JP2014112729A - White light emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact white light emitting element which uses a blue or violet light emitting diode and has high luminance.SOLUTION: A white light emitting element comprises a combination of a blue or violet light emitting diode and one or more kinds of phosphor which absorb light emitted by the light emitting diode and emits light in a visible range. In the white light emitting element, the phosphor is selected so that light emission color of the light emitting diode and the light emission color of the phosphor have complementary color relation with each other, and white light having a light emission chromaticity point in a region shown by W on chromaticity coordinates in Fig.1 is emitted.

Description

  The present invention relates to a white light-emitting element that can be used as an indoor, outdoor, or underwater display, or as a light source or a backlight for a display, and has high brightness and excellent weather resistance and life characteristics.

  Conventionally, only green to red light emitting elements have been put into practical use as visible light emitting diodes, but in recent years blue light emitting diodes have begun to be put into practical use, and accordingly, blue, green and red light emitting elements are combined into one pixel. A large full-color display combined with the

  On the other hand, in order to obtain a white light emitting element that emits white light with a diode alone, each light emitting element of blue, green, and red can emit light at the same time, and can be mixed to whiten, but a small white display, Combining the above-described light emitting elements to obtain a light source or a backlight such as a liquid crystal display has the disadvantage that the pixels themselves become too large, and that the driving control becomes complicated if the driving conditions for each color are different. It was.

  On the other hand, Patent Document 1, Patent Document 2, and the like describe a light emitting element in which a (Ga, Al) N blue light emitting diode and a fluorescent pigment or a fluorescent material are combined. There is no mention of obtaining luminescence.

JP-A-5-152609 JP-A-7-99345

  Therefore, the present invention intends to provide a high-intensity and compact white light-emitting element using a blue or blue-violet light-emitting diode.

  As a result of intensive studies to achieve the above object, the present inventors have focused on the fact that blue or blue-violet light emitting diodes exhibit sharp blue light emission with high brightness and narrow bandwidth. Investigate phosphors that can be excited by light emission, and find a phosphor that emits white light by adding colors when mixing the light emission color of the diode and the light emission color of the phosphor. Made it possible to provide

That is, the configuration of the present invention is as follows.
(1) and blue color light-emitting diodes, in the white light emitting device emitting absorbed by the combination of two kinds or more of phosphors you emitting in the visible region of the light emitting diode, the emission color of the light emitting diode and the phosphor The phosphors are selected so that they are complementary to each other and have a complementary color relationship ,
The phosphor includes a phosphor that emits yellow light using part of the light emission of the light emitting diode as excitation light, and a phosphor that emits red light using part of the light emission of the light emitting diode as excitation light, and the phosphor that emits yellow light _{(Y 1-u, Gd u} ) 3 (AI 1-v Ga v) 5 O 12: Ce, Eu phosphor (where, u and v, respectively, 0 ≦ u ≦ 0.3, and 0 ≦ v ≦ 0 .5),
The emission chromaticity point (x, y) of the emission color of the white light emitting element is 0.21 ≦ x ≦ 0.48, 0.19.
≦ y ≦ 0.45, the emission spectrum of the emission color has an emission peak in the red emission region,
The white light emitting element characterized by the above-mentioned.
(2) the light emitting diode _{(In x, Al y, Ga} 1-xy) N ( where, 0 ≦ x, 0 ≦ y , x + y ≦ 1) white light emitting device according to a above (1).

(3) The white light emitting element according to (1) or (2), wherein the light emitting diode and the phosphor are covered with a transparent resin mold.
(4) The white light-emitting element according to (1) or (2), wherein a transparent resin or a glass cap is attached to the top of the light-emitting diode and the phosphor.
(5) The above-mentioned (1), wherein the phosphor emitting yellow light is Y ₃ AI ₅ O ₁₂ : Ce, Eu phosphor and / or Y _0.8 , Gd _0.2 ) ₃ AI ₅ O ₁₂ : Ce phosphor. The white light emitting element according to any one of (4) to (4).

(5) The phosphor is a (Zn, Cd) S: Ag, Cl phosphor, (Zn, Cd) S: Ag, Al phosphor, (Zn, Cd) S: Cu, Al phosphor, (Zn, Cd) ) S: Cu, Cl phosphor, (Zn, Cd) S: Cu, Au, Al phosphor and (Y, Gd) ₃ (Al, Ga) ₅ O ₁₂
The white light-emitting element according to any one of (1) to (4) above, wherein the white light-emitting element is at least one phosphor selected from the group of Ce and Eu phosphors.
(6) selected from the group of the light emitting diode _{(In x, Al y, Ga} 1-xy) N ( where, 0 ≦ x, 0 ≦ y , x + y ≦ 1), SiC, BN and Zn (S, Se) The white light-emitting element according to any one of (1) to (5) above, wherein the white light-emitting element is any one of the above-described (1) to (5).

