TW201910490A - Fluorescent substance, production method thereof, fluorescent substance sheet, and lighting device - Google Patents

Abstract

Provided is a phosphor which is represented by general formula (1) and which contains at least a fluorescent substance that satisfies conditions (1)-(3). General formula (1): (BaySr1-y)1-xGa2S4:Eux (in general formula (1), 0.025 ≤ x ≤ 0.20 and 0.15 ≤ y ≤ 0.49 are satisfied). Condition (1): The maximum peak of the diffraction intensity in an XRD pattern is a diffraction peak that appears at a diffraction angle 2[Theta]=23.7 DEG to 24.1 DEG and is attributed to the (422) plane of SrGa2S4. Condition (2): The second highest peak of the diffraction intensity appears at a diffraction angle 2[Theta]=38.1 DEG to 38.5 DEG and is attributed to the (444) plane of SrGa2S4. Condition (3): Diffraction peaks having a relative intensity of 5-20% of the maximum peak of the diffraction intensity appear at a diffraction angle 2[Theta]=30.0 DEG to 30.4 DEG.

Description

Fluorescent powder and its manufacturing method, fluorescent powder sheet and lighting device

The invention relates to a fluorescent powder and a manufacturing method thereof, a fluorescent powder sheet and a lighting device.

In the past, the pseudo white LED used in low-priced TVs or monitors used yellow fluorescent powder YAG:Ce. This method is not suitable for red and green color filters because it reduces the color purity of green and red.

On the other hand, in recent years, LCD TVs and displays have pursued a wide color gamut. However, in the foregoing manner, the color purity of green and red is lowered, and the color gamut is narrowed. Instead of the yellow phosphor, a three-wavelength white LED suitable for the green light-emitting phosphor of the color filter and the red-emitting phosphor is used, which is advantageous in widening the color gamut (wide color gamut).

As a green light-emitting phosphor, SrGa ₂ S ₄ :Eu phosphor powder is widely known. Since SrGa ₂ S ₄ :Eu is excited by light in the near-ultraviolet to blue-wavelength, it has been noted as a green-emitting phosphor for exciting blue LEDs. In addition it was also proposals on SrGa ₂ S _4: Eu phosphor of the art, for example, the purpose of improving the internal quantum efficiency of SrGa ₂ S _4: Eu phosphor; or MGa ₂ S _4: Eu phosphor (M = Ba (Ba), (锶) Sr or/and (calcium) Ca) (for example, refer to Patent Documents 1 and 2).

In order to realize a three-wavelength type LED of a wide color gamut, it is necessary to have a green luminescent phosphor having high luminance and high color purity. Therefore, green luminescent phosphors having high brightness and high color purity are sought.

[Prior Art Document] [Patent Document] [Patent Document 1] Japanese Patent No. 4343267 (Patent Document 2) Japanese Patent No. 4708507

[Problems to be Solved by the Invention] An object of the present invention is to solve the above-described problems in the prior art and achieve the following objects. That is, an object of the present invention is to provide a green light-emitting phosphor having high brightness and high color purity, a method of manufacturing the same, a phosphor powder sheet having the same, and a lighting device having the same .

[Means for Solving the Problems] The following is a means for solving the above problems: <1> A phosphor powder comprising at least the following formula (1) and satisfying the following condition (1) to (3) Fluorescent substance, (Ba _y Sr _1-y ) _1-x Ga ₂ S ₄ :Eu _x Formula (1) However, in the formula (1), 0.025 ≦ x ≦ 0.20, and 0.15 ≦ y ≦ 0.49. Condition (1): The maximum peak of the diffraction intensity of the XRD pattern is a diffraction peak appearing at the diffraction angle 2θ=23.7 to 24.1°, which is returned to the (422) plane of SrGa ₂ S ₄ ; Condition (2): Diffraction The second peak of the intensity is a diffraction peak appearing at a diffraction angle of 2θ=38.1 to 38.5° and returning to the SrGa ₂ S ₄ (444) plane; Condition (3): having a diffraction angle of 2θ=30.0 to 30.4° The relative intensity of the largest peak relative to the diffraction intensity is a diffraction peak of 5 to 20%. <2> The phosphor powder according to the above <1>, wherein the y value of the fluorescent substance based on the CIE1931 color system is 0.687 or more. The phosphor powder according to any one of the above aspects, wherein the fluorescent material has an internal quantum efficiency of 0.64 or more. <4> A phosphor powder sheet comprising a phosphor powder layer, wherein the phosphor powder layer contains the phosphor powder according to any one of <1> to <3>, and a red phosphor powder. <5> A lighting device comprising the phosphor powder sheet according to <4> above. The method for producing a phosphor powder according to any one of the above-mentioned items, wherein the method of producing a phosphor powder comprises a precipitation precipitation process for dissolving a cerium compound, a cerium compound, and a cerium compound. And the first liquid containing the powdered gallium compound is mixed with the second liquid containing sulfite to obtain a precipitate which is a precipitate containing barium sulfite, barium sulfite and barium sulfite and the powdered gallium compound mixture. The method for producing a phosphor according to the above <6>, which further comprises a baking process for firing the precipitate under a hydrogen sulfide atmosphere.

[Effect of the Invention] According to the present invention, the aforementioned problems in the prior art can be solved, and the above object can be attained, and a green light-emitting phosphor powder having high brightness and high color purity can be provided, and a method of manufacturing the same, and having the same a phosphor powder sheet, and a lighting device having the phosphor powder sheet.

(Fluorescent Powder) The phosphor powder of the present invention contains at least a fluorescent substance and contains other components such as a coating layer as needed.

(fluorescent substance) The fluorescent substance can be represented by the following formula (1): (Ba _y Sr _1-y ) _1-x Ga ₂ S ₄ : Eu _x Formula (1) However, the formula (1) Among them, 0.025 ≦ x ≦ 0.20, and 0.15 ≦ y ≦ 0.49.

