LED filament lamps with white filament appearance

Patent metadata

Field	Value
Publication number	US-10495263-B2
Application number	US-201815922021-A
Country	US
Kind code	B2
Filing date	Mar 15, 2018
Priority date	Oct 27, 2017
Publication date	Dec 3, 2019
Grant date	Dec 3, 2019

Abstract

An overcoated LED filament includes an LED filament comprising one or more LED dies coated with an underlying layer of a phosphor material exhibiting a colored appearance, and an over-coated layer comprising a resinous material loaded with a scattering agent that causes the LED filament to appear white.

First claim

The invention claimed is:

1. An overcoated LED filament comprising:
an LED filament comprising a plurality of LED dies mounted serially along the length of a transparent substrate, the LED dies and the transparent substrate being encapsulated within an underlying layer coating of a phosphor material exhibiting a colored appearance; and
an over-coated layer completely coating the underlying layer coating and comprising a resinous material loaded with a scattering agent that causes the LED filament to appear white;
wherein the LED filament is in an unlit state.

2. The overcoated LED filament of claim 1 , wherein the colored appearance of the underlying layer coating of the phosphor material is a yellow, orange, or red appearance.

3. The overcoated LED filament of claim 1 , wherein the underlying layer coating of the phosphor material comprises a doped phosphor with a fluoride host.

4. The overcoated LED filament of claim 1 , wherein the underlying layer coating of the phosphor material comprises PFS phosphor having the formula K 2 SiF 6 :Mn 4+ .

5. The overcoated LED filament of claim 1 , wherein the underlying layer coating of the phosphor material comprises a yellow-emitting phosphor, yellow-green- emitting phosphor or a garnet phosphor.

6. The overcoated LED filament of claim 1 , wherein the underlying layer coating of the phosphor material comprises an red-emitting Eu 2 + red nitride phosphor.

7. The overcoated LED filament of claim 1 , wherein the underlying layer coating of the phosphor material comprises an absorbing agent.

8. The overcoated LED filament of claim 1 , wherein the underlying layer coating comprises the resinous material.

9. The overcoated LED filament of claim 1 , wherein the resinous material loaded with a scattering agent exhibits a uniform reflectance across a visible range of light.

10. The overcoated LED filament of claim 1 , wherein the resinous material exhibits a refractive index substantially matching a refractive index of the underlying layer coating.

11. The overcoated LED filament of claim 1 , wherein the resinous material exhibits a coefficient of thermal expansion substantially matching a coefficient of thermal expansion of the underlying layer coating.

12. The overcoated LED filament of claim 1 , wherein the scattering agent is inorganic and the resinous material and the scattering agent exhibit different indexes of refraction.

13. The overcoated LED filament of claim 12 , wherein a difference between the index of refraction for the scattering agent and the index of refraction for the resinous material is at least 0.17.

14. The overcoated LED filament of claim 13 , wherein the difference between the index of refraction for the scattering agent and the index of refraction for the resinous material is in a range of from 0.17 to 1.21.

15. The overcoated LED filament of claim 1 , wherein the scattering agent comprises one or more of a fluoropolymer or a cyclic olefin copolymer.

16. The overcoated LED filament of claim 1 , wherein the scattering agent comprises one or more non-absorbing metal oxides, metal nitrides or metal halides.

17. The overcoated LED filament of claim 1 , wherein the scattering agent comprises one or more non-absorbing semiconductor oxides, semiconductor nitrides or semiconductor halides.

18. The overcoated LED filament of claim 1 , wherein the scattering agent comprises one or more of alumina, titania, silica, zirconia, quartz, or glass powder.

19. The overcoated LED filament of claim 1 , wherein the scattering agent comprises 0.1-10% by weight alumina.

20. The overcoated LED filament of claim 1 , wherein the scattering agent comprises 0.01% -1% by weight titania.

21. The overcoated LED filament of claim 1 , wherein the scattering agent comprises a combination of 3.0-7.0 by weight alumina and 0.1-0.5% by weight titania.

22. The overcoated LED filament of claim 1 , wherein the over-coated layer comprises an absorbing agent.

23. The overcoated LED filament of claim 1 , wherein the over-coated layer comprises a Neodymium compound.

24. A lighting apparatus comprising the overcoated LED filament of claim 1 .

25. The overcoated LED filament of claim 1 , wherein the transparent substrate is held in an envelope.

26. The overcoated LED filament of claim 1 , wherein the over-coated layer further comprises one or more phosphors.

27. The overcoated LED filament of claim 26 , wherein the one or more phosphors comprises one or more of a doped phosphor with a fluoride host, a PFS phosphor having the formula K 2 SiF 6 :Mn 4+ , a garnet phosphor or an Eu + red nitride phosphor.

28. The overcoated LED filament of claim 1 , wherein the over-coated layer has a thickness in a range from 0.4 mm to 4.4 mm.

29. The overcoated LED filament of claim 1 , wherein the LED filament comprises more than one LED dies.

30. The overcoated LED filament of claim 1 , wherein the transparent substrate is glass or sapphire.

Assignees

• Ge Lighting Solutions Llc
• Consumer Lighting Us Llc

Inventors

• Chowdhury Ashfaqul I
• Stimac Tomislav Josip
• Benner Kevin Jeffrey
• Firis James William

Classifications

• H10W90/00

  Package configurations · CPC title

• F21K9/232 Primary

  specially adapted for generating an essentially omnidirectional light distribution, e.g. with a glass bulb · CPC title

• F21V3/10

  characterised by coatings · CPC title

• H01L25/00

  Electricity · mapped topic

• F21K9/23 Primary

  Retrofit light sources for lighting devices with a single fitting for each light source, e.g. for substitution of incandescent lamps with bayonet or threaded fittings · CPC title