JP4661419B2 - Phosphor and light emitting device using the same - Google Patents

Description

The present invention relates to a phosphor with high luminous efficiency and a light emitting device using the phosphor. Specifically, red or orange light-emitting phosphors exhibiting high-efficiency light emission and the red or orange light-emitting phosphors used as wavelength conversion materials for wavelength-converting at least part of light from an excitation light source such as a semiconductor light-emitting element were used. The present invention relates to a light emitting device with high efficiency and high color rendering.
The present invention also relates to an illumination device and an image display device using such a light emitting device.

  Excitation of phosphors of three colors of blue, green, and red with ultraviolet light generated by mercury discharge to generate white light is a technology realized in a fluorescent lamp. In recent years, blue light-emitting GaN-based semiconductor light-emitting elements with high luminous efficiency have been developed. The blue light is used to excite a phosphor that emits yellow light, and white light is emitted using the complementary color relationship between blue and yellow. A method of obtaining has been disclosed. However, it has been pointed out that in this method, there is no red component in white light and color rendering is inferior. For this reason, a method has been proposed in which phosphors of three colors, blue, green, and red, are excited by a semiconductor light emitting element that emits near ultraviolet light based on the same principle as a fluorescent lamp. Although this method is still inferior in efficiency and color rendering as compared with a fluorescent lamp, if the semiconductor light emitting device and the phosphor are improved, the performance of the fluorescent lamp can be surpassed.

As red to orange light-emitting phosphors that can be used for this purpose, phosphors doped with Eu ²⁺ and Mn ²⁺ are known. In this phosphor, Eu ²⁺ generally acts as a sensitizer and Mn ²⁺ generally acts as an activator. That is, Eu ²⁺ absorbs photons emitted from the excitation source and transmits the absorbed energy to Mn ²⁺ . As a result, Mn ²⁺ enters an excited state and emits red or orange light. Eu is usually more trivalent than bivalent, and Eu ₂ O ₃ is used as the Eu source. Therefore, in order to convert Eu into a divalent ion that effectively acts as a sensitizer for Mn, it is necessary to reduce the trivalent ion. However, in the past, there was no means for clarifying how much of the total Eu was reduced to divalent, and guidelines for manufacturing process design were not clear.

Regarding the quantification of Eu ²⁺ , as disclosed in Non-Patent Document 1, an X-ray Absorption Near Edge Structure (hereinafter abbreviated as “XANES”) analysis of Eu X-ray absorption near-end fine structure spectrum (X-ray Absorption Near Edge Structure) Eu ²⁺ is quantified. For example, Patent Document 1 discloses that a phosphor having a composition formula represented by Ca _0.92 Sr _0.05 Eu _0.03 MgSi ₂ O ₆ was measured, and that En ²⁺ was 78% of the total Eu. is doing. However, this phosphor has been developed for a plasma display panel excited by ultraviolet rays in the vacuum ultraviolet region (wavelength 145 nm or 172 nm), and is a phosphor having a low Eu content of 0.03.
JP 2005-68169 A Yutaka Shimizukawa and two others, "Local structure of Eu2 + -doped strontium aluminosilicate glass exhibiting long afterglow", 1999, p. 50, Lectures of Annual Meeting of the Ceramic Society of Japan

The present invention has been made in view of the above-described conventional situation, and clarifies the amount of Eu ²⁺ required in a phosphor in order to realize a phosphor having high emission efficiency by excitation light in the near ultraviolet region. Thus, an object is to achieve stable production of highly efficient phosphors.
Another object of the present invention is to provide a light-emitting device having high efficiency and high color rendering using such a phosphor with high light-emitting efficiency, and an illumination device and an image display device using the light-emitting device.

The present inventors specify a composition range in which high-efficiency luminescence can be obtained in a phosphor composed of europium / manganese co-activated alkaline earth metal silicate, and quantify the amount of Eu ²⁺ , thereby achieving optimum production. A process was realized to complete the present invention.
That is, the gist of the present invention is as follows.

[1] Composition _formula: In _{(Ba a Ca b Sr c Mg} d Eu x Mn y) phosphor consisting activated alkaline earth metal silicate europium-manganese co represented by SiO _4, in the composition formula, coefficient a, b, c, d, x and y are a + b + c + d + x + y = 2
0 <a <2
0 <b <2
0 ≦ c <0.5
0 ≦ d <0.5
0 <x ≦ 0.5
0 <y ≦ 0.5
And 50% or more of the total Eu ions are Eu ²⁺ ions.

[2] The phosphor according to [1], which emits red or orange light.

[3] A method for producing a phosphor according to [1] or [2], wherein the element source compounds of Ba, Ca, Eu, Mn and Si, and the elements of Sr and / or Mg used as necessary A method for producing a phosphor, comprising firing a mixture with a source compound in a non-oxidizing gas atmosphere in the presence of carbon.

[4] The method for producing a phosphor according to [3], wherein the non-oxidizing gas is a reducing gas and / or an inert gas.