This fluorescent substance satisfies the following conditions (1) to (3). Condition (1): The maximum peak of the diffraction intensity of the XRD pattern is a diffraction peak which appears at the diffraction angle 2θ=23.7 to 24.1° and returns to the (422) plane of SrGa ₂ S ₄ . Condition (2): The second peak of the diffraction intensity is a diffraction peak which appears at the diffraction angle 2θ=38.1 to 38.5° and returns to the SrGa ₂ S ₄ (444) plane. Condition (3): The diffraction intensity of the maximum peak with respect to the diffraction intensity is a diffraction peak of 5 to 20% at the diffraction angle 2θ=30.0 to 30.4°.

Among the phosphors, a gallium/(铕+钡+锶) ratio (i.e., a ratio of Ga/(Eu+Ba+Sr) element) is preferably 1.80 to 2.50, and preferably 1.90 to 2.30.

The luminescence peak wavelength of the fluorescent substance is, for example, 529 nm to 535 nm.

The luminescence peak intensity (for the YAG ratio) of the fluorescent substance can be, for example, 2.46 to 3.64.

The absorbance of the test material of the fluorescent substance can be, for example, 64% to 82%.

The value of x of the CIE1931 color system based on the fluorescent substance is preferably 0.271 or less. The x value of the CIE1931 color system based on the fluorescent substance can be, for example, 0.210 to 0.271 or 0.235 to 0.271.

The y value of the CIE1931 color system based on the fluorescent material is preferably 0.687 or more. The y value of the CIE1931 color system based on the fluorescent substance is, for example, 0.687 to 0.710 or 0.687 to 0.695.

The internal quantum efficiency of the fluorescent material is preferably 0.64 (64%) or more. The internal quantum efficiency of the fluorescent substance is, for example, 0.64 (64%) to 0.80 (80%).

The external quantum efficiency of the fluorescent material is preferably 0.40 (40%) or more. As the external quantum efficiency of the fluorescent substance, for example, 0.40 (40%) to 0.65 (65%) can be exemplified.

As the luminance (for the YAG ratio) of the fluorescent material, for example, 124% to 187% can be exemplified.

The full width at half maximum of the fluorescent substance is, for example, 48 nm to 50 nm.

Each of the above characteristics can be measured, for example, by the following method.

[Measurement of the luminescence (PL) spectrum] The luminescence peak wavelength in the PL spectrum (photoluminescence spectrum) is measured using an integrating sphere option of a spectrofluorometer FP-6500 (manufactured by JASCO Corporation). The intensity of the luminescence peak, and the full width of the luminescence half value. The luminescence peak intensity indicates a relative value based on the PL spectrum data of a general YAG phosphor powder P46-Y3 material manufactured by Optronics.

[Calculation of various conversion efficiencies] As the conversion efficiency of the phosphor powder, the efficiency (absorption rate) of absorbing the excitation light, the efficiency of converting the absorbed excitation light into fluorescence (internal quantum efficiency), and the like are calculated; The product of the values, the efficiency at which the excitation light is converted to fluorescence (external quantum efficiency). The light-emitting characteristics were measured using an integrating sphere option of a spectrofluorometer FP-6500 (manufactured by JASCO Corporation). Fluorescent powder powder was filled in a dedicated tank, and blue excitation light having a wavelength of 450 nm was irradiated to measure a fluorescence spectrum. As a result, the quantum efficiency was calculated using the quantum efficiency calculation software included in the spectrofluorometer.

[Evaluation of Crystallinity] Evaluation of crystallinity was performed based on measurement of X-ray diffraction. The position (2θ) and the half-value width of the diffraction peak in the X-ray diffraction (XRD) pattern of the CuKα line were measured using a powder X-ray diffraction meter (X' Pert PRO manufactured by PANalytical Co., Ltd.). Fitting is performed by the peak search function of the attached analysis software, and the characteristics of the XRD pattern of the fluorescent powder are analyzed.

<Cover Layer> As a further preferable aspect of the phosphor powder of the present invention, for example, a phosphor powder coated with a fluorine-containing resin as a coating layer on the surface of the phosphor material can be exemplified. . By improving the moisture resistance and water resistance of the fluorescent substance, it is possible to prevent the hydrolysis reaction due to water or the like and to prevent deterioration of the light-emitting characteristics. In order to improve the moisture resistance and water resistance of the fluorescent substance, it is preferred to cover the surface of the fluorescent substance with a fluorine-containing resin. In this way, deterioration of the fluorescent material due to hydrolysis or the like can be prevented, and deterioration of the light-emitting characteristics such as the intensity of the luminescence peak can be suppressed.

Depending on the composition of the fluorescent substance, the crystal structure, and the like, the values of various physical properties such as the wavelength of the luminescence peak, the full width at half of the luminescence, the intensity of the luminescence peak, the internal quantum efficiency, and the external quantum efficiency are also different. However, the phosphor powder of the present invention can be produced by the production method of the present invention described later, and can be a green light-emitting phosphor having a novel crystal structure and having high luminance and high color purity.

(Manufacturing Method of Fluorescent Powder) The method for producing the phosphor powder of the present invention includes at least a precipitation precipitating process, and further includes other processes such as a baking process and a coating process as needed. The method for producing the phosphor powder is a method for producing the phosphor powder of the present invention.

<Precipitation and Sedimentation Process> The precipitation and precipitation process is not particularly limited as long as it is a process of mixing the first liquid and the second liquid to obtain a precipitate, and can be appropriately selected depending on the purpose.

<<First Liquid>> This first liquid system dissolves a cerium compound, a cerium compound, and a cerium compound, and contains a powdered gallium compound.

As a method of obtaining the first liquid, for example, a method in which a cerium compound, a cerium compound, and a cerium compound are dissolved in water, and then a powdered gallium compound is mixed therein can be exemplified.

As the ruthenium compound, for example, barium nitrate [Ba(NO _{3 ) 2} ], barium oxide [BaO], barium bromide [BaBr ₂ · xH ₂ O], barium chloride [BaCl ₂ · xH ₂ O], acetic acid can be used.钡 [Ba(CH ₃ COO) ₂ ], cesium iodide [BaI ₂ · xH ₂ O], cesium hydroxide [Ba(OH) ₂ ], strontium sulfide [BaS], and the like.

