JP2007073466A - Plasma display panel improved in color reproducibility and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma display panel capable of expressing wider and more brilliant color rendering and to provide its manufacturing method. <P>SOLUTION: The plasma display panel has three kinds of phosphors emitting at least three primary colors of red (R), green (G), and blue (B). The display panel has a phosphor which can emit light of a color in the color gamut of 0<x<0.2, 0.5<y<0.6 in the CIE chromaticity diagram (xy chromaticity coordinate) other than these three kinds of phosphors. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a plasma display panel using a phosphor as a vacuum ultraviolet light excitation light emitting element, and more particularly to a plasma display panel with improved color reproducibility and a method for manufacturing the same.

  In recent years, flat panel displays such as a plasma display panel (PDP), a field emission display (FED), and an electroluminescence (EL) panel have attracted attention as next-generation display devices. In the field of these next-generation display devices, there is a great expectation for large screens and high resolutions. In particular, PDPs can be used for cathode ray tubes (CRTs) because they can display at high speed, and can be easily enlarged and thinned. Research is being actively promoted as the mainstream of alternative next-generation display devices.

  A PDP is a display element configured by arranging a large number of minute discharge spaces (also referred to as “discharge cells” or “display cells”) in a matrix, and each discharge cell is provided with a discharge electrode. A phosphor is applied to the inner wall of the. A rare gas such as He—Xe, Ne—Xe, or Ar is sealed in the space in each discharge cell. By applying a voltage to the discharge electrode, the rare gas discharge occurs in the discharge cell, and the plasma state And vacuum ultraviolet rays are emitted. The phosphor is excited by the vacuum ultraviolet rays and emits visible light. An image is displayed by the light emission of the phosphor of the discharge cell at the position where the signal is input in the display element. Full-color display can be performed by using phosphors that emit red (R), green (G), and blue (B) as phosphors used in each discharge cell and coating them in a matrix. it can.

  In a general PDP, an address electrode is formed on a glass substrate as a back plate, and a partition layer is formed thereon. Further, using a phosphor paste in which phosphor particles are dispersed in a binder resin, a desired pattern is applied by a method such as a screen printing method, and then the binder resin component is removed by baking at a temperature of about 500 ° C. in air. To form a phosphor layer.

  In the PDP, the RGB phosphor layers of the three colors are excited by the vacuum ultraviolet rays emitted by the discharge of the rare gas in the discharge cell at the position where the signal is input, and the chromaticity points of the phosphors of the three colors are emitted. Color display within a color space range determined by the additive color mixture is performed.

Conventionally, the above three colors are red (chromaticity coordinates (0.67, 0.33)) and green (chromaticity coordinates (0.21, 0.33)) as xy chromaticity points determined by the NTSC (National Television Standards Committee) standard. 0.71)), blue (chromaticity coordinates (0.14, 0.08)), or IEC sRGB standard xy chromaticity point red (chromaticity coordinates (0.64, 0.33)) ), Green (chromaticity coordinates (0.3, 0.6)), and blue (chromaticity coordinates (0.15, 0.06)), red is (Y, Gd) BO as a phosphor material. ₃ : Eu ³⁺ (chromaticity coordinates (0.66, 0.335)), green is Zn ₂ SiO ₄ : Mn ²⁺ (chromaticity coordinates (0.21, 0.72)), blue is BaMgAl ₁₀ O _17: Eu ²⁺ (chromaticity Such as target (0.08,0.09)) is used.

  However, the color range that can express the NTSC-RGB or sRGB color gamut is very narrow compared to all color spaces that can be perceived by humans, and the color reproduction range that can be expressed is limited. Further, in the three-color additive color mixture, only the inside of a triangle having three points as vertices can be expressed, so the range of expression is naturally limited.

  Therefore, it is only necessary to reproduce color in a relatively limited application such as recreating a scene in the studio captured by an RGB 3-band camera under a standard light source. However, it has been expressed in subtractive color mixing systems such as paintings that can be used under any light source, paintings that are reproduced with high-density oil paints, films and prints that are reproduced with dyes and pigments, etc. Therefore, it cannot be used as a high-definition plasma display device that requires natural and wider color reproduction such as reliable reproduction of colors.

  In order to solve such a problem, a plasma display device having four to six types of phosphors or color filters and performing color reproduction by adding and mixing four to six primary colors has been proposed. As a result, by combining four types of phosphors and color filters, the color coordinates of the four colors are red and xy color coordinates (0.36, 0...) Having xy color coordinates (0.66, 0.335), respectively. 62), a cyan-green color having an xy color coordinate (0.05, 0.486), and a blue color having a color coordinate (0.15, 0.03). It is disclosed that red 21.9, green 60.4, cyan-green 14.8, and blue 3.42 are set for a maximum luminance of 100 (see Patent Document 1).

However, the effect of expanding the color gamut obtained by the disclosed technique is not sufficient, and a plasma display panel capable of more natural and wider color expression is desired.
JP 2003-249174 A

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a plasma display panel capable of expressing a wider and more vivid color and a manufacturing method thereof.

  The above object of the present invention is achieved by the following configurations.

  (1) In a plasma display panel having at least three phosphors emitting light of three primary colors of red (R), green (G) and blue (B), the panel has a CIE color in addition to these three phosphors. A plasma display panel having a phosphor capable of emitting light of a color gamut 0 <x <0.2 and 0.5 <y <0.6 in a degree diagram (xy chromaticity coordinates) .

  (2) The plasma display panel according to (1) above, wherein the plasma display panel has a color reproducibility of NTSC ratio of 125% or more.

  (3) The plasma display according to (1) or (2), wherein at least one of the phosphors is produced by a liquid phase synthesis method in which a phosphor raw material is reacted in a liquid phase. panel.

  (4) The plasma display according to any one of (1) to (3), wherein an average particle diameter of at least one of the phosphors is 0.01 μm or more and 1 μm or less. panel.

  (5) A method for producing a plasma display panel, comprising producing the plasma display panel according to any one of (1) to (4).

  With the configuration of the present invention, it is possible to provide a plasma display panel capable of expressing a wider and more vivid color and a manufacturing method thereof.

  The plasma display panel of the present invention has at least three phosphors that emit at least three primary colors of red (R), green (G), and blue (B), and other than these three phosphors. And having a phosphor capable of emitting light of a color gamut 0 <x <0.2, 0.5 <y <0.6 in the CIE chromaticity diagram (xy chromaticity coordinates), Further, it has a color reproducibility (wide chromaticity range) of 125% or more of NTSC ratio.

  Here, “NTSC” is an abbreviation for National Television System Committee. “NTSC ratio” means the XY chromaticity gamut defined by the NTSC standard, that is, the color reproduction range for the color gamut in the CIE chromaticity diagram (CIE: Commission Internationale de l'Eclairage). This refers to the area ratio (%) representing (color characteristics and degree of color reproduction).

  Hereinafter, the present invention, components, and the like will be described in detail.

(Phosphor)
The composition of the phosphor according to the present invention is not particularly limited. For example, JP-A-50-6410, JP-A-61-65226, JP-A-62-2987, JP-A-64-60671, JP-A-1-168911 and the like. It is possible to apply the various known compositions described. Specifically, metal oxides typified by Y ₂ O ₃ , Zn ₂ SiO ₄ , phosphates typified by Ca ₅ (PO ₄ ) ₃ Cl, etc., typified by ZnS, SrS, CaS, etc. A silicon compound containing sulfide, Si, SiO ₂ or the like is used as a phosphor crystal matrix, and Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, etc. A combination of rare earth metal ions, metal ions such as Ag, Al, Mn, Sb, Zn or metal elements as activators or coactivators is preferred.

  Preferred examples of the crystal matrix are listed below.

ZnS, SrS, GaS, (Zn , Cd) S, SrGa 2 S 4, YO 3, Y 2 O 2 S, Y 2 O 3, Y 2 SiO 3, SnO 2, Y 3 Al 5 O 12, Zn 2 SiO ₄ , Sr ₄ Al ₁₄ O ₂₅ , CeMgAl ₁₀ O ₁₉ , BaAl ₁₂ O ₁₉ , BaMgAl ₁₀ O ₁₇ , BaMgAl ₁₄ O ₂₃ , Ba ₂ Mg ₂ Al ₁₂ O ₂₂ , Ba ₂ Mg ₄ Al ₈ O ₁₈ , Ba ₃ Mg ₅ Al ₁₈ O ₃₅ , (Ba, Sr, Mg) O.aAl ₂ O ₃ , (Ba, Sr) (Mg, Mn) Al ₁₀ O ₁₇ , (Ba, Sr, Ca) (Mg, Zn, Mn) Al ₁₀ O ₁₇ , Sr ₂ P ₂ O ₇ , (La, Ce) PO ₄ , Ca ₁₀ (PO ₄ ) ₆ (F, Cl) ₂ , (Sr, Ca, Ba, Mg) ₁₀ (PO ₄ ) ₆ Cl ₂ , GdMgB ₅ O ₁₀ , (Y, Gd) BO _{3 and the} like.