[5] In a light-emitting device having an excitation light source and a phosphor that converts the wavelength of at least part of light from the excitation light source, the phosphor described in [1] or [2] or [3] Or a phosphor obtained by the production method according to [4].

[6] An illumination device including the light-emitting device according to [5].

[7] An image display device comprising the light emitting device according to [5].

As described above, in order to obtain a highly efficient red or orange light emitting phosphor, Eu added as a raw material is reduced to Eu ²⁺ because it acts as a sensitizer for Mn ²⁺ ions emitting red to orange light. There is a need.

According to the present invention, in a europium / manganese co-activated alkaline earth metal silicate phosphor having a specific composition, it is necessary and sufficient in the production process by quantifying Eu ²⁺ to be present in the phosphor. Therefore, it is possible to design a highly efficient phosphor, and it is possible to stably produce a highly efficient phosphor, particularly a red or orange light-emitting phosphor, by an optimum production process.
By using the red or orange light emitting phosphor, a white light emitting device with high efficiency and high color rendering can be provided, and a high performance lighting device and image display device are provided using the light emitting device. .

  Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the present invention.

[Phosphor]
Phosphor of the present invention, the europium-manganese co-activated alkaline earth metal silicate _{(Ba a Ca b Sr c Mg} d Eu x Mn y) SiO 4, coefficients a, b, c, d, x and y a + b + c + d + x + y = 2
0 <a <2
0 <b <2
0 ≦ c <0.5
0 ≦ d <0.5
0 <x ≦ 0.5
0 <y ≦ 0.5
And 50% or more of the total Eu ions are Eu ²⁺ ions.

In the composition formula _{(Ba a Ca b Sr c Mg} d Eu x Mn y) SiO 4, alkaline earth metals Ba, Ca, Sr, Mg, and the Eu and Mn as an activator, the molar number of total a + b + c + d + x + y = 2 To establish. However, since the value of a + b + c + d + x + y may deviate by about ± 1% depending on the purity of the element source compound, experimental error, etc., the case of deviation of about ± 1% is also included in the scope of the present invention.

The coefficient a of Ba is normally 0 <a <2, and preferably 0.5 <a <2.0 from the viewpoint of red to orange light emission intensity.
The coefficient b of Ca is usually 0 <b <2, and preferably 0 <b <1.5 from the viewpoint of red to orange emission intensity.
The coefficient c of Sr is usually 0 ≦ c <0.5, and preferably 0 ≦ c <0.25 in terms of red to orange emission intensity.
The coefficient d of Mg is usually 0 ≦ d <0.5, and preferably 0 ≦ d <0.25 from the viewpoint of red or orange emission intensity.
The Eu coefficient x is usually 0 <x ≦ 0.5, and preferably 0.05 ≦ x ≦ 0.4 from the viewpoint of the emission intensity of red to orange.
The coefficient y of Mn is usually 0 <y ≦ 0.3, and preferably 0.05 ≦ y ≦ 0.2 from the viewpoint of red or orange emission intensity.

  The ratio of Ba to Ca (molar ratio a / b) is preferably 1.50 or more and 4.13 or less, more preferably 2.8 or more and 3.2 or less. From the aspect of red to orange emission intensity, the ratio of the total of Ba and Ca in the alkaline earth metal is preferably 70 mol% or more, more preferably 90 mol% or more, and 100 mol%. Is more preferable.

  Si can be partially substituted by Ge or other tetravalent elements, but preferably contains 90 mol% or more of Si and Ge in total, and contains 80 mol% or more of Si in terms of red to orange emission intensity, etc. It is more preferable that all are made of Si. Examples of tetravalent elements other than Si and Ge include Zn, Ti, Hf, and the like, and these may be included within a range that does not impair performance in terms of red or orange emission intensity.

For Eu molar ratio x, since ^{Eu 2+} replaces the alkaline earth metal element _{(Ba a Ca b Sr c Mg} d Eu x Mn y) can be expressed as SiO _4, wherein, x is 0 <x It is a number satisfying ≦ 0.5. If the Eu molar ratio x is too small, the sensitizing effect is small and the emission intensity tends to be small. On the other hand, if it is too large, the improvement of the sensitization effect may not be significant. In addition, concentration quenching occurs and the emission intensity decreases. Generally, in excitation by near ultraviolet light, Eu is directly excited as compared with ultraviolet light excitation in the vicinity of a wavelength of 254 nm used in vacuum ultraviolet light or a fluorescent lamp, and therefore a relatively high concentration of Eu is preferable. The lower limit is preferably 0.05 ≦ x, more preferably 0.1 ≦ x, and the upper limit is more preferably x ≦ 0.4.

In the present invention, the ratio of Eu ^{2+ to} the total Eu is preferably as high as possible, and is usually 50% or more, preferably 80% or more, more preferably 90% or more, and most preferably 95% or more.

