Phosphor, light emitting apparatus, and liquid crystal display apparatus using the same

1. A divalent europium-activated oxynitride green light emitting phosphor which is a β-type SiAlON substantially represented by a general formula (A): Eu a Si b Al c O d N e (where a, b, c, d, and e are numbers satisfying 0.005≦a≦0.4, b+c=12, and d+e=16), and having an average particle size (d1) (determined by an air permeability method) of 9 to 16 μm, a median diameter (50% D) in particle size distribution of 12.5 to 35 μm, and 50% D/d1 of 1.4 to 2.2.

2. The phosphor according to claim 1 , having an absorptance at 600 nm of not more than 8.0%.

3. The phosphor according to claim 2 , having d1 satisfying 10 μm≦d1≦13 μm, 50% D/d1 of 1.6 to 2.0, and an absorptance at 600 nm of not more than 7.0%.

4. The phosphor according to claim 2 , wherein “c” satisfies c≧0.3 in the general formula (A).

5. The phosphor according to claim 2 , wherein “a” satisfies 0.0≦a≦0.2 in the general formula (A).

6. A light emitting apparatus, comprising:

a light emitting element which is a gallium nitride-based semiconductor emitting primary light having a peak wavelength of 430 to 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 the primary light,

said light converter including a divalent europium-activated oxynitride green light emitting phosphor which is a β-type SiAlON substantially represented by a general formula (A): Eu a Si b Al c O d N e (where a, b, c, d, and e are numbers satisfying 0.005≦a≦0.4, b+c=12, and d+e=16), and having an average particle size (d1) (determined by an air permeability method) of 9 to 16 μm, a median diameter (50% D) in particle size distribution of 12.5 to 35 μm, and 50% D/d1 of 1.4 to 2.2.

7. The light emitting apparatus according to claim 6 , wherein the divalent europium-activated oxynitride green light emitting phosphor which is said β-type SiAlON has an absorptance at 600 nm of not more than 8.0%.

8. The light emitting apparatus according to claim 7 , wherein the divalent europium-activated oxynitride green light emitting phosphor which is said β-type SiAlON has d1 satisfying 10 μm≦d1≦13 μm, 50% D/d1 of 1.6 to 2.0, and an absorptance at 600 nm of not more than 7.0%.

9. The light emitting apparatus according to claim 7 , wherein “c” satisfies c≧0.3 in the general formula (A).

10. The light emitting apparatus according to claim 7 , wherein “a” satisfies 0.0≦a≦0.2 in the general formula (A).

11. The light emitting apparatus according to claim 7 , including, in the light converter, a divalent europium-activated nitride red light emitting phosphor substantially represented by a general formula (B): (MI 1-x Eu x )MIISiN 3 (where MI indicates at least one alkaline-earth metal element selected from Mg, Ca, Sr, and Ba, MII indicates at least one trivalent metal element selected from Al, Ga, In, Sc, Y, La, Gd, and Lu, and x is a number satisfying 0.001≦x≦0.10).

12. The light emitting apparatus according to claim 11 , wherein MII in the general formula (B) is at least one element selected from Al, Ga, and In.

13. A back-light light source apparatus including a plurality of the light emitting apparatuses according to claim 7 as point light sources.

14. A liquid crystal display apparatus, comprising:

a liquid crystal panel; and

the back-light light source apparatus according to claim 13 disposed on a back surface of the liquid crystal panel.