  The compound containing the crystal matrix element and the activator or coactivator element is not particularly limited in the composition of the element, and may be partially replaced with a similar element, and absorbs excitation light in the ultraviolet region and emits visible light. Any combination can be used. In particular, it is preferable to use an inorganic oxide phosphor or an inorganic halide phosphor.

  Specific examples of phosphor compounds that can be used in the present invention are shown below, but the present invention is not limited to these compounds.

[Red-emitting phosphor compound]
RL1: Y ₂ O ₂ S: Eu ³⁺
_{RL2: (Ba, Mg) 2} SiO 4: Eu 3+
RL3: Ca ₂ Y ₈ (SiO ₄ ) ₆ O ₂ : Eu ³⁺
RL4: LiY ₉ (SiO ₄ ) ₆ O ₂ : Eu ³⁺
RL5: (Ba, Mg) Al 16 O 27: Eu 3+
RL6: (Ba, Ca, Mg) ₅ (PO ₄ ) ₃ Cl: Eu ³⁺
RL7: YVO _4: Eu ^{3+
_{RL8: YVO 4: Eu 3+,}} Bi 3+
RL9: CaS: Eu ³⁺
RL10: Y ₂ O ₃ : Eu ₃₊
RL11: 3.5MgO, 0.5MgF ₂ GeO ₂ : Mn
RL12: YAlO ₃ : Eu ³⁺
RL13: YBO ₃ : Eu ³⁺
RL14: (Y, Gd) BO 3: Eu 3+
[Green light-emitting phosphor compound]
GL1:: (Ba, Mg) Al ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺
_{GL2: Sr 4 Al 14 O 25} : Eu 2+
GL3: (Sr, Ba) Al 2 Si 2 O 8: Eu 2+
_{GL4: (Ba, Mg) 2} SiO 4: Eu 2+
_{GL5: Y 2 SiO 5: Ce} 3+, Tb 3+
_{GL6: Sr 2 P 2 O 7} -Sr 2 B 2 O 5: Eu 2+
GL7: (Ba, Ca, Mg) ₅ (PO ₄ ) ₃ Cl: Eu ²⁺
_{GL8: Sr 2 Si 3 O 8} -2SrC l2: Eu 2+
GL9: Zr ₂ SiO ₄ , MgAl ₁₁ O ₁₉ : Ce ³⁺ , Tb ³⁺
GL10: Ba ₂ SiO ₄ : Eu ²⁺
GL11: ZnS: Cu, Al
GL12: (Zn, Cd) S: Cu, Al
GL13: ZnS: Cu, Au, Al
GL14: Zn ₂ SiO ₄ : Mn
GL15: ZnS: Ag, Cu
GL16: (Zn, Cd) S: Cu
GL17: ZnS: Cu
GL18: Gd ₂ O ₂ S: Tb
GL19: La ₂ O ₂ S: Tb
GL20: Y ₂ SiO ₅ : Ce, Tb
GL21: Zn ₂ GeO ₄ : Mn
GL22: CeMgAl ₁₁ O ₁₉ : Tb
GL23: SrGa ₂ S ₄ : Eu ²⁺
GL24: ZnS: Cu, Co
GL25: MgO.nB ₂ O ₃ : Ce, Tb
GL26: LaOBr: Tb, Tm
GL27: La ₂ O ₂ S: Tb
GL28: SrGa ₂ S ₄ : Eu ²⁺ , Tb ³⁺ , Sm ²⁺
[Blue light emitting phosphor compound]
BL1: Sr ₂ P ₂ O ₇ : Sn ⁴⁺
_{BL2: Sr 4 Al 14 O 25} : Eu 2+
_{BL3: BaMgAl 10 O 17: Eu} 2+
BL4: SrGa ₂ S ₄ : Ce ³⁺
BL5: CaGa ₂ S ₄ : Ce ³⁺
BL6: (Ba, Sr) ( Mg, Mn) Al 10 O 17: Eu 2+
BL7: (Sr, Ca, Ba, Mg) ₁₀ (PO ₄ ) _{6 Cl 2} : Eu ²⁺
BL8: ZnS: Ag
BL9: CaWO ₄
BL10: Y ₂ SiO ₅ : Ce
BL11: ZnS: Ag, Ga, Cl
BL12: Ca ₂ B ₅ O ₉ Cl: Eu ²⁺
BL13: BaMgAl ₁₄ O ₂₃ : Eu ²⁺
BL14: BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , Tb ³⁺ , Sm ²⁺
BL15: BaMgAl ₁₄ O ₂₃ : Sm ²⁺
BL16: Ba ₂ Mg ₂ Al ₁₂ O ₂₂ : Eu ²⁺
BL17: Ba ₂ Mg ₄ Al ₈ O ₁₈ : Eu ²⁺
BL18: Ba ₃ Mg ₅ Al ₁₈ O ₃₅ : Eu ²⁺
BL19: (Ba, Sr, Ca ) (Mg, Zn, Mn) Al 10 O 17: Eu 2+
[Others: Luminescent phosphor compounds of colors other than RGB three primary colors]
XL1: Sr ₄ Al ₁₄ O ₂₅ : Eu ²⁺ , Dy ³⁺
XL2: Ba ₂ SiO ₄ : Eu ²⁺
_{XL3: BaMg 2 Al 16 O 27} : Eu 2+, Mn 2+
The four types of phosphors according to the present invention include Pointer Gamut (MR Pointer, “The Gamut of Real Surface Colors”, Color Res. .5, pp.145-155 (1980)) and SOCS (JISTR X0012: 1998, Standard object color spectro database for color reproduction evaluation) which is a spectral reflectance database. Four colors are selected that can maximally cover the gamut range.

(Phosphor production method)
The phosphor according to the present invention can be generally obtained by a solid phase synthesis method, a gas phase synthesis method, and a liquid phase synthesis method in which a precursor is prepared in a liquid phase and baked. The liquid phase synthesis method is preferable as a method for realizing a high value. This is because the concentration of the activator and the coactivator can be uniformly controlled with higher accuracy by using the liquid phase synthesis method, and the uniform production including the matrix component is very high.

  The liquid phase synthesis method according to the present invention (also simply referred to as “liquid phase method”) is a method in which a compound containing an element that is a raw material of a phosphor is reacted in a liquid phase. This is a method of synthesizing phosphor precursors by mixing together a solution containing the elements constituting the matrix and a solution containing activator elements. Reaction in the liquid phase such as reaction crystallization, coprecipitation, sol-gel method, etc. It represents the method. In the present invention, phosphors can be produced by appropriately selecting these methods.

  In the liquid phase synthesis method, since the phosphor raw material is reacted in the liquid phase, the reaction is performed between element ions constituting the phosphor, and a stoichiometrically high purity phosphor is easily obtained. On the other hand, in the conventional solid phase synthesis method, since it is a reaction between solid phases, surplus impurities which do not react and by-product salts generated by the reaction often occur, resulting in stoichiometrically high-purity fluorescence. Hard to get a body. Therefore, light emission efficiency and yield can be increased by obtaining a phosphor having a stoichiometrically high purity by a liquid phase synthesis method.

  Further, in the solid phase synthesis method, since the solids are mechanically stirred while pulverizing each other during the reaction, the obtained phosphor is often a polyhedron, and the particle size distribution tends to be wide. On the other hand, in the liquid phase synthesis method, since element ions are reacted in a liquid, the average particle size, particle shape, particle size distribution, light emission characteristics, etc. of the phosphor can be controlled more precisely, and the particle size 0.01 Small particle size particles such as ˜1 μm can be obtained with a narrow particle size distribution.

  Next, the general manufacturing method by the liquid phase method of the phosphor of the present invention will be described.

  The phosphor basically includes (A) a precursor formation step in which a solution containing a constituent metal element of an inorganic phosphor is mixed to form a precursor of the inorganic phosphor, and (B) a sub-step from the phosphor precursor. A desalting step for removing impurities such as salt, (C) a drying step for drying the precursor obtained by the precursor forming step after the precursor forming step, and (D) a dried precursor after the drying step. And a phosphor forming step of firing to form a phosphor.

