Coated phosphor filler and a method of forming the coated phosphor filler
An improved coated phosphor filler for an optical device includes a plurality of individual phosphor filler particles, and a coating layer having a plastic substance coated on each of the phosphor filler particles.
1. A coated phosphor filler, comprising:
a plurality of individual phosphor filler particles; and
a coating layer coated on the phosphor filler particles, wherein the coating layer comprises a plastic substance, wherein the phosphor filler particles are unstable phosphor compound particles coated with a moisture-proof barrier film, the coating layer being provided on the outer surface of said barrier film, wherein the thickness of the coating layer is at least twice the thickness of said barrier film.
2. The coated phosphor filler according to claim 1 , wherein the plastic substance comprises an optically transparent epoxy composition.
3. The coated phosphor filler according to claim 1 , wherein the phosphor compound particles comprise at least one of the components SrGa 2 S 4 :Eu 2+ , SrS:Eu 2+ , (Sr,Ca)S:Eu 2+ , and ZnS:Ag.
4. The coated phosphor filler according to claim 1 , wherein said barrier film is formed of an inorganic passivation material.
5. The coated phosphor filler according to claim 4 , wherein said inorganic passivation material includes a material selected from the group consisting of aluminum oxide, silicon monoxide, zinc sulphide and silicon nitride.
6. The coated phosphor filler according to claim 1 , wherein the thickness of the coating layer is in the range of 2 to 6 μm.
7. The coated phosphor filler according to claim 1 , wherein the thickness of the moisture-proof barrier film is in the range of 0.1 to 2 μm.
8. The coated phosphor filler according to claim 1 , wherein the thickness of said coating layer is 2 to 10 times the thickness of said barrier film.
9. The coated phosphor filler according to claim 2 , wherein said epoxy composition includes hydrophobic residues forming a moisture-repellent barrier.
10. A method for forming a coated phosphor filler, said method comprising:
coating each of a plurality of individual phosphor filler particles with a moisture proof barrier film; and
coating the outer surface of said moisture proof barrier film with a coating layer comprising a plastic substance, wherein the thickness of the coating layer is at least twice the thickness of the moisture proof barrier film.
11. The method according to claim 10 , wherein said step of coating each of said plurality of individual phosphor filler particles is performed by using the Wet Chemical process.
12. The method according to claim 11 , wherein said step of coating the outer surface of said moisture proof barrier film with said coating layer is performed by physically depositing said coating layer on said moisture proof barrier film.
13. The method according to claim 10 , wherein an inorganic passivation material is used as said barrier film.
14. A coated phosphor filler, comprising:
a plurality of stable phosphor filler particles, wherein the stable phosphor filler particles comprise at least one member of the garnet phosphor family; and
a coating layer coated on the phosphor filler particles, wherein the coating layer comprises a plastic substance, wherein the plastic substance comprises an optically transparent epoxy composition.
15. The coated phosphor filler according to claim 14 , wherein the stable phosphor filler particles comprise (YGd) 3 A 15 O 12 including Ce 3+ -impurities.