An example of a method for obtaining the ratio of Eu ^{2+ to} the total Eu is shown below.
The ratio of Eu ^{2+ to} the total Eu can be calculated, for example, by measuring the XANES spectrum at the Eu-L3 absorption edge. XANES is a general term for resonance absorption peaks appearing at and near the characteristic absorption edge of each element, and sensitively reflects the valence and structure of the element. In general, it is known that the strong resonance peak energy appearing in the L3 absorption edge XANES spectrum of rare earth is determined by the valence of the rare earth element. In the case of Eu, the Eu ²⁺ peak has an energy about 8 eV lower than the Eu ³⁺ peak. It is possible to separate and quantify the two.

The Mn molar ratio y, ^{Mn 2+} can be so replacing alkaline earth metal elements and _{(Ba a Ca b Sr c Mg} d Eu x Mn y) SiO 4 notation, where, y is 0 <y It is a number satisfying ≦ 0.5. If the concentration of Mn ²⁺ is too small, the emission intensity is low, and if it is too high, the emission intensity is also lowered due to concentration quenching. A preferred range of y is 0 <y ≦ 0.3, more preferably 0.05 <y ≦ 0.2.

[Phosphor production method]
In the phosphor of the present invention, an alkaline earth metal source, an Si source, and an element source compound of Eu and Mn, which are activators, so as to have the composition as described above are prepared by the following (A) or ( It can be produced by heating and firing the mixture (hereinafter referred to as “raw material mixture”) mixed by the mixing method of B).
(A) Dry pulverizer such as hammer mill, roll mill, ball mill, jet mill, etc., pulverization using mortar and pestle, etc., mixer such as ribbon blender, V-type blender and Henschel mixer, or mortar and pestle Dry mixing method combined with mixing.
(B) A wet mixing method in which water or the like is added and mixed in a slurry state or a solution state by a pulverizer, a mortar and pestle, or an evaporating dish and a stirring rod, and then dried by spray drying, heat drying, natural drying or the like.

  The alkaline earth metal source, silicon source, and active element Eu and Mn source compounds used in the preparation of the raw material mixture include oxides, hydroxides, carbonates, nitrates, sulfates, oxalates, and carboxyls. Acid salts, halides and the like can be mentioned, and these are selected in consideration of reactivity to the composite oxide and non-generation of NOx, SOx, etc. during firing.

Specific examples of the Ba, Ca, Sr, and Mg source compounds mentioned as alkaline earth metals include BaO, Ba (OH) ₂ .8H ₂ O, BaCO ₃ , Ba. (NO ₃ ) ₂ , BaSO ₄ , Ba (OCO) ₂ .2H ₂ O, Ba (OCOCH ₃ ) ₂ , BaCl _2, etc., and Ca source compounds include CaO, Ca (OH) ₂ , CaCO ₃ , Ca (NO ₃ ) ₂ .4H ₂ O, CaSO ₄ .2H ₂ O, Ca (OCO) ₂ .H ₂ O, Ca (OCOCH ₃ ) ₂ .H ₂ O, CaCl _{2 and the} like are also used as Sr source compounds. Are SrO, Sr (OH) ₂ .8H ₂ O, SrCO ₃ , Sr (NO ₃ ) ₂ , SrSO ₄ , Sr (OCO) ₂ .H ₂ O, Sr (OCOCH ₃ ) ₂ .0.5H ₂ O, Examples thereof include SrCl ₂ . The Mg source _{compound, MgO, Mg (OH) 2} , MgCO 3, Mg (OH) 2 · 3MgCO 3 · 3H 2 O, Mg (NO 3) 2 · 6H 2 O, MgSO 4, Mg (OCO) 2 · 2H ₂ O, Mg (OCOCH ₃ ) ₂ .4H ₂ O, MgCl _{2 and the} like.

Specific examples of compounds that are raw materials for Si and Ge include SiO ₂ , H ₄ SiO ₄ , Si (OCOCH ₃ ) _{4 and the} like as the Si source compound, and GeO as the Ge source compound. ₂ , Ge (OH) ₄ , Ge (OCOCH ₃ ) ₄ , GeCl _{4 and the} like.

Further, with respect to Eu and Mn mentioned as the activator elements, specific examples of the element source compound include Eu ₂ O ₃ , Eu ₂ (SO ₄ ) ₃ , Eu ₂ ( OCO) ₆ , EuCl ₂ , EuCl ₃ , Eu (NO ₃ ) ₃ .6H ₂ O, etc., as the Mn source compound, Mn (NO ₃ ) ₂ .6H ₂ O, MnO ₂ , Mn ₂ O ₃ , Mn ₃ Examples include O ₄ , MnO, Mn (OH) ₂ , MnCO ₃ , Mn (OCOCH ₃ ) ₂ .2H ₂ O, Mn (OCOCH ₃ ) ₃ .nH ₂ O, MnCl ₂ .4H ₂ O, and the like.

  Each of these element source compounds may be used alone or in combination of two or more.