As the ruthenium compound, for example, strontium nitrate [Sr(NO _{3) 2} ], strontium oxide [SrO], strontium bromide [Sr Br ₂ · xH ₂ O], cesium chloride [SrCl ₂ · xH ₂ O], Barium carbonate [SrCO ₃ ], barium oxalate [SrC2O ₄ · H ₂ 0], barium fluoride [SrF ₂ ], barium iodide [SrI ₂ · xH ₂ 0], barium sulfate [SrSO ₄ ], barium hydroxide [Sr(OH) ₂ · xH ₂ O], strontium sulfide [SrS], and the like.

As the ruthenium compound, for example, ruthenium nitrate [Eu(NO ₃ ) ₃ · xH ₂ O], bismuth oxalate [Eu(C ₂ O ₄ ) ₃ · xH ₂ O], cesium carbonate [Eu ₂ (CO _{3 ) can be used. 3} ·xH ₂ O], barium sulfate [Eu ₂ (SO ₄ ) ₃ ], barium chloride [EuCl ₃ · xH ₂ O], barium fluoride [EuF ₃ ], hydrogenated hydrazine [EuH _x ], strontium sulfide [ EuS], triisopropoxy fluorene [Eu(OiC ₃ H ₇ ) ₃ ], cerium acetate [Eu(O-CO-CH ₃ ) ₃ ], and the like.

As the powdered gallium compound, for example, gallium oxide [Ga ₂ O ₃ ], gallium sulfate [Ga ₂ (SO ₄ ) ₃ · xH ₂ O], gallium nitrate [Ga(NO ₃ ) ₃ · xH ₂ O], bromine can be used. Gallium [GaBr ₃ ], gallium chloride [GaCl ₃ ], gallium iodide [GaI ₃ ], gallium sulfide (II) [GaS], gallium sulfide (III) [Ga ₂ S ₃ ], oxygen (hydrogen) Gallium [GaOOH] and the like.

The content of barium (Ba), strontium (Sr), europium (Eu), and gallium (Ga) in the first liquid is not particularly limited, and may be appropriately selected depending on the purpose.

<<Second liquid>> The second liquid contains sulfite. As a method of obtaining the second liquid, for example, a method of dissolving sulfite in water can be exemplified. The content of the sulfite in the second liquid is not particularly limited, and may be appropriately selected depending on the purpose.

As the sulfite, for example, ammonium sulfite, sodium sulfite, potassium sulfite, or the like can be exemplified.

The mixing ratio of the first liquid and the second liquid is not particularly limited, and may be appropriately selected depending on the purpose, and may be, for example, a molar amount of lanthanum, cerium, and lanthanum in the first liquid. In other words, the molar amount of the sulfite is 1.00 to 1.50 times.

<<Precipitate>> This precipitate is a mixture of a precipitate and the powdered gallium compound. The precipitate contains barium sulfite, barium sulfite and barium sulfite. The first liquid dissolves the cerium compound, the cerium compound, and the cerium compound, and is in a uniform state therein, and in the precipitate, the cerium sulfite, the sulfite sulfite, and the sulfite sulfite are uniformly mixed therein. Further, among the precipitates, the powdered gallium compound, barium sulfite, barium sulfite and barium sulfite are uniformly mixed.

Further, it is preferred that the precipitate is washed before being subjected to a firing process which will be described later. The conditions for the washing are not particularly limited, and may be appropriately selected depending on the purpose, and may be, for example, washed with water to a conductivity of 0.1 mS/cm or less.

<Sintering Process> The firing process is not particularly limited as long as it is a process for firing the precipitate in a hydrogen sulfide-containing atmosphere, and may be appropriately selected depending on the purpose. The firing temperature of the baking process can be, for example, 900 to 950 °C. The baking time of this baking process can be, for example, 1 hour to 5 hours. The proportion of hydrogen sulfide in the atmosphere in the firing process is not particularly limited, and may be appropriately selected depending on the purpose, and for example, hydrogen sulfide is supplied in an amount of 0.1 L/min to 0.5 L/min to firing. In an ambience.

The phosphor material in the phosphor powder of the present invention can be obtained by the firing process.

<Coating Process> The coating process is not particularly limited as long as it is a process of coating the surface of the fluorescent material obtained by the baking process by a coating layer, and may be appropriately selected according to the purpose. Make a choice. The coating process can coat the fluorine-containing resin, for example, in a non-aqueous atmosphere.

For example, it is used in a fluorine-containing resin solution containing a fluorine-containing solvent of a hydrofluoroether such as ethoxy nonafluorobutane, and a fluorine-containing resin solution, and the obtained fluorescent light is obtained. The substance is mixed into the fluorine-containing resin solution, and mixed by a stirring drum or the like. Next, the powder is recovered by adsorption filtration, and the powder is dried at a temperature of about 80 ° C to 100 ° C for 0.5 to 1.5 hours. Thereby, a phosphor powder having a coating layer of a fluorine-containing resin on the surface can be obtained.

(Fluorescent Powder Sheet) The phosphor powder sheet of the present invention has at least a phosphor powder layer, and may have other members such as a water vapor barrier film as needed.

<Fluorescent Powder Layer> The phosphor powder layer contains at least the phosphor powder and the red phosphor powder of the present invention, and may contain other components such as a resin as needed. The phosphor layer is, for example, a phosphor powder of the present invention in which a layered resin is dispersed, and a red phosphor powder.

<Red Fluorescent Powder> The red fluorescent powder is not particularly limited and may be appropriately selected depending on the purpose. For example, it may be composed of a sulfide type phosphor powder, an oxide type phosphor powder, a nitride type phosphor powder, a fluoride type phosphor powder, etc. depending on the type of the phosphor powder, the absorption spectrum band, the light emission band, and the like. One or two or more are used.