  By adopting the above configuration, the present invention obtains a compact, inexpensive, and simple white light emitting element that cannot be obtained by a conventional combination of blue, green and red light emitting diodes or a combination of blue and yellow light emitting diodes. This greatly contributes to the diversification and diversification of the display.

It is the figure which showed the range W of the luminescent color of the white light emitting element of this invention by the chromaticity coordinate. It is the schematic sectional drawing which illustrated the structure of the white light emitting element of this invention. 2 is an emission spectrum of a GaN diode which is an example of a blue light emitting diode used in the white light emitting element of the present invention. It is an excitation spectrum of the ZnS: Ag, Cl phosphor used in the present invention. It is an excitation spectrum of ZnS; Cu, Al phosphor used in the present invention. This is an excitation spectrum of a (Zn _0.15 , Cd _0.85 ) S: Ag, Cl phosphor used in the present invention. It is an excitation spectrum of a Y ₃ Al ₅ O ₁₂ : Ce, Eu phosphor used in the present invention. It is an excitation spectrum of (Y _0.8 , Gd _0.2 ) ₃ Al ₅ O ₁₂ : Ce phosphor used in the present invention. It is an emission spectrum when the ZnS: Ag, Cl phosphor used in the present invention is excited with 450 nm light. It is an emission spectrum when the ZnS: Cu, Al phosphor used in the present invention is excited with 450 nm light. It is an emission spectrum when the (Zn _0.15 , Cd _0.85 ) S: Ag, Cl phosphor used in the present invention is excited with 450 nm light. It is an emission spectrum when the Y ₃ Al ₅ O ₁₂ : Ce, Eu phosphor used in the present invention is excited with 450 nm light. It is an emission spectrum when the (Y _0.8 , Gd _0.2 ) ₃ Al ₅ O ₁₂ : Ce phosphor used in the present invention is excited with 450 nm light. In embodiments, GaN blue light-emitting diodes and _{(Y 0.8, Gd 0.2) 3} Al 5 O 12: an emission spectrum of a white light emitting device that combines Ce phosphor. In an Example, it is an emission spectrum of the white light emitting element which combined the GaN blue light emitting diode, ZnS: Cu, Al fluorescent substance, and ( _Zn0.15 , _Cd0.85 ) S: Ag, Cl fluorescent substance. In embodiments, a GaN blue light-emitting _{diodes, Y 3 Al 5 O 12:} Ce, E u phosphor and _{(Zn 0.15, Cd 0.85) S} : Ag, an emission spectrum of a white light emitting device that combines Cl phosphor.

  The present invention is a white light-emitting element combining a blue or blue-violet light-emitting diode and one or more phosphors, and selects a phosphor that absorbs light emitted from the light-emitting diode and emits light in the visible region. In addition, by selecting phosphors that are complementary to each other when the emission colors of the light-emitting diode and the phosphor are added, high-luminance white light emission is made possible.

  FIG. 2 is a schematic view showing a cross-sectional structure as an example of the white light emitting device of the present invention. A blue or blue-violet light emitting diode chip 4 is set on the frame 3, a phosphor is applied thereon, the whole is covered with a transparent resin mold, and electrode terminals 5 and 6 from the chip are drawn to form an element. Is.

Blue or blue-violet light emitting diodes used in the present invention include (In _x , Al _y , Ga _1-xy ) N (where 0 ≦ x, 0 ≦ y, x + y ≦ 1), SiC, BN and Zn (S , Se) and the like, and combinations thereof can also be used. FIG. 3 shows an emission spectrum of the GaN light emitting diode. The emission peak wavelength of this emission spectrum is about 450 nm. The phosphor of the present invention is excited by using a part of the light emitted from the light emitting diode. As a result, the emission color of the light emitting diode and the emission color of the excited phosphor are mixed. When the two are in a complementary color relationship, white light is emitted due to the mixed color.

  The phosphor used in the present invention is a phosphor having an excitation wavelength in a range of approximately 400 to 500 nm, which emits a part of the light emission of a blue or blue-violet light emitting diode as excitation light, and the emission color of the light emitting diode A phosphor is selected such that the emission color of the phosphor has a complementary color relationship and white color is exhibited by color mixture. Specific examples include phosphors represented by the following composition formula that absorb light emitted from the light-emitting diode and emit blue to red visible light.

