Light emitting device provided with lens for controlling light distribution characteristic

• US 8,558,446 B2
• Filed: 05/27/2009
• Issued: 10/15/2013
• Est. Priority Date: 02/18/2005
• Status: Active Grant

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Miki, Tomohide, Takine, Kenji, Yamashita, Ryohei
• Primary Examiner(s): Guharay, Karabi
• Application Number:
  US12/473,121
• Publication Number:
  US 20090231833A1
• Time in Patent Office: 1,602 Days
• Field of Search: 313501-502, 313/512, 313/503, 257/98
• US Class Current: 313/502
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• 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 2924/00014 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 33/505 characterised by the shape, e.g. plate or foil
• 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 33/54 having a particular shape
• CPC Class Codes: H01L 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls

Abstract

The light emitting device comprises a substrate (2), a positive electrode (6) and a negative electrode (4) formed on the substrate (2), a light emitting diode (8) connected to the positive electrode (6) and the negative electrode (4), the transparent resin (12 and 14) that covers the light emitting diode (8), a fluorescent material (16) that absorbs at least part of light emitted by the light emitting diode (8) and converts it to light of longer wavelength, and the lens that changes the direction of light emission from the light emitting diode (8) and/or the fluorescent material (16). The resin (12 and 14) includes the fluorescent material (16) and is formed so as to constitute the lens of substantially semi-cylindrical shape, and the fluorescent material (16) included in the resin (12 and 14) is distributed with a higher concentration in a region near the surface of the light emitting diode (8) than in a region near the surface of the portion that constitutes the lens.

Claims

1. A light emitting device comprising:

a substrate,

a positive electrode and a negative electrode formed on said substrate,

a light emitting diode mounted on said substrate, said light emitting diode being connected to said positive electrode and said negative electrode,

a sealing resin layer which is a single layer, said sealing resin layer directly covering said light emitting diode such that said sealing resin layer directly contacts said light emitting diode,

a fluorescent material absorbing at least part of light emitted by said light emitting diode and converting the absorbed light longer wavelength,

wherein

said sealing resin layer includes said fluorescent material,

said sealing resin layer is formed so as to constitute a lens for changing the direction of light emission from said light emitting diode or said fluorescent material,

said fluorescent material is distributed with a higher concentration in a region near the surface of said light emitting diode than in a region near the surface of said sealing resin layer, and

a partial area on the surface of said sealing resin layer has a concave shape such that a straight segment joining two points of said partial area lies outside said sealing resin layer, in a cross section perpendicular to a principal plane of said substrate,

wherein said substrate and said sealing resin layer are cut to have a coplanar face on a side face of said light emitting device so that said sealing resin layer including said fluorescent material is exposed on said side face.

2. The light emitting device according to claim 1, wherein said sealing resin layer is formed from a thermosetting resin of which viscosity once decreases and then increases again as the temperature rises during a curing process.

3. The light emitting device according to claim 1, wherein said sealing resin layer includes at least one kind selected from the group consisting of epoxy resin, silicone resin, hard silicone resin, modified silicone resin, urethane resin, oxetane resin, acryl resin, polycarbonate resin and polyimide resin.

4. The light emitting device according to claim 1, wherein said sealing resin layer is formed into a lens shape by compression molding process.

5. The light emitting device according to claim 1, wherein said fluorescent material is not substantially included in the portion where said sealing resin layer is formed into a lens shape.

6. The light emitting device according to claim 1, wherein the concentration of said fluorescent material in the vicinity of the surface of said light emitting diode is 20 times or more higher than the concentration of said fluorescent material in the vicinity of the surface of said sealing resin layer.

7. The light emitting device according to claim 1, wherein said lens has substantially semi-cylindrical shape or substantially semi-spherical shape.

8. The light emitting device according to claim 1, wherein said light emitting device is a side view type light emitting device where one of a pair of opposing side faces is used as the mounting surface.

9. The light emitting device according to claim 1, wherein said light emitting diode has a nitride semiconductor light emitting layer that emits ultraviolet ray or blue light.

10. The light emitting device according to claim 1, wherein said fluorescent material is capable of emitting white light by itself or by blending light emitted by the fluorescent material and light emitted said light emitting diode.

