JP2000345148A - Plasma display panel, phosphor, phosphor film, and method for producing phosphor - Google Patents

Abstract

(57) [Problem] To provide a phosphor capable of obtaining excellent panel luminance even when used for a PDP having a cell configuration as fine as that of a high-definition television, a manufacturing method thereof, and a PDP using the phosphor. provide. SOLUTION: Agglomerated particles in a phosphor obtained in a coarse particle state are pulverized, and the average particle diameter of the phosphor is determined by comparing the average particle diameter of the phosphor with primary particles while comparing measured values of respective particle diameters by a Coulter counter method and an air transmission method. (Single crystal particles).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphor, a method of manufacturing the phosphor, and a plasma display panel using the phosphor.

[0002]

2. Description of the Related Art In a display device that performs color display using phosphors, phosphors that emit fluorescent light in three colors of red (R), green (G), and blue (B) are generally arranged in a matrix or on a display surface. A desired display is performed by applying the phosphor in a stripe shape and irradiating the phosphor at a specific position with an electron beam or an ultraviolet ray.

[0003] Phosphors used in such display devices are manufactured, for example, by the following method. That is, the blue phosphor (BaMgAl ₁₀ O ₁₇ : Eu) first
Barium carbonate (BaCO ₃ ), magnesium carbonate (Mg
CO ₃ ), aluminum oxide (α-Al ₂ O ₃ ) to Ba,
It is blended so that the atomic ratio of Mg and Al becomes 1: 1: 1: 10. Next, a predetermined amount of europium oxide (Eu ₂ O ₃ ) is added to the mixture. Then, the mixture was mixed with an appropriate amount of flux (AlF ₂ , BaCl ₂ ) in a ball mill,
Baking is performed at 400 ° C. to 1650 ° C. for a predetermined time (for example, 0.5 hour) in a reducing atmosphere (in H ₂ or N ₂ ).

A red phosphor (Y_TwoO_Three: Eu) is hydroxylated
Thorium Y_Two(OH)_ThreeAnd boric acid (H _ThreeBO_Three) And Y, B
Are blended so that the atomic ratio becomes 1: 1. Next,
A predetermined amount of europium oxide (Eu_TwoO_Three)
Add, mix with a ball mill with an appropriate amount of flux,
1200 ° C to 1450 ° C in air for a predetermined time (for example, 1 hour
Pause) firing.

Green phosphors (Zn ₂ SiO ₄ : Mn) include zinc oxide (ZnO) and silicon oxide (SiO ₂ ) of Zn, Si
Are blended so that the atomic ratio becomes 2: 1. Next, a predetermined amount of manganese oxide (Mn ₂ O ₃ ) is added to the mixture, mixed with a ball mill, and fired in air at 1200 ° C. to 1350 ° C. for a predetermined time (for example, 0.5 hour). After the firing, the mixture is loosened (crushed) to obtain a phosphor.

As a display device using a phosphor produced as described above, a CRT has been widely used in the past. However, in recent years, there is a high expectation for a high-definition, large-screen display device such as a high-definition television. In the meantime, the plasma display panel (hereinafter “P
DP ”) is attracting attention. In PDP, two glass plates are opposed to each other, a plurality of partition walls (ribs) are formed in a stripe shape, phosphors are applied between the partition walls for each color of RGB, and air-tightly bonded, and a discharge between the partition walls and the glass plate is performed. The discharge is performed by ultraviolet rays (UV) generated by a discharge gas sealed in the space to emit fluorescent light.

A PDP having such a structure is relatively easy to realize a large screen, and a 50-inch class product has already been developed.

[0008]

Incidentally, the PDP has a property that the intensity of ultraviolet rays generated in the discharge space is proportional to the size of the discharge space. The full-spec 42-inch high-definition television, which is expected from recent years, has 192 pixels.
0 × 1125, cell pitch 0.15mm × 0.48m
m makes the cell area as fine as 0.072 mm ² ,
When a PDP of this specification is manufactured with a conventional cell configuration,
The intensity of the ultraviolet light is lower than the above properties, the fluorescent light emission of the phosphor is weakened, and the panel luminous efficiency is 0.15 to 0.17 l.
m / W, which is 1/7 to that of NTSC PDP
It is expected to decrease to about 1/8.