In addition, a firing aid (also referred to as a flux) can be added to and mixed with the raw material mixture as necessary, and the addition of the firing aid can be expected to promote particle growth and lower the reaction temperature. It is effective for synthesizing phosphors. The sintering aids, for example, _NH 4 ammonium halide, such as Cl or _{NH 4 F · HF, NaCO 3} , alkali metal carbonate such as LiCO _3, LiCl, NaCl, alkali halides KCl, etc., CaCl _2, Alkaline earth metal halides such as CaF ₂ and BaF ₂ , borate compounds such as B ₂ O ₃ , H ₃ BO ₃ , and NaB ₄ O ₇ , Li ₃ PO ₄ , NH ₄ H ₂ PO ₄ 1 type (s) or 2 or more types, such as such a phosphate compound, can be used.

As a firing atmosphere of the raw material mixture, an atmosphere necessary for obtaining an ion state (valence) in which the activating element contributes to light emission is selected. In the present invention, the emission center element that causes red or orange emission is Mn ²⁺ ions. Eu that is a coactivator needs to be Eu ²⁺ , but a raw material such as Eu ₂ O _{3 in which} Eu ions are 3+ is usually used. Therefore, in order to obtain a phosphor that emits red or orange light of Eu ²⁺ , it is necessary to reduce trivalent Eu to divalent Eu during firing. For this reason, conventionally, firing is generally performed in some kind of reducing atmosphere such as carbon monoxide, nitrogen / hydrogen, or hydrogen.

  On the other hand, the present inventors specialize that carbon (solid carbon) coexists when the raw material mixture is calcined and trivalent Eu ions are reduced to divalent ions and simultaneously introduced into the host crystal. It has been found that red or orange light-emitting phosphors capable of emitting light with high luminance can be realized by firing under various reducing conditions.

  Here, various types of materials can be used as the solid carbon. For example, 1 type (s) or 2 or more types, such as carbon black, activated carbon, pitch, coke, graphite, can be used.

  Here, the firing in the presence of carbon is sufficient if carbon is present in the same firing container, and it is not necessary to mix the raw material mixture and carbon for firing. In general, when carbon is mixed in a phosphor product, the black carbon absorbs light and the efficiency is lowered. As an example of coexistence, there is a method of using a graphite crucible as a firing container. In addition, when using a crucible other than graphite, for example, an alumina crucible, a method of coexisting graphite beads, granules, blocks and the like as follows can be mentioned. That is, in the same crucible, use a container with carbon in a separate container without a lid (a lid with a gap so that the atmosphere communicates even if there is a lid). Place in the raw material powder, or on the other hand, without another lid (a lid with a gap so that the atmosphere communicates even if there is a lid), fill the container with the raw material mixture, and place carbon around it And the like. In any case, it is important to devise so that the coexisting carbon and the raw material mixture are present in the same atmosphere and that carbon is not mixed into the phosphor from which the carbon is obtained.

The firing is performed in a heat-resistant container such as a crucible or a tray using a material having low reactivity with the raw material mixture, usually at a temperature of 750 to 1400 ° C., preferably 900 to 1300 ° C., in a non-oxidizing gas atmosphere, for example, Conditions for coexistence with carbon as described above in a reducing gas and / or inert gas atmosphere, specifically, in a single or mixed atmosphere of gases such as carbon monoxide, carbon dioxide, nitrogen, hydrogen, and argon For 10 minutes to 24 hours. In addition, after heat processing, washing | cleaning, drying, a classification process, etc. are made as needed.
After such heat treatment, washing, drying, classification, etc. are performed as necessary.

  In addition, when manufacturing a light-emitting device by the below-mentioned method using the obtained fluorescent substance, it is preferable to disperse | distribute in resin after performing well-known surface treatment, for example, a calcium phosphate process.

[Light emitting device]
The light emitting device of the present invention uses the phosphor of the present invention as a phosphor as a wavelength conversion material in a light emitting device having an excitation light source and a phosphor that converts the wavelength of at least part of light from the excitation light source. In combination with an excitation light source as described below, a light emitting device of white or any color tone can be configured.

In the light emitting device of the present invention, the excitation light source for irradiating the phosphor with light generates light having a wavelength shorter than 470 nm. Specific examples of the excitation light source include a light emitting diode (LED) or a laser diode (LD). A laser diode is more preferable in terms of low power consumption. Among them, GaN LEDs and LDs using GaN compound semiconductors are preferable. This is because GaN-based LEDs and LDs have significantly higher light emission output and external quantum efficiency than SiC-based LEDs that emit light in this region, and are extremely bright with very low power when combined with the phosphor. This is because light emission can be obtained. For example, for a current load of 20 mA, the GaN system usually has a light emission intensity 100 times or more that of the SiC system. GaN-based LEDs and LDs preferably have an Al _X Ga _Y N light emitting layer, a GaN light emitting layer, or an In _X Ga _Y N light emitting layer. Among the GaN-based LEDs, those having an In _X Ga _Y N light-emitting layer are particularly preferable because the emission intensity is very strong, and in the GaN-based LD, the multiple quantum of the In _X Ga _Y N layer and the GaN layer is preferable. A well structure is particularly preferable because the emission intensity is very strong. In the above, the value of X + Y is usually a value in the range of 0.8 to 1.2. In the GaN-based LED, those in which the light emitting layer is doped with Zn or Si or those without a dopant are preferable for adjusting the light emission characteristics. A GaN-based LED has these light-emitting layer, p-layer, n-layer, electrode, and substrate as basic components, and the light-emitting layer is an n-type and p-type Al _X Ga _Y N layer, GaN layer, or In _X Those having a heterostructure sandwiched between Ga _Y N layers and the like have high luminous efficiency, and those having a heterostructure in a quantum well structure have higher luminous efficiency and are more preferable.

