US 7,560,859 B2
Fluorescent material having two layer structure and light emitting apparatus employing the same
Hajime Saito, Nara (Japan); Tatsuya Morioka, Ikoma (Japan); Shizuo Fujita, 4-7-21, Sakuragaoka, Seika-cho, Soraku-gun, Kyoto 619-0232 (Japan); Yoichi Kawakami, 665-6, Shimogasa-cho, Kusatsu-shi, Shiga 525-0029 (Japan); Mitsuru Funato, 48-3, Katsura Hitsujisaru-cho, Nishigyo-ku, Kyoto-Shi, Kyoto 615-8084 (Japan); Masafumi Harada, 5-730-1143, Gakuendaiwa-cho, Nara-shi, Nara 631-0041 (Japan); and Shigeo Fujita, Kyoto (Japan); Kyoko Fujita, legal representative
Assigned to Shizuo Fujita, Kyoto (Japan); Yoichi Kawakami, Kusatsu-Shiga (Japan); Mitsuru Funato, Kyoto (Japan); Masafumi Harada, Nara (Japan); and Sharp Kabushiki Kaisha, Osaka (Japan)
Filed on Sep. 13, 2005, as Appl. No. 11/224,131.
Claims priority of application No. 2004-266939 (JP), filed on Sep. 14, 2004.
Prior Publication US 2006/0158089 A1, Jul. 20, 2006
Int. Cl. H01J 1/62 (2006.01); C09K 11/77 (2006.01)
U.S. Cl. 313—498  [313/499; 252/301.4  R; 977/774] 18 Claims
OG exemplary drawing
 
10. A light-emitting apparatus comprising a red fluorescent material and a green fluorescent material homogeneously dispersed in a medium for presenting white emission as a whole by absorbing blue excitation light with said red fluorescent material and said green fluorescent material and generating secondary light, wherein
said red fluorescent material comprises a two-layer structure of a core of a particle size having a quantum effect and a shell covering said core, wherein particle size of the core and composition ratio of the fluorescent material are such that the ground state energy of said core is in the range of 1.85 to 2.05 eV, and the high order energy of said core is not in the ranges of 2.3 to 2.5 eV and 2.65 to 2.8 eV, and
said green fluorescent material comprises a two-layer structure of a core of a particle size having a quantum effect and a shell covering said core, wherein praticle size of the core and composition ratio of the fluorescent material are such that the ground state energy of said core is in the range of 2.3 to 2.5 eV, and the high order energy of said core is not in the range of 2.65 to 2.8 eV.