For this reason, when fabricating a fine cell such as a high-definition television using a PDP, it is necessary to greatly improve the luminance as compared with the conventional PDP. In order to realize this, it is conceivable to take measures to increase the filling rate of the phosphor particles in the phosphor layer and to effectively take out the fluorescence emitted by the ultraviolet rays from the entire surface of the panel. However, generally, the phosphor produced by the above-described production method is substantially a single crystal particle (hereinafter, referred to as a primary particle).
Are present alone, and a group of particles (hereinafter referred to as coarse particles) in which a mixture of particles in which several or more primary particles are aggregated (hereinafter referred to as secondary particles) are present. Obtained in a state. FIG. 3 is a diagram showing a state of the phosphor in the coarse particle state.

As shown in FIG. 3, the phosphor in the coarse particle state includes secondary particles which are aggregated particles, and includes phosphors having extremely various particle diameters. Therefore, when the phosphor layer of the PDP is formed of the phosphor in a coarse particle state, there is a problem that a gap is formed in the phosphor layer and the filling rate is difficult to be excellent. If there is a gap in the phosphor layer, it causes a bad influence on the luminous efficiency, for example, the fluorescence emission is irregularly reflected inside the phosphor layer.

To solve these problems, a method of pulverizing the phosphor has been conventionally considered. However, although the packing ratio of the phosphor layer is improved, the phosphor is inevitably pulverized excessively and the crystallinity of the phosphor is impaired. Therefore, it is difficult to improve the luminous efficiency by this method, and conversely, the luminous efficiency may be reduced. As described above, at present, particularly in the case of a phosphor used for a PDP, when the cell configuration is as fine as that of a high-definition television, a phosphor capable of realizing excellent panel luminance while improving the filling rate of the phosphor layer is obtained. It is said that it is difficult.

The present invention has been made in view of such a problem, and an object of the present invention is to obtain a good panel luminance even when the cell configuration is used for a PDP as fine as a high-definition television. An object of the present invention is to provide a phosphor, a method for producing the phosphor, and a PDP using the phosphor.

[0013]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that the luminous efficiency can be surely improved by defining the degree of aggregation of the secondary particles in the phosphor to be small. Was. Specifically, the average particle size of the phosphor in the coarse particle state is measured by an air permeation method, and a value substantially close to the average particle size of the primary particles in the phosphor in the coarse particle state is obtained. I do. In the present invention, the measured value of the average particle size of the phosphor in the coarse particle state by the air permeation method is regarded as the average particle size of the primary particles.

On the other hand, a Coulter counter method was applied to the same phosphor, and it was confirmed that an average particle size as a phosphor in a coarse particle state was obtained. The reason why the object indicated by the measured value can be distinguished by the above two types of measurement methods will be described in detail later. However, the air permeation method is roughly applied to the measurement object by the specific surface area and the coulter counter method. Is caused by measuring the particle size based on the respective volumes.

Accordingly, the present invention provides a method for performing a crushing step on a phosphor in a coarse particle state after synthesis, and performing a crushing treatment to a value substantially equal to the average particle diameter of the primary particles or close to a certain level thereof. In addition, the phosphor was adjusted to have an average particle size such that the variation in the particle size of each phosphor particle was reduced while maintaining the original crystallinity. Specifically, from the experimental results described later, it was found that it is desirable to adjust the average particle diameter of the phosphor in the coarse particle state to be equal to or more than 1.5 times the average particle diameter of the primary particles. In addition, "crushing" here means "relaxing"
This is not about "crushing" under load.

As described above, according to the present invention, the dispersion is adjusted so as to suppress the variation in the particle diameter of the phosphor by the crushing step. The filling ratio is improved as compared with the conventional case. In the crushing step, the average particle size of the phosphor in the coarse particle state is adjusted based on the average particle size of the primary particles, so that the phosphor is excessively destroyed and crystallinity is lost as in the conventional case. Is avoided. Therefore, a phosphor having a uniform particle size and high luminous efficiency can be obtained.
Thus, excellent panel luminance can be obtained.

Further, the average particle size of the primary particles can be adjusted by a known method such as adjusting the temperature condition so as to be small at the time of synthesizing the phosphor. Good luminance can be obtained even with a PDP having a structure.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 <Method for Manufacturing Phosphor> A method for manufacturing a phosphor according to Embodiment 1 will be described below. In the first embodiment, generally, P
The following phosphor material used for the phosphor layer of DP is used. The present invention is, of course, not limited to the phosphor materials having these compositions.

Blue phosphor: BaMgAl ₁₀ O ₁₇ : Eu Green phosphor: Zn ₂ SiO ₄ : Mn Red phosphor: Y ₂ O ₃ : Eu FIG. 1 shows a manufacturing process of the phosphor of the first embodiment. FIG. Each manufacturing process will be