JP6908460B2 - Phosphor, its manufacturing method, phosphor sheet, and lighting equipment - Google Patents

Description

The present invention relates to a phosphor, a method for producing the same, a phosphor sheet, and a lighting device.

Conventionally, pseudo-white LEDs using the yellow phosphor YAG: Ce have been used in low-priced TVs and displays. In this method, the characteristics of the red and green color filters are not matched, and the color purity of green and red is lowered.

On the other hand, in recent years, liquid crystal TVs and displays are required to have a wide color gamut. However, in the above method, since the color purity of green and red is lowered, the color gamut is narrowed. In order to widen the color gamut (widen the color gamut), a three-wavelength white LED using a green-emitting phosphor and a red-emitting phosphor that match the transmission characteristics of the color filter is advantageous instead of the yellow phosphor. be.

As a green light emitting phosphor, SrGa ₂ S ₄ : Eu phosphor is known. Since the SrGa ₂ S ₄ : Eu phosphor is excited by light in the near-ultraviolet to blue region, it is attracting attention as a green light emitting phosphor for exciting a blue LED.
SrGa ₂ S ₄ : related to the Eu fluorophore, for example, SrGa ₂ S ₄ : Eu fluorophore, or MGa ₂ S ₄ : Eu fluorophore (M = Ba, Sr and / or) for the purpose of improving internal quantum efficiency. Ca) has been proposed (see, for example, Patent Documents 1 and 2).

In order to realize a three-wavelength white LED having a wide color gamut, a green light emitting phosphor having high color purity is required.

Further, the phosphor used for the white LED is used adjacent to the LED, or is contained in the sheet and used at a position separated from the LED to some extent.
The phosphor is exposed to a temperature of 100 ° C. or higher by receiving the heat generated by the LED, not only when it is used adjacent to the LED but also when it is contained in the sheet and placed at a position separated from the LED to some extent. There is. At that time, the emission intensity of the phosphor may decrease.

Therefore, there is a demand for a green light emitting phosphor having high color purity and suppressing a decrease in light emission intensity at high temperature.

Japanese Patent No. 4343267 Japanese Patent No. 4708507

An object of the present invention is to solve the above-mentioned problems in the past and to achieve the following object. That is, the present invention has a fluorescent substance that emits green light with high color purity and suppressed decrease in emission intensity at high temperature, a method for producing the same, a phosphor sheet having the phosphor, and the phosphor sheet. The purpose is to provide a lighting device.

The means for solving the above-mentioned problems are as follows. That is,
<1> A fluorescent substance represented by the following general formula (1) and containing at least a fluorescent substance satisfying the following conditions (1) and (2).
_{(Ba y Sr 1-y)} 1-x Ga 2 S 4: Eu x ··· formula (1)
However, in the general formula (1), 0.025 ≦ x ≦ 0.20 and 0.50 <y <1.00.
Condition (1): The maximum diffraction intensity peak of the XRD pattern appears at a diffraction angle of 2θ = 23.0 to 23.6 °, and is a diffraction peak attributable to the (311) plane of _{BaGa 2} S _{4.
Condition (2): A diffraction peak attributed to the (422) plane of SrGa 2} S _{4 at} a diffraction angle of 2θ = 23.7 to 24.2 °, and the relative intensity with respect to the maximum diffraction intensity peak is 5 to 90%. Has a diffraction peak that is.
<2> In the temperature dependence of the peak intensity of the emission peak wavelength of the fluorescent substance, the value of the peak intensity of the emission peak wavelength at 100 ° C is 0 with respect to the value of the peak intensity of the emission peak wavelength at 25 ° C. The phosphor according to the above <1>, which is .55 or more.
<3> The fluorescent substance according to any one of <1> to <2>, wherein the internal quantum efficiency of the fluorescent substance is 0.65 or more.
<4> The phosphor sheet is characterized by having a phosphor layer containing the phosphor according to any one of <1> to <3> and a red phosphor.
<5> A lighting device characterized by having the phosphor sheet according to <4>.
<6> A method for producing a fluorescent substance, which comprises producing the fluorescent substance according to any one of <1> to <3>.
A first solution containing a barium compound, a strontium compound, and a europium compound and containing a powdered gallium compound is mixed with a second solution containing a sulfite salt to obtain barium sulfite, strontium sulfite, and europium sulfite. A method for producing a phosphor, which comprises a precipitation-precipitation step of obtaining a precipitate which is a mixture of the contained precipitate and the powdered gallium compound.
<7> The method for producing a phosphor according to <6>, further comprising a firing step of firing the precipitate in an atmosphere containing hydrogen sulfide.

According to the present invention, a fluorescent phosphor that emits green light, which can solve the above-mentioned problems in the past, can achieve the above object, has high color purity, and suppresses a decrease in emission intensity at high temperature, and production thereof. A method, a phosphor sheet having the phosphor, and a lighting device having the phosphor sheet can be provided.

FIG. 1 is a schematic cross-sectional view showing a configuration example of the end portion of the phosphor sheet. FIG. 2 is a schematic cross-sectional view showing an edge light type lighting device. FIG. 3 is a schematic cross-sectional view showing a direct type lighting device. FIG. 4 is a graph showing CIEx, y of the phosphors of Examples 1 to 11 and Comparative Examples 1 to 4. FIG. 5 is a graph showing the temperature dependence of the emission peak intensity of the phosphors of Examples 2, 5, 8 and 11 and Comparative Examples 1 and 2. FIG. 6 is an X-ray diffraction pattern of the phosphors of Examples 1, 3, 5, 8, 11 and Comparative Examples 1 to 4.

(Fluorescent material)
The phosphor of the present invention contains at least a fluorescent substance and, if necessary, other components such as a coating layer.