  Here, the “precursor” of the phosphor according to the present invention is a crystal that is precipitated from a mixed solution in the manufacturing method and is not subjected to a baking treatment at a high temperature. Refers to a crystal in a state that hardly exhibits light emission at a predetermined wavelength.

  Below, each said process which comprises the manufacturing method of fluorescent substance is demonstrated.

(A) Precursor formation step In the precursor formation step, as described above, any liquid phase synthesis method such as a reaction crystallization method, a coprecipitation method, or a sol-gel method may be applied. For example, with respect to a red light emitting phosphor ((Y, Gd) BO ₃ : Eu ³⁺ ) and a blue light emitting phosphor (BaMgAl ₁₀ O ₁₇ : Eu ²⁺ ) that are generally used in PDP, protective colloids described later are used. It is particularly preferable that the phosphor precursor is formed by reaction crystallization in the presence of. By manufacturing in this way, a phosphor with a narrower particle size distribution and higher emission intensity can be obtained with fine particles.

Further, the green light emitting phosphor (Zn ₂ SiO ₄ : Mn ²⁺ ) is preferably formed by coprecipitation using silica as a phosphor matrix. By producing in this way, it is possible to obtain fine particles having excellent emission intensity and short afterglow time. Hereinafter, the reaction crystallization method and the coprecipitation method will be described.

  The reaction crystallization method refers to a method of synthesizing a phosphor precursor by mixing a solution containing an element as a phosphor raw material by utilizing a crystallization phenomenon. Crystallization is a phenomenon in which the solid phase precipitates from the liquid phase when the physical or chemical environment changes due to cooling, evaporation, pH adjustment, concentration, or when the state of the mixed system changes due to a chemical reaction. This refers to the phenomenon that occurs.

  The method for producing a phosphor precursor by the reactive crystallization method in the present invention means a production method by physical and chemical operations that can cause the occurrence of the crystallization phenomenon as described above.

  Any solvent may be used as the solvent for applying the reaction crystallization method as long as the reaction raw material dissolves, but water is preferable from the viewpoint of ease of supersaturation control. In the case of using a plurality of reaction raw materials, the addition order of the raw materials may be simultaneous or different, and an appropriate order can be appropriately assembled depending on the activity.

  The coprecipitation method uses a coprecipitation phenomenon to mix a solution containing an element as a phosphor raw material, and further add a precipitant to form an activator around the core of the phosphor precursor. A method of synthesizing a phosphor precursor in a state where a metal element or the like is deposited. The coprecipitation phenomenon refers to a phenomenon in which when precipitation is caused from a solution, ions that have sufficient solubility in the situation and should not precipitate are accompanied by precipitation. In the production of a phosphor, it refers to a phenomenon in which a metal element or the like constituting an activator is deposited around the mother nucleus of the phosphor precursor.

  As described above, this coprecipitation method is preferably used when obtaining a green phosphor composed of a silicate phosphor. In that case, a silicon compound such as silica is used as the mother nucleus of the phosphor precursor, and this is mixed with a solution containing a metal element that can constitute a green phosphor such as Zn or Mn, and further a precipitant is added. It is preferable to react the metal-containing solution on the surface of the silicon compound by adding the containing solution.

  As silica, vapor phase method silica, wet silica, colloidal silica, and the like can be preferably used, and it is preferably substantially insoluble in the following solvents.

  As a solvent applied in the coprecipitation method, water, alcohols, or a mixture thereof can be used. In the case of using a silicon compound such as silica, methanol, ethanol, isopropanol, propanol, butanol and the like in which the silicon compound can be dispersed are exemplified. Of these, ethanol that is relatively easy to disperse the silicon compound is preferable.

  As the precipitant, an organic acid or an alkali hydroxide is preferable. As the organic acid, an organic acid having a —COOH group is preferable, and examples thereof include oxalic acid, formic acid, acetic acid, and tartaric acid. In particular, when oxalic acid is used, it is more preferable because it easily reacts with cations such as Zn and Mn, and cations such as Zn and Mn easily precipitate as oxalate. Moreover, you may use as a precipitating agent what produces oxalic acid by a hydrolysis etc., for example, dimethyl oxalate etc.

  The alkali hydroxide may be any one having an —OH group, or any one that reacts with water to generate an —OH group or generates an —OH group by hydrolysis, such as ammonia, water, and the like. Sodium oxide, potassium hydroxide, urea and the like can be mentioned, and ammonia containing no alkali metal is preferable.

  When the precursor is synthesized by the liquid phase synthesis method, including the reaction crystallization method and the coprecipitation method, depending on the type of phosphor, various factors such as reaction temperature, addition rate, addition position, stirring conditions, pH, etc. It is preferable to adjust the physical property values. Further, ultrasonic waves may be irradiated when the mother nucleus of the phosphor precursor is dispersed in the solution or during the reaction. It is also preferable to add a protective colloid or a surfactant for controlling the average particle diameter. It is also one of preferred embodiments that the liquid is concentrated and / or aged as necessary after the addition of the raw materials.

  By controlling the amount of protective colloid to be added, ultrasonic irradiation time, stirring conditions, etc., and making the dispersion state of the mother core of the phosphor precursor in the solution preferable, the particle size and aggregation of the phosphor precursor particles The state can be controlled, and the average particle diameter of the phosphor particles after firing can be set to a desired size.

  As the protective colloid used for particle size control, various polymer compounds can be used regardless of natural or artificial, but protein is particularly preferable. At that time, the average molecular weight of the protective colloid is preferably 10,000 or more, more preferably 10,000 or more and 300,000 or less, and particularly preferably 10,000 or more and 30,000 or less.

  Examples of the protein include gelatin, water-soluble protein, and water-soluble glycoprotein. Specific examples include albumin, ovalbumin, casein, soy protein, synthetic protein, and protein synthesized by genetic engineering. Among these, gelatin can be particularly preferably used.

  Examples of gelatin include lime-processed gelatin and acid-processed gelatin, and these may be used in combination. Furthermore, a hydrolyzate of these gelatins and an enzyme degradation product of these gelatins may be used.

  The protective colloid need not have a single composition, and various binders may be mixed. Specifically, for example, a graft polymer of the above gelatin and another polymer can be used.

  The protective colloid can be added to one or more of the raw material solutions. You may add to all the raw material solutions. By forming the phosphor precursor in the presence of the protective colloid, the phosphor precursors can be prevented from aggregating with each other, and the phosphor precursor can be made sufficiently small. Thereby, various characteristics of the phosphor can be improved, such as the phosphor after firing having finer particles, a narrow particle size distribution, and good light emission characteristics. When the reaction is carried out in the presence of a protective colloid, it is necessary to give sufficient consideration to the control of the particle size distribution of the phosphor precursor and the exclusion of impurities such as secondary salts.

(B) Desalting step After the phosphor precursor is synthesized in the phosphor precursor forming step, impurities such as sub-salts are removed from the phosphor precursor by performing a desalting step prior to the drying step and the firing step. It is preferable to remove. As the desalting step, various membrane separation methods, coagulation sedimentation methods, electrodialysis methods, methods using ion exchange resins, Nudelle washing methods, and the like can be applied.

  By conducting the desalting step, the electrical conductivity after desalting of the precursor is preferably in the range of 0.01 to 20 mS / cm, more preferably 0.01 to 10 mS / cm, and particularly preferably 0. 0.01 to 5 mS / cm.

  When the electrical conductivity is less than 0.01 mS / cm, the productivity is lowered. On the other hand, if it exceeds 20 mS / cm, the secondary salt and impurities are not sufficiently removed, so that the coarsening of the particles and the particle size distribution become wide, and the emission intensity deteriorates. Any method can be used as the method for measuring the electrical conductivity, but a commercially available electrical conductivity measuring device may be used. Thereafter, the precursor is recovered by a method such as filtration, evaporation to dryness, and centrifugation.

(C) Drying process In this invention, a drying process is performed about the collect | recovered precursor. The method for drying the phosphor precursor is not particularly limited, and any method such as vacuum drying, airflow drying, fluidized bed drying, spray drying, and the like can be used.

  Although drying temperature is not limited, It is preferable that it is the temperature near the temperature which the used solvent evaporates, and it is preferable that it is specifically the range of 50-300 degreeC. When the drying temperature is high, firing may be performed at the same time as drying, and the phosphor may be obtained without performing the firing step described below.

(D) Firing step: phosphor forming step The phosphor according to the present invention is obtained by firing the phosphor precursor obtained in the precursor pair forming step.

