HIGH REFLECTIVE SUBSTRATE OF LIGHT EMITTING DEVICES WITH IMPROVED LIGHT OUTPPUT

• US 20110248287A1
• Filed: 04/09/2010
• Published: 10/13/2011
• Est. Priority Date: 04/09/2010
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Keller, Bernd, Le Toquin, Ronan, Yuan, Thomas Cheng-Hsin, Lowes, Theodore
• Granted Patent: US 9,012,938 B2
• Time in Patent Office: Days
• US Class Current: 257/88
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/60 Reflective elements

Abstract

Apparatuses and methods for producing light emitting devices maximizing luminous flux output are disclosed. In one possible embodiment, a light emitting device comprises a substrate and a reflective layer at least partially covering the substrate. The reflective layer is non-yellowing, and may be substantially light transparent. One or more light emitting diode (LED) chips are disposed on the substrate. The light emitting device may emit white light. The reflective layer may comprise a silicone carrier with light reflective particles dispersed in the silicone carrier. A light diffusion lens may also be disposed on the substrate and surrounding the LED chips. Furthermore, one or more microspheres, light scattering particles, and/or phosphor particles may be dispersed in the lens. In one possible method for producing a light emitting device, a substrate is provided. One or more LED chips are coupled with the substrate, and a high reflective, non-yellowing coating is applied on at least a portion of the top surface of the substrate. The coating comprises a carrier with reflective particles dispersed throughout.

Claims

17. A light emitting device, comprising:

a substrate;

a stable reflective coating at least partially covering said substrate, said reflective coating comprising a silicone carrier;

light reflective particles dispersed in said carrier;

one or more light emitting diode (LED) chips disposed on said substrate; and

a light diffusion lens disposed on said substrate and over said LED chips.

18. The device of claim 17, wherein said coating is substantially resistant to discoloration through use.

19. The device of claim 17, wherein said coating is substantially resistant to yellowing through use.

20. The device of claim 17, wherein said light emitting particles comprise one or more of titanium dioxide or aluminum oxide.

21. The device of claim 17, wherein said reflective layer covers said substrate outside the perimeter of said LED chips or is disposed on said substrate between each of said LED chips and outside the perimeter of said LED chips.

22. The device of claim 17, wherein said light diffusion lens comprises one or more of light scattering particles, phosphor particles, or hollow microspheres.

23. The device of claim 17, wherein said light diffusion lens comprises one or more of silicone, plastic, or glass.

24. A light emitting device, comprising:

a substrate;

one or more light emitting diode (LED) chips disposed on said substrate;

a light diffusion lens disposed on said substrate and surrounding said LED chips;

one or more microspheres dispersed in said light diffusion lens; and

a stable reflective coating at least partially covering said substrate.

1. A light emitting device, comprising:

a substrate;

a reflective coating at least partially covering said substrate, with said reflective coating being substantially resistant to discoloration over time; and

one or more light emitting diode (LED) chips disposed on said substrate.

2. The device of claim 1, wherein said reflective coating is substantially resistant to yellowing over time.

3. The device of claim 1, wherein said substrate comprises a printed circuit board.

4. The device of claim 1, wherein said reflective layer comprises a carrier, with light reflective particles dispersed in said carrier.

5. The device of claim 4, wherein said carrier comprises one or more of silicone, plastic, glass, or a polymeric matrix.

6. The device of claim 4, wherein said light reflective particles comprise one or more of titanium dioxide or aluminum oxide.

7. The device of claim 4, wherein said light reflective particles have a reflective index different from the reflective index of said carrier.

8. The device of claim 1, wherein said reflective layer is substantially light transparent, with said reflective layer being substantially non-discoloring and non-degrading over time, prolonged use, or exposure to blue light.

9. The device of claim 1, wherein said reflective layer covers said substrate outside the perimeter of said LED chips.

10. The device of claim 9, wherein said reflective layer is further disposed on said substrate between each of said LED chips.

11. The device of claim 1, further comprising a light diffusing lens disposed on said substrate and LED chips, with said light diffusing lens comprising one or more of light scattering particles, hollow microspheres, or phosphor particles.

12. The device of claim 11, wherein said reflective layer redirects light that is scattered or back-reflected from said light scattering particles, hollow microspheres, or phosphor particles such that said light is effectively emitted from said device, increasing the light output of said device.

13. The device of claim 11, wherein said light diffusing lens comprises one or more of silicone, glass, or plastic.

14. The device of claim 1, wherein said light emitting device comprises an LED lamp.

15. The device of claim 14, wherein said lamp comprises one or more walls with an interior surface in the light emission paths of said LED chips, said interior surfaces coated with said reflective layer.

16. The device of claim 1, wherein said light emitting device emits red light, green light, blue light, yellow light, white light, or any combination thereof.

25. The device of claim 24, wherein said reflective coating comprising a carrier substantially light transparent light from at least one of said LED chips, and a reflective material.

26. The device of claim 24, wherein said reflective coating at least partially covers said substrate.

27. The device of claim 24, wherein said reflective coating is substantially resistant to discoloration.

28. The device of claim 24, wherein said microspheres comprise hollow glass, said microspheres enhancing the light scattering and mixing of light emitted by said LED chips.

29. The device of claim 24, wherein said light diffusion lens further comprises one or more of light scattering particles or phosphor particles.

28-1. The device of claim 24, wherein said reflective coating comprises a silicone carrier, with one or more of titanium dioxide or aluminum particles dispersed in said carrier.

30. A method for producing a light emitting device, said method comprising:

providing a substrate;

mounting one or more light emitting diode (LED) chips to said substrate; and

applying a reflective, discoloration resistant coating on at least a portion of the top surface of said substrate, said coating comprising a carrier with reflective particles dispersed in said carrier.

31. The method of claim 30, further comprising disposing a light diffusion lens on said substrate and LED chips, said light diffusion lens comprising one or more of scattering particles, hollow microspheres, or phosphor particles.

32. The method of claim 30, wherein said carrier comprises one or more of silicone, plastic, or glass, and said reflective particles comprise one or more of titanium dioxide or aluminum oxide.

33. The method of claim 30, further comprising applying said coating on said substrate outside the perimeter of said LED chips or between each of said LED chips as well as outside the perimeter of said LED chips.

34. The method of claim 30, further comprising applying said coating on said substrate by one or more of the following methods:

printing, brushing on, or utilizing a dispensing mechanism.