| US 7,513,669 B2 | ||
| Light source for LCD back-lit displays | ||
| Janet Bee Yin Chua, Penang (Malaysia); and Yue Hoong Lau, Penang (Malaysia) | ||
| Assigned to Avago Technologies General IP (Singapore) Pte. Ltd., Singapore (Singapore) | ||
| Filed on Aug. 01, 2005, as Appl. No. 11/195,200. | ||
| Prior Publication US 2007/0081329 A1, Apr. 12, 2007 | ||
| Int. Cl. F21V 7/04 (2006.01); H01J 1/62 (2006.01) | ||
| U.S. Cl. 362—606 [362/608; 362/609; 362/612; 362/618; 362/627; 313/501; 313/502] | 4 Claims |

| 1. An apparatus comprising:
a light pipe comprising a layer of transparent material having a top surface, a bottom surface, and an edge surface, said
light pipe being positioned to receive said light within a cone of angles through said edge surface such that said light within
said predetermined cone of angles is totally reflected from said top surface, said light pipe comprising features that redirect
some of said light within said cone of angles at angles such that some of said redirected light exits through said top surface;
a light source comprising a plurality of LED dies arranged in an array on a substrate, said substrate being coplanar with
said light pipe, each LED emitting light having an excitation wavelength, said light source emitting light within a cone of
angles, said light source further comprising a reflector adjacent said plurality of LED dies to reflect light from said LED
dies into said edge surface of said light pipe;
an index matching compound between said light source and said light pipe edge surface; and
a light conversion layer overlying said top surface, said light conversion layer converting light of said excitation wavelength
to light in an output spectrum having wavelengths different from said excitation wavelength;
wherein said light conversion layer comprises soluble phosphor compounds dissolved in a transparent medium;
wherein a portion of said light of said excitation wavelength exits from said light conversion layer, said portion being greater
than 10 percent of said light of said excitation wavelength that enters said light conversion layer.
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