  Any method may be used in the firing step, and the firing temperature and time may be adjusted as appropriate. For example, a desired phosphor can be obtained by filling a phosphor precursor in an alumina boat and firing it at a predetermined temperature in a predetermined gas atmosphere. The gas atmosphere may be any condition such as a reducing atmosphere, an oxidizing atmosphere, or in the presence of a sulfide, and an inert gas, and can be selected as appropriate. As an example of preferable firing conditions, there may be firing in the atmosphere between 600 ° C. and 1800 ° C. for an appropriate time. Also effective is a method in which baking is performed at 1100 ° C. for 90 minutes in the air after baking at about 800 ° C. to oxidize organic substances.

  As the baking apparatus (baking container), any apparatus known at present can be used. For example, a box furnace, a crucible furnace, a cylindrical tube type, a boat type, a rotary kiln and the like are preferably used. As the atmosphere, oxidizing, reducing, inert gas, or the like can be used in accordance with the precursor composition.

Moreover, you may add a sintering inhibitor as needed at the time of baking. When a sintering inhibitor is added, it can be added as a slurry when the phosphor precursor is formed. The powdery material may be mixed with the dried precursor and fired. The sintering inhibitor is not particularly limited, and is appropriately selected depending on the type of phosphor and firing conditions. For example, the calcination at 800 ° C. or less depending on the firing temperature range of the phosphor used is a metal oxide such as TiO _2, it is SiO ₂ in firing at 1000 ° C. or less, in the firing at 1700 ° C. or less Al ₂ O ₃ is preferably used in each case. Further, after firing, reduction treatment or oxidation treatment may be performed as necessary.

  After the firing step, various steps such as a cooling step, a surface treatment step, and a dispersion step may be performed, or classification may be performed. In the cooling step, a process for cooling the fired product obtained in the firing step is performed. At this time, the fired product can be cooled while being filled in the firing device. Although the cooling treatment is not particularly limited, it can be appropriately selected from known cooling methods, for example, a method of forcibly lowering the temperature while controlling the temperature using a cooler even in a method of lowering the temperature by leaving it alone. Either may be sufficient.

  The phosphor produced in the present invention can be subjected to surface treatment such as adsorption and coating for various purposes. The point at which the surface treatment is performed depends on the purpose, and the effect becomes more prominent when appropriately selected. For example, when preparing a phosphor paste as described later, it is preferable to perform a surface treatment in order to improve the dispersibility of the phosphor.

(Plasma display panel)
Next, a typical embodiment of the plasma display panel (PDP) according to the present invention will be described with reference to FIG. The PDP can be broadly classified from the electrode structure and operation mode into a DC type that applies a DC voltage and an AC type that applies an AC voltage. FIG. 1 shows the configuration of the AC PDP. A schematic example is shown.

  A PDP 1 shown in FIG. 1 is divided into a predetermined shape by two substrates 10 and 20 provided with electrodes 11 and 21, a partition 30 provided between the substrates 10 and 20, and the partition 30. It has a plurality of micro discharge spaces (hereinafter referred to as discharge cells) 31. The discharge cell 31 shown in FIG. 1 is a so-called stripe type. When the substrates 10 and 20 are horizontally arranged, the partition walls 30 are provided in parallel at predetermined intervals (that is, in a stripe shape). It is. The structure of the discharge cell is not limited to this stripe type, and may be a grid type discharge cell 41 in which barrier ribs 40 are provided in a grid shape in plan view as shown in FIG. As shown in FIG. 3, a honeycomb-shaped (octagonal) discharge cell 51 may be constituted by a set of bent partition walls 50 which are mutually targeted.

  Each discharge cell 31R, 31G, 31B is provided with phosphor layers 35R, 35G, 35B made of a phosphor that emits light in any of red (R), green (G), and blue (B). Inside each discharge cell 31, a discharge gas is sealed, and at least one point where the electrodes 11 and 21 intersect in a plan view is provided. In the PDP 1 according to the present invention, the phosphor layers 35R, 35G, and 35B are manufactured using the phosphor according to the present invention.

  Hereinafter, each component of PDP1 is demonstrated.

  First, of the two substrates, the configuration on the front plate 10 side arranged on the display side will be described. The front plate 10 transmits visible light emitted from the discharge cells 31 and displays various information on the substrate, and functions as a display screen of the PDP 1.

  A material that transmits visible light, such as soda lime glass (blue plate glass), can be preferably used as the front plate 10. The thickness of the front plate 10 is preferably in the range of 1 to 8 mm, more preferably 2 mm.

  The front plate 10 is provided with a display electrode 11, a dielectric layer 12, a protective layer 13, and the like. A plurality of display electrodes 11 are provided on the surface of the front plate 10 facing the back plate 20 and are regularly arranged. The display electrode 11 includes a transparent electrode 11a and a bus electrode 11b, and has a structure in which a bus electrode 11b similarly formed in a strip shape is laminated on a transparent electrode 11a formed in a wide strip shape. The width of the bus electrode 11b is narrower than that of the transparent electrode 11a. Further, the display electrode 11 is orthogonal to the partition wall 30 in plan view. The display electrode 11 is a set of two display electrodes 11 that are arranged to face each other with a predetermined discharge gap.

  A transparent electrode such as a nesa film can be used as the transparent electrode 11a, and the sheet resistance is preferably 100Ω or less. The width of the transparent electrode 7 is preferably in the range of 10 to 200 μm.

  The bus electrode 11b is for lowering the resistance and can be formed by sputtering of Cr / Cu / Cr or the like. The width of the bus electrode 11b is preferably in the range of 5 to 50 μm.

  The dielectric layer 12 covers the entire surface of the front plate 10 on which the display electrodes 11 are disposed. The dielectric layer 12 can be formed of a dielectric material such as low-melting glass. The thickness of the dielectric layer 12 is preferably in the range of 20 to 30 μm.

  The surface of the dielectric layer 12 is entirely covered with the protective layer 13. The protective layer 13 can use an MgO film. As thickness of the protective layer 13, the range of 0.5-50 micrometers is preferable.

  Next, the configuration on the back plate 20 side which is the other of the two substrates 10 and 20 will be described. The back plate 20 is provided with address electrodes 21, dielectric layers 22, partition walls 30, phosphor layers 35R, 35G, and 35B.

  As the back plate 20, soda lime glass (blue plate glass) or the like can be used similarly to the front plate 10. As thickness of the backplate 20, the range of 1-8 mm is preferable, More preferably, it is about 2 mm.

  A plurality of the address electrodes 21 are provided on the surface of the back plate 20 facing the front plate 20. The address electrode 21 is also formed in a strip shape like the transparent electrode 11a and the bus electrode 11b. A plurality of address electrodes 21 are provided at predetermined intervals so as to be orthogonal to the display electrodes 11 in plan view.

  The address electrode 21 can be a metal electrode such as an Ag thick film electrode. The width of the address electrode 21 is preferably in the range of 100 to 200 μm.

  At the time of display, a discharge cell to be displayed is selected by selectively causing trigger discharge between the address electrode 21 and one of the pair of display electrodes 11 and 11. Thereafter, a sustain discharge is performed between the pair of display electrodes 11 and 11 in the selected discharge cell, thereby generating ultraviolet rays caused by the discharge gas, and generating visible light from the phosphor layers 35R, 35G, and 35B. be able to.

  The dielectric layer 22 covers the entire surface of the back plate 20 on which the address electrodes 21 are disposed. The dielectric layer 22 can be formed of a dielectric material such as low melting glass. The thickness of the dielectric layer 22 is preferably in the range of 20 to 30 μm.

  The partition wall 30 is provided on the dielectric layer 22 so as to protrude from the back plate 20 side to the front plate 10 side. The barrier ribs 30 are formed long and are provided on both sides of the address electrode 21, and as described above, the discharge cells 31 are formed in stripes in a plan view.

  The partition wall 30 can be formed of a dielectric material such as low-melting glass. The width of the partition wall 30 is preferably in the range of 10 to 500 μm, and more preferably about 100 μm. The height (thickness) of the partition wall 30 is usually in the range of 10 to 100 μm, and preferably about 50 μm.

  As described above, any one of the phosphor layers 35R, 35G, and 35B that emit light of each color is provided in the discharge cell 31 in a regular order. The thickness of each phosphor layer 35R, 35G, 35B is not particularly limited, but is preferably in the range of 5 to 50 μm.

  In forming the phosphor layers 35R, 35G, and 35B, the phosphor manufactured as described above is dispersed in a mixture of a binder, a solvent, a dispersant, and the like, and a phosphor paste adjusted to an appropriate viscosity is applied to the discharge cell 31. By filling and then drying or baking (baking), phosphor layers 35R, 35G, and 35B having phosphors attached to the partition wall side surface 30a and the bottom surface 30a are formed.