  In the light emitting device of the present invention, in addition to the method of using the phosphor of the present invention as a wavelength conversion material, particularly a red or orange light emitting phosphor alone, it can be used in combination with a phosphor having other emission characteristics. A light-emitting device that emits the color can be configured. As an example of this, an ultraviolet LED light emitting device having a wavelength of 330 to 420 nm, a blue phosphor having an emission peak at a wavelength of 450 to 500 nm and a green phosphor having an emission peak at a wavelength of 500 to 550 nm. And the phosphor of the present invention.

Here, the blue phosphor having a peak value of fluorescence intensity in the wavelength range of 450 nm to 500 nm is not particularly limited, but oxides, nitrides, and oxynitrides are preferable because they have good thermal stability. Specific examples of the blue phosphor include the following (1) to (4).
(1) M ₅ (PO ₄ ) ₃ (X): Eu ²⁺
(In the formula, M represents metal Ba and / or Ca or a combination of these with Sr, and X represents halogen F and / or Cl)
(2) ZnS: Ag
(3) M ^* ₃ MgSi ₂ O ₈ : Eu ²⁺
(In the formula, M ^* represents one or more of the metals Ba, Ca, and Sr)
(4) M ^** MgAl ₁₀ O ₁₇ : Eu ²⁺
(Wherein M ^** represents a metal Eu and / or Sr, or a combination thereof with Ba)

The green phosphor having a peak value of fluorescence intensity in the wavelength range of 500 nm to 550 nm is not particularly limited, but oxides, nitrides, and oxynitrides are preferable because they have good thermal stability. Specific green phosphors include, for example, MSi ₂ N ₂ O ₂ : Eu, M-Si—Al—O—N: Ce, M-Si—Al—O—N: Eu (where M is one kind) Or two or more alkaline earth metals), preferably, SrSi ₂ N ₂ O ₂ : Eu, Ca—Si—Al—O—N: Ce, Ca—Si—Al—O—N: Eu, and the like. Is mentioned. As another example, a phosphor containing at least Ce as the emission center ion in the host crystal represented by the following general formula (1) or (2) has high luminance and high fluorescence intensity in the green region. It is preferable because the temperature quenching is small.

M ¹ _a M ² _b M ³ _c O _d (1)
(Here, M ¹ is a divalent metal element, M ² is a trivalent metal element, M ³ is a tetravalent metal element, and a, b, c, and d are numbers in the following ranges, respectively. .
2.7 ≦ a ≦ 3.3
1.8 ≦ b ≦ 2.2
2.7 ≦ c ≦ 3.3
11.0 ≦ d ≦ 13.0)

M ⁴ _e M ⁵ _f O _g (2)
(Here, M ⁴ represents a divalent metal element, M ⁵ represents a trivalent metal element, and e, f, and g are numbers in the following ranges, respectively.
0.9 ≦ e ≦ 1.1
1.8 ≦ f ≦ 2.2
3.6 ≦ g ≦ 4.4)

By using the red or orange light emitting phosphor of the present invention in combination with the blue phosphor and the green phosphor as described above, the phosphor is irradiated with ultraviolet rays emitted from the LED as the excitation light source. Then, light of three colors of red, green, and blue is emitted, and a white light emitting device can be realized by mixing them.
In addition, light emission of blue light emitting LED can also be used as it is as a blue component.

  Hereinafter, a light-emitting device of the present invention including such an excitation light source and a phosphor will be described in detail with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view showing an embodiment of a light-emitting device of the present invention having an excitation light source (such as a semiconductor light-emitting element that generates light having a wavelength shorter than 470 nm) and a phosphor. It is typical sectional drawing which shows one Example of the surface emitting illumination device incorporating the light-emitting device shown in FIG. 1 and 2, 1 is a light emitting device, 2 is a mount lead, 3 is an inner lead, 4 is an excitation light source, 5 is a phosphor-containing resin part, 6 is a conductive wire, 7 is a molding member, and 8 is a surface emitting light. An illuminating device, 9 is a diffusion plate, and 10 is a holding case.