<Fluorescent substance>
The fluorescent substance is represented by the following general formula (1).
_{(Ba y Sr 1-y)} 1-x Ga 2 S 4: Eu x ··· formula (1)
However, in the general formula (1), 0.025 ≦ x ≦ 0.20 and 0.50 <y <1.00. As for x, 0.050 ≦ x ≦ 0.150 is preferable, and 0.050 ≦ x ≦ 0.125 is more preferable. As for y, 0.550 ≦ y <1.00 is preferable, and 0.550 ≦ y ≦ 0.750 is more preferable.

The fluorescent substance satisfies the following conditions (1) and (2).
Condition (1): The maximum diffraction intensity peak of the XRD pattern appears at a diffraction angle of 2θ = 23.0 to 23.6 °, and is a diffraction peak attributable to the (311) plane of _{BaGa 2} S _{4.
Condition (2): A diffraction peak attributed to the (422) plane of SrGa 2} S _{4 at} a diffraction angle of 2θ = 23.7 to 24.2 °, and the relative intensity with respect to the maximum diffraction intensity peak is 5 to 90%. Has a diffraction peak that is.

In the fluorescent substance, the Ga / (Eu + Ba + Sr) ratio (elemental ratio) is preferably 1.80 to 2.50, more preferably 1.90 to 2.30.

Examples of the emission peak wavelength of the fluorescent substance include 518 nm to 532 nm.

Examples of the emission peak intensity (ratio to YAG) of the fluorescent substance include 1.99 to 3.19.

Examples of the sample absorption rate of the fluorescent substance include 61% to 77%.

Examples of the x value based on the CIE 1931 color system of the fluorescent substance include 0.200 to 0.254.

Examples of the y value based on the CIE1931 color system of the fluorescent substance include 0.634 to 0.689.

The internal quantum efficiency of the fluorescent substance is preferably 0.65 (65%) or more.
Examples of the internal quantum efficiency of the fluorescent substance include 0.65 (65%) to 0.80 (80%).

The external quantum efficiency of the fluorescent substance is preferably 0.41 (41%) or more.
Examples of the external quantum efficiency of the fluorescent substance include 0.41 (41%) to 0.60 (60%).

Examples of the brightness (ratio to YAG) of the fluorescent substance include 107% to 165%.

Examples of the full width at half maximum of the emission of the fluorescent substance include 49 nm to 62 nm.

In the temperature dependence of the peak intensity of the emission peak wavelength of the fluorescent substance, the value of the peak intensity of the emission peak wavelength at 100 ° C. is 0.55 (value) with respect to the value of the peak intensity of the emission peak wavelength at 25 ° C. 55%) or more is preferable. The peak intensity value is more preferably 0.55 (55%) to 1.0 (100%).

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

[Measurement of emission (PL) spectrum]
The emission peak wavelength, emission peak intensity, and full width at half maximum of emission in the PL spectrum are measured using the integrating sphere option of the spectrofluorometer FP-6500 (manufactured by Nippon Kogaku Co., Ltd.). The emission peak intensity is shown as a relative value based on the PL spectrum data of a general YAG phosphor P46-Y3 material manufactured by Kasei Optronics.

[Calculation of various conversion efficiencies]
As the conversion efficiency of the phosphor, the efficiency of absorbing the excitation light (absorption rate), the efficiency of converting the absorbed excitation light into fluorescence (internal quantum efficiency), and the efficiency of converting the excitation light which is the product of them into fluorescence (external). Quantum efficiency) is calculated. The emission characteristics are measured using the integrating sphere option of the spectrofluorometer FP-6500 (manufactured by JASCO Corporation). The dedicated cell is filled with phosphor powder, irradiated with blue excitation light having a wavelength of 450 nm, and the fluorescence spectrum is measured. The quantum efficiency of the result is calculated using the quantum efficiency calculation software attached to the spectrofluorometer.

[Evaluation of crystallinity]
Crystallinity is evaluated by measuring X-ray diffraction. Using a powder X-ray diffractometer (X'Pert PRO manufactured by PANalytical), the position (2θ) and full width at half maximum of the diffraction peak in the X-ray diffraction (XRD) pattern of CuKα rays are measured. Fitting is performed by the peak search function of the attached analysis software, and the characteristics of the XRD pattern of the phosphor are analyzed.

[Measurement of temperature dependence of emission (PL) spectrum]
Using a high-temperature powder cell unit (HPC-503 type) of the spectrofluorometer FP-6500 (manufactured by JASCO Corporation), the sample temperature is changed from room temperature (25 ° C) to 175 ° C to 200 ° C, and the PL spectrum is measured. do. Obtain the emission peak wavelength, emission peak intensity, and emission integrated intensity at each sample temperature. The emission peak intensity / emission integral intensity of the PL spectrum is shown as a relative value based on the value at room temperature (25 ° C.).

<Coating layer>
A further preferred embodiment of the fluorescent substance of the present invention is a fluorescent substance in which the surface of the fluorescent substance is coated with a fluororesin as a coating layer.
By improving the moisture resistance and water resistance of the fluorescent substance, it is possible to prevent the hydrolysis reaction by water or the like and prevent the deterioration of the light emitting characteristics.
In order to improve the moisture resistance and water resistance of the fluorescent substance, it is preferable to coat the surface of the fluorescent substance with a fluororesin. By doing so, deterioration of the fluorescent substance due to hydrolysis or the like can be prevented, and deterioration of light emission characteristics such as emission peak intensity can be further suppressed.

Each physical property value such as emission peak wavelength, emission half width, emission peak intensity, internal quantum efficiency, and external quantum efficiency differs depending on the composition of the fluorescent substance, the crystal structure, and the like.
However, the phosphor of the present invention is produced by the production method of the present invention described later, and thus has a novel crystal structure, high color purity, and green emission in which a decrease in emission intensity at high temperature is suppressed. It becomes a phosphor.