Incidentally, the capacitance of the discharge cell is 0.5~30μF / m ^2, preferably a 0.5~10μF / m ^2, more preferably from 1~7μF / m ^2. When the capacitance is less than 0.5 μF / m ² or more than 30 μF / m ² , good light emission cannot be obtained, which is not preferable. The capacitance of the discharge cell can be measured with a capacitor meter or the like.

(Method for forming phosphor layer)
In the formation of the phosphor layer according to the present invention, in a typical method, the phosphor obtained by the above process is dispersed in a mixture of a binder, a solvent, a dispersant and the like, and the phosphor paste is adjusted to an appropriate viscosity. The phosphor paste is applied or filled on the inner surfaces of the discharge cells 31R, 31G, and 31B (side surfaces and bottom surfaces of the discharge cells) by various methods such as a screen printing method, a photoresist film method, and an ink jet method. In a later step, the phosphor paste in the discharge cell is baked to form phosphor layers on the side and bottom surfaces of the barrier ribs.

  In the case of the inkjet method, the phosphor paste adjusted to an appropriate viscosity is intermittently discharged several times from the inkjet nozzle toward the inner surface of the discharge cell (the side surface and the bottom surface of the discharge cell) using an inkjet device. By doing.

  The ink-jet method is excellent in that the phosphor paste can be applied or filled uniformly with high accuracy and low cost between the barrier ribs even when the pitch of the barrier ribs is narrow and the discharge cells are finely formed. Yes. In this method, it is preferable to use phosphor particles having an average particle diameter of 0.01 to 1 μm. This is because nozzle clogging, ejection failure, and precipitation of phosphor particles are suppressed even when the ink jet method is applied, and a thin phosphor layer can be formed accurately and uniformly.

  As the phosphor constituting the phosphor layer according to the present invention, a phosphor having an average particle diameter of 0.01 to 7 μm can be used. A preferable average particle diameter is 0.01 μm to 1 μm, and more preferably 0.01 μm to 0.8 μm. Here, the average particle diameter of the phosphor is an average obtained by measuring the average particle diameter of 300 phosphor particles in the phosphor layer using an electron microscope (for example, S-900 manufactured by Hitachi, Ltd.). Value. In addition, the particle diameter referred to here means the length of the ridge of the phosphor particles when the phosphor particles are so-called normal crystals of a cube or octahedron. When it is not a normal crystal, for example, when the phosphor particles are spherical, rod-like or tabular, it means the diameter when considering a sphere equivalent to the volume of the phosphor particles.

  In the present invention, when the phosphor layer is composed of a very fine phosphor having an average particle diameter of 0.01 to 1 μm, the phosphor layer is composed of a conventional phosphor having an average particle diameter of 1.3 μm to 7 μm. Compared with the case, even if it is a fluorescent substance layer of the same thickness, a fluorescent substance can be efficiently filled in the layer. Therefore, the amount of the phosphor involved in light emission increases, and the brightness of the PDP can be improved reliably.

  In addition, the conventional phosphor layer has to have a thickness of 20 to 30 [mu] m in order to achieve a certain luminance while securing a discharge space. However, in the present invention, it is possible to reduce the film thickness in the range of 5 to 20 μm by forming the phosphor layer using the fine particle phosphor having an average particle diameter of 0.01 to 1 μm. As a result, it is possible to expand the discharge space and increase the amount of ultraviolet rays that cause the phosphor to emit light. Further, as described above, the amount of the phosphor contained in the phosphor layer increases even if the thickness is the same as the conventional one. For this reason, even if the phosphor layer is made thin, the manufactured PDP can have high luminance.

  Further, when a phosphor layer is formed by an inkjet method using a fine particle phosphor having an average particle diameter of 0.01 to 1 [mu] m, a fluorescence having an average particle diameter of 1.3 to 7 [mu] m, which has been conventionally used, is used. Compared with the body, the gap generated on the contact surface between the phosphor ink and the inner surface of the discharge cell can be reduced, and the decrease in the adhesion force of the phosphor ink to the inner surface of the discharge cell can be prevented. Therefore, the phosphor adhering to the side surface of the discharge cell moves to the bottom surface side of the discharge cell due to its own weight, and the thickness of the phosphor layer on the side surface becomes thinner than the thickness of the phosphor layer on the bottom surface of the discharge cell. Thus, the luminance and viewing angle of the discharge cell can be improved.

  In addition, the phosphor layer can have a dense and uniform structure, and variations in phosphor quality between discharge cells can be prevented. Therefore, the light emission amount for each discharge cell becomes equal, and the light emission amount can be made uniform over the entire surface of the plasma display panel.

  Moreover, since the surface irregularities of the phosphor layer are small and the smoothness of the surface is high, the light emitted from the phosphor layer is irregularly reflected by the surface irregularities and light is not lost as in the prior art.

  Accordingly, it is possible to prevent a decrease in luminance and light emission unevenness and efficiently use light emission for display.

  In addition, for example, compared with the case where the phosphor layer is made of a phosphor having an average particle diameter of 1.3 μm to 7 μm, which has been conventionally used, even if the phosphor layer has the same thickness, the phosphor is contained in the layer. Can be filled efficiently. Therefore, the amount of the phosphor involved in light emission increases, and the brightness of the PDP can be improved reliably.

  In addition, the conventional phosphor layer has to have a thickness of 20 to 30 [mu] m in order to achieve a certain luminance while securing a discharge space. However, in the present invention, a thin film can be formed in the range of 5 to 20 μm by forming the phosphor layer using the above-described fine particle phosphor.

  As a result, it is possible to expand the discharge space and increase the amount of ultraviolet rays that cause the phosphor to emit light. Further, as described above, the amount of the phosphor contained in the phosphor layer increases even if the thickness is the same as the conventional one. For this reason, even if the phosphor layer is made thin, the manufactured PDP can have high luminance.

  In the present invention, as described above, the thickness of the phosphor layer 35 is preferably 5 to 20 μm, more preferably 5 to 15 μm. The thickness of the layer here refers to an average value of six arbitrary points, and for example, using an electron microscope (S-900 manufactured by Hitachi, Ltd.), the top surface of the phosphor layer from the bottom surface or side surface of the discharge cell. Can be obtained from the measured value.

  The order of forming the phosphor layers by the ink jet method can be arbitrarily changed. For example, when the phosphor layer is first formed on the bottom surface of the discharge cell and then the phosphor layer is formed on the side surface of the discharge cell. The discharge cell is adjusted while adjusting the rotation angle of the head and the amount of movement in the front-rear direction so that the inkjet nozzle faces the bottom side of the discharge cell and the phosphor paste discharged from the inkjet nozzle does not adhere to other than the bottom surface of the discharge cell. A phosphor layer is formed over the entire bottom surface. Then, after the formation of the phosphor layer on the bottom surface of the discharge cell is completed, the inkjet nozzle is directed to one of the side surfaces of the discharge cell, and the phosphor paste discharged from the inkjet nozzle is transferred to the other side surface of the discharge cell. The phosphor layer is formed on the side surface while adjusting the rotation angle of the head and the amount of movement in the front-rear direction so as not to adhere to the bottom surface. The phosphor layer can be formed in the discharge cell by performing the same operation on the other side surfaces. Further, for example, by combining a step of discharging the phosphor paste once or a plurality of times on the bottom surface of the discharge cell and a step of discharging the phosphor paste once or a plurality of times on the side surface of the discharge cell, the bottom surface of the discharge cell And the phosphor layers on the side surfaces may be formed almost simultaneously. In addition, it is good also as a structure which attaches a some head to a moving body so that it may respond | correspond to the pitch (arrangement space | interval of the left-right direction) of a discharge cell, and sprays a fluorescent substance paste from a some inkjet nozzle simultaneously. In this case, the workability of the phosphor layer forming operation can be improved.

  As described above, the present invention employs a so-called on-demand type ejection method in which the head is moved relative to the substrate and ink is intermittently ejected a plurality of times to a predetermined position in the discharge cell. Conventionally, a so-called continuous discharge method is known as another discharge method. In the continuous type, the phosphor paste is continuously discharged from the bottom surface of the discharge cell by continuously discharging the phosphor paste into the discharge cell while moving the head relative to the substrate. . The continuous discharge method is effective from the viewpoint of shortening the working time for a stripe-type discharge cell composed of straight barrier ribs. However, in the case of a lattice-type discharge cell in which a partition wall exists in a direction perpendicular to the head traveling direction (front-rear direction) or a honeycomb-type discharge cell having a complicated partition structure that is embedded in the left and right sides, the inkjet nozzle is located above the partition wall. There is a possibility that the phosphor paste may be continuously discharged even when passing through the tube, and there is a possibility that the phosphor paste adheres to the upper part of the partition wall.