  As shown in FIG. 1, the light emitting device 1 has a general shell shape, and an excitation light source (350 to 470 nm excitation light source) made of a GaN-based light emitting diode or the like is placed in the upper cup of the mount lead 2. 4 is fixed by being coated with a phosphor-containing resin portion 5 formed by mixing and dispersing the phosphor in a binder such as silicon resin, epoxy resin or acrylic resin, and pouring it into the cup. ing. On the other hand, the excitation light source 4 and the mount lead 2, and the excitation light source 4 and the inner lead 3 are respectively connected by a conductive wire 6, and these are entirely covered and protected by a mold member 7 made of epoxy resin or the like.

  In addition, as shown in FIG. 2, the surface-emitting illumination device 8 incorporating the light-emitting device 1 has a large amount of light emission on the bottom surface of a rectangular holding case 10 whose inner surface is light-opaque such as a white smooth surface. The device 1 is arranged with a power source and a circuit (not shown) for driving the light emitting device 1 provided outside thereof, and a milky white acrylic plate or the like is provided at a position corresponding to the lid portion of the holding case 10. The diffusion plate 9 is fixed for uniform light emission.

  Then, by driving the surface emitting illumination device 8 and applying a voltage to the excitation light source 4 of the light emitting device 1, light having a wavelength shorter than 470 nm is emitted, and part of the emitted light is emitted from the phosphor-containing resin portion 5. The phosphor absorbs and emits visible light having a longer wavelength (wavelength of 490 to 700 nm). On the other hand, light emission with high color rendering properties is obtained by mixing with blue light or the like that is not absorbed by the phosphor. Light passes through the diffusion plate 9 and is emitted upward in the drawing, so that illumination light with uniform brightness can be obtained within the surface of the diffusion plate 9 of the holding case 10.

  The phosphor-containing resin portion 5 in the light emitting device 1 has the following effects. That is, the light from the excitation light source and the light from the phosphor are usually directed in all directions, but when the phosphor powder is dispersed in the resin, a part of the light is reflected when it goes out of the resin. Since the direction of the light can be changed to some extent, the light is mixed and the light distribution tends to be made uniform. Therefore, since the light can be guided to an efficient direction to some extent, it is preferable to use the phosphor powder dispersed in a resin. Further, when the phosphor is dispersed in the resin, since the total irradiation area of the light from the excitation light source to the phosphor is increased, there is an advantage that the emission intensity from the phosphor can be increased.

  As a resin that can be used for the phosphor-containing resin part, various kinds such as silicone resin, epoxy resin, polyvinyl resin, polyethylene resin, polypropylene resin, polyester resin, etc. are used alone or in combination of two or more. In view of good dispersibility of the phosphor powder, silicone resins and epoxy resins are preferable. When the phosphor powder is dispersed in the resin, the weight ratio of the phosphor powder to the total of the phosphor powder and the resin is usually 0.1 to 20% by weight, preferably 0.3 to 15% by weight, More preferably, it is 0.5 to 10% by weight. If there is too much phosphor within this range, the luminous efficiency may decrease due to aggregation of the phosphor powder, and if it is too small, the luminous efficiency may decrease due to light absorption or scattering by the resin. In this resin, an extender or a diffusing agent may be added in order to prevent color spots (unevenness).

  As described above, the phosphor is preferably dispersed in the resin after performing a known surface treatment if necessary.

  In the present invention, it is particularly preferable to use a surface-emitting type illuminant, particularly a surface-emitting type GaN-based laser diode, as an excitation light source, since it increases the luminous efficiency of the entire light-emitting device. A surface-emitting type illuminant is an illuminant that emits strong light in the surface direction of a film. In a surface-emitting GaN-based laser diode, the crystal growth of a light-emitting layer or the like is controlled, and a reflective layer or the like is well By devising, the light emission in the surface direction can be made stronger than the edge direction of the light emitting layer. Compared to the type that emits light from the edge of the light emitting layer by using a surface emitting type, as a result of taking a large emission cross-sectional area per unit light emission amount, when irradiating the phosphor as a wavelength conversion material, Since the irradiation area can be made very large with the same amount of light and the irradiation efficiency can be improved, stronger light emission can be obtained from the phosphor as the wavelength conversion material.

  Thus, when using a surface emitting type as an excitation light source, it is preferable to form the phosphor as the wavelength conversion material in a film shape. Since the cross-sectional area of the light from the surface-emitting type excitation light source is sufficiently large, if the phosphor is formed in a film shape in the direction of the cross-section, the irradiation cross-sectional area per unit amount of the phosphor from the excitation light source increases. The intensity of light emitted from the body can be further increased.

  In addition, when a surface emitting type light source is used as the excitation light source and a phosphor is formed in a film shape, it is preferable to have a shape in which the film-shaped phosphor is directly in contact with the light emission surface of the excitation light source. . Contact here means creating a state in which the excitation light source and the phosphor are in close contact with each other without air or gas. As a result, it is possible to avoid a light amount loss in which light from the excitation light source is reflected by the phosphor film surface and oozes out, so that the light emission efficiency of the entire apparatus can be improved.

