices including nonhomogeneous luminophoric particle size layers

• US 8,742,654 B2
• Filed: 02/25/2011
• Issued: 06/03/2014
• Est. Priority Date: 02/25/2011
• Status: Active Grant

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Cabalu, Jasper, Bergmann, Michael John
• Primary Examiner(s): Hollweg, Thomas A
• Application Number:
  US13/035,520
• Publication Number:
  US 20120217865A1
• Time in Patent Office: 1,194 Days
• Field of Search: 313/483, 313/498, 313/501, 313/506, 257/79, 257/98, 257/100
• US Class Current: 313/501
• CPC Class Codes: H01J 1/63 characterised by the luminescent material
• CPC Class Codes: H01J 1/68 with superimposed luminescent layers
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials

Abstract

A light emitting device includes an LED and a layer of luminophoric particles, such as phosphor, that are non-homogeneous in size as a function of distance away from the LED. For example, a first layer of relatively large size phosphor particles may be provided between a second layer of relatively small size phosphor particles and the LED. The large particles can provide high brightness and the small particles can reduce angular color temperature variation in emitted light.

Claims

1. A light emitting device comprising:

a solid state light emitting source; and

a remote layer comprising luminophoric particles having an equivalent particle diameter that decreases with increasing distance away from the solid state light emitting source,

wherein the remote layer is spaced apart from the solid state light emitting source and no other layer comprising luminophoric particles is between the solid state light emitting source and the remote layer, and

wherein the equivalent particle diameter decreases non-monotonically with increasing distance away from the solid state light emitting source.

2. A light emitting device comprising:

a solid state light emitting source; and

a remote layer comprising luminophoric particles having an equivalent particle diameter that decreases with increasing distance away from the solid state light emitting source,

wherein the remote layer is spaced apart from the solid state light emitting source and no other layer comprising luminophoric particles is between the solid state light emitting source and the remote layer, and

wherein the luminophoric particles are a first type of luminophoric particles, the remote layer further comprising a second type of luminophoric particles having an equivalent particle diameter that does not decrease with increasing distance away from the solid state light emitting source.