  On the other hand, since the on-demand type discharge method that can be used in the present invention discharges phosphor paste intermittently at a predetermined timing, not only stripe-type discharge cells but also lattice-type and honeycomb-type discharge cells In contrast, the phosphor paste can be accurately discharged to a predetermined portion, and the problem of the phosphor paste adhering to the upper part of the barrier rib can be prevented. Further, since the thickness of the phosphor layer can be freely adjusted, the phosphor layer does not have an unnecessarily thick thickness, and the waste of the phosphor paste can be minimized to contribute to cost reduction. Furthermore, since the inkjet nozzle is separated from the substrate and the partition wall by a distance of several millimeters to several tens of millimeters in the inkjet method, the phosphor can be easily applied to a relatively large area color PDP substrate in which warpage and undulation are in millimeters. Layers can be formed.

  In general, when an ink jet device is used as a device for forming a phosphor layer of a plasma display panel, the diameter of the ink jet nozzle used is about 20 μm to 100 μm. The diameter of the inkjet nozzle is preferably about 50 μm to 100 μm. In order to eject ink from an inkjet nozzle having such a diameter, the average particle diameter of the phosphor is less than 2 μm from the viewpoint of preventing nozzle clogging. However, when a phosphor is manufactured by a solid phase synthesis method that has been generally used conventionally, since the particle size thereof is about 1.3 to 7 μm, there is a high possibility that the nozzle will be clogged. End up. However, according to the phosphor manufacturing method described in the present embodiment, the average particle diameter of the phosphor is in the range of 0.01 μm to 1 μm. Even when applied to a method for manufacturing a plasma display panel, clogging of nozzles can be prevented.

  Hereinafter, a typical method for preparing the phosphor paste will be described in detail.

(Preparation of phosphor paste)
The phosphor paste according to the present invention is obtained by dispersing a phosphor in a mixture of a binder, a solvent, a dispersant and the like and adjusting the viscosity to an appropriate level. The phosphor content in the phosphor paste is preferably in the range of 30% by mass to 60% by mass.

  By changing the ratio of the phosphor and the non-volatile component in the phosphor paste, the filling rate of the phosphor in the phosphor layer can be controlled. In addition, the non-volatile component said here is another component remove | excluding the fluorescent substance and the solvent from the fluorescent substance paste.

  When preparing the phosphor paste, in order to improve the dispersibility of the phosphor particles in the paste, a surface treatment such as attaching or coating an oxide, an organic polymer compound or a fluoride on the surface of the phosphor particles is performed. And preferred. The thickness and coverage of the coating layer when these surface treatments are performed can be arbitrarily controlled as appropriate.

Examples of the oxide include an oxide containing at least one element selected from Si, Ti, Al, Zr, Zn, In, and Sn. Examples thereof include magnesium oxide (MgO), aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO ₂ ), indium oxide (InO ₃ ), zinc oxide (ZnO), and yttrium oxide (Y ₂ O ₃ ). Among them, SiO ₂ is known as a negatively charged oxide, while ZnO, Al ₂ O ₃ and Y ₂ O ₃ are known as positively charged oxides, and in particular these oxides are attached. Alternatively, coating is effective. Examples of the fluoride include magnesium fluoride (MgF ₂ ) and aluminum fluoride (AlF ₃ ).

  When the surface of the phosphor is coated with an oxide or fluoride, it is possible to suppress a decrease in phosphor crystallinity during the dispersion treatment, and to prevent emission energy from being captured by phosphor surface defects. And the fall of emitted light intensity can be controlled.

  On the other hand, when the surface of the phosphor is coated with an organic polymer compound or the like, the properties such as weather resistance are improved, and a phosphor having excellent durability can be obtained.

  Next, a binder, a solvent, a dispersant and the like mixed with the phosphor when preparing the phosphor paste will be described.

Examples of the binder suitable for favorably dispersing the phosphor particles include ethyl cellulose and polyethylene oxide (ethylene oxide polymer), and in particular, the content of ethoxy group (—OC ₂ H ₅ ) is 49 to 54%. It is preferable to use ethyl cellulose. A photosensitive resin can also be used as the binder. The binder content is preferably in the range of 0.15% by mass to 10% by mass. In addition, in order to adjust the shape of the phosphor paste applied between the barrier ribs 30, it is preferable to set the binder content to a large extent within a range where the paste viscosity does not become too high.

As the solvent, it is preferable to use a mixture of an organic solvent having a hydroxyl group (OH group). Specific examples of the organic solvent include terpineol (C ₁₀ H ₁₈ O), butyl carbitol acetate, pentanediol (2 2,4-trimethylpentanediol monoisobutyrate), dipentene (also known as Limonen), butyl carbitol and the like. A mixed solvent obtained by mixing these organic solvents is preferable because it is excellent in solubility for dissolving the above binder and the dispersibility of the phosphor paste is improved.

  In order to improve the dispersion stability of the phosphor particles in the phosphor paste, it is preferable to add a surfactant as a dispersant. The content of the surfactant in the phosphor paste is preferably 0.05% by mass to 0.3% by mass from the viewpoint of effectively obtaining the effect of improving the dispersion stability or the effect of neutralization described later.

  As specific examples of the surfactant, (a) anionic surfactant, (b) cationic surfactant, and (c) nonionic surfactant can be used. There is something.

  (A) Examples of the anionic surfactant include fatty acid salts, alkyl sulfates, ester salts, alkylbenzene sulfonates, alkyl sulfosuccinates, and naphthalene sulfonate polycarboxylic acid polymers.

  Examples of (b) cationic surfactants include alkylamine salts, quaternary ammonium salts, alkylbetaines, and amine oxides.

  (C) Nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene derivatives, sorbitan fatty acid esters, glycerin fatty acid esters, polyoxyethylene alkylamines, and the like.

  Furthermore, it is preferable to add a static eliminating substance to the phosphor paste. The above-mentioned surfactants generally have a charge eliminating action for preventing the phosphor paste from being charged, and many of them correspond to charge eliminating substances. However, since the charge eliminating action varies depending on the type of phosphor, binder and solvent, it is preferable to test various types of surfactants and select the ones with good results.

  Examples of the charge removal material include fine particles made of a conductive material in addition to the surfactant. The conductive fine particles include carbon fine powder including carbon black, fine graphite powder, fine metal powder such as Al, Fe, Mg, Si, Cu, Sn, Ag, and fine powder composed of these metal oxides. Is mentioned. The amount of such conductive fine particles added is preferably in the range of 0.05 to 1.0 mass% with respect to the phosphor paste.

  By adding a charge-removing substance to the phosphor paste, the phosphor paste is charged. For example, the phosphor layers 35R, 35G, and 35B rise at the break of the address electrode in the center of the panel, and the discharge cells 31R, 31G, and 31B Defective formation of the phosphor layers 35R, 35G, and 35B, such as a slight variation in the amount of phosphor paste applied and the state of adhesion to the grooves, is prevented, and uniform fluorescence is generated in each discharge cell 31R, 31G, 31B. The body layers 35R, 35G, and 35B can be formed.

  In addition, when a surfactant or carbon fine powder is used as a charge removal material as described above, the charge removal material is also evaporated or burned off in the baking step to remove the solvent and binder contained in the phosphor paste. No neutralizing substance remains in the phosphor layers 35R, 35G, and 35B after firing. Therefore, there is no possibility that the driving (light emitting operation) of the PDP 1 will be hindered by the fact that the charge removal material remains in the phosphor layers 35R, 35G, and 35B.

  When dispersing the phosphor in the above various mixtures, for example, a high-speed stirring impeller-type disperser, colloid mill, roller mill, ball mill, vibrating ball mill, attritor mill, planetary ball mill, sand mill, etc. Then, it is possible to use those that are atomized by both the crash and the shearing force, or dry type dispersers such as a cutter mill, a hammer mill, and a jet mill, an ultrasonic disperser, and a high-pressure homogenizer.

  Among these, in the present invention, it is particularly preferable to use a wet media type disperser using a dispersion medium (media), and it is more preferable to use a continuous wet media type disperser capable of continuous dispersion treatment. . A mode in which a plurality of continuous wet media type dispersers are connected in series is also applicable. The medium here refers to a dispersion medium of solid particles such as zirconia beads, alumina beads, and glass beads. In addition, “continuous dispersion processing is possible” means that at least the phosphor and the dispersion medium are dispersed while being supplied to the disperser without interruption at a constant ratio per hour, and at the same time, manufactured in the disperser. It refers to a form in which the dispersion is discharged from the disperser without being interrupted in the form of being pushed out to supply. In the case of using a wet media type disperser that uses a medium as a dispersion treatment step in the phosphor manufacturing method, the dispersion chamber container (vessel) can be appropriately selected from a vertical type and a horizontal type.

