LIGHT EMITTING DEVICE

• US 20080211386A1
• Filed: 12/26/2007
• Published: 09/04/2008
• Est. Priority Date: 12/26/2006
• Status: Active Grant

• Current Assignee: Seoul Semiconductor Co., Ltd.
• Original Assignee: Seoul Semiconductor Co., Ltd.
• Inventors: Choi, Hyuck Jung, Park, Kwang II
• Granted Patent: US 7,906,892 B2
• Time in Patent Office: Days
• US Class Current: 313/503
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• 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 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials

Abstract

Disclosed herein is a light emitting device. The light emitting device includes a light emitting diode disposed on a substrate to emit light of a first wavelength. A transparent molding part encloses the LED, a lower wavelength conversion material layer is disposed on the transparent molding part, and an upper wavelength conversion material layer is disposed on the lower wavelength conversion material layer. The lower wavelength conversion material layer contains a phosphor converting the light of the first wavelength into light of a second wavelength longer than the first wavelength, and the upper wavelength conversion material layer contains a phosphor converting the light of the first wavelength into light of a third wavelength, which is longer than the first wavelength but shorter than the second wavelength. Light produced via wavelength conversion is prevented from being lost by the phosphor. Light emitting devices including a multilayer reflection mirror are also disclosed.

Claims

1. A light emitting device comprising.

a light emitting diode disposed on a substrate to emit light of a first wavelength;

a transparent molding part enclosing the light emitting diode;

a lower wavelength conversion material layer disposed on the transparent molding part and containing a phosphor for converting the light of the first wavelength emitted from the light emitting diode into light of a second wavelength longer than the first wavelength; and

an upper wavelength conversion material layer disposed on the lower wavelength conversion material layer and containing a phosphor for converting the light of the first wavelength emitted from the light emitting diode into light of a third wavelength longer than the first wavelength, the third wavelength being shorter than the second wavelength.

2. The light emitting device according to claim 1, wherein the transparent molding part, the lower wavelength conversion material layer, and the upper wavelength conversion material layer have refractive indexes increasing in this order.

3. The light emitting device according to claim 1, wherein the lower wavelength conversion material layer comprises at least one opening through which the transparent molding part is exposed, the opening being filled with the upper wavelength conversion material layer.

4. The light emitting device according to claim 1, wherein the light of the first wavelength is blue light, the light of the second wavelength is red light, and the light of the third wavelength is green light.

5. The light emitting device according to claim 1, wherein the transparent molding part and the upper and lower wavelength conversion material layers are formed using a mold.

6. The light emitting device according to claim 5, wherein the transparent molding part is formed of silicone and the upper and lower wavelength conversion material layers are formed of epoxy.

7. The light emitting device according to claim 1, further comprising:

a lower dielectric multilayer reflection mirror interposed between the transparent molding part and the lower wavelength conversion material layer; and

an upper dielectric multilayer reflection mirror interposed between the lower wavelength conversion material layer and the upper wavelength conversion material layer.

8. The light emitting device according to claim 7, wherein each of dielectric layers in the lower dielectric multilayer reflection mirror has a thickness satisfying the relationship of (2m−

1)λ

₂/4n₂ (where n₂ indicates a refractive index of each of the dielectric layers, λ

₂ indicates the second wavelength, and m indicates an integer greater than or equal to

     1); and

wherein each of dielectric layers in the upper dielectric multilayer reflection mirror has a thickness satisfying the relationship of (2k−

1)λ

₃/4n₃ (where n₃ indicates a refractive index of each of the dielectric layers, λ

₃ indicates the third wavelength, and k indicates an integer greater than or equal to

     1).

9. The light emitting device according to claim 7, wherein the lower wavelength conversion material layer comprises at least one opening through which the transparent molding part is exposed, the opening being filled with the upper wavelength conversion material layer.

10. The light emitting device according to claim 9, wherein the upper dielectric multilayer reflection mirror extends into the opening to be interposed between the transparent molding part and the upper wavelength conversion material layer in the opening.

11. A light emitting device comprising:

a first light emitting diode disposed on a substrate to emit light of a first wavelength;

a wavelength conversion material enclosing the first light emitting diode and containing a phosphor for performing wavelength conversion of a portion of the light of the first wavelength emitted from the first light emitting diode;

a second light emitting diode separated from the first light emitting diode and disposed on the substrate to emit light of a second wavelength longer than the first wavelength;

a dielectric multilayer reflection mirror formed on the wavelength conversion material and including at least one pair of dielectric layers, one having a higher refractive index and the other having a lower refractive index, to reflect the light of the second wavelength incident on the wavelength conversion material.

12. The light emitting device according to claim 11, wherein each of the dielectric layers has a thickness “

d”

satisfying the relationship;

d=(2m−

1)λ

/4n (where n indicates a refractive index of each of the dielectric layers, λ

indicates the second wavelength, and m indicates an integer greater than or equal to

     1).

13. The light emitting device according to claim 11, further comprising:

a sealing resin enclosing the wavelength conversion material and the second light emitting diode, the sealing resin having a lower refractive index than the dielectric layer having the higher refractive index.

14. The light emitting device according to claim 11, further comprising:

another second light emitting diode symmetrically disposed to the second light emitting diode centered on the first light emitting diode.

15. The light emitting device according to claim 11, wherein the dielectric multilayer reflection mirror is partially formed on the wavelength conversion material.

16. The light emitting device according to claim 11, wherein the wavelength conversion material is a material layer formed on the light emitting diode and having a uniform thickness.

17. The light emitting device according to claim 11, wherein the first light emitting diode emits blue light or ultraviolet rays having a peak wavelength of 490 nm or less;

and

wherein the second light emitting diode emits red light having a peak wavelength of 580 nm or more.