Light emitting device provided with lens for controlling light distribution characteristic

• US 20060186431A1
• Filed: 02/17/2006
• Published: 08/24/2006
• Est. Priority Date: 02/18/2005
• Status: Active Grant

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Miki, Tomohide, Yamashita, Ryohei, Takine, Kenji
• Granted Patent: US 7,710,016 B2
• Time in Patent Office: Days
• US Class Current: 257/100
• 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 connected to said positive electrode and said negative electrode;

a transparent layer covering said light emitting diode;

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

a lens changing the direction of light emission from said light emitting diode and/or said fluorescent material;

wherein said transparent layer includes said fluorescent material and is formed so as to constitute an approximately semi-cylindrical shaped lens; and

said fluorescent material included in said layer 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 the portion that constitutes said lens.

17. The light emitting device according to any one of claims 1, 2 and 10, 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.

18. The light emitting device according to any one of claims 1, 2 and 10, wherein said light emitting diode has a nitride semiconductor light emitting layer that emits ultraviolet ray or blue light.

19. The light emitting device according to any one of claims 1, 2 and 10, 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.

2. A light emitting device comprising:

a substrate;

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

a light emitting diode connected to said positive electrode and said negative electrode;

a transparent layer covering said light emitting diode; and

a fluorescent material dispersed in said transparent layer, so as to excite said fluorescent material dispersed in said transparent layer by means of the light emitted by said light emitting diode to emit light of a color different from that of the light emitted by said light emitting diode;

wherein said transparent layer covering said light emitting diode comprises a first transparent layer including said fluorescent material and a second transparent layer formed on said first transparent layer;

said second transparent layer is formed to have a curved shape so as to form a lens on the top surface thereof; and

said first transparent layer and said second transparent layer are cut to have a coplanar face on a pair of opposed side faces of said light emitting device so that said first transparent layer is exposed.

3. The light emitting device according to claim 2, wherein said first transparent layer has substantially semi-cylindrical shape.

4. The light emitting device according to claim 2, wherein the periphery of said first transparent layer substantially agrees with the periphery of said positive and negative electrodes when viewed from above the top surface said first transparent layer.

5. The light emitting device according to claim 2, wherein said first transparent layer has substantially a shape of rectangular parallelepiped.

6. The light emitting device according to claim 2, wherein said first transparent layer covers the entire wires that connect said light emitting diode and said positive and negative electrodes.

7. The light emitting device according to claim 2, wherein said first transparent layer is 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 and glass.

8. The light emitting device according to claim 2, wherein said second transparent layer is formed to have a curved surface on the top surface so as to form a cylindrical lens.

9. The light emitting device according to claim 2, wherein said second transparent layer is 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 and glass.

10. A light emitting device comprising:

a substrate,

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

a light emitting diode connected to said positive electrode and said negative electrode,

a sealing resin layer covering 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, and

a lens changing the direction of light emission from said light emitting diode and/or said fluorescent material;

wherein said sealing resin layer includes said fluorescent material and is formed so as to constitute said lens; and

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.

11. The light emitting device according to claim 10, 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.

12. The light emitting device according to claim 10 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, and oxetane resin, acryl resin, polycarbonate resin and polyimide resin.

13. The light emitting device according to claim 10, wherein said sealing resin layer is formed into a lens shape by compression molding process.

14. The light emitting device according to claim 10, wherein said fluorescent material is not substantially included in the portion where said sealing resin layer is formed into a lens shape.

15. The light emitting device according to claim 10, 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.

16. The light emitting device according to claim 10, wherein said lens has substantially semi-cylindrical shape or substantially semi-spherical shape.