Specific examples of the red phosphor powder include, for example, (ME:Eu)S, (M:Sm) _x (Si, Al) ₁₂ (O, N) ₁₆ , ME ₂ Si ₅ N ₈ :Eu, (ME :Eu)SiN ₂ , (ME:Eu)AlSiN ₃ , (ME:Eu) ₃ SiO ₅ , (Ca:Eu)SiN ₂ , (Ca:Eu)AlSiN ₃ ,Y ₂ O ₃ :Eu,YVO ₄ :Eu Y(P, V)O ₄ :Eu, 3.5MgO·0.5MgF ₂ ·Ge ₂ :Mn, CaSiO ₃ :Pb, Mn, Mg ₆ AsO ₁₁ :Mn, (Sr, Mg) ₃ (PO ₄ ) ₃ : Sn, La ₂ O ₂ S: Eu, Y ₂ O ₂ S: Eu, and the like. Among these red phosphors, it is preferred to use CaS:Eu or (Ba,Sr) ₃ SiO ₅ :Eu which can realize a wide color gamut. Here, "ME" means at least one atom selected from the group consisting of Ca, Cr, and Ba; "M" means at least one selected from the group consisting of Li, Mg, and Ca. The kind of atom. In addition, the front of ":" indicates the main body, and the rear of ":" indicates the activator.

<<Resin>> Examples of the resin include a polyolefin copolymer, a cured product of a photocurable (meth)acrylic resin, and the like.

The polyolefin copolymer may, for example, be a styrene type copolymer or a hydrogenated product thereof. As such a styrene type copolymer or a hydride thereof, for example, a styrene-ethylene-butylene-styrene block copolymer or a hydride thereof, a styrene-ethylene-propylene block is preferably exemplified. Copolymer or its hydride. Among these, from the viewpoint of transparency or gas barrier properties, it is preferred to use a styrene-ethylene-butylene-styrene block copolymer. By containing a polyolefin copolymer, good light resistance and low water absorption can be obtained.

Examples of the photocurable (meth)acrylic resin include urethane (meth) acrylate, polyester (meth) acrylate, and epoxy (meth) acrylate. Among these, an amino (meth) acrylate is preferably used from the viewpoint of heat resistance after photocuring. By containing a photocurable (meth)acrylic resin, good light resistance and low water absorbability can be obtained.

<Water vapor barrier film> As the water vapor barrier film, for example, alumina, magnesium oxide, or cerium oxide is formed on the surface of a plastic substrate or film such as PET (polyethylene terephthalate). A gas barrier film or the like of a metal oxide film. Further, a multilayer structure such as PET/SiO _x (yttria)/PET can also be used.

Here, an example of the phosphor powder sheet will be described with reference to the drawings. Fig. 1 is a schematic cross-sectional view showing a configuration example of an end portion of a phosphor powder sheet. This phosphor powder sheet is such that the phosphor powder layer 11 is sandwiched by the first water vapor barrier film 12 and the second water vapor barrier film 13.

The phosphor layer 11 contains: the phosphor powder of the present invention which emits green fluorescence; and a red phosphor which emits red fluorescence having a wavelength of 620 to 660 nm by irradiation of blue excitation light. The phosphor layer 11 converts the irradiated blue light into white light.

Further, as the other green light-emitting phosphor other than the phosphor powder of the present invention, for example, Zn ₂ SiO ₄ : Mn, Y ₃ Al ₅ O ₁₂ : Ce ³⁺ , (Y, Gd) Al may be used. ₃ (BO ₃ ) ₄ : Tb ³⁺ , Ca ₃ Sc ₂ Si ₃ O ₁₂ :Ce, CaSc ₂ O ₄ :Ce, Ba ₃ Si ₆ O ₁₂ N ₂ :Eu, β-SiAlON (antimony aluminum nitride) : one of Eu ²⁺ or the like or a combination of two or more.

The phosphor layer 11 is a film obtained by forming a resin composition containing a powdery powder of the present invention and a red phosphor.

Further, among the phosphor powder sheets of Fig. 1, preferably, the end portion of the first water vapor barrier film 12 and the end portion of the second water vapor barrier film 13 are sealed by the covering member 14, and the covering member 14 has 1 g/ Water vapor transmission rate below m ² /day.

As the covering member 14, an adhesive tape for applying the adhesive 142 to the base material 141 having a water vapor transmission rate of 1 g/m ² /day or less can be applied. As the substrate 141, a metal foil such as an aluminum foil or water vapor barrier films 12 and 13 can be used. Aluminum foil can be made of glossy white aluminum or matt black aluminum. If it is necessary to have a good color tone at the end of the phosphor powder sheet, it is preferable to use white aluminum. Further, the width W of the covering member 14 attached to the water vapor barrier film is preferably from 1 mm to 10 mm, and preferably from 1 mm to 5 mm, from the viewpoint of water vapor barrier properties or strength. According to the covering member 14 having such a structure, it is possible to prevent water vapor from intruding into the phosphor layer from the end portion of the water vapor barrier film, and to prevent deterioration of the phosphor powder in the phosphor layer.

(Lighting Device) The lighting device of the present invention has the phosphor powder sheet of the present invention. An example of a lighting device of the present invention will be described using a diagram. Fig. 2 is a schematic cross-sectional view showing a sidelight type illumination device. As shown in FIG. 2, the illuminating device includes a blue LED 31, and a light guide plate 32 that diffuses blue light of the blue LED 31 incident from the side surface and derives uniform light on the surface; the phosphor powder sheet 33 is made of blue light. Obtaining white light; and optical film 34. These constitute a so-called "sidelight type backlight".

The blue LED 31 is, for example, a so-called "LED package" having an InGaN-type LED chip as a blue light-emitting element. The light guide plate 32 causes light introduced from an end surface of a transparent substrate such as an acrylic plate to emit light uniformly on the ground. The phosphor powder sheet 33 is, for example, a phosphor powder sheet as shown in Fig. 1 . The phosphor powder contained in the phosphor powder sheet 33 is one having an average particle diameter of several μm to several tens μm. Thereby, the light scattering effect of the phosphor sheet 33 can be improved. The optical film 34 can be configured, for example, as a reflective polarizing film or a diffusion film for improving the sharpness of the liquid crystal display device.