  FIG. 3 is a schematic perspective view showing an example of a light emitting device to which a surface emitting type light source is used as an excitation light source and a phosphor is formed in a film shape. In FIG. 3, 11 is a film-like light emitter having the phosphor, 12 is a surface-emitting GaN-based LD as an excitation light source, and 13 is a substrate. In order to create a state in which they are in contact with each other, the LD of the excitation light source 12 and the phosphor-containing film 11 may be formed separately, and their surfaces may be brought into contact with each other by an adhesive or other means. The phosphor 11 may be formed (molded) on the surface. As a result, the LD 12 and the phosphor 11 can be brought into contact with each other.

  The light-emitting device of the present invention includes an excitation light source and the phosphor of the present invention as the wavelength conversion material, and the phosphor of the present invention as the wavelength conversion material absorbs light having a wavelength shorter than 470 nm emitted from the excitation light source. Thus, the light-emitting device emits light in a wavelength region longer than 590 nm representing red or orange, has good color rendering properties and can generate high-intensity visible light regardless of the use environment.

  Such a light emitting device of the present invention is suitable for a light source such as a backlight source, a light source such as a traffic light, an image display device such as a color liquid crystal display, and a lighting device such as a surface emitting device. Examples of the image display device include a fluorescent display tube (VFD), a field emission display (FED), a plasma display panel (PDP), a cathode ray tube (CRT), and the like. Further, the light emitting device of the present invention can also be used for a backlight for an image display device.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

  In the following, the X-ray absorption near-edge fine structure (XANES) spectrum of the Eu-L3 absorption edge of the manufactured phosphor is a high-intensity optical science research center large emission In the XAFS measurement apparatus installed in the beam hatch BL19B2 first hatch of the light facility (SPring-8), measurement was performed using a Si (111) 2 crystal spectrometer and a high-order light removal mirror. The X-ray energy calibration was performed by setting the angle of the spectroscope at the pre-edge peak appearing at 8980.3 eV in the Cu-K absorption edge XANES spectrum of the metal copper foil to 12.7185 degrees, and further, before and after the sample measurement, the europium oxide Eu- An L3 absorption edge XANES measurement was performed to correct a minute shift of the spectroscope with time.

  The emission spectrum was measured using a GaN-based light emitting diode (main wavelength: 400 nm) as an excitation light source. In the measurement, in order to remove the influence of the excitation light source, light having a wavelength of 420 nm or less was cut. The peak emission wavelength and peak emission intensity of the phosphors obtained in the examples and comparative examples are shown in Table 1 described later. Here, the peak emission intensity was expressed as a relative intensity with respect to the standard value, with the intensity of the phosphor obtained in Example 3 being 100% (standard value).

The measurement of the XANES spectrum was performed by the transmission method at an interval of about 0.4 eV (0.00094 degrees as a spectroscope angle) in the vicinity of the Eu-L3 absorption edge (near 6970 eV) and an integration time of 2 seconds at each point. In other words, ionization chambers with electrode lengths of 17 cm and 31 cm filled with nitrogen gas are used as detectors for incident X-rays and X-rays transmitted through the sample, respectively, and the X-ray absorption coefficient is expressed as μt = ln (I ₀₎ according to the Lambert-Beer equation. / I) where I ₀ is the incident X-ray intensity and I is the transmitted X-ray intensity.
As a sample for measurement, phosphor powder that passed through a sieve after firing was mixed with about 70 mg of boron nitride until uniform in an agate mortar, and formed into a tablet with a diameter of 10 mm under a pressure of 150 kg weight / cm ² . A thing was used.

When the Eu-L3 absorption edge XANES spectrum obtained in this way is subjected to first-order differentiation to remove the influence of the background, the spectrum patterns derived from Eu ²⁺ and Eu ³⁺ are in the vicinity of 6965-6976 eV and 6976-6990 eV, respectively. Appeared. Therefore, the difference between the maximum value and the minimum value of the differential spectrum within each energy range was obtained, and this was normalized by dividing by the difference between the maximum value and the minimum value of the Eu ²⁺ and Eu ³⁺ standard samples of the Eu-L3XANES differential spectrum. Those were defined as Eu ²⁺ and Eu ³ peak intensities p and q, and the ratio r of Eu ²⁺ in the total Eu was defined as r = p / (p + q).

Example 1
BaCO ₃ , CaCO ₃ , Eu ₂ O ₃ , MnCO ₃ and SiO ₂ are used as raw material compounds, and the molar ratio of Ba, Ca, Eu, Mn and Si is 1.444: 0.481: 0.025: 0.05: Weighed to 1 and added NH ₄ Cl as flux and mixed for 1 hour in a ball mill. The raw material was weighed in a small alumina crucible with a lid, lightly covered, and placed on the bottom of a large alumina crucible. Activated carbon was filled in the gap between the large crucible and the small crucible. Was prepared phosphor _{Ba 1.444 Ca 0.481 Eu 0.025 Mn 0.05} SiO 4 by heating for 4 hours under a stream of nitrogen gas 1200 ° C. containing 4% hydrogen in this state.
Table 1 shows the Eu ²⁺ / Eu ratio, peak emission wavelength, and peak emission intensity obtained for the obtained phosphor. The XANES spectrum is shown in FIG.

