Patent ID: 8729788

Claim:
A light-emitting device, comprising: a light-emitting element for emitting primary light; and a wavelength conversion unit for absorbing part of the primary light and emitting secondary lights having wavelengths longer than a wavelength of the primary light, wherein said wavelength conversion unit includes plural kinds of phosphors having different emission peak wavelengths and different median diameters that are in the order of several microns, the different median diameters are adjusted so that the plural kinds of phosphors have different settling speeds, the plural kinds of phosphors include a red phosphor for emitting red light and a green phosphor for emitting green light, and a concentration of the red phosphor adjacent the light-emitting element is higher than a concentration of the green phosphor adjacent the light-emitting element, and wherein said red phosphor for emitting red light includes a divalent europium-activated nitride phosphor represented by (MIII 1-j ,Eu j )MIVSiN 3 , where MIII represents at least one kind of element selected from Mg, Ca, Sr and Ba, MIV represents at least one kind of element selected from Al, Ga, In, Sc, Y, La, Gd and Lu, and j represents a number satisfying 0.001≦j≦0.05; and said green phosphor for emitting green light includes at least one kind selected from a divalent europium-manganese co-activated aluminate phosphor represented by a(M2,Eu e ,Mn f )O.bAl 2 O 3 , a divalent europium-activated silicate phosphor represented by 2(M1 1-g ,Eu g )O.SiO 2 , and a trivalent cerium-activated silicate phosphor represented by MI 3 (MII 1-h ,Ce h ) 2 (SiO 4 ) 3 , where M2 represents at least one kind of element selected from Mg, Ca, Sr, Ba and Zn; a, b, e, and f represent numbers satisfying a>0, b>0, 0.1≦a/b≦1.0, and 0.3≦f/e≦5.0; M1 represents at least one kind of element selected from Mg, Ca, Sr and Ba; g represents a number satisfying 0.005≦g≦0.10; MI represents at least one kind of element selected from Mg, Ca, Sr and Ba; MII represents at least one kind of element selected from Al, Ga, In, Sc, Y, La, Gd and Lu; and h represents a number satisfying 0.005≦h≦0.5.