Light emitting device with fluorescent member excited by semiconductor light emitting element

• US 20030038295A1
• Filed: 08/22/2002
• Published: 02/27/2003
• Est. Priority Date: 08/22/2001
• Status: Active Grant

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Koda, Shigetsugu
• Granted Patent: US 6,737,681 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/8592 Applying permanent coating, e.g. protective coating
• 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 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 33/507 the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than the semiconductor body
• CPC Class Codes: H01L 33/508 having a non-uniform spatial arrangement or non-uniform concentration, e.g. patterned wavelength conversion layer, wavelength conversion layer with a concentration gradient of the wavelength conversion material
• CPC Class Codes: H01L 33/60 Reflective elements

Abstract

A reflector that functions as a fluorescent member is formed of a transparent resin material including a fluorescent substance dispersed therein capable of emitting light by excitation of light emitted from a semiconductor light emitting element, on the bottom of the case so as to surround the semiconductor light emitting element, having an inner surface of curved surface of concave arc shape having a section extending from the height of the bottom of the case obliquely upward, in a shape that continues along substantially the entire circumference of an oval or elongated round shape, thereby achieving uniform light emission without color heterogeneity, for example, white light of high output power.

Claims

1. A light emitting device comprising:

a semiconductor light emitting element emitting at least part of light from side faces thereof; and

a fluorescent member provided at a distance from the semiconductor light emitting element;

the fluorescent member being capable of emitting light by wavelength-conversion due to absorption of part of light emitted from the semiconductor light emitting element and including at least yttrium aluminum garnet fluorescent substance as a component having at least one element selected from the group consisting of Y, Lu, Sc, La, Gd and Sm, at least one element selected from the group consisting of Al, Ga and In, at least Ce and at least one element selected from the group consisting of Pr, Sm, Cu, Ag, Au, Fe, Cr, Nd, Dy, Ni, Ti, Tb and Eu;

wherein the fluorescent member has a first portion at a first distance from the semiconductor light emitting element and a second portion at a second distance farther than the first distance from the semiconductor light emitting element and the first portion has a higher efficiency of absorption of light emitted from the semiconductor light emitting element than that of the second portion.

2. A light emitting device comprising:

a semiconductor light emitting element emitting at least part of light from side faces thereof; and

a fluorescent member provided at a distance from the semiconductor light emitting element;

the fluorescent member being capable of emitting light by wavelength-conversion due to absorption of part of light emitted from the semiconductor light emitting element;

wherein the fluorescent member has a first portion at a first distance from the semiconductor light emitting element and a second portion at a second distance farther than the first distance from the semiconductor light emitting element and the first portion has a higher efficiency of absorption of light emitted from the semiconductor light emitting element than that of the second portion.

3. The light emitting device of claim 2, wherein the fluorescent member is formed of a transparent resin material with a fluorescent substance dispersed therein, and said efficiency of absorption is changed continuously or stepwise correspondingly to the absolute quantity of the fluorescent substance.

4. The light emitting device of claim 3, wherein the first portion has a higher density of the fluorescent substance in the fluorescent member than that of the second portion.

5. The light emitting device of claim 2, wherein the fluorescent member includes multiple layers stacked, each layer including different kind of fluorescent substance and said efficiency of absorption in each layer is changed correspondingly to the light conversion efficiency of each fluorescent substance.

6. The light emitting device of claim 2, wherein the fluorescent member contains a fluorescent substance and a light-diffusing agent as components, and said efficiency of absorption is changed correspondingly to the density of the light-diffusing agent.

7. The light emitting device of claim 6, wherein the first portion has a higher density of the light-diffusing agent in the fluorescent member than that of the second portion.

8. The light emitting device of claim 2, wherein the fluorescent member is provided near the side faces of the semiconductor light emitting element and has a flat or curved surface that reflects light emitted from the semiconductor light emitting element.

9. The light emitting device of claim 2, wherein the device generate a light mixed with both the visible light emitted from the semiconductor light emitting element and the visible light emitted from the fluorescent substance.

10. The light emitting device of claim 9, wherein the mixed light is white light.

11. A light emitting device comprising:

electrodes provided on a base surface;

a semiconductor light emitting element that is mounted on the base surface at a distance from the electrodes and emits part of light from side faces thereof;

a connecting member that electrically connects the semiconductor light emitting element and the electrodes; and

a fluorescent member formed of a transparent resin material with a fluorescent substance dispersed therein, the fluorescent substance capable of emitting light by excitation of the light emitted from the semiconductor light emitting element, the fluorescent member being provided to surround the semiconductor light emitting element;

wherein the fluorescent member has a curved surface that reflects the light emitted from the side faces of the semiconductor light emitting element away from the base surface.