Example 2
BaCO ₃ , CaCO ₃ , Eu ₂ O ₃ , MnCO ₃ , and SiO ₂ are used as raw material compounds, and the molar ratio of Ba, Ca, Eu, Mn, and Si is 1.35: 0.45: 0.15: 0.05: A phosphor Ba _1.35 Ca _0.45 Eu _0.15 Mn _0.05 SiO ₄ was produced in the same manner as in Example 1 except that the weight was adjusted to 1.
Table 1 shows the Eu ²⁺ / Eu ratio, peak emission wavelength, and peak emission intensity obtained for the obtained phosphor. The XANES spectrum is shown in FIG.

Example 3
BaCO ₃ , CaCO ₃ , Eu ₂ O ₃ , MnCO ₃ , and SiO ₂ are used as raw material compounds, and the molar ratio of Ba, Ca, Eu, Mn, and Si is 1.237: 0.413: 0.3: 0.05: A phosphor Ba _1.237 Ca _0.413 Eu _0.3 Mn _0.05 SiO ₄ was produced in the same manner as in Example 1 except that the weight was _adjusted to 1.
Table 1 shows the Eu ²⁺ / Eu ratio, peak emission wavelength, and peak emission intensity obtained for the obtained phosphor. The XANES spectrum is shown in FIG.

Comparative Example 1
BaCO ₃ , CaCO ₃ , Eu ₂ O ₃ , MnCO ₃ , and SiO ₂ as raw material compounds have a molar ratio of Ba, Ca, Eu, Mn, and Si of 1.012: 0.338: 0.6: 0.05: A phosphor Ba _1.012 Ca _0.338 Eu _0.6 Mn _0.05 SiO ₄ was produced in the same manner as in Example 1 except that the weight was _adjusted to 1.
Table 1 shows the Eu ²⁺ / Eu ratio, peak emission wavelength, and peak emission intensity obtained for the obtained phosphor. The XANES spectrum is shown in FIG.

Comparative Example 2
BaCO ₃ , CaCO ₃ , Eu ₂ O ₃ , MnCO ₃ , and SiO ₂ are used as raw material compounds, and the molar ratio of Ba, Ca, Eu, Mn, and Si is 1.35: 0.45: 0.15: 0.05: The phosphor Ba _1.35 Ca _0.45 Eu _0. was treated in the same manner as in Example 1 except that the sample was weighed to 1 and heated in an air atmosphere instead of under a nitrogen gas flow containing 4% hydrogen _{. 15} Mn _0.05 SiO ₄ was produced.
Table 1 shows the Eu ²⁺ / Eu ratio, peak emission wavelength, and peak emission intensity obtained for the obtained phosphor. The XANES spectrum is shown in FIG.

According to Table 1, the phosphor of the present invention composed of europium / manganese co-activated alkaline earth metal silicate having a specific composition and having a Eu ²⁺ / Eu of 50% or more is a red or orange light emitting phosphor with high luminous efficiency. I understand that there is.

It is typical sectional drawing which shows embodiment of the light-emitting device of this invention. It is typical sectional drawing which shows an example of the surface emitting illumination apparatus using the light-emitting device of this invention. It is a typical perspective view which shows other embodiment of the light-emitting device of this invention. It is a figure which shows the XANES spectrum of the fluorescent substance obtained in Examples 1-3 and Comparative Examples 1,2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1; Light-emitting device 2; Mount lead 3; Inner lead 4; Excitation light source 5; Phosphor containing resin part 6; Conductive wire 7; Mold member 8;

Claims (7)

Composition _formula: In _{(Ba a Ca b Sr c Mg} d Eu x Mn y) consisting of europium-manganese activated alkaline earth with both metal silicate represented by SiO ₄ phosphor,
In the composition formula, coefficients a, b, c, d, x and y are a + b + c + d + x + y = 2.
0 <a <2
0 <b <2
0 ≦ c <0.5
0 ≦ d <0.5
0 <x ≦ 0.5
0 <y ≦ 0.5
And 50% or more of the total Eu ions are Eu ²⁺ ions.   The phosphor according to claim 1, which emits red or orange light.   It is a manufacturing method of the fluorescent substance of Claim 1 or 2, Comprising: The mixture of the element source compound of Ba, Ca, Eu, Mn, and Si, and the element source compound of Sr and / or Mg used as needed Is fired in a non-oxidizing gas atmosphere in the presence of carbon.   The method for producing a phosphor according to claim 3, wherein the non-oxidizing gas is a reducing gas and / or an inert gas.   In the light-emitting device which has an excitation light source and the fluorescent substance which wavelength-converts at least one part of the light from this excitation light source, this fluorescent substance of Claim 1 or 2 or Claim 3 or 4 A light-emitting device comprising a phosphor obtained by a manufacturing method.   An illumination device comprising the light-emitting device according to claim 5.   An image display device comprising the light-emitting device according to claim 5.

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