11. The light emitting device according to claim 1, wherein said lens

is curved in a cross section along a longer axis of said light emitting device so as to bend light toward a normal direction, and

is not curved in a cross section along a shorter axis of said light emitting device so as to allow light to propagate straight.

12. The light emitting device according to claim 1, wherein said light emitting diode emits light in the range of not less than 400 nm and not larger than 530 nm.

13. The light emitting device according to claim 1, wherein said light emitting diode emits ultraviolet light.

14. The light emitting device according to claim 1, wherein a refractive index is continuous inside said lens.

15. The light emitting device according to claim 1, wherein said fluorescent material is not substantially included in a portion of said sealing resin layer that is formed into said lens.

16. The light emitting device according to claim 1, wherein a side face of said substrate and a side face of said sealing resin layer are cut so as to be substantially flush, and said fluorescent material is distributed up to said exposed side face of said sealing resin layer.

17. The light emitting device according to claim 1, wherein said lens is convex.

18. The light emitting device according to claim 1, wherein said lens is concave.

19. The light emitting device according to claim 1, wherein the concentration of said fluorescent material in the vicinity of the surface of said light emitting diode is 50 times or more higher than the concentration of said fluorescent material in the vicinity of the surface of said sealing resin layer.

20. The light emitting device according to claim 1, wherein the concentration of said fluorescent material in the vicinity of the surface of said light emitting diode is 100 times or more higher than the concentration of said fluorescent material in the vicinity of the surface of said sealing resin layer.

21. The light emitting device according to claim 1, wherein a diffusion agent is included in said sealing resin layer near its surface.

22. The light emitting device according to claim 1, wherein a curvature of said sealing resin layer changes to become flat at the edges of the device.

23. The light emitting device according to claim 22, wherein said sealing resin layer does not substantially include said fluorescent material in the flat region.

24. The light emitting device according to claim 1, wherein a portion of said sealing resin layer which includes said fluorescent material directly contacts said light emitting diode.

25. The light emitting device according to claim 1, wherein said sealing resin layer is formed so as to constitute a lens for changing the direction of light emission from said light emitting diode and said fluorescent material.

26. The light emitting device according to claim 1, wherein said substrate and said sealing resin layer are cut to have a coplanar face on a pair of opposed side faces of said light emitting device, one of said pair of opposed side faces being said side face of said light emitting device,

so that said sealing resin layer including said fluorescent material is exposed.

27. A light emitting device as recited in claim 1, wherein said light emitting diode is connected by a wire to one of said positive and negative electrodes.

28. A light emitting device comprising:

a substrate,

a positive electrode and a negative electrode formed on said substrate,

a light emitting diode mounted on said substrate, said light emitting diode being connected to said positive electrode and said negative electrode,

a sealing resin layer which is a single layer, said sealing resin layer directly covering said light emitting diode such that said sealing resin layer directly contacts said light emitting diode,

a fluorescent material absorbing at least part of light emitted by said light emitting diode and converting the absorbed light to longer wavelength,

wherein

said sealing resin layer includes said fluorescent material,

said sealing resin layer is formed so as to constitute a lens for changing the direction of light emission from said light emitting diode or said fluorescent material,

said fluorescent material is distributed with a higher concentration in a region near the surface of said light emitting diode than in a region near the surface of said sealing resin layer, and

said sealing resin layer has a convex portion constituting said lens, and a flat portion which extends substantially along said substrate, above said substrate,

wherein said substrate and said sealing resin layer are cut to have a coplanar face on a side face of said light emitting device so that said sealing resin layer including said fluorescent material is exposed on said side face.

29. The light emitting device according to claim 28, wherein said sealing resin layer has a bend portion connecting said convex portion and said flat portion.

30. The light emitting device according to claim 28, wherein a portion of said sealing resin layer which includes said fluorescent material directly contacts said light emitting diode.

31. The light emitting device according to claim 28, wherein said sealing resin layer is formed so as to constitute a lens for changing the direction of light emission from said light emitting diode and said fluorescent material.