(Manufacturing method of phosphor)
The method for producing a phosphor of the present invention includes at least a precipitation-precipitation step, and further includes other steps such as a firing step and a coating step, if necessary.
The method for producing the fluorescent substance is the method for producing the fluorescent substance of the present invention.

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

<< First liquid >>
The first liquid dissolves a barium compound, a strontium compound, and a europium compound, and contains a powdered gallium compound.

Examples of the method for obtaining the first liquid include a method in which a barium compound, a strontium compound, and a europium compound are dissolved in water, and a gallium compound powder is mixed therein.

Examples of the barium compound include barium nitrate [Ba (NO ₃ ) ₂ ], barium oxide [BaO], barium bromide [BaBr ₂ · xH ₂ O], barium chloride [BaCl ₂ · xH ₂ O], and barium acetate. [Ba (CH ₃ COO) ₂ ], barium iodide [BaI ₂ · xH ₂ O], barium hydroxide [Ba (OH) ₂ ], barium sulfide [BaS] and the like can be used.

As the strontium compound, e.g., strontium nitrate _{[Sr (NO 3) 2]} , strontium oxide [SrO], strontium bromide _{[SrBr 2 · xH 2 O]} , strontium chloride _{[SrCl 2 · xH 2 O]} , strontium carbonate [SrCO ₃ ], strontium oxalate [SrC ₂ O ₄ · H ₂ O], strontium fluoride [SrF ₂ ], strontium iodide [SrI ₂ · xH ₂ O], strontium sulfate [SrSO ₄ ], strontium hydroxide [Sr (OH) ₂ · xH ₂ O], strontium sulfide [SrS] and the like can be used.

Examples of the europium compound include europium nitrate [Eu (NO ₃ ) ₃ · xH ₂ O], europium oxalate [Eu ₂ (C ₂ O ₄ ) ₃ · xH ₂ O], and europium carbonate [Eu ₂ (CO ₃ )). ₃ · _xH 2 O], europium sulfate _{[Eu 2 (SO 4) 3} ], europium chloride _{[EuCl 3 · xH 2 O]} , fluoride europium _[EuF 3], hydrogenated europium _[EuH x], europium sulfide [EuS ], Tri-i-propoxyeuropium [Eu (O-i-C ₃ H ₇ ) ₃ ], Europium acetate [Eu (O-CO-CH ₃ ) ₃ ] and the like can be used.

Examples of the powdered gallium compound include 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], and odor. Gallium gallium [GaBr ₃ ], gallium chloride [GaCl ₃ ], gallium iodide [GaI ₃ ], gallium sulfide (II) [GaS], gallium sulfide (III) [Ga ₂ S ₃ ], gallium oxyhydroxide [GaOOH] Etc. can be used.

The contents of Ba, Sr, Eu, and Ga in the first liquid are not particularly limited and may be appropriately selected depending on the intended purpose.

<< Second liquid >>
The second liquid contains sulfites.
Examples of the method for obtaining the second liquid include a method of dissolving sulfite in water.
The content of the sulfite in the second liquid is not particularly limited and may be appropriately selected depending on the intended purpose.

Examples of the sulfite include ammonium sulfite, sodium sulfite, potassium sulfite and the like.

The mixing ratio of the first liquid and the second liquid is not particularly limited and may be appropriately selected depending on the intended purpose. For example, of Eu, Ba, and Sr in the first liquid. For example, mixing is performed so that the molar amount of sulfite is 1.00 to 1.50 times the total molar amount.

<< Precipitate >>
The precipitate is a mixture of the precipitate and the powdered gallium compound.
The precipitate contains barium sulfite, strontium sulfite, and europium sulfite.
The barium compound, strontium compound, and europium compound are dissolved and homogenized in the first liquid, so that barium sulfite, strontium sulfite, and europium sulfite are uniformly mixed in the precipitate. ..
Further, in the precipitate, the powdered gallium compound, barium sulfite, strontium sulfite, and europium sulfite are uniformly mixed.

The precipitate is preferably washed before being subjected to the firing step described later. The cleaning conditions are not particularly limited and may be appropriately selected depending on the intended purpose. For example, washing with water until the conductivity becomes 0.1 mS / cm or less can be mentioned.

<Baking process>
The firing step is not particularly limited as long as it is a step of firing the precipitate in an atmosphere containing hydrogen sulfide, and can be appropriately selected depending on the intended purpose.
Examples of the firing temperature in the firing step include 900 ° C. to 950 ° C.
Examples of the firing time in the firing step include 1 hour to 5 hours.
The ratio of hydrogen sulfide in the atmosphere in the firing step is not particularly limited and can be appropriately selected depending on the intended purpose. For example, 0.1 L / min to 0.5 L / min of hydrogen sulfide is fired. Supplying in the atmosphere can be mentioned.

The fluorescent substance in the fluorescent substance of the present invention can be obtained by the firing step.

<Coating process>
The coating step is not particularly limited as long as it is a step of coating the surface of the fluorescent substance obtained by the firing step with a coating layer, and can be appropriately selected depending on the intended purpose.
The coating step can be performed, for example, by coating the fluororesin in a non-aqueous atmosphere.

For example, a fluorine-based resin solution containing a fluorine-based resin in a fluorine-containing solvent such as hydrofluoroethers such as ethoxynonafluorobutane is used, and the fluorescent substance obtained above is mixed with the fluorine-based resin solution. Mix with a mix rotor or the like. Next, the powder is collected by suction filtration, and the powder is dried at a temperature of about 80 ° C. to 100 ° C. for 0.5 hours to 1.5 hours. This makes it possible to obtain a phosphor having a coating layer made of a fluororesin on the surface.

(Fluorescent sheet)
The fluorophore sheet of the present invention has at least a fluorophore layer and, if necessary, other members such as a water vapor barrier film.

<Fluorescent layer>
The fluorescent material layer contains at least the fluorescent material of the present invention and a red fluorescent material, and further contains other components such as a resin, if necessary.
The fluorescent substance layer is formed by, for example, the fluorescent substance of the present invention and the red fluorescent substance dispersed in the layered resin.