3 is a schematic cross-sectional view showing a direct type illumination device. As shown in FIG. 3, the illuminating device includes a substrate 42 in which a blue LED 41 is two-dimensionally arranged, a diffusing plate 43 that diffuses blue light of the blue LED 41, and a phosphor sheet 33 that is disposed apart from the substrate 42. And white light is obtained from blue light; and optical film 34. These constitute the so-called "direct type backlight".

The blue LED 41 is, for example, a so-called "LED package" having an InGaN-type LED chip as a blue light-emitting element. The substrate 42 is made of a glass cloth substrate made of a resin such as phenol, epoxy resin or polyimide. On the substrate 42, the blue LED 41 corresponds to the entire surface of the phosphor powder sheet 33 at regular intervals. Ground for two-dimensional configuration. Further, a reflection treatment may be applied to the mounting surface of the blue LED 41 on the substrate 42 as needed. The substrate 42 and the phosphor powder sheet 33 are disposed so as to be spaced apart from each other by about 10 to 50 mm, and the illumination device constitutes a so-called "remote phosphor powder structure". The gap between the substrate 42 and the phosphor powder sheet 33 is supported by a plurality of support columns or reflectors, and is arranged such that the support column or the reflection plate surrounds the space formed by the substrate 42 and the phosphor powder sheet 44 in all directions. The diffuser 43 has a wide range of objects such that the emitted light from the blue LED 41 is diffused to such an extent that the shape of the light source is not visible, and has a total light transmittance of, for example, 20% or more and 80% or less.

Further, the present invention is not limited to the above-described embodiments, and various updates may be added without departing from the spirit and scope of the invention. For example, in the above embodiment, an example in which the illumination device is applied to a backlight source for a display device is shown, and it is also applicable to a light source for illumination. In the case of being suitable for a light source for illumination, it is mostly in the case where the optical film 34 is not required. Further, the phosphor-containing powder resin may be not only a flat sheet but also a three-dimensional shape having a cup shape or the like.

[Examples] Hereinafter, the present invention will be specifically described by way of Examples and Comparative Examples, but the present invention is not limited thereto. Measurements of the luminescence spectrum, calculation of various conversion efficiencies, and evaluation of crystallinity were performed in the examples as follows.

[Measurement of Luminescence (PL) Spectrum] Using the integrating sphere option of a spectrofluorometer FP-6500 (manufactured by JASCO Corporation), the wavelength of the luminescence peak, the intensity of the luminescence peak, and the full width at half maximum of the luminescence were measured. The luminescence peak intensity is a relative value under the basis of PL spectrum data of a general YAG phosphor powder P46-Y3 material manufactured by Optronics.

[Calculation of various conversion efficiencies] As the conversion efficiency of the phosphor powder, the efficiency of absorbing the excitation light (absorption rate), the efficiency of converting the absorbed excitation light into fluorescence (internal quantum efficiency), and the like are calculated. The product is the efficiency of converting the light into fluorescence (external quantum efficiency). The light-emitting characteristics were measured using an integrating sphere option of a spectrofluorometer FP-6500 (manufactured by JASCO Corporation). Fluorescent powder powder was filled in a dedicated tank, and blue excitation light having a wavelength of 450 nm was irradiated to measure a fluorescence spectrum. As a result, the quantum efficiency was calculated using the quantum efficiency calculation software included in the spectrofluorometer.

[Evaluation of Crystallinity] Evaluation of crystallinity was performed based on measurement of X-ray diffraction. The position (2θ) and the half-value width of the diffraction peak in the X-ray diffraction (XRD) pattern of the CuKα line were measured using a powder X-ray diffraction meter (X' Pert PRO manufactured by PANalytical Co., Ltd.). Fitting is performed by the peak search function of the attached analysis software, and the characteristics of the XRD pattern of the fluorescent powder are analyzed.

(Example 1) First, Ga ₂ O ₃ (purity 6N), Ba(NO ₃ ) ₂ (purity 3N), Sr(NO ₃ ) ₂ (purity 3N), and Eu(NO ₃ ) ₃ ·nH ₂ O ( Purity 3N, n = 6.06), and ammonium sulfite hydrate. Next, as shown in Table 1, among the phosphor powders represented by the composition formula (Ba _y Sr _1-y ) _1-x Ga ₂ S ₄ :Eu _x , the composition ratio of x=0.025, y=0.15 (Eu concentration) : 2.5 mol%, Ba substitution ratio: 15%), and the weight value of each raw material in the case where 0.1 mol is obtained is calculated. In the case of Example 1, it is a ruthenium compound (Eu(NO ₃ ) ₃ · nH ₂ O) 1.115 g, a ruthenium compound (Ba(NO ₃ ) ₂ ) 3.822 g, and a ruthenium compound (Sr(NO ₃ ) ₂ ) 17.539 g . The hydrazine compound, the hydrazine compound, and the hydrazine compound were added to 300 ml of pure water, and the mixture was sufficiently stirred until the residue was not dissolved. A mixed solution containing cerium (Eu), cerium (Ba), and strontium (Sr) was obtained. Next, 18.744 g of a powdery gallium compound (powdered Ga ₂ O ₃ ) was added so that the molar amount of the molar amount of Eu, Ba, and Sr was 2.0 times. Stirring was sufficiently performed to prepare a mixed solution of nitrate and gallium oxide powder. Next, 15.487 g of ammonium sulfite having a molar number of 1.15 times the total number of moles of Eu, Ba, and Sr was dissolved in 100 ml of pure water to prepare a sulfite solution. The sulfite solution was dropped to the mixed solution of the nitrate and the gallium oxide powder to obtain a precipitate and a precipitate. The precipitates and precipitates are a mixture of barium sulfite, barium, and strontium powder and gallium oxide powder. In addition, the precipitates and precipitates were washed and filtered with pure water until the conductivity became 0.1 mS/cm or less, and dried at 120 ° C for 15 hours. Thereafter, a powdery mixture containing Eu, Ba, Ga, and Sr was obtained by passing through a gold mesh having a nominal mesh opening of 100 μm. This powder mixture is a mixture containing: yttrium sulfite, yttrium and yttrium powder [a powder composed of (Ba, Sr, Eu) SO ₃ ]; and gallium oxide. Next, the powder mixture was fired in an electric furnace. The firing conditions are as follows. The temperature was raised to 925 ° C over 1.5 hours, thereafter maintained at 1.5 hours, 925 ° C, and then cooled to room temperature over two hours. In the firing, hydrogen sulfide was introduced into the electric furnace at a ratio of 0.3 liter/min. Thereafter, it was passed through a screen having a nominal mesh opening of 25 μm to obtain phosphor powder particles of (Ba _y Sr _1-y ) 1- _x Ga ₂ S ₄ :Eu _x (x=0.025, y=0.15). . The above test material preparation method is expressed in Table 1 as a wet method.