Blue-emitting (Zn _1-x , Cd _x ) S: Ag, Cl phosphor (where 0 ≦ x ≦ 0.07), (Zn _1-x , Cd _x ) S: Ag, Al phosphor (where 0 ≦ x ≦ 0.07) and the like. (Zn _1-x , Cd _x ) S: Cu, Al phosphor (provided that 0 ≦ x ≦ 0.15), (Zn _1-x , Cd _x ) S: Cu, Cl phosphor (provided that 0 ≦ x ≦ 0.20), (Zn _1−x , Cd _x ) S: Ag, Cl phosphor (where 0.07 ≦ x ≦ 0.50), (Zn _1−x , Cd _x ) S: Ag, Al phosphor (however, 0.07 ≦ x ≦ 0.50), ZnS: Au, Cu, Al phosphor, etc.

Yellow-emitting (Y _1-u , Gd _u ) ₃ (Al _1-v , Ga _v ) ₅ O ₁₂ : Ce, Eu phosphor (where 0 ≦ u ≦ 0.3, 0 ≦ v ≦ 0.5) etc. (Zn _1-x , Cd _x ) S: Cu, Al phosphor (provided that 0.15 ≦ x ≦ 0.30), (Zn _1-x , Cd _x ) S: Cu, Cl fluorescence emitting orange or red light Body (provided that 0.20 ≦ x ≦ 0.30), (Zn _1−x , Cd _x ) S: Ag, Cl phosphor (provided that 0.50 ≦ x ≦ 0.90), (Zn _1−x , Cd _x ) S: Ag, Al phosphor (provided that 0.50 ≦ x ≦ 0.90), etc.

The phosphor of the present invention has an excitation wavelength in the range of 400 to 500 nm.
When used in combination with a blue or blue-violet light emitting diode used at the same time from among two or more species, the emission chromaticity point (x, y) of the emitted color is 0.21 ≦ x ≦ 0.48, 0. The combination of phosphors is selected so that it falls within the range of 19 ≦ y ≦ 0.45, enters the region W in the chromaticity coordinates of FIG. 1, and emits substantially white light.

  Note that when the values of x, y, u, and v are out of the above range depending on the type of phosphor used in combination with the light emitting diode and the mixing ratio of the mixed phosphor, the chromaticity and luminance of the white light emitting element obtained are The characteristics of the invention cannot be obtained.

  The production of the white light emitting device of the present invention is performed by mixing a predetermined amount of a phosphor, which is mixed with a transparent resin such as an acrylic resin, an epoxy resin, or a polyimide resin diluted in an organic solvent such as acetone or toluene. Apply several tens of micrograms on a light emitting diode chip from such a thin nozzle. Further, a water-soluble resin may be used instead of the above resin, or an alkali silicate may be used.

  After the light emitting diode chip coated with the phosphor is dried, a transparent resin such as an epoxy resin or a glass cap is attached to the phosphor coated portion of the light emitting chip to complete a white light emitting element. The light emitting device of the present invention can emit white light by applying a rated DC load of up to 5 V and 30 mA to emit light.

4 to 8 illustrate the excitation spectrum for giving the main light emission of the phosphor used in the present invention, FIG. 4 is a ZnS: Ag, Cl phosphor, and FIG. 5 is a ZnS; Cu, Al phosphor. 6 shows (Zn _0.15 , Cd _0.85 ) S: Ag, Cl phosphor, FIG. 7 shows Y ₃ Al ₅ O ₁₂ : Ce, Eu phosphor, and FIG. 8 shows (Y _0.8 , Gd _0.2 ) ₃ Al ₅ O _12. : Explains excitation spectrum of Ce phosphor.

9 to 13 show emission spectra when the above phosphors are excited at 450 nm which is an emission peak of a commercially available GaN blue light emitting diode, and FIG. 9 shows ZnS: Ag, Cl phosphors, FIG. 10 is ZnS; Cu, Al phosphor, FIG. 11 is (Zn _0.15 , Cd _0.85 ) S: Ag, Cl phosphor, FIG. 12 is Y ₃ Al ₅ O ₁₂ : Ce, Eu phosphor, and FIG. 13 is (Y _0.8 , Gd _0.2 ) ₃ Al ₅ O ₁₂ : Ce emission spectrum.

