White light emitting device comprising a plurality of light emitting diodes with different peak emission wavelengths and a wavelength converter

• US 8,071,988 B2
• Filed: 05/03/2005
• Issued: 12/06/2011
• Est. Priority Date: 05/06/2004
• Status: Active Grant

• Current Assignee: Seoul Semiconductor Co., Ltd.
• Original Assignee: Seoul Semiconductor Co., Ltd.
• Inventors: Lee, Chung-Hoon, Roth, Gundula, Tews, Walter
• Primary Examiner(s): Pizarro, Marcos D
• Assistant Examiner(s): MUNOZ, ANDRES F
• Application Number:
  US11/568,769
• Publication Number:
  US 20090262515A1
• Time in Patent Office: 2,408 Days
• Field of Search: None
• US Class Current: 257/88
• CPC Class Codes: H01L 2224/32013 the layer connector being larger than the bonding area, e.g. bond pad
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2224/8592 Applying permanent coating, e.g. protective coating
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• 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 33/486 adapted for surface mounting
• CPC Class Codes: H01L 33/50 Wavelength conversion elements
• CPC Class Codes: H01L 33/60 Reflective elements

Abstract

Disclosed herein is a light emitting device including one or more light emitting diodes to primarily emit light having different wavelengths in the wavelength range of ultraviolet rays and/or blue light, and a wavelength-conversion means to convert the primary light into secondary light in the visible light wavelength range. The light emitting device of the current invention has a high color temperature of 2000 to 8000 K or 10000 K and a high color rendering index of 90 or more, thus easily realizing desired emission on the color coordinate system. Therefore, the lighting emitting device is applicable to mobile phones, notebook computers, and keypads or backlight units for various electronic products, and, in particular, automobiles and exterior and interior lighting fixtures.

Claims

1. A light emitting device, comprising:

at least two light emitting diodes comprising a first light emitting diode and a second light emitting diode, the first light emitting diode to emit primary light having a first peak emission wavelength in a wavelength range of ultraviolet above 360 nm and below 380 nm, the second light emitting diode to emit primary light having a second peak emission wavelength in a wavelength range of blue light, and the first peak emission wavelength being different from the second peak emission wavelength; and

a wavelength converter to convert the primary light of the first peak emission wavelength and the second peak emission wavelength into secondary light in a visible light wavelength range,

wherein the light emitting device emits white light comprising the primary light of the second peak emission wavelength and the secondary light converted from the primary light of the first peak emission wavelength and the primary light of the second peak emission wavelength by the wavelength converter.

2. The device according to claim 1, wherein the at least two light emitting diodes and the wavelength converter are mounted in a single package.

3. The device according to claim 2, wherein the single package is formed into a chip package, which comprises a substrate, the at least two light emitting diodes mounted on the substrate, and the wavelength converter disposed on the at least two light emitting diodes.

4. The device according to claim 3, wherein the substrate comprises a metal.

5. The device according to claim 4, further comprising a radiation sheet mounted on the substrate, wherein the radiation sheet comprises a metal.

6. The device according to claim 3, further comprising a molded part to enclose the at least two light emitting diodes and the wavelength converter on the substrate.

7. The device according to claim 6, wherein the wavelength converter is uniformly distributed in the molded part.

8. The device according to claim 2, wherein the single package is formed into a top package, which comprises a substrate having a reflector formed thereon, the at least two light emitting diodes mounted on the substrate, and the wavelength converter disposed on the at least two light emitting diodes.

9. The device according to claim 2, wherein the single package is formed into a lamp package, the lamp package comprising a pair of lead electrodes, the at least two light emitting diodes mounted on one of the pair of lead electrodes, the wavelength converter disposed on the at least two light emitting diodes, and a molded part to enclose the at least two light emitting diodes and the wavelength converter.

10. The device according to claim 2, wherein the single package is formed into a high output package, the high output package comprising at least two light emitting diodes, the wavelength converter disposed on the at least two light emitting diodes, and a heat sink.

11. The device according to claim 10, further comprising a radiation sheet.

12. The device according to claim 1, wherein the wavelength converter comprises a plurality of phosphors having different properties.

13. The device according to claim 1, wherein the wavelength converter is disposed on at least one of a side surface, an upper surface, and a lower surface of at least one of the at least two light emitting diodes, or is used in a mixture with an adhesive or a molding material.

14. The device according to claim 1, wherein the wavelength converter comprises

a first phosphor having a peak emission wavelength between 440 and 500 nm,

a second phosphor having a peak emission wavelength between 500 and 590 nm, and

a third phosphor having a peak emission wavelength between 590 and 700 nm.

15. The device according to claim 14, wherein at least one of the first phosphor, the second phosphor and the third phosphor comprises a plurality of phosphor components having different properties.

16. The device according to claim 1, wherein the at least two light emitting diodes each comprise a substrate comprising silicon carbide or sapphire and a nitride epitaxial layer formed on the substrate.

17. The device according to claim 1, wherein the wavelength converter comprises at least one of

a first phosphor having a peak emission wavelength between 440 and 500 nm,

a second phosphor having a peak emission wavelength between 601 and 700 nm,

and mixtures thereof.

18. The device according to claim 1, wherein the light emitting device further comprises a third light emitting diode to emit primary light having a third peak emission wavelength between 430 and 500 nm, the third peak emission wavelength being different from the first emission wavelength and the second emission wavelength, and

wherein the second light emitting diode comprises a peak emission wavelength between 400 and 450 nm.