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Light emitting apparatus and light emitting method

Inactive Publication Date: 2005-01-06
TOYODA GOSEI CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0025] It is an object of the invention to provide light emitting apparatus and light emitting method that can improve the color rendering property as to red color.

Problems solved by technology

Therefore, it lacks in color rendering property as to red color.
Also, oxide system phosphors generally have a problem that the spectrum intensity lowers significantly when the excitation wavelength exceeds 400 nm.
Therefore, in white LED that YAG system oxide phosphor is coated on the surface of InGaN system blue LED, the excitation energy of YAG system oxide phosphor does not coincide with the excitation energy of blue LED light source, and therefore the excitation energy cannot be efficiently converted.
Thus, it is difficult to enhance the brightness of white LED.

Method used

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  • Light emitting apparatus and light emitting method
  • Light emitting apparatus and light emitting method

Examples

Experimental program
Comparison scheme
Effect test

example 1

Preparation of Single-Phase α-Sialon

[0273] Examples (1-1) to (1-2) relate to preparation of single-phase α-sialon phosphor.

Example (1-1)

[0274] In preparing single-phase α-sialon phosphor, a ball mill apparatus (Fliche, planetary mill) is used to mix eight raw powders below. The mole ratio of chemical reagents in raw powder is described below (1) to (8). [0275] (1) Ca-α-sialon (Ca0.75Si0.75Al2.25N15.25O0.75) [0276] silicon nitride (Si3N4): aluminum nitride (AlN): calcium oxide (CaO)=13:9:3 [0277] (2) Eu-α-sialon (Eu0.5Si9.75Al2.25N15.25O0.75) [0278] silicon nitride (Si3N4): aluminum nitride (AlN): europium oxide (Eu2O3)=13:9:1 [0279] (3) Pr-α-sialon (Pr0.6Si9.75Al2.25N15.25O0.75) [0280] silicon nitride (Si3N4): aluminum nitride (AlN): praseodymium oxide (Pr6O11)=30:27:1 [0281] (4) Tb-α-sialon (Tb0.5Si9.75Al2.25N15.25O0.75) [0282] silicon nitride (Si3N4): aluminum nitride (AlN): terbium oxide (Tb4O7)=26:18:1 [0283] (5) Dy-α-sialon (Dy0.5Si9.75Al2.25N15.25O0.75) [0284] silicon nitri...

example 2

Preparation of Mixed α-Sialon Phosphor

[0340] Examples (2-1) to (2-5) relate to preparation of mixed α-sialon phosphor.

Example (2-1)

[0341] A mixture of Si3N4:Eu2O3:CaO:AlN=79.0:1.5:2.2:15.8 (molar ratio) (where calcium carbonate is added as CaO) is molded in a 10 mm diameter mold at 200 kg / cm2. Then, it is hot-press sintered at a pressure of 20 MPa in nitrogen atmosphere (1 atm) of 1700° C. for one hour. After the heating, the sintered body is powdered. As the result of powder X-ray diffraction analysis (Rigaku-sha, RINT2200), a material of 66 weight α-sialon, 18 weight % β-sialon and 15 weight % unreacted α-silicon nitride is obtained.

[0342] The entire powder composition is represented by α-sialon composition formula: (Ca0.11, Eu0.14)(Si, Al)12(O, N)16.

[0343]FIG. 38 is a spectrum diagram showing excitation spectra in Example 2-1 (full line (1)) and Example 2-2 (broken line (2)) of mixed α-sialon phosphor. FIG. 39 is a spectrum diagram showing emission spectra in Example 2-1 (fu...

example

(2-5)

[0356] Next, various Ca-α-sialon:Eu2+ phosphors are prepared and the fluorescent properties are measured. Samples A to G are single-phase α-sialon phosphors and Samples X to N are mixed α-sialon phosphors.

[0357] In preparing Ca-α-sialon:Eu2+ phosphor, starting materials, CaO, Si3N4, AlN, Al2O3 and Eu2O3 are weighed to have a given ratio, then wet-mixed with acetone. The mixed material powder is filled into Mo container, which is made using 0.1 mm thick Mo (module) plate. Then, it is sintered using RF is induction heater in argon atmosphere of 100-1750° C., atmospheric pressure for two hours, as shown by temperature profile in FIG. 40.

[0358]FIG. 41 is a table showing the composition (molar ratio) of Samples A to N, Ca-α-sialon:Eu2+ phosphors. FIG. 42 is a table showing atom % of Samples A to N. Ca-α-sialon:Eu2+ phosphors. In FIGS. 41 and 42, ※3015 means m=3.0 and n=1.5 in general formula of Ca-α-sialon; C0.5mSi12−(m+n)Al(m+n)OnN6−n. In like manner, 2010 means m=2.0 and n=1.0, ...

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Abstract

A light emitting apparatus has a light emitting element with an emission wavelength in the range of 360 to 550 nm and a rare-earth element doped oxide nitride phosphor or cerium ion doped lanthanum silicon nitride phosphor. Part of light radiated from the light emitting element is wavelength-converted by the phosphor. The light emitting apparatus radiates white light generated by a mixture of the wavelength-converted light and the other part of light radiated from the light emitting element.

Description

[0001] The present application is based on Japanese patent application No. 2002-349286, the entire contents of which are incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] This invention relates to light emitting apparatus and light emitting method that can be applied to a field requiring reliability such as disaster prevention light and traffic light, a field requiring light weight and small size such as in-vehicle light and LCD backlight and a field requiring visibility such as station guide plate, and more particularly to light emitting apparatus and light emitting method that has a structure with light emitting element and phosphor combined. [0004] 2. Description of the Related Art [0005] Conventionally, a light emitting apparatus is developed that part of light from light emitting element is wavelength-converted, then mixed with light not wavelength-converted to offer light with emission color different from that of the light e...

Claims

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Application Information

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IPC IPC(8): C09K11/08C09K11/64C09K11/77C09K11/79C09K11/80H01L33/06H01L33/32H01L33/50H01L33/56H01L33/60H01L33/62
CPCC04B35/584H01L2924/12041C04B35/6455C04B2235/3208C04B2235/3217C04B2235/3224C04B2235/3225C04B2235/3852C04B2235/3865C04B2235/3869C04B2235/3873C04B2235/766C04B2235/80C09K11/0883C09K11/7734G02F2001/133614H01L33/502H01L2224/49107H01L2924/01025H01L2924/01079Y02B20/181H01L2924/01019H01L2924/01066H01L2924/01068C04B35/597Y02B20/00G02F1/133614C09K11/77348
Inventor YOSHIMURA, NAOKISUEHIRO, YOSHINOBUTAKAHASHI, YUJIOTA, KOICHIMITOMO, MAMORUENDO, TADASHIKOMATSU, MASAKAZU
Owner TOYODA GOSEI CO LTD
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