White-light led with dielectric omni-directional reflectors

• US 20040119083A1
• Filed: 03/25/2003
• Published: 06/24/2004
• Est. Priority Date: 12/20/2002
• Status: Active Grant

• Current Assignee: Transpacific IP I Limited (Transpacific IP Group Limited)
• Original Assignee: Industrial Technology Research Institute
• Inventors: Lo, Jun-Ren, Su, Jung-Chieh, Chi, Jim-Yong
• Granted Patent: US 6,833,565 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil
• CPC Class Codes: H01L 33/60 Reflective elements

Abstract

A white-light LED with omni-directional reflectors includes an LED chip for emitting white-light. A light transmitting material surrounding the LED and phosphor grains is dispersed in order to excite fluorescence via emission of LED. Two omni-directional reflectors are implemented on the top and/or bottom of the LED symmetrically surrounding the light transmitting material and the LED chip. The light from the LED was reflected omni-directionally, via the dielectric omni-directional reflectors, to increasing the efficiency and/or spectral characteristics and uniformity of the visible light emission.

Claims

1. A white-light light-emitting diode (LED) with dielectric omni-directional reflectors, comprising:

an LED chip for emitting white-light through an outgoing surface;

a light transmitting material surrounding the LED chip and a plurality of phosphor grains being dispersed to excite fluorescence via emission of the LED chip; and

two dielectric omni-directional reflectors implemented on the top and bottom of the LED chip symmetrically surrounding the light transmitting material and the LED chip, the one facing the outgoing surface being a front dielectric omni-directional reflector and the other being a rear dielectric omni-directional reflector;

wherein light emitted from the LED chip was reflected omni-directionally, via the dielectric omni-directional reflectors.

2. The white-light LED of claim 1, wherein the LED chip is selected from the group consisting of UV LED chip and blue LED chip.

3. The white-light LED of claim 1, wherein a light outgoing surface of the LED chip is installed with a short wave pass filter to increase the outgoing flux of the LED chip.

4. The white-light LED of claim 1, wherein the visible-light spectrum of the phosphor grains has to be compatible with the desired wavelength of the LED chip.

5. The white-light LED of claim 1, wherein the front dielectric omni-directional reflector is formed by coating a multi-layer dielectric stack structure with alternately high and low refractive index.

6. The white-light LED of claim 5, wherein the material of the multi-layer dielectric stack is selected from one or more member(s) of the group consisting of SiO₂/Al₂O₃, TiO₂/SiO₂, and Ta₂O₃/SiO₂.

7. The white-light LED of claim 1, wherein the light viewing side surface of glass plate where the front dielectric omni-directional reflector coated is selected from the group consisting of a diffractive optical element (DOE) total internal reflection (TIR) lens, dome lens, non-imaging Fresnel lens, microlens, microlens array, a diffuser, and an anti-reflection (AR) coating.

8. The white-light LED of claim 1, wherein the front dielectric omni-directional reflector is a dielectric stack of optical thin-film coating layers.

9. The white-light LED of claim 1, wherein the manufacturing method of the front dielectric omni-directional reflector is selected from the group consisting of self-assembly, sol-gel deposition process by spin coating, dipping, sputtering, E-gun deposition, and chemical vapor deposition (CVD).

10. The white-light LED of claim 1, wherein the rear dielectric omni-directional reflector is selected from the group consisting of a metal thin-film coating and a visible/UV mirror.

11. The white-light LED of claim 1, wherein the rear dielectric omni-directional reflector is formed by coating a multi-layer dielectric stack structure with alternately high and low refractive index.

12. The white-light LED of claim 11, wherein the material of the multi-layer dielectric stack is selected from one or more member(s) of the group consisting of SiO₂/Al₂O₃, TiO₂/SiO₂, and Ta₂O₃/SiO₂.

13. The white-light LED of claim 1, wherein the manufacturing method of the rear dielectric omni-directional reflector is selected from the group consisting of self-assembly, sol-gel deposition process by spin coating, dipping sputtering, E-gun, and chemical vapor deposition (CVD).