<< Red Fluorescent Material >>
The red phosphor is not particularly limited and may be appropriately selected depending on the intended purpose. For example, from sulfide-based phosphors, oxide-based phosphors, nitride-based phosphors, fluoride-based phosphors and the like. , 1 type or a combination of 2 or more types can be used depending on the type of phosphor, absorption band, light emission band and the like.

Specific examples of the red phosphor include (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, CaS: Eu or (Ba, Sr) ₃ SiO ₅ : Eu, which can realize a wide color gamut, is preferably used. Here, "ME" means at least one kind of atom selected from the group consisting of Ca, Sr and Ba, and "M" means at least one kind selected from the group consisting of Li, Mg and Ca. Means an atom. In addition, ":" indicates the mother's body, and ":" indicates the activator.

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

Examples of the polyolefin copolymer include a styrene-based copolymer or a hydrogenated product thereof. As such a styrene-based copolymer or a hydrogenated product thereof, a styrene-ethylene-butylene-styrene block copolymer or a hydrogenated product thereof, a styrene-ethylene-propylene block copolymer or a hydrogenated product thereof is preferably mentioned. be able to. Among these, a hydrogenated product of a styrene-ethylene-butylene-styrene block copolymer can be particularly preferably used from the viewpoint of transparency and gas barrier property. By containing such a polyolefin copolymer, excellent 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, from the viewpoint of heat resistance after photocuring. Therefore, urethane (meth) acrylate can be preferably used. By containing such a photocurable (meth) acrylic resin, excellent light resistance and low water absorption can be obtained.

<Water vapor barrier film>
Examples of the water vapor barrier film include a gas barrier film in which a metal oxide thin film such as aluminum oxide, magnesium oxide, or silicon oxide is formed on the surface of a plastic substrate such as PET (Polyethylene terephthate) or a film. Further, a multilayer structure such as PET / SiOx / PET may be used.

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

The phosphor layer 11 contains the phosphor of the present invention that emits green fluorescence and a red phosphor that emits red fluorescence having a wavelength of 620 to 660 nm when irradiated with blue excitation light, and converts the irradiated blue light into white light. Convert.

Further, as a green light emitting phosphor other than the phosphor of the present invention, Zn ₂ SiO ₄ : Mn, Y ₃ Al ₅ O ₁₂ : Ce ³⁺ , (Y, Gd) Al 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: Eu ^2+, etc. good.

The phosphor layer 11 is formed by forming a powdery resin composition containing the fluorescent substance of the present invention and a red fluorescent substance.

Further, in the phosphor sheet of FIG. 1, the cover member 14 in which the end portion of the first water vapor barrier film 12 and the end portion of the second water vapor barrier film 13 have a water vapor transmittance of ^{1 g / m 2 / day or less.} It is preferably sealed with.

As the cover member 14, an adhesive tape in which the pressure-sensitive adhesive 142 is applied to a base material 141 having a water vapor permeability of ^{1 g / m 2 / day or less can be used.} As the base material 141, a metal foil such as an aluminum foil or water vapor barrier films 12 and 13 can be used. As the aluminum foil, either glossy white aluminum or non-glossy black aluminum may be used, but when a good color tone of the edge of the phosphor sheet is required, white aluminum is preferably used. Further, the width W of the cover member 14 to be attached on the water vapor barrier film is preferably 1 mm to 10 mm, more preferably 1 mm to 5 mm, from the viewpoint of water vapor barrier property and strength. According to the cover member 14 having such a configuration, it is possible to prevent the invasion of water vapor from the end portion of the water vapor barrier film into the phosphor layer, and it is possible to prevent the deterioration of the phosphor in the phosphor layer. ..

(Lighting device)
The lighting device of the present invention has the phosphor sheet of the present invention.
An example of the lighting device of the present invention will be described with reference to the drawings.
FIG. 2 is a schematic cross-sectional view showing an edge light type lighting device. As shown in FIG. 2, the lighting device includes a blue LED 31, a light guide plate 32 that diffuses the blue light of the blue LED 31 incident from the side surface and emits uniform light on the surface, and a phosphor that obtains white light from the blue light. It constitutes a so-called "edge light type backlight" including a sheet 33 and an optical fill 34.

The blue LED 31 constitutes a so-called "LED package" having, for example, an InGaN-based LED chip as a blue light emitting element. The light guide plate 32 uniformly surface-emits light emitted from the end surface of a transparent substrate such as an acrylic plate. The fluorescent material sheet 33 is, for example, the fluorescent material sheet shown in FIG. The phosphor powder contained in the phosphor sheet 33 has an average particle size of several μm to several tens of μm. This makes it possible to improve the light scattering effect of the phosphor sheet 33. The optical film 34 is composed of, for example, a reflective polarizing film or a diffusion film for improving the visibility of a liquid crystal display device.

Further, FIG. 3 is a schematic cross-sectional view showing a direct type lighting device. As shown in FIG. 3, the lighting device is arranged apart from the substrate 42 in which the blue LED 41 is two-dimensionally arranged, the diffuser plate 43 for diffusing the blue light of the blue LED 41, and the substrate 42, and the blue light to the white light. It constitutes a so-called "direct-type backlight" including a phosphor sheet 33 for obtaining the above and an optical film 34.