32. The light emitting device according to claim 28, wherein said substrate and said sealing resin layer are cut to have a coplanar face on a pair of opposed side faces of said light emitting device, one of said pair of opposed side faces is said side face of said light emitting device,

so that said sealing resin layer including said fluorescent material is exposed.

33. A light emitting device as recited in claim 28, wherein said light emitting diode is connected by a wire to one of said positive and negative electrodes.

34. A light emitting device comprising:

a substrate comprising an insulating material,

a positive electrode and a negative electrode formed on said substrate,

a light emitting diode mounted on said substrate, said light emitting diode being connected to said positive electrode and said negative electrode,

a sealing resin layer directly covering said light emitting diode such that said sealing resin layer directly contacts said light emitting diode,

a fluorescent material absorbing at least part of light emitted by said light emitting diode and converting the absorbed light longer wavelength,

wherein

said sealing resin layer includes said fluorescent material,

said sealing resin layer is formed so as to constitute a lens for changing the direction of light emission from said light emitting diode or said fluorescent material,

said fluorescent material is distributed with a higher concentration in a region near the surface of said light emitting diode than in a region near the surface of said sealing resin layer, and

a partial area on the surface of said sealing resin layer has a concave shape such that a straight segment joining two points of said partial area lies outside said sealing resin layer, in a cross section perpendicular to a principal plane of said substrate,

wherein said substrate and said sealing resin layer are cut to have a coplanar face on a side face of said light emitting device so that said sealing resin layer including said fluorescent material is exposed on said side face.

35. The light emitting device according to claim 34, wherein said sealing resin layer is formed so as to constitute a lens for changing the direction of light emission from said light emitting diode and said fluorescent material.

36. The light emitting device according to claim 34, wherein said substrate and said sealing resin layer are cut to have a coplanar face on a pair of opposed side faces of said light emitting device, one of said pair of opposed side faces is said side face of said light emitting device,

so that said sealing resin layer including said fluorescent material is exposed.

37. A light emitting device as recited in claim 34, wherein said light emitting diode is connected by a wire to one of said positive and negative electrodes.

38. A light emitting device comprising:

a substrate comprising an insulating material,

a positive electrode and a negative electrode formed on said substrate,

a light emitting diode mounted on said substrate, said light emitting diode being connected to said positive electrode and said negative electrode,

a sealing resin layer directly covering said light emitting diode such that said sealing resin layer directly contacts said light emitting diode,

a fluorescent material absorbing at least part of light emitted by said light emitting diode and converting the absorbed light to longer wavelength,

wherein

said sealing resin layer includes said fluorescent material,

said sealing resin layer is formed so as to constitute a lens for changing the direction of light emission from said light emitting diode or said fluorescent material,

said fluorescent material is distributed with a higher concentration in a region near the surface of said light emitting diode than in a region near the surface of said sealing resin layer, and

said sealing resin layer has a convex portion constituting said lens, and a flat portion which extends substantially along said substrate, above said substrate,

wherein said substrate and said sealing resin layer are cut to have a coplanar face on a side face of said light emitting device so that said sealing resin layer including said fluorescent material is exposed on said side face.

39. The light emitting device according to claim 38, wherein said sealing resin layer is formed so as to constitute a lens for changing the direction of light emission from said light emitting diode and said fluorescent material.

40. The light emitting device according to claim 38, wherein said substrate and said sealing resin layer are cut to have a coplanar face on a pair of opposed side faces of said light emitting device, one of said pair of opposed side faces is said side face of said light emitting device,

so that said sealing resin layer including said fluorescent material is exposed.

41. A light emitting device as recited in claim 38, wherein said light emitting diode is connected by a wire to one of said positive and negative electrodes.