14 to 16 show the emission spectrum of the white light emitting device of the present invention combined with a GaN blue light emitting diode, and the phosphor used in FIG. 14 is (Y _0.8 , Gd _0.2 ) ₃ Al ₅ O ₁₂ : The phosphors used in FIG. 15 are ZnS: Cu, Al and (Zn _0.15 , Cd _0.85 ) S: Ag, Cl, and the phosphors used in FIG. 16 are Y ₃ Al ₅ O ₁₂ : Ce, Eu and (Zn _0.15 , Cd _0.85 ) S: Ag, Cl.

[Example 1]
Epoxy resin (NT8014, manufactured by Nitto Denko Corporation) 1 gr
1g of acid anhydride curing agent
Phosphor _{(Y 0.8, Gd 0.2) 3} Al 5 O 12: Ce 2mg
Using a syringe, the mixture of the above phosphor and resin was dropped on a GaN blue light-emitting diode chip (0.4 mm square) having an emission peak at 450 nm, dried, and then further semicircular transparent A white light emitting device was obtained by covering with an epoxy resin cap.
This white light emitting element shows the emission spectrum of FIG. 14, and its emission chromaticity W ₃ is x = 0.27.
5, y = 0.335. The emission chromaticity of the phosphor was Y _1.

[Example 2]
Acrylic resin (Nihon Carbite Industries, Nikkasol, solid content 50%) 1gr
Deionized water 5gr
Phosphor ZnS: Cu, Al 1 mg
(Zn _0.15 , Cd _0.85 ) S: Ag, Cl 0.5 mg
Using a syringe, the mixture of the above phosphor and resin was dropped on a GaN blue light-emitting diode chip (0.4 mm square) having an emission peak at 450 nm, dried, and then further semicircular transparent A white light emitting device was obtained by covering with an epoxy resin cap. This white light emitting element shows the emission spectrum of FIG. 15, and its emission chromaticity W ₂ is x = 0.237, y = 0.
274. The emission chromaticity of the phosphor was G ₂ and R.

Example 3
1 glass of water glass (Okaseal A, manufactured by Tokyo Ohkasha)
Barium acetate 10gr
Phosphor Y ₃ Al ₅ O ₁₂ : Ce, Eu _0.001 1mg
(Zn _0.15 , Cd _0.85 ) S: Ag, Cl 0.5 mg
Using a syringe, the mixture of the above phosphor and water glass was dropped on a GaN blue light-emitting diode chip (4 mm square) having a light emission peak at 450 nm, dried, and then further semicircular transparent epoxy resin A white light emitting device was obtained by covering with a cap.
This white light emitting element shows the emission spectrum of FIG. 16, and its emission chromaticity W ₁ is x = 0.22.
3, y = 0.253. The emission chromaticity of the phosphor was Y ₂ and R.

1. 1. Resin mold 2. Phosphor 3. Frame 4. 4. Light emitting diode chip Electrode terminal

Claims (5)

And blue light emitting diodes, the white light emitting element emitting absorbed by the combination of two kinds or more of phosphors you emitting in the visible region of the light emitting diode, the emission color of the light emitting diode and the phosphor additive color And select the phosphors so that they are complementary to each other .
The phosphor includes a phosphor that emits yellow light using part of the light emission of the light emitting diode as excitation light, and a phosphor that emits red light using part of the light emission of the light emitting diode as excitation light, and the phosphor that emits yellow light _{(Y 1-u, Gd u} ) 3 (AI 1-v Ga v) 5 O 12: Ce, Eu phosphor (where, u and v, respectively, 0 ≦ u ≦ 0.3, and 0 ≦ v ≦ 0 .5),
The emission chromaticity point (x, y) of the emission color of the white light emitting element is in the range of 0.21 ≦ x ≦ 0.48, 0.19 ≦ y ≦ 0.45, and the emission spectrum of the emission color is red. Having an emission peak in the emission region,
The white light emitting element characterized by the above-mentioned. The light emitting diode _{(In x, Al y, Ga} 1-xy) N ( where, 0 ≦ x, 0 ≦ y , x + y ≦ 1) a white light emitting device according to claim 1. The white light emitting element according to claim 1, wherein the light emitting diode and the phosphor are covered with a transparent resin mold. The white light emitting element according to claim 1 or 2, wherein a transparent resin or a glass cap is attached to the top of the light emitting diode and the phosphor.   The phosphor emitting yellow light is Y ₃ AI ₅ O ₁₂ : Ce, Eu phosphor and / or Y _0.8 , Gd _0.2 ) ₃ AI ₅ O ₁₂ The white light-emitting element according to claim 1, wherein the white light-emitting element is a Ce phosphor.

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