(Examples 2 to 7, and Comparative Examples 1 to 3) As shown in Table 1, the phosphor powder represented by the composition formula (Ba _y Sr _1-y ) _1-x Ga ₂ S ₄ :Eu _x was calculated. In the composition ratios of the x value and the y value of each of the examples and the comparative examples, the weight value of each raw material in the case of 0.1 mol. Except for this, the same wet method as in Example 1 was used to obtain a firefly of (Ba _y Sr _1-y ) _1-x Ga ₂ S ₄ :Eu _x from each of the examples and the comparative examples. Light powder particles.

(Comparative Example 4) First, Ga ₂ O ₃ (purity 6N), BaCO ₃ (purity 3N), SrCO ₃ (purity 3N), and Eu ₂ O ₃ (purity 3N) were prepared. Next, as shown in Table 1, the composition ratio of x=0.10 and y=0.35 among the phosphors represented by the composition formula (Ba _y Sr _1-y ) _1-x Ga ₂ S ₄ :Eu _x was calculated. (Eu concentration: 10 mol%, Ba substitution ratio: 35%), and the weight value of each raw material in the case of 0.05 mol. In the case of Example 4, 0.8798 g of ruthenium compound (Eu ₂ NO ₃ ), 4.318 g of ruthenium compound (SrCO ₃ ), 3.108 g of ruthenium compound (BaCO ₃ ), and 9.372 g of gallium compound (Ga ₂ O ₃ ) were used. The ruthenium compound, the ruthenium compound, the ruthenium compound, and the gallium compound were mixed in ethanol in a ball mill. After the completion of the mixing, the mixture was adsorbed and filtered, and dried at 80 ° C for 12 hours. Thereafter, the gold mesh was opened by passing through a 100 μm nominal mesh opening. A powder mixture containing Eu, Sr, Ba, and Ga is obtained. Next, the powder mixture was placed in an alumina calcined plate and fired in an electric furnace. The firing conditions are as follows. The temperature was raised to 925 ° C over 1.5 hours, thereafter maintained at 1.5 hours, 925 ° C, and then cooled to room temperature over 2 hours. In the firing, hydrogen sulfide was introduced into the electric furnace at a ratio of 0.3 liter/min. Thereafter, it was passed through a screen having a nominal mesh opening of 25 μm to obtain a phosphor powder particle of (Ba _y Sr _1-y ) ₁ - _x Ga ₂ S ₄ :Eu _x (x=0.10, y=0.35). . The above test material preparation method is expressed in Table 1 as a dry method.

By arranging the above, the composition range of the phosphor powder produced in the examples 1-7 can be expressed as: among the phosphor powder represented by the composition ratio (Ba _y Sr _1-y ) _1-x Ga ₂ S ₄ :Eu _x , x = 0.025 to 0.20; y = 0.15 to 0.49.

[Table 1]

(Luminescence Evaluation Results) Table 2 shows the evaluation results of the luminescent properties of the phosphors as Examples 1-7 and Comparative Examples 1-4, and the following numerical values were shown: luminescence peak wavelength, peak intensity, test material absorption rate, internal quantum efficiency , external quantum efficiency, x, y value of CIE chromaticity, brightness, full width at half maximum of light emission (FWHM).

From the PL spectrum measurement results of Example 1, it was found that the luminescence peak appeared at a wavelength of 534 nm, the luminescence peak intensity was 2.50 (YAG ratio), the luminance was 141.1% (YAG ratio), and the full width at half time of the luminescence was 49 nm. In addition, the CIE x, y chromaticity points are (0.267, 0.688). Further, as a result of calculating the conversion efficiency, the absorption rate was 64.2%, the internal quantum efficiency was 69.9%, and the external quantum efficiency was 44.9%.

Similarly, the results of evaluation of the light-emitting characteristics of Examples 2-7 are shown in Table 2. The luminescence peak wavelength is 529 to 535 nm; the luminescence peak intensity is 2.46 to 3.64 (YAG ratio); the luminance is 124.7 to 187.0% (YAG ratio); and the luminescence half value is 48 to 50 nm. In addition, the CIE x, y chromaticity points are shown as coordinates in the range of (0.235, 0.695) to (0.271, 0.687). Further, the conversion efficiency was calculated as follows: the absorption rate was 66.4 to 81.8%; the internal quantum efficiency was 64.6 to 79.0%; and the external quantum efficiency was 43.4 to 64.6%.

Similarly, the evaluation results of the light-emitting characteristics of Comparative Examples 1 to 4 are also shown in Table 2. The luminescence peak wavelength is 528 to 538 nm; the luminescence peak intensity is 1.25 to 3.43 (YAG ratio); the luminance is 68.1 to 192.7% (YAG ratio); and the full half width of the luminescence is 48 to 54 nm. Further, regarding the CIE x, y chromaticity point, the CIE x value is in the range of 0.231 to 0.288, and the CIE y value is in the range of 0.672 to 0.686, which is a discrete coordinate position. Further, the conversion efficiency was calculated as follows: the absorption rate was 62.6 to 80.1%; the internal quantum efficiency was 37.6 to 75.3%; and the external quantum efficiency was 24.9 to 60.3%.