  The filling amount of the medium in the vessel of the wet media disperser is preferably in the range of 50% by volume to 90% by volume, and more preferably in the range of 60% by volume to 80% by volume. When the media filling amount is less than 50% by volume, phosphor dispersion is insufficient, and when it exceeds 90% by volume, the media distribution in the vessel becomes non-uniform and the dispersion proceeds locally. Absent. The peripheral speed when using the wet media disperser is not particularly limited, but is preferably 3 m / s to 20 m / s in practice.

  In the case of dispersing using a media disperser, the integrated power per unit mass applied to the media disperser from the viewpoint of obtaining a very good phosphor dispersion and excellent reproducibility of the average particle size distribution. Is suitably adjusted in the range of 0.1 kWh / kg to 10 kWh / kg.

  Also, when preparing the phosphor paste, from the viewpoint of preventing deterioration of various properties such as the luminance of the phosphor, a dispersion treatment is performed while controlling the dispersion temperature from the start to the end of the dispersion so as not to exceed 70 ° C. It is more preferable that the dispersion treatment is performed while controlling so as not to exceed 50 ° C.

  Moreover, in order to perform dispersion | distribution favorably, the 1st dispersion | distribution process which performs rough dispersion | distribution using a disperser with weak dispersion power (low energy application), and a disperser with strong dispersion power (high energy application) are used Thus, it is preferable to carry out at least twice a dispersion step in which the energy imparted to the dispersoid during dispersion is different, such as a second dispersion step for producing a solid fine particle dispersion.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to this.

Example 1
In this example, an RGB phosphor having an average particle size of 0.15 μm and a phosphor having a predetermined color gamut according to the present invention were produced, and the obtained phosphor was prepared in a paste form. Then, this paste was intermittently discharged into the discharge cell by an ink jet method, and a phosphor layer having a layer thickness of 10 μm was formed on the bottom and side surfaces of the discharge cell. And using this fluorescent substance layer, PDP was produced and various evaluation was performed.

[Manufacture of phosphor]
(1) Production of red-emitting R phosphor: (Y, Gd) BO ₃ : Eu ³⁺ (chromaticity x = 0.66, y = 0.335; average particle size 0.15 μm) In the presence of protective colloid A red light emitting phosphor precursor was formed by reactive crystallization. First, gelatin (average molecular weight of about 15,000) was dissolved in 1000 ml of water so as to have a concentration of 10% by mass to obtain a solution A. Moreover, yttrium nitrate hexahydrate was added so that the ion concentration of yttrium nitrate was 0.4659 mol / L, the ion concentration of gadolinium was 0.2716 mol / L, and the ion concentration of europium was 0.0388 mol / L in 500 ml of water, Liquid B was dissolved in gadolinium nitrate and europium nitrate hexahydrate.

  Furthermore, boric acid was dissolved in 50 ml of water so that the ion concentration of boron was 0.7763 mol / L to prepare a solution C.

  Next, liquid A was put into the reaction vessel, the temperature was kept at 60 ° C., and stirring was performed using a stirring blade. In this state, liquid B and liquid C, which were also kept at 60 ° C., were added at a constant rate of 60 ml / min from the lower nozzle of the reaction vessel containing liquid A. After the addition, aging was performed for 10 minutes to obtain a red light emitting precursor. Thereafter, the red light emitting precursor was filtered and dried (105 ° C., 16 hours) to obtain a dry red light emitting phosphor precursor. Furthermore, the dried red light-emitting phosphor precursor was baked for 2 hours under 1,200 ° C. oxidation conditions to obtain a red light-emitting R phosphor having an average particle size of 0.15 μm.

(2) Production of green-emitting G phosphor: Zn ₂ SiO ₄ : Mn ²⁺ (chromaticity x = 0.36, y = 0.62; average particle size 0.15 μm) A nucleus was formed by coprecipitation. First, liquid A was prepared by mixing 4.51 g of silicon dioxide (AEROSIL200 manufactured by Nippon Aerosil Co., Ltd., BET specific surface area 200 m ^{2 /} g) with 297.95 g of pure water. At this time, ultrasonic dispersion was performed for 15 minutes while keeping the liquid A at 20 ° C. or lower. Next, zinc nitrate hexahydrate 42.39g and manganese nitrate hexahydrate 2.15g were melt | dissolved in the pure water 126.84g, and B liquid was prepared. Furthermore, C liquid was prepared by dissolving 21.90 g of aqueous ammonia (28%) in 125.67 g of pure water.

  Next, while stirring the liquid A, the liquid B and the liquid C were simultaneously added to the surface of the liquid A by a double jet at a rate of 10 ml / min using a roller pump. After completion of the addition of the liquid B and the liquid C, washing was sufficiently performed using ethanol while performing solid-liquid separation by suction filtration. Subsequently, drying was performed at 100 ° C. for 12 hours to obtain a dried precursor. The obtained precursor was baked at 1200 ° C. for 3 hours in an atmosphere of 100% nitrogen to obtain a green light-emitting G phosphor having an average particle size of 0.15 μm.

(3) Production of blue light-emitting B phosphor: BaMgAl ₁₀ O ₁₇ : Eu ²⁺ (chromaticity x = 0.15, y = 0.03; average particle size 0.15 μm) Similar to red light-emitting phosphor R described above Then, gelatin (average molecular weight of about 15,000) was dissolved in 1000 ml of water so that the concentration thereof was 10% by mass to obtain a solution A. Barium chloride dihydrate and magnesium chloride 6 water so that the ion concentration of barium is 0.090 mol / L, the ion concentration of magnesium is 0.100 mol / L, and the ion concentration of europium is 0.010 mol / L in 500 ml of water. A Japanese product, europium chloride was dissolved to prepare a B solution.

  Solution C was prepared by dissolving aluminum chloride hexahydrate and europium chloride hexahydrate so that the ion concentration of aluminum was 1.000 mol / L in 500 ml of water.

  A blue light emitting phosphor precursor is formed by reaction crystallization in the same manner as the red light emitting phosphor R described above for the A, B and C liquids prepared as described above, and reduced atmosphere at 1600 ° C. for 2 hours. Baking was performed below to obtain a blue light-emitting B phosphor having an average particle size of 0.15 μm.

(4) Production of XL1 phosphor: Sr ₄ Al ₁₄ O ₂₅ : Eu ²⁺ , Dy ³⁺ (chromaticity x = 0.05, y = 0.486) Strontium nitrate, alumina sol, dysprosium nitrate, and europium nitrate The title XL1 phosphor having an average particle size of 0.15 μm was obtained by a method in accordance with the above-described method for producing a blue light-emitting B phosphor.

(5) Production of XL2 phosphor: Ba ₂ SiO ₄ : Eu ²⁺ (chromaticity x = 0.03, y = 0.563) Green emission G fluorescence using barium nitrate, silicon dioxide, and europium nitrate as raw materials The title XL2 phosphor having an average particle size of 0.15 μm was obtained by a method based on the method for producing a body.

[Preparation of phosphor paste]
(1) Preparation of red light emitting R phosphor paste Using the above red light emitting R phosphor having an average particle size of 0.15 μm, each phosphor suspension was prepared with the following composition to obtain a red light emitting phosphor composition: did. This was stirred with a stirrer.

Red light-emitting R phosphor 45% by mass
A mixture of terpineol and pentanediol in a 1: 1 ratio of 545.5% by mass
Ethyl cellulose (ethoxy group content: 50%) 0.3% by mass
Polyoxyethylene alkyl ether 0.2% by mass
The composition was preliminarily dispersed using a homogenizer manufactured by IKA JAPAN. The conditions for preliminary dispersion are as follows.

Blade diameter: 20 mm
Rotation speed: 8000rpm
Preliminary dispersion time: 2 minutes Subsequently, this dispersion treatment was carried out under the following dispersion conditions using a horizontal continuous media disperser (DISPERMATT SL-C5 manufactured by VMA-GETZMANN) to obtain a red light emitting R phosphor paste.

Disk rotation speed: 5,520 rpm
Bead type: Zirconia Bead diameter: 0.3 mm
Bead filling rate: 70%
Flow rate: 120 ml / min
Dispersion time: 3 minutes (2) Preparation of green light-emitting G phosphor paste In the preparation of the red light-emitting R phosphor paste described above, the average particle size is 0.1 mm instead of the red light-emitting phosphor R having an average particle size of 0.15 μm. A phosphor paste was prepared in the same manner as the red light-emitting R phosphor paste described above except that a 15 μm green-emitting G phosphor was used.

