Phosphor particle group and light emitting apparatus using the same
View Patent ↗Provided is a phosphor particle group of divalent europium-activated oxynitride green light emitting phosphor particles each of which is a β-type SiAlON substantially represented by a general formula: EuaSibAlcOdNe, where 0.005≦a≦0.4, b+c=12, d+e=16, wherein 60% or more of the phosphor particle group is composed of the phosphor particles in which a value obtained by dividing a longer particle diameter by a shorter particle diameter is greater than 1.0 and not greater than 3.0. A high-efficiency and stable light emitting apparatus using a β-type SiAlON, which includes a light converter using the phosphor particle group, and a phosphor particle group therefor are also provided.
1. A light emitting apparatus comprising: a light emitting element of a gallium nitride-based semiconductor emitting primary light having a peak wavelength of 430-480 nm; and a light converter absorbing a part of said primary light to emit secondary light having a wavelength longer than a wavelength of said primary light,
said light converter including a phosphor particle group of divalent europium-activated oxynitride green light emitting phosphors each of which is a β-type SiAlON substantially represented by a general formula:
Eu a Si b Al c O d N e ,
where 0.005≦a≦0.4, b+c=12, d+e=16,
the light converter further comprising phosphor particles of a divalent europium-activated nitride red light emitting phosphor expressed by a general formula (MI 1-f Eu f )MIISiN 3 , wherein MI is an alkaline-earth metal selected from the groups consisting of Mg, Ca, Sr and Ba; and MII is a trivalent metallic element selected from the group consisting of Al, Ga, In, Sc, Y, La, Gd and Lu; and 0.001<f<0.10,
said phosphor particle group consisting of columnar phosphor particles in which a value obtained by dividing a longer particle diameter by a shorter particle diameter is greater than 1.0 and not greater than 3.0.
2. The light emitting apparatus according to claim 1 , wherein a median diameter of the phosphor particle group is in a range of 6-20 μm.
3. The light emitting apparatus according to claim 1 , wherein the phosphor particle group is dispersed finely in the light converter.