The blue LED 41 constitutes a so-called "LED package" having, for example, an InGaN-based LED chip as a blue light emitting element. The substrate 42 is made of a glass cloth base material using a resin such as phenol, epoxy, or polyimide, and blue LEDs 41 are formed on the substrate 42 at regular intervals corresponding to the entire surface of the phosphor sheet 33. Arranged in a dimension. Further, if necessary, the mounting surface of the blue LED 41 on the substrate 42 may be subjected to a reflection treatment. The substrate 42 and the phosphor sheet 33 are arranged at a distance of about 10 to 50 mm, and the lighting device constitutes a so-called "remote phosphor structure". The gap between the substrate 42 and the phosphor sheet 33 is held by a plurality of support columns and reflectors, and the space formed by the substrate 42 and the phosphor sheet 33 is provided so that the support columns and the reflector surround the space formed by the support columns and the reflector. .. The diffuser plate 43 diffuses the synchrotron radiation from the blue LED 41 over a wide range so that the shape of the light source becomes invisible, and has, for example, a total light transmittance of 20% or more and 80% or less.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the gist of the present invention. For example, in the above-described embodiment, the example in which the lighting device is applied to the backlight light source for the display device is shown, but it may be applied to the lighting light source. When applied to an illumination light source, the optical film 34 is often unnecessary. Further, the phosphor-containing resin may have a three-dimensional shape such as a cup-shaped shape as well as a flat sheet shape.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In the examples, the measurement of the emission spectrum, the calculation of various conversion efficiencies, and the evaluation of crystallinity were performed as follows.

[Measurement of emission (PL) spectrum]
The emission peak wavelength, emission peak intensity, and emission half width in the PL spectrum were measured using the integrating sphere option of the spectrofluorometer FP-6500 (manufactured by Nippon Kogaku Co., Ltd.). The emission peak intensity is shown as a relative value based on the PL spectrum data of a general YAG phosphor P46-Y3 material manufactured by Kasei Optronics.

[Calculation of various conversion efficiencies]
As the conversion efficiency of the phosphor, the efficiency of absorbing the excitation light (absorption rate), the efficiency of converting the absorbed excitation light into fluorescence (internal quantum efficiency), and the efficiency of converting the excitation light which is the product of them into fluorescence (external). Quantum efficiency) was calculated. The emission characteristics were measured using the integrating sphere option of the spectrofluorometer FP-6500 (manufactured by JASCO Corporation). The dedicated cell was filled with phosphor powder, irradiated with blue excitation light having a wavelength of 450 nm, and the fluorescence spectrum was measured. As a result, the quantum efficiency was calculated using the quantum efficiency calculation software attached to the spectrofluorometer.

[Evaluation of crystallinity]
The crystallinity was evaluated by measuring X-ray diffraction. Using a powder X-ray diffractometer (X'Pert PRO manufactured by PANalytical), the position (2θ) and full width at half maximum of the diffraction peak in the X-ray diffraction (XRD) pattern of CuKα rays were measured. Fitting was performed using the peak search function of the attached analysis software, and the characteristics of the XRD pattern of the phosphor were analyzed.

[Measurement of temperature dependence of emission (PL) spectrum]
Using a high-temperature powder cell unit (HPC-503 type) of the spectrofluorometer FP-6500 (manufactured by JASCO Corporation), the sample temperature is changed from room temperature (25 ° C) to 175 ° C to 200 ° C, and the PL spectrum is measured. did. The emission peak wavelength, emission peak intensity, and emission integrated intensity at each sample temperature were determined. The emission peak intensity / emission integral intensity of the PL spectrum is shown as a relative value based on the value at room temperature (25 ° C.).

[Evaluation of crystallinity]
The crystallinity was evaluated by measuring X-ray diffraction. Using a powder X-ray diffractometer (X'Pert PRO manufactured by PANalytical), the position (2θ) and full width at half maximum of the diffraction peak in the X-ray diffraction (XRD) pattern of CuKα rays were measured. Fitting was performed using the peak search function of the attached analysis software, and the characteristics of the XRD pattern of the phosphor were 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 sulfate monohydrate were prepared.
Then, as shown in Table 1, the composition formula _{(Ba y Sr 1-y)} 1-x Ga 2 S 4: in the phosphor represented by Eu _x, x = 0.125, and y = 0.543 The weighing value of each raw material was calculated so that the composition ratio (Eu concentration: 12.5 mol%, Ba substitution ratio: 54.3%) was 0.1 mol. In the case of Example 1, the europium compound (Eu (NO ₃ ) _3. nH ₂ O) 5.583 g, the barium compound (Ba (NO ₃ ) ₂ ) 12.415 g, and the strontium compound (Sr (NO ₃ ) ₂ ) 8 It is .464 g.
The europium compound, the barium compound, and the strontium compound were added to 300 ml of pure water and stirred sufficiently until there was no undissolved residue to obtain a mixed solution containing Eu, Ba, and Sr. Next, 18.744 g of _{powdered gallium compound (powdered Ga 2} O ₃ ) calculated so that the molar amount of Ga was 2.0 times the sum of the molar amounts of Eu, Ba, and Sr was added. , Stir well to prepare a mixed solution of nitrate and gallium oxide powder.
Next, 15.487 g of ammonium sulfite having 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.
A precipitate / precipitate was obtained by dropping this sulfite solution into the above mixed solution of nitrate and gallium oxide powder. This precipitate / precipitate is a mixture of europium sulfite / barium / strontium powder and gallium oxide powder.
Then, the precipitate / precipitate was washed and filtered with pure water until the conductivity became 0.1 mS / cm or less, and dried at 120 ° C. for 15 hours. Then, a powder mixture containing Eu, Ba, Ga, and Sr was obtained by passing through a wire mesh having a nominal opening of 100 μm. This powder mixture is a mixture containing europium sulfite, barium, and strontium powder [ _{powder composed of (Ba, Sr, Eu) SO 3} ] and gallium oxide.
Then, the powder mixture was fired in an electric furnace. The firing conditions were as follows. The temperature was raised to 925 ° C. in 1.5 hours, then maintained at 925 ° C. for 1.5 hours, and then lowered to room temperature in 2 hours. During firing, hydrogen sulfide was flowed through the electric furnace at a rate of 0.3 liters / minute. Then, through a 25μm mesh opening nominal _{th, (Ba y Sr 1-y} ) 1-x Ga 2 S 4: to obtain phosphor particles consisting of Eu x (x = 0.125, y = 0.543) ..
The above sample preparation method is referred to as a wet method.

