Light emitting element and lighting instrument

• US 7,573,190 B2
• Filed: 02/15/2005
• Issued: 08/11/2009
• Est. Priority Date: 02/18/2004
• Status: Active Grant

• Current Assignee: National Institute for Materials Science
• Original Assignee: National Institute for Materials Science
• Inventors: Yamamoto, Hajime, Sakuma, Ken, Ueda, Kyota, Hirosaki, Naoto
• Primary Examiner(s): MACCHIAROLO, PETER J
• Application Number:
  US10/588,007
• Publication Number:
  US 20070159091A1
• Time in Patent Office: 1,638 Days
• Field of Search: 313/512, 313484-487, 313/489, 313/467, 313/468, 313/499, 313501-503, 257/98, 257/99, 257/100, 257/80, 257/79, 257/783, 362/235, 362/227, 362/231, 362/293, 362/545, 362/555, 362/800, 345/44, 345/46, 345/80, 252/301.4 F
• US Class Current: 313/503
• CPC Class Codes: C09K 11/0883 Arsenides; Nitrides; Phosphides
• CPC Class Codes: C09K 11/77348 Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• 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 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 33/502 Wavelength conversion materials
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

The present invention provides a white light emitting diode for emitting white light with warmness at a higher luminance, and an intermediate color light emitting diode satisfying light emission with diversified color tones at a higher luminance. A fluorescent material which emits yellowish red or red light and has a CaAlSiN₃ crystal phase including, dissolved therein in a solid state, one or more element(s) selected from Mn, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. The fluorescent material is mixed with another fluorescent material emitting green, yellowish green, or yellow light, and the mixed phosphor is combined with a semiconductor light emitting element for emitting bluish purple or blue light, to fabricate a white light emitting diode which efficiently emits a warm white light with a high efficiency.

Claims

1. A visible light emitting device, comprising at least:

a semiconductor light emitting element configured to emit bluish purple or blue light;

a support member formed with a depression for placing said semiconductor light emitting element therein, said depression constituted as a visible wavelength light reflective surface;

terminals configured to supply electric power to said semiconductor light emitting element; and

a phosphor configured to absorb a part or the whole of light emitted from said light emitting element, and to emit fluorescence at a wavelength different from that of the absorbed light, the phosphor including X % of a first fluorescent material configured to emit green, yellowish green, or yellow light, and Y % of a second fluorescent material configured to emit yellowish red or red light, at a mixing ratio meeting a condition of 0≦

X<

100, 0<

Y≦

100, and 0<

X+Y≦

100,

wherein said second fluorescent material comprises a CaAlSiN₃ crystal phase including, dissolved therein in a solid state, one or more element(s) selected from Mn, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

2. The light emitting device of claim 1, wherein said second fluorescent material contains at least Eu.

3. The light emitting device to emit arbitrary colors of claim 1, wherein said semiconductor light emitting element is a blue light emitting diode having a main emission wavelength of 380 nm to 485 nm.

8. The light emitting device to emit arbitrary colors of claim 1, wherein said semiconductor light emitting element is a light emitting semiconductor diode element made of InGaN.

9. The light emitting device to emit arbitrary colors of claim 1, wherein said semiconductor light emitting element is a light emitting semiconductor diode element comprising a substrate made of sapphire.

10. The light emitting device to emit arbitrary colors of claim 1, wherein said first fluorescent material is a phosphor having a main emission wavelength of 495 nm to 585 nm.

11. The light emitting device to emit arbitrary colors of claim 10, wherein said first fluorescent material is a yttrium/aluminum/garnet based phosphor.

12. The light emitting device to emit arbitrary colors of claim 1, wherein said second fluorescent material is a phosphor having a main emission wavelength in a range of “

red”

by a general chromaticity classification, according to system color names of JIS Z8110.

13. The light emitting device to emit arbitrary colors of claim 1, wherein said phosphors are dispersed in a transparent material.

14. The light emitting device to emit arbitrary colors of claim 13, wherein said transparent material is an epoxy resin, a silicone resin, or a glass.

4. A lighting apparatus, comprising three or more light source units, each light source unit including at least one light emitting device,

said light emitting device including at least:

a semiconductor light emitting element configured to emit bluish purple or blue light;

a support member formed with a depression for placing said semiconductor light emitting element therein, said depression constituted as a visible wavelength light reflective surface;

terminals configured to supply electric power to said semiconductor light emitting element; and

a phosphor configured to absorb a part or the whole of light emitted from said light emitting element, and to emit fluorescence at a wavelength different from that of the absorbed light, the phosphor including at least one of a first fluorescent material configured to emit green, yellowish green, or yellow light, and a second fluorescent material mainly including CaAlSiN₃ crystal phase and configured to emit yellowish red or red light,

wherein each of said light source units or each of said light emitting device has a mixing ratio of said first fluorescent material to said second fluorescent material, which mixing ratio is different from those of the other light source units or other light emitting devices, in a manner that different light emission colors are visible, site by site of said lighting apparatus.

5. The lighting apparatus of claim 4, wherein the phosphor includes X % of said first fluorescent material, and Y % of said second fluorescent material, at a mixing ratio meeting a condition of 0≦

X<

100, 0<

Y≦

100, and 0<

X+Y≦

100, and

wherein said second fluorescent material comprises said CaAlSiN₃ crystal phase including, dissolved therein in a solid state, one or more kinds of element(s) selected from Mn, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

6. The lighting apparatus of claim 5, wherein each light source unit is optically connected with a light guiding member including a scattering element.

7. The lighting apparatus of claim 6, wherein said scattering element comprises air bubbles, and said light guiding member is a rod-like member made of transparent resin.