Comparing the evaluation results of the luminescent properties of the phosphors of Examples 1-7 and 1-4 with the input composition ratios of Table 1, it was confirmed that there was a general tendency that the peak wavelength was 钡(Ba). The shorter the wavelength is, the longer the erbium (Eu) concentration increases, and the longer the wavelength is. Further, as shown in FIG. 4, when the wavelength of the luminescence peak is shortened, the intensity of the luminescence peak tends to decrease. In contrast to Comparative Examples 1 to 4, Examples 1 to 7 can be said to maintain relatively high luminous intensity while simultaneously generating a short wavelength. The brightness also has the same tendency as the intensity of the luminescence peak. Further, in Examples 1 to 7, it was found that the internal quantum efficiency was high and the light-emitting characteristics with high efficiency were obtained by comparing the same emission wavelengths.

On the other hand, in Examples 1 to 7 and Comparative Examples 1 to 4, the x and y chromaticity points of CIE are shown in Fig. 5 . Examples 1 to 7 are indicated by "◆"; Comparative Examples 1 to 4 are indicated by "Δ". In addition, the greenness point (0.210, 0.710) of NTSC is expressed as "■". The chromaticity points of Examples 1 to 7 were shifted in the range of (0.271, 0.687) to (0.235, 0.695) on a nearly single curve as the wavelength was shortened. Further, in comparison with Comparative Examples 1 to 4, the CIE values of Examples 1 to 7 were large and were close to the greenness point of NTSC. Therefore, it was found that the green purity of Examples 1 to 7 was high.

[Table 2]

Next, the phosphors of Examples 1 to 7 and Comparative Examples 1 to 4 were evaluated for crystallinity based on X-ray diffraction. Table 3 shows the evaluation results of the crystallinity of the phosphors of Examples 1 to 7 and Comparative Examples 1 to 4. Further, the X-ray diffraction patterns of Examples 1, 4, 5, and 7 and Comparative Examples 1 to 4 are as shown in Fig. 6 . As a result of thorough analysis of the results of the evaluation of the crystallinity, it was found that Examples 1 to 7 have a unique crystal structure. Specifically, the diffraction peak appears at a diffraction angle 2θ=30.0 to 30.4°, and the relative intensity with respect to the maximum peak represents a specific range. Observing the X-ray diffraction spectrum of Example 1 as shown in Fig. 6, the peak with the largest diffraction intensity is: the diffraction of the (422) plane which is returned to the SrGa ₂ S ₄ at the diffraction angle 2θ = 24.02°. The peak appears; the second peak of the diffraction intensity is: appears at the diffraction angle 2θ=38.38°, and the diffraction peak that returns to the (444) plane appears. Further, at a position of 30.2° between the diffraction angles 2θ = 30.0 to 30.40, a peak having a relative intensity of 8.8% with respect to the maximum peak of the diffraction intensity appeared.

Similarly, with respect to Examples 2-7, Comparative Examples 1-4 are also the same, and the following are summarized in Table 3: the diffraction intensity is the largest and the second diffraction angle 2θ position; at the diffraction angle 2θ = 30.0 to 30.40 ° The position of the peak appearing and the relative intensity relative to the maximum peak. In any of Embodiments 2-7, the maximum peak of the diffraction intensity is: at a diffraction angle of 2θ=23.82 to 23.96°, a diffraction peak which returns to the (422) plane of SrGa ₂ S ₄ appears; The second peak of the diffraction intensity is: at the diffraction angle 2θ=38.17~38.3°, the diffraction peak returning to the (444) plane appears. Further, at a position of 30.17 to 30.21° among the diffraction angles 2θ=30.0 to 30.4°, a peak having a relative intensity of 7.7 to 14.8% with respect to the maximum peak of the diffraction intensity appears. Representative examples of the X-ray diffraction spectra of Examples 4, 5, and 7 are shown in Fig. 6, and the specific crystal structure described above can be confirmed.

On the other hand, the X-ray diffraction spectrum in Comparative Example 1 is shown in Fig. 6. The peak with the highest diffraction intensity is: at the diffraction angle 2θ = 24.06°, returning to the (422) plane of SrGa ₂ S ₄ The diffraction peak appears; the second peak of the diffraction intensity is: at the diffraction angle 2θ=38.42°, the diffraction peak returning to the (444) plane appears, but the diffraction angle is 2θ=30.0～30.4° A peak appears. In other words, in Comparative Example 1, the composition ratio of x=0.10 and y=0 (铕(Eu) concentration: 10 mol%, 钡(Ba) substitution ratio: 0%) does not contain 钡 (Ba). In this composition, a unique diffraction peak having a diffraction angle of 2θ = 30.0 to 30.4° does not occur.

In Comparative Example 2, the X-ray diffraction spectrum is shown in Fig. 6, except that the peak with the highest diffraction intensity appears at the diffraction angle 2θ = 34.36°; the peak with the second diffraction intensity appears at the diffraction angle 2θ = 17.00°. It exhibits a structure different from that of the SrGa ₂ S ₄ structure, and no peak appears at the diffraction angle 2θ=30.0 to 30.4°. That is to say, Comparative Example 2 is a composition ratio of x=0.025, y=0.05 (铕(Eu) concentration: 2.5 mol%, 钡(Ba) substitution ratio: 5%), and the ratio of substitution in Ba (Ba) Among the small compositions, there is no characteristic diffraction peak of the diffraction angle 2θ = 30.0 to 30.4°.

In Comparative Example 3, the X-ray diffraction spectrum is shown in Fig. 6, except that the peak with the highest diffraction intensity appears at the diffraction angle 2θ = 23.44°, and the peak with the second diffraction intensity appears at the diffraction angle 2θ = 31.82°. It exhibits a structure different from that of SrGa ₂ S ₄ . A peak of 38.7% relative to the maximum intensity of the diffraction intensity peak appeared at the 30.15° position in the diffraction angle 2θ=30.0 to 30.4°. That is, Comparative Example 3 is a case where the composition ratio of x=0.05 and y=0.55 (铕(Eu) concentration: 5 mol%, 钡(Ba) substitution ratio: 55%), in this composition, diffraction The second peak of the strength exhibits a structure different from that of the SrGa ₂ S ₄ structure, meaning that the main structure is another structure among the components in which the substitution ratio of barium (Ba) is excessive.