(Examples 2 to 11 and Comparative Examples 1 to 4)
As shown in Table 1, the composition formula _{(Ba y Sr 1-y)} 1-x Ga 2 S 4: in the phosphor represented by Eu _x, x values of the examples and comparative examples, shown in y value The weighed value of each raw material was calculated so as to have a composition ratio of 0.1 mol. Other than this, a wet method in the same manner as in Example 1, the Examples, and Comparative Examples _{(Ba y Sr 1-y)} 1-x Ga 2 S 4: to obtain phosphor particles consisting of Eu _x.

(Emission evaluation result)
In Table 2, as the evaluation results of the emission characteristics of the phosphors of Examples 1 to 11 and Comparative Examples 1 to 4, the emission peak wavelength, peak intensity, sample absorption rate, internal quantum efficiency, external quantum efficiency, and ClE chromaticity x , Y value, brightness, and half-value emission full width (FWHM) values are shown.

From the results of measuring the PL spectrum for Example 1, an emission peak appears at a wavelength of 532 nm, the emission peak intensity is 3.19 (YAG ratio), the brightness is 164.3% (YAG ratio), and the full width at half maximum of emission is 49 nm. there were. Further, it was a CIEx, y chromaticity point (0.254, 0.689). As a result of calculating the conversion efficiency, the absorption rate was 76.6%, the internal quantum efficiency was 78.2%, and the external quantum efficiency was 59.9%.

Similarly, the evaluation results of the light emission characteristics of Examples 2 to 11 are also shown in Table 2.
The emission peak wavelength was 518 to 531 nm, the emission peak intensity was 1.99 to 3.11 (YAG ratio), the brightness was 107.4 to 161.7% (YAG ratio), and the full width at half maximum of emission was 51 to 62 nm. The CIEx, y chromaticity points showed coordinates in the range of (0.200, 0.634) to (0.249, 0.685). As a result of calculating the conversion efficiency, the absorption rate was 61.7 to 75.5%, the internal quantum efficiency was 65.9 to 79.3%, and the external quantum efficiency was 41.3 to 59.8%. ..

On the other hand, similarly, the evaluation results of the light emission characteristics of Comparative Examples 1 to 4 are also shown in Table 2.
According to the y value (Ba substitution ratio) in the composition formula, it is roughly divided into two groups, Comparative Examples 1 to 3 and Comparative Example 4.
In Comparative Examples 1 to 3, the emission peak wavelength was 529 to 532 nm, the emission peak intensity was 2.48 to 3.36 (YAG ratio), the brightness was 124.7 to 170.4% (YAG ratio), and the full width at half maximum of emission was It was 48 to 50 nm. The CIEx, y chromaticity points showed coordinates in the range of (0.235, 0.695) to (0.260, 0.692). As a result of calculating the conversion efficiency, the absorption rate was 67.2 to 81.8%, the internal quantum efficiency was 64.6 to 78.5%, and the external quantum efficiency was 43.4 to 62.2%. ..

In Comparative Example 4, an emission peak appeared at a wavelength of 508 nm, the emission peak intensity was 2.03 (YAG ratio), the brightness was 89.3% (YAG ratio), and the full width at half maximum of emission was 61 nm. Further, it was a CIEx, y chromaticity point (0.159, 0.569). As a result of calculating the conversion efficiency, the sample absorption rate was 61.4%, the internal quantum efficiency was 71.1%, and the external quantum efficiency was 43.7%.

Comparing the evaluation results of the emission characteristics of the phosphors of Examples 1 to 11 and Comparative Examples 1 to 4 in Table 2 with the input composition ratios in Table 1, the peak wavelength becomes shorter as the Ba substitution ratio increases. It can be confirmed that the wavelength becomes longer as the Eu concentration is increased.

The full width at half maximum (FWHM) of Examples 1 to 11 was widened as the Ba substitution ratio was increased, and the CIE chromaticity y value tended to decrease remarkably. Further, in Examples 1 to 11, it can be said that relatively high emission intensity and quantum efficiency can be maintained even if the wavelength is shortened.

On the other hand, the CIEx and y chromaticity points are shown in FIG. 4 with respect to Examples 1 to 11 and Comparative Examples 1 to 4. Examples 1 to 11 are indicated by "◆", and Comparative Examples 1 to 4 are indicated by "Δ". The Green chromaticity points (0.210, 0.710) of NTSC are indicated by "■". As the wavelength of the chromaticity points of Examples 1 to 11 is shortened, the chromaticity points are separated from the Green chromaticity points of NTSC, and the color purity is lowered, but (0.254, 0.689) to (0.200, 0. It shows a locus on an almost single curve of 634), and it can be seen that a characteristic chromaticity can be realized in the blue-green region.

Next, the temperature dependence of the emission characteristics of the phosphors of Examples 1 to 11 and Comparative Examples 1 to 4 was evaluated.
Typically, for Comparative Examples 1, 2 and Examples 2, 5, 8 and 11, the temperature dependence of the emission peak intensity is shown in FIG. 5, and the emission peak wavelength at 25 ° C. in each example, 100 ° C. and Table 3 shows the value of the emission peak intensity at 150 ° C. (relative value with the value at 25 ° C. as 100%).
Looking at FIG. 5, roughly, all of them show a behavior that the peak intensity decreases as the measurement temperature (sample temperature) is increased. When compared with the y value of the composition formula in Table 1, the higher the y value (Ba substitution ratio), the higher the peak intensity tends to be.
Looking at the details in Table 3, Comparative Examples 1 and 2 showed a large decrease of 47.4 to 53.4% at 100 ° C. and 16.4 to 18.3% at 150 ° C., whereas Examples 2, 5 and 2. 8 and 11 showed high values of 68.2 to 78.6% at 100 ° C. and 37.6 to 55.0% at 150 ° C., and there was a large difference in temperature-dependent behavior between the comparative example and the example. I understand.
In particular, when Comparative Example 2 (528 nm) and Example 2 (527 nm), which have similar peak wavelengths at 25 ° C., are compared, there is a difference of 20% or more in the peak intensity values at 100 ° C. and 150 ° C., and the difference is. it is obvious.
As described above, it can be seen that, as compared with Comparative Examples 1 to 3, in Examples 1 to 11, when the emission wavelengths are about the same, the temperature characteristics are excellent.

