JP5182399B2 - White light emitting device - Google Patents

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) A white light-emitting element in which a blue or blue-violet light-emitting diode and one or more phosphors that absorb light emitted from the light-emitting diode and emit light in the visible range are combined. A white light-emitting element, wherein the phosphor is selected so that the luminescent color of the body is added to form a complementary color relationship.
(2) The phosphors so as to emit white light having emission chromaticity points in the region indicated by W in the chromaticity coordinates of FIG. The white light-emitting element according to (1) above, wherein

(3) 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, The white light emitting element as described in (1) or (2).
(4) The white light-emitting element according to any one of (1) to (3), wherein light having a wavelength of 400 to 500 nm of the light-emitting diode is used as excitation light of the phosphor.

(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 : Ce, Eu phosphor The white light-emitting element according to any one of (1) to (4), wherein the white light-emitting element is at least one kind of phosphor.
(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. It is an emission spectrum of the GaN diode which is an example of the blue light emitting diode used for the white light emitting element of this 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. It 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. Used in the present invention _{(Y 0.8, Gd 0.2) 3} Al 5 O 12: is an excitation spectra of Ce phosphor. 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, Eu 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, and when used in combination with a blue or blue-violet light emitting diode used simultaneously from one or more of these phosphors, The emission chromaticity point (x, y) of the emission color falls within the range of 0.21 ≦ x ≦ 0.48 and 0.19 ≦ y ≦ 0.45, and enters the region W in the chromaticity coordinates of FIG. The combination of phosphors is selected so as to exhibit almost white light emission.

  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 is dropped on a GaN blue light-emitting diode chip (4 mm square) having an 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 (9)

Is set on the frame _{(In x, Al y, Ga} 1-xy) N ( where, 0 ≦ x, 0 ≦ y , x + y ≦ 1) of the blue color represented by the composition formula of the light emitting diode and the light emitting diode on a mixed layer of a coating formed inorganic phosphor and a transparent resin, an inorganic phosphor mixture layer is a yellow light emitting part of the emission of the blue light-emitting diode as the excitation light, blue light-emitting diode Is a mixed layer of an inorganic phosphor and a transparent resin made of an inorganic phosphor that emits orange or red light and a transparent resin using a part of the light emitted as excitation light, and the inorganic phosphor that emits yellow light is (Y _{1- u, Gd u) 3 (Al} 1-v Ga v) 5 O 12: Ce, with Eu phosphor (wherein each u and v, 0 ≦ u ≦ 0.3, and 0 ≦ v ≦ 0.5) Having a mixed layer,
Of the luminescence of the light emitting diode, the luminescent color that is not absorbed by the inorganic phosphor and the luminescent color of the inorganic phosphor that is excited using a part of the luminescence of the light emitting diode are mixed, and the emission chromaticity point (x, y ) Emits white light falling within the range of 0.21 ≦ x ≦ 0.48 and 0.19 ≦ y ≦ 0.45, and the white light emission spectrum has an emission peak in the red light emitting region. Light emitting element. Mixed layer between the inorganic phosphor and a transparent resin, on the blue light emitting diode, a layer formed by coating by dropping a mixed solution of an inorganic phosphor and a transparent resin using a thin nozzle The white light emitting element according to claim 1, wherein   The white light emitting element of Claim 1 or 2 with which the mixed layer of the said inorganic fluorescent substance and transparent resin is coat | covered with the transparent resin mold.   The white light emitting element of Claim 1 or 2 with which the transparent resin or glass-made caps are attached to the upper part of the mixed layer of the said inorganic fluorescent substance and transparent resin. The inorganic phosphor that emits yellow light is Y ₃ Al ₅ O ₁₂ : Ce, Eu phosphor and / or (Y _0.8 , Gd _0.2 ) ₃ Al ₅ O ₁₂ : Ce phosphor. The white light emitting device according to item 1. Is set on the frame _{(In x, Al y, Ga} 1-xy) N ( where, 0 ≦ x, 0 ≦ y , x + y ≦ 1) of the blue color represented by the composition formula of the light emitting diodes and light emitting diodes on A method for producing a white light emitting device having a mixed layer of an inorganic phosphor and a transparent resin formed on the substrate,
Step of setting the blue light-emitting diodes on the frame,
To yellow emitting part of the emission of the blue light-emitting diode as the excitation _{light, (Y 1-u, Gd} u) 3 (Al 1-v Ga v) 5 O 12: Ce, Eu phosphor (where, u and v respectively, 0 ≦ u ≦ 0.3, and 0 ≦ v ≦ 0.5) is a inorganic phosphor and an orange or red emission to inorganic phosphors a part of the emission of the blue light-emitting diode as the excitation light Mixing with transparent resin,
The mixture of the obtained inorganic phosphor and a transparent resin, on the light emitting diodes of blue which is set on the frame, a mixed layer of an inorganic phosphor and a transparent resin is applied dropwise using a thin nozzle A light emitting diode that emits light that is not absorbed by the inorganic phosphor and a color that emits light from the inorganic phosphor that is excited by using part of the light emitted from the light emitting diode. Selecting a phosphor combination such that the chromaticity point (x, y) emits white light falling within the range of 0.21 ≦ x ≦ 0.48, 0.19 ≦ y ≦ 0.45; A method for manufacturing a white light emitting device, wherein the emission spectrum of the emitted light has a light emission peak in a red light emitting region. The manufacturing method of the white light emitting element of Claim 6 whose said transparent resin is transparent resin chosen from the group which consists of an acrylic resin, an epoxy resin, and a polyimide resin. The manufacturing method of the white light emitting element of Claim 6 or 7 which further includes the process of coat | covering the mixed layer of the said inorganic fluorescent substance and transparent resin with a transparent resin mold. The manufacturing method of the white light emitting element of any one of Claims 6-8 which further includes the process of attaching transparent resin or a glass cap to the upper part of the mixed layer of the said inorganic fluorescent substance and transparent resin.

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