14. A white-light light-emitting diode (LED) with dielectric omni-directional reflectors, comprising:

a plurality of LED chips for emitting white-light through an outgoing surface;

a light transmitting material surrounding the LED chip and a plurality of phosphor grains being dispersed to excite fluorescence via emission of the LED chip; and

two dielectric omni-directional reflectors implemented on the top and bottom of the LED chip symmetrically surrounding the light transmitting material and the LED chip, the one facing the outgoing surface being a front dielectric omni-directional reflector and the other being a rear dielectric omni-directional reflector, and the top of the rear dielectric omni-directional reflector being covered with a transparent electrode layer to form a circuit;

wherein light emitted from the LED chip was reflected omni-directionally, via the dielectric omni-directional reflectors.

15. The white-light LED of claim 14, wherein the LED chip is selected from the group consisting of UV LED chip and blue LED chip.

16. The white-light LED of claim 14, wherein a light outgoing surface of the LED chip is installed with a short wave pass filter to increase the outgoing flux of the LED chip.

17. The white-light LED of claim 14, wherein the visible-light spectrum of the phosphor grains has to be compatible with the desired wavelength of the LED chip.

18. The white-light LED of claim 14, wherein the front dielectric omni-directional reflector is formed by coating a multi-layer dielectric stack structure with alternately high and low refractive index.

19. The white-light LED of claim 18, wherein the material of the multi-layer dielectric stack is selected from one or more member(s) of the group consisting of SiO₂/Al₂O₃, TiO₂/SiO₂, and Ta₂O₃/SiO₂.

20. The white-light LED of claim 14, wherein the light viewing side surface of glass plate where the front dielectric omni-directional reflector coated is selected from the group consisting of a diffractive optical element (DOE) total internal reflection (TIR) lens, dome lens, non-imaging Fresnel lens, microlens, microlens array, a diffuser, and an anti-reflection (AR) coating.

21. The white-light LED of claim 14, wherein the front dielectric omni-directional reflector is a dielectric stack of optical thin-film coating layers.

22. The white-light LED of claim 14, wherein the manufacturing method of the front dielectric omni-directional reflector is selected from the group consisting of self-assembly, sol-gel deposition process by spin coating, dipping, sputtering, E-gun deposition, and chemical vapor deposition (CVD).

23. The white-light LED of claim 14, wherein the rear dielectric omni-directional reflector is selected from the group consisting of a metal thin-film coating and a visible/UV mirror.

24. The white-light LED of claim 14, wherein the rear dielectric omni-directional reflector is formed by coating a multi-layer dielectric stack structure with alternately high and low refractive index.

25. The white-light LED of claim 24, wherein the material of the multi-layer dielectric stack is selected from one or more member(s) of the group consisting of SiO₂/Al₂O₃, TiO₂/SiO₂, and Ta₂O₃/SiO₂.

26. The white-light LED of claim 14, wherein the manufacturing method of the rear dielectric omni-directional reflector is selected from the group consisting of self-assembly, sol-gel deposition process by spin coating, dipping sputtering, E-gun, and chemical vapor deposition (CVD).

27. The white-light LED of claim 14, wherein the transparent electrode layer is ITO.

28. A white-light LED with dielectric omni-directional reflectors comprising:

an LED chip installed in a supporting body having an upper surface with a depression having an opening in the upper surface for emitting white-light, a light transmitting material surrounding the LED and a plurality of phosphor grains being dispersed to excite fluorescence via light emission of the LED chip through the light transmitting material, wherein the white-light LED is characterized in that;

the surface of the light transmitting material having an dielectric omni-directional reflector to reflect the light from the LED chip omni-directionally irrespective of polarization.

29. The white-light LED of claim 28, wherein the LED chip is selected from the group consisting of an UV LED chip and a blue LED chip.

30. The white-light LED of claim 28, wherein the visible-light spectrum of the phosphor grains has to be compatible with the desired wavelength of the LED chip.

31. The white-light LED of claim 28, wherein the dielectric omni-directional reflector is a dielectric optical thin-film coating.

32. The white-light LED of claim 28, wherein the dielectric omni-directional reflector is formed by coating a multi-layer dielectric stack structure with alternately high and low refractive index.

33. The white-light LED of claim 32, wherein the material of the multi-layer dielectric stack is selected one or more member(s) of the group consisting of SiO₂/Al₂O₃, TiO₂/SiO₂, and Ta₂O₃/SiO₂.