Next, the crystallinity of the phosphors of Examples 1 to 11 and Comparative Examples 1 to 4 was evaluated by X-ray diffraction.
Table 4 shows the crystallinity evaluation results of the phosphors of Examples 1 to 11 and Comparative Examples 1 to 4. Further, the X-ray diffraction patterns of Examples 1, 3, 5, 8, 11 and Comparative Examples 1 to 4 are shown in FIG.
As a result of diligent analysis of the crystallinity evaluation results, it was found that Examples 1 to 11 have a peculiar crystal structure. Specifically, the peak of the maximum diffraction intensity of the XRD pattern of the phosphor is a diffraction peak attributed to the (311) plane of _{BaGa 2} S _{4 appearing at a diffraction angle of 2θ = 23.0 to 23.6 °, and the diffraction} The relative intensity of the diffraction peak belonging to the (422) plane of _{SrGa 2} S ₄ appearing at the diffraction angle 2θ = 23.7 to 2.42 ° with respect to the peak indicates a certain range.
Looking at the X-ray diffraction pattern of Example 1 as shown in FIG. 6, a diffraction peak attributed to the (311) plane of _{BaGa 2} S ₄ appears at a diffraction angle of 2θ = 23.52 ° as the peak of the maximum diffraction intensity. , A diffraction peak attributed to the (422) plane of _{SrGa 2} S ₄ appears at a diffraction angle of 2θ = 23.93 ° adjacent to the previous diffraction peak, and a diffraction peak of the (311) plane of _{the previous BaGa 2} S _{4 appears.} The relative intensity of the diffraction peak on the (422) plane of SrGa ₂ S _{4 was 87%.}
Similarly, in Examples 2 to 11 and Comparative Examples 1 to 4, the diffraction angle 2θ position of the diffraction peak attributed to the (311) plane of _{BaGa 2} S _{4 and} the diffraction attributable to the (422) plane of _{SrGa 2} S ₄ Table 4 summarizes the diffraction angle 2θ position of the peak and the relative intensity of the diffraction peak on the (422) plane of _{SrGa 2} S ₄ with respect to the diffraction peak on the (311) plane of _{BaGa 2} S _4.
In each of Examples 2 to 11, a diffraction peak attributed to the (311) plane of _{BaGa 2} S ₄ appears at a diffraction angle of 2θ = 23.40 to 23.52 ° as the peak of the maximum diffraction intensity, and the previous diffraction peak appears. Adjacent to, a diffraction peak attributed to the (422) plane _{of SrGa 2} S ₄ appears at a diffraction angle of 2θ = 23.82 to 23.99 °, with respect to the diffraction peak of the (311) plane of _{the previous BaGa 2} S _4. The relative intensity of the diffraction peak on the (422) plane of SrGa ₂ S _{4 was 5 to 52%.} Of these, the X-ray diffraction patterns of Examples 3, 5, 8 and 11 are typically shown in FIG. 6, and the above-mentioned unique crystal structure can be confirmed.
On the other hand, for Comparative Examples 1 to 4, the crystallinity evaluation results are shown in Table 4 and the X-ray diffraction pattern is shown in FIG.
In Comparative Example 1, the X-ray diffraction pattern is shown in FIG. 6, and as the peak of the maximum diffraction intensity, a diffraction peak attributed to the (422) plane of _{SrGa 2} S _{4 appears at a diffraction angle of 2θ = 23.82 °.} The diffraction peak attributed to the (311) plane of _{BaGa 2} S _{4 does not appear.}
Similar results were obtained in Comparative Example 2.
Tsumari, Comparative Example 1 has a composition ratio of x = 0.100, y = 0.350 (Eu concentration: 10 mol%, Ba substitution ratio: 35%), and Comparative Example 2 has x = 0.050, y. In the case of a composition ratio of = 0.450 (Eu concentration: 5 mol%, Ba substitution ratio: 45%), the main structure is SrGa ₂ S ₄ structure in this composition, and the structure of BaGa ₂ S ₄ is confirmed. Can not.
In Comparative Example 3, as the peak with the maximum diffraction intensity, a diffraction peak attributed to the (422) plane of _{SrGa 2} S _{4 appeared at a diffraction angle of 2θ = 23.82 °.} A diffraction peak attributed to the (311) plane _{of BaGa 2} S ₄ appears at a diffraction angle of 2θ = 23.55 °, but its intensity is relatively small, and the diffraction peak of the (311) plane of _{BaGa 2} S ₄ The relative intensity of the diffraction peak on the (422) plane of _{SrGa 2} S ₄ with respect to SrGa 2 S 4 could be calculated to be 212%. That is, Comparative Example 3 is a case of a composition ratio (Eu concentration: 12.5 mol%, Ba substitution ratio: 50%) in which x = 0.125 and y = 0.50, and in this composition, the main structure is SrGa _2. It indicates S ₄ structure, BaGa ₂ S ₄ structure is to be detected as a second structure, suggesting the composition of the transition region.
In Comparative Example 4, a diffraction peak attributed to the (311) plane of _{BaGa 2} S ₄ appeared at a diffraction angle of 2θ = 23.31 ° as the peak of the maximum diffraction intensity _{, but SrGa 2} S was adjacent to the previous diffraction peak. _No diffraction peak attributed to the (422) plane of 4 has appeared. That is, Comparative Example 4 is a case of a composition ratio (Eu concentration: 10 mol%, Ba substitution ratio: 100%) in which x = 0.100 and y = 1.000. In this composition, the main structure is BaGa ₂ S. _It shows 4 structures, and the structure of SrGa ₂ S ₄ cannot be confirmed.