42. A light emitting device comprising:

a substrate,

a positive electrode and a negative electrode formed on said substrate,

a light emitting diode mounted on said substrate, said light emitting diode being connected to said positive electrode and said negative electrode,

a sealing resin layer directly covering said light emitting diode such that said sealing resin layer directly contacts said light emitting diode,

wherein one of said positive and negative electrodes is disposed under one side of said light emitting diode, and said sealing resin layer contacts an opposite side of said light emitting diode,

a fluorescent material absorbing at least part of light emitted by said light emitting diode and converting the absorbed light longer wavelength,

wherein

said sealing resin layer includes said fluorescent material,

said sealing resin layer is formed so as to constitute a lens for changing the direction of light emission from said light emitting diode or said fluorescent material,

said fluorescent material is distributed with a higher concentration in a region near the surface of said light emitting diode than in a region near the surface of said sealing resin layer, and

a partial area on the surface of said sealing resin layer has a concave shape such that a straight segment joining two points of said partial area lies outside said sealing resin layer, in a cross section perpendicular to a principal plane of said substrate,

wherein said substrate and said sealing resin layer are cut to have a coplanar face on a side face of said light emitting device so that said sealing resin layer including said fluorescent material is exposed on said side face.

43. The light emitting device according to claim 42, wherein said sealing resin layer is formed so as to constitute a lens for changing the direction of light emission from said light emitting diode and said fluorescent material.

44. The light emitting device according to claim 42, wherein said substrate and said sealing resin layer are cut to have a coplanar face on a pair of opposed side faces of said light emitting device, one of said pair of opposed side faces is said side face of said light emitting device,

so that said sealing resin layer including said fluorescent material is exposed.

45. A light emitting device as recited in claim 42, wherein said light emitting diode is connected by a wire to one of said positive and negative electrodes.

46. A light emitting device comprising:

a substrate,

a positive electrode and a negative electrode formed on said substrate,

a light emitting diode mounted on said substrate, said light emitting diode being connected to said positive electrode and said negative electrode,

a sealing resin layer directly covering said light emitting diode such that said sealing resin layer directly contacts said light emitting diode,

wherein one of said positive and negative electrodes is disposed under one side of said light emitting diode, and said sealing resin layer contacts an opposite side of said light emitting diode,

a fluorescent material absorbing at least part of light emitted by said light emitting diode and converting the absorbed light to longer wavelength,

wherein

said sealing resin layer includes said fluorescent material,

said sealing resin layer is formed so as to constitute a lens for changing the direction of light emission from said light emitting diode or said fluorescent material,

said fluorescent material is distributed with a higher concentration in a region near the surface of said light emitting diode than in a region near the surface of said sealing resin layer, and

said sealing resin layer has a convex portion constituting said lens, and a flat portion which extends substantially along said substrate, above said substrate,

wherein said substrate and said sealing resin layer are cut to have a coplanar face on a side face of said light emitting device so that said sealing resin layer including said fluorescent material is exposed on said side face.

47. The light emitting device according to claim 46, wherein said sealing resin layer is formed so as to constitute a lens for changing the direction of light emission from said light emitting diode and said fluorescent material.

48. The light emitting device according to claim 46, wherein said substrate and said sealing resin layer are cut to have a coplanar face on a pair of opposed side faces of said light emitting device, one of said pair of opposed side faces is said side face of said light emitting device,

so that said sealing resin layer including said fluorescent material is exposed.

49. A light emitting device as recited in claim 46, wherein said light emitting diode is connected by a wire to one of said positive and negative electrodes.

50. A light emitting device comprising:

a substrate,

a positive electrode and a negative electrode formed on said substrate,

a light emitting diode mounted on said substrate, said light emitting diode being connected to said positive electrode and said negative electrode,

a sealing resin layer which is a single layer, said sealing resin layer directly covering said light emitting diode such that said sealing resin layer directly contacts said light emitting diode,

a fluorescent material absorbing at least part of light emitted by said light emitting diode and converting the absorbed light longer wavelength,

wherein

said sealing resin layer includes said fluorescent material,

said sealing resin layer is formed so as to constitute a lens for changing the direction of light emission from said light emitting diode or said fluorescent material,

said fluorescent material is distributed with a higher concentration in a region near the surface of said light emitting diode than in a region near the surface of said sealing resin layer, and

a partial area on the surface of said sealing resin layer has a concave shape such that a straight segment joining two points of said partial area lies outside said sealing resin layer, in a cross section perpendicular to a principal plane of said substrate,

wherein a side face of said substrate and a side face of said sealing resin layer are cut so as to be substantially flush, and said fluorescent material is distributed up to the exposed side face of said sealing resin layer.