12. The light emitting device of claim 11, wherein the inner surface of the fluorescent member is formed so as to substantially constitute a part of paraboloid of revolution, ellipsoid of revolution or hyperboloid of revolution.

15. The light emitting device of claim 11, wherein the transparent resin material of the fluorescent member is an epoxy resin, silicone resin, amorphous polyamide resin or fluorocarbon.

17. The light emitting device of claim 11, wherein the fluorescent substance in the fluorescent member is yttrium aluminum garnet (YAG).

19. The light emitting device of claim 11, wherein the fluorescent substance in the fluorescent member is a nitride fluorescent substance that includes nitrogen at least in the fundamental elements.

21. The light emitting device of claim 11, wherein the fluorescent substance in the fluorescent member is a mixture of two or more kinds of the fluorescent materials.

23. The light emitting device of claim 21, wherein the two or more kinds of fluorescent materials emit light of colors complementary to each other.

25. The light emitting device of claim 11, wherein the fluorescent member includes a pigment having a body color similar to the color of light emitted from the fluorescent substance.

27. The light emitting device of claim 11, wherein the fluorescent member is formed of a transparent synthetic resin material that has viscosity in a range from 2,500 mPa·

s to 20,000 mPa·

s.

29. The light emitting device of claim 11, wherein the fluorescent member is formed of a material mixed 40 to 100 parts by weight of the fluorescent substance with 100 parts by weight of the synthetic resin material.

31. The light emitting device of claim 11, wherein the fluorescent substance in the fluorescent member has mean particle size of ranging from 6 to 25 μ

m.

33. The light emitting device of claim 11, wherein the fluorescent member is formed spontaneously by potting a transparent resin material including the fluorescent substance mixed therein.

35. The light emitting device of claim 11, further comprising a sealing resin for sealing the semiconductor light emitting element.

37. The light emitting device of claim 11, wherein a light diffusion member for diffusing light is provided above the semiconductor light emitting element.

39. The light emitting device of claim 11, wherein a light collecting member for collecting light is provided above the semiconductor light emitting element.

13. A light emitting device comprising:

electrodes provided on a base surface;

a semiconductor light emitting element that is mounted on the base surface at a distance from the electrodes and emits part of light from side faces thereof;

a connecting member that electrically connects the semiconductor light emitting element and the electrodes; and

a fluorescent member formed of a transparent resin material with a fluorescent substance dispersed therein, the fluorescent substance capable of emitting light by excitation of the light emitted from the semiconductor light emitting element, the fluorescent member being provided to surround the semiconductor light emitting element;

wherein density of the fluorescent substance included in the fluorescent member is changed continuously or stepwise with the height from the base surface.

14. The light emitting device of claim 13, wherein density of the fluorescent substance in the fluorescent member is made higher as the height from the base surface decreases.

16. The light emitting device of claim 13, wherein the transparent resin material of the fluorescent member is an epoxy resin, silicone resin, amorphous polyamide resin or fluorocarbon.

18. The light emitting device of claim 13, wherein the fluorescent substance in the fluorescent member is yttrium aluminum garnet (YAG).

20. The light emitting device of claim 13, wherein the fluorescent substance in the fluorescent member is a nitride fluorescent substance that includes nitrogen at least in the fundamental elements.

22. The light emitting device of claim 13, wherein the fluorescent substance in the fluorescent member is a mixture of two or more kinds of the fluorescent materials.

24. The light emitting device of claim 22, wherein the two or more kinds of fluorescent materials emit light of colors complementary to each other.

26. The light emitting device of claim 13, wherein the fluorescent member includes a pigment having a body color similar to the color of light emitted from the fluorescent substance.

28. The light emitting device of claim 13, wherein the fluorescent member is formed of a transparent synthetic resin material that has viscosity in a range from 2,500 mPa·

s to 20,000 mPa·

s.

30. The light emitting device of claim 13, wherein the fluorescent member is formed of a material mixed 40 to 100 parts by weight of the fluorescent substance with 100 parts by weight of the synthetic resin material.

32. The light emitting device of claim 13, wherein the fluorescent substance in the fluorescent member has mean particle size of ranging from 6 to 25 μ

m.

34. The light emitting device of claim 13, wherein the fluorescent member is formed spontaneously by potting a transparent resin material including the fluorescent substance mixed therein.

36. The light emitting device of claim 13, further comprising a sealing resin for sealing the semiconductor light emitting element.

38. The light emitting device of claim 13, wherein a light diffusion member for diffusing light is provided above the semiconductor light emitting element.

40. The light emitting device of claim 13, wherein a light collecting member for collecting light is provided above the semiconductor light emitting element.