Summarizing the above results, the unique crystal structure seen in Examples 1 to 11 can be defined under the following conditions.
A diffraction peak diffraction intensity maximum peak of the XRD pattern of the phosphor is attributed to (311) plane of the BaGa ₂ S ₄ appearing at diffraction angle 2θ = 23.0~23.6 °, with respect to the diffraction intensity maximum peak , The relative intensity of the diffraction peak belonging to the (422) plane of _{SrGa 2} S ₄ appearing at the diffraction angle 2θ = 23.7 to 24.2 ° shows 5 to 90%.
Also, seen in Examples 1 to 11, specific crystal structure, composition formula _{(Ba y Sr 1-y)} 1-x Ga 2 S 4: in the phosphor represented by Eu _x, x = 0.025 It is suggested that ~ 0.20 and y appear in the range greater than 0.5 and less than 1.0.

Summarizing the above results, the fluorescent materials prepared in Examples 1 to 11 are
The composition formula _{(Ba y Sr 1-y)} 1-x Ga 2 S 4: Eu in the phosphor represented by _{x, x} = _0.025~0.20, and y is in the range of greater than 10 than 0.5 Can be represented by the value of.
Furthermore, the unique crystal structure seen in Examples 1 to 11 can be defined under the following conditions.
A diffraction peak diffraction intensity maximum peak of the XRD pattern of the phosphor is attributed to (311) plane of the BaGa ₂ S ₄ appearing at diffraction angle 2θ = 23.0~23.6 °, with respect to the diffraction intensity maximum peak , The relative intensity of the diffraction beak belonging to the (422) plane of _{SrGa 2} S ₄ appearing at the diffraction angle 2θ = 23.7 to 24.2 ° is 5 to 90%.

The phosphors produced in Examples 1 to 11 had an emission peak wavelength of 518 to 532 nm, an emission peak intensity of 1.99 to 3.19 (YAG ratio), and a brightness of 107.4 to 164.3% (YAG ratio). The full width at half maximum of light emission was 49 to 62 nm. The CIEx, y chromaticity points showed characteristic chromaticity coordinates in the blue region in the range of (0.200, 0.634) to (0.254, 0.689). In terms of conversion efficiency, the absorption rate is 61.7 to 76.6%, the internal quantum efficiency is 65.9 to 79.3%, and the external quantum efficiency is 41.3 to 59.9%. showed that.
Further, in terms of the temperature dependence of the emission characteristics, in Examples 1 to 11 as compared with Comparative Examples 1 to 3, when the emission wavelengths were about the same, the characteristics of excellent temperature characteristics were observed.
As described above in Examples 1 to 11, the phosphor has characteristic emission characteristics in the blue-green region while maintaining high emission intensity and high efficiency emission in the wavelength band of 518 to 532 nm. It is possible to stably produce a phosphor having chromaticity and excellent temperature characteristics.

As described above, the production method of this example has a unique crystal structure and is characteristic in the blue-green region while maintaining high emission intensity and high efficiency emission in the wavelength band of 518 to 532 nm. It was confirmed that it is possible to produce a phosphor having chromaticity and excellent temperature characteristics.

Although the present invention has been described above based on preferred examples, the present invention is not limited to these examples. Various production conditions, raw materials and the like used in the method for producing green luminescent phosphor particles described in the examples are examples, and can be changed as appropriate.

11 Fluorescent layer 12 1st water vapor barrier film 13 2nd water vapor barrier film 14 Cover member 141 Base material 142 Adhesive

Claims (7)

A fluorescent substance represented by the following general formula (1) and containing at least a fluorescent substance satisfying the following conditions (1) and (2).
_{(Ba y Sr 1-y)} 1-x Ga 2 S 4: Eu x ··· formula (1)
However, in the general formula (1), 0.050 ≦ x ≦ 0.150 and 0.50 <y <1.00.
Condition (1): The maximum diffraction intensity peak of the XRD pattern appears at a diffraction angle of 2θ = 23.0 to 23.6 °, and is a diffraction peak attributable to the (311) plane of _{BaGa 2} S _{4.
Condition (2): A diffraction peak attributed to the (422) plane of SrGa 2} S _{4 at} a diffraction angle of 2θ = 23.7 to 24.2 °, and the relative intensity with respect to the maximum diffraction intensity peak is 5 to 90%. Has a diffraction peak that is. In the temperature dependence of the peak intensity of the emission peak wavelength of the fluorescent substance, the value of the peak intensity of the emission peak wavelength at 100 ° C is 0.55 or more with respect to the value of the peak intensity of the emission peak wavelength at 25 ° C. The phosphor according to claim 1. The fluorescent substance according to any one of claims 1 to 2, wherein the internal quantum efficiency of the fluorescent substance is 0.65 or more. A phosphor sheet having a phosphor layer containing the phosphor according to any one of claims 1 to 3 and a red phosphor. A lighting device comprising the phosphor sheet according to claim 4. A method for producing a fluorescent substance, which comprises producing the fluorescent substance according to any one of claims 1 to 3.
A first solution containing a barium compound, a strontium compound, and a europium compound and containing a powdered gallium compound is mixed with a second solution containing a sulfite salt to obtain barium sulfite, strontium sulfite, and europium sulfite. A method for producing a phosphor, which comprises a precipitation-precipitation step of obtaining a precipitate which is a mixture of the contained precipitate and the powdered gallium compound. The method for producing a phosphor according to claim 6, further comprising a firing step of firing the precipitate in an atmosphere containing hydrogen sulfide.

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