In Comparative Example 4, the X-ray diffraction spectrum is shown in Fig. 6. However, the peak with the highest diffraction intensity is: (422) plane diffraction peak which is returned to SrGa ₂ S ₄ at the diffraction angle 2θ=24.06°. Appears; the second peak of the diffraction intensity is: at the diffraction angle 2θ=38.37°, the diffraction peak that returns to the (444) plane appears; but the diffraction angle 2θ=30.0~30.4° does not appear. That is to say, Comparative Example 4 is a composition ratio of x=0.10 and y=0.35 (铕(Eu) concentration: 10 mol%, 钡(Ba) substitution ratio: 35%), and the ratio of substitution in Ba (Ba) Among the small compositions, a characteristic diffraction peak having a diffraction angle of 2θ = 30.0 to 30.4° does not appear.

[table 3]

When the above results were collected, the specific crystal structure found in Examples 1 to 7 was defined under the following conditions. It has the following characteristics: the peak with the largest diffraction intensity is: the diffraction angle 2θ=23.7~24.1°, the diffraction peak which returns to the (422) plane of SrGa ₂ S ₄ , and the second peak of the diffraction intensity is: It appears at the diffraction angle 2θ=38.1~38.5°, and returns to the diffraction peak of the (444) plane of SrGa ₂ S ₄ ; at the diffraction angle 2θ=30.0～30.4°, it has relative to the maximum peak of the diffraction intensity. A diffraction peak with a strength of 5 to 20%.

Further, the specific crystal structure seen in Examples 1 to 7 appeared in the phosphor powder represented by the composition formula (Ba _y Sr _1-y ) _1-x Ga ₂ S ₄ :Eu _x , x=0.025 to 0.20. ; y = 0.15 ~ 0.49 in the range.

When the above results were collected, the phosphor powders produced in Examples 1 to 7 were used in the phosphor powder represented by the composition formula (Ba _y Sr _1-y ) _1-x Ga ₂ S ₄ :Eu _x . = 0.025 to 0.20; the value in the range of y = 0.15 to 0.49 is expressed.

Further, the specific crystal structure seen in Examples 1 to 7 can be defined by the following conditions.・The maximum peak of the diffraction intensity is: a diffraction peak that appears at the diffraction angle 2θ=23.7 to 24.1° and returns to the (422) plane of SrGa2S4.・The second peak of the diffraction intensity is: a diffraction peak that appears at a diffraction angle of 2θ=38.1 to 38.5° and returns to the SrGa2S4 (444) plane.・The diffraction peak has a relative intensity of 5 to 20% with respect to the maximum peak of the diffraction intensity at the diffraction angle 2θ=30.0 to 30.4°.

11‧‧‧Fluorescent powder layer

12‧‧‧First water vapor barrier film

13‧‧‧Second water vapor barrier film

14‧‧‧ Covering parts

31‧‧‧Blue LED

32‧‧‧Light guide plate

33‧‧‧Flame powder

34‧‧‧Optical film

41‧‧‧Substrate

42‧‧‧Substrate

43‧‧‧Diffuser

141‧‧‧Substrate

142‧‧‧Adhesive

Fig. 1 is a schematic cross-sectional view showing a configuration example of an end portion of a phosphor powder sheet. Fig. 2 is a schematic cross-sectional view showing an illumination device of an edge light. Fig. 3 is a schematic cross-sectional view showing a direct type illumination device. Fig. 4 is a graph showing the relationship between the luminescence peak wavelength of the phosphor powder of Example 1-7 and Comparative Example 1-4 and the luminescence peak intensity. Fig. 5 is a graph showing the x value and the y value of CIE of the phosphor powders of Example 1-7 and Comparative Example 1-4. Fig. 6 is an X-ray diffraction pattern of the phosphors of Examples 1, 4, 5, and 7 and Comparative Examples 1-4.

Claims (7)

A fluorescent powder characterized by comprising at least a fluorescent substance represented by the following formula (1) and satisfying the following conditions (1) to (3), (Ba _y Sr _1-y ) _1-x Ga ₂ S ₄ :Eu _x Formula (1) However, in the formula (1), 0.025 ≦ x ≦ 0.20, and 0.15 ≦ y ≦ 0.49, Condition (1): The maximum diffraction intensity of the XRD pattern appears in the winding The angle of incidence 2θ=23.7 to 24.1°, which is regressed to the diffraction peak of the (422) plane of SrGa ₂ S ₄ ; Condition (2): The second peak of diffraction intensity appears at the diffraction angle 2θ=38.1～38.5°, regression a diffraction peak on the SrGa ₂ S ₄ (444) plane; Condition (3): a relative intensity of 5 to 20% relative to the maximum peak of the diffraction intensity at a diffraction angle 2θ=30.0 to 30.4° Shoot the peak. The phosphor powder according to claim 1, wherein the y value of the fluorescent substance based on the CIE1931 color system is 0.687 or more. The phosphor powder according to claim 1, wherein the fluorescent material has an internal quantum efficiency of 0.64 or more. A phosphor powder sheet comprising a phosphor powder layer, the phosphor powder layer comprising the phosphor powder according to any one of claims 1 to 3, and a red phosphor powder. A lighting device characterized by having the phosphor powder sheet of claim 4. A method for producing a phosphor powder according to any one of claims 1 to 3, characterized by comprising: a precipitation precipitation process for dissolving a cerium compound, a cerium compound and a cerium compound and containing powdered gallium The first liquid of the compound is mixed with the second liquid containing sulfite to obtain a precipitate which is a mixture of precipitates containing barium sulfite, barium sulfite, and barium sulfite and the powdered gallium compound. The method for producing a phosphor powder according to claim 6, further comprising a baking process for firing the precipitate under a hydrogen sulfide-containing atmosphere.