(3) Preparation of blue light-emitting B phosphor paste Preparation of green light-emitting phosphor paste F In the preparation of the above-mentioned red light-emitting R phosphor paste, instead of the red light-emitting phosphor R having an average particle size of 0.15 μm, the average particle size A phosphor paste was prepared in the same manner as the red light emitting R phosphor paste described above except that 0.15 μm of the blue light emitting B phosphor was used.

(4) Preparation of XL1 phosphor paste In the preparation of the above red light emitting R phosphor paste, instead of the red light emitting phosphor R having an average particle size of 0.15 µm, an XL1 phosphor having an average particle size of 0.15 µm was used. A phosphor paste was prepared in the same manner as the red light emitting R phosphor paste described above except that it was used.

(5) Preparation of XL2 phosphor paste In the preparation of the above red light emitting R phosphor paste, instead of the red light emitting phosphor R having an average particle size of 0.15 µm, an XL2 phosphor having an average particle size of 0.15 µm was used. A phosphor paste was prepared in the same manner as the red light emitting R phosphor paste described above except that it was used.

[Production of PDP]
The AC surface discharge type PDP 1 having the stripe type cell structure shown in FIG. 1 was manufactured.

  First, a transparent electrode 11a and a bus electrode 11b are arranged at predetermined positions on a glass substrate to be the front plate 10, and then a display electrode is formed by sputtering Cr—Cu—Cr and performing photoetching thereon. 11 is formed. Then, a low-melting glass is printed on the front plate 10 through the display electrode 11, and this is baked at 500 to 600 ° C. to form the dielectric layer 12, and further MgO is applied to the electron beam as an electron beam. The protective film 13 is formed by vapor deposition.

  On the other hand, an address electrode 21 is formed by printing an Ag thick film on a glass substrate to be the back plate 20 and baking it. Then, a striped partition wall 30 is formed on the back plate 20. This is formed by printing low-melting glass with a pitch of 0.2 mm and baking.

  Further, the phosphor pastes that emit light of the respective colors prepared above are discharged onto the bottom surface 31a facing the inside of the cell 31 partitioned by the partition walls 30 and the side surfaces 30a of the partition walls 30 by an ink jet method. At this time, the following three types of back plates for PDP were formed.

  That is, R, G, B, and XL phosphor pastes having an average particle size of phosphor of 0.15 μm were ejected to adjacent cells one by one in a regular order by the inkjet method. At this time, both the bottom surface of the discharge cell to be formed and the thickness of the phosphor layer on the side wall of the partition wall are set to 20 μm as a target value, and the discharge amount by one discharge from the nozzle is 100 pl which is about 1/100 of the cell volume. did.

  At this time, the thickness of the phosphor layer on the bottom surface and side surface of the discharge cell to be formed was set to a target value of 20 μm, and the discharge amount by one discharge from the nozzle was set to 100 pl which is about 1/100 of the cell volume.

  A single color phosphor paste is used for each discharge cell 31. Thereafter, the phosphor paste was dried or baked to remove organic components in the paste, and phosphor layers 35R, 35G, 35B and the like having different emission colors were formed in the discharge cells 31R, 31G, 31B, etc., respectively.

  Then, the front plate 10 on which the electrodes 11, 21, etc. are arranged and any one of the back plates 20 are aligned so that the electrode arrangement surfaces face each other, and a gap of about 1 mm is maintained by the partition wall 30. In the state, the periphery is sealed with seal glass. A gas mixed with xenon (Xe) that generates ultraviolet rays by discharge and neon (Ne) as a main discharge gas was sealed between the substrates 10 and 20 and hermetically sealed, followed by aging.

  The PDP produced by the above method is as follows.

PDP1 (Comparative Example 1):
BaMgAl ₁₀ O ₁₇ : Eu ²⁺ as B phosphor (chromaticity x = 0.15, y = 0.03)
Zn ₂ SiO ₄ : Mn ²⁺ as G phosphor (chromaticity x = 0.36, y = 0.62)
As R phosphor _{(Y, Gd) BO 3:} Eu 3+ ( chromaticity x = 0.66, y = 0.335)
The above three color phosphors were used.

PDP2 (Comparative Example 2):
BaMgAl ₁₀ O ₁₇ : Eu ²⁺ as B phosphor (chromaticity x = 0.15, y = 0.03)
Zn ₂ SiO ₄ : Mn ²⁺ as G phosphor (chromaticity x = 0.36, y = 0.62)
(Y, Gd) BO ₃ : Eu ³⁺ as R phosphor (chromaticity x = 0.66, y = 0.335)
As a phosphor of the fourth color, Sr ₄ Al ₁₄ O ₂₅ : Eu ²⁺ , Dy ³⁺ (chromaticity x = 0.05, y = 0.486)
The above four-color phosphors were used.

PDP3 (present invention):
BaMgAl ₁₀ O ₁₇ : Eu ²⁺ as B phosphor (chromaticity x = 0.15, y = 0.03)
Zn ₂ SiO ₄ : Mn ²⁺ as G phosphor (chromaticity x = 0.36, y = 0.62)
(Y, Gd) BO ₃ : Eu ³⁺ as R phosphor (chromaticity x = 0.66, y = 0.335)
Ba ₂ SiO ₄ : Eu ²⁺ as the fourth color phosphor (chromaticity x = 0.03, y = 0.563)
The above four-color phosphors were used.

[Evaluation]
(1) Evaluation of NTSC ratio The color gamut in the CIE chromaticity diagram for the light emission color of each PDP was expressed as an area ratio (%) to the color gamut defined by the NTSC standard.

  In addition, chromaticity and a brightness | luminance were measured using Konica Minolta Sensing Co., Ltd. product color luminance meter CS-100A.

(2) Evaluation of vividness Vividness was divided into the following five stages and visually evaluated.

1. 1. Inferior Somewhat inferior. Usually, 4. Good, 5. Extremely good (3) Evaluation of luminance The luminance of the manufactured PDP was measured using the color luminance meter CS-100A.

  Note that Comparative Example 1 (PDP1) is regarded as equivalent to a conventional general PDP, and the relative luminance with respect to the reference value is obtained with the white luminance of the comparative example as the reference value 100. The brightness was evaluated.

  The evaluation results are shown in Table 1.

  As is apparent from Table 1, the PDP 3 of the present invention is superior in the NTSC ratio, vividness, and luminance to the comparative example.

Example 2
In the same manner as in Example 1, a red light-emitting R phosphor having an average particle size of 1.3 μm, a green light-emitting G phosphor having an average particle size of 1.8 μm, and a blue light-emitting phosphor D having an average particle size of 2.1 μm (average particle size) 2.1 μm), and Ba ₂ SiO ₄ : Eu ²⁺ , and then each phosphor paste was prepared. Further, each phosphor paste was applied to the discharge cell 31 by a screen coating method to produce PDP4. Although the NTSC ratio of this PDP4 was 128%, the relative luminance with respect to PDP1 was 70. From this result, it can be seen that the effect of the present invention is more effectively exhibited when a phosphor having an average particle diameter of 1 μm or less is used.

The perspective view which showed an example of the plasma display panel (PDP) based on this invention. The principal part perspective view which showed an example of the structure of a discharge cell. The principal part perspective view which showed an example of the structure of a discharge cell.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plasma display panel 10 Substrate 20 Substrate 30 Partition 31 Discharge cell 35R, 35G, 35B, 35XL Phosphor layer 40 Partition 41 Discharge cell 50 Partition 51 Discharge cell

Claims (5)

In a plasma display panel having at least three phosphors emitting three primary colors of red (R), green (G), and blue (B), the panel has a CIE chromaticity diagram (in addition to these three phosphors). A plasma display panel comprising a phosphor capable of emitting light in a color gamut 0 <x <0.2 and 0.5 <y <0.6 in an xy chromaticity coordinate). The plasma display panel according to claim 1, wherein the plasma display panel has a color reproducibility of 125% or more of NTSC ratio. 3. The plasma display panel according to claim 1, wherein at least one of the phosphors is manufactured by a liquid phase synthesis method in which a phosphor material is reacted in a liquid phase. 4. The plasma display panel according to claim 1, wherein an average particle diameter of at least one of the phosphors is 0.01 μm or more and 1 μm or less. 5. A method for producing a plasma display panel, comprising producing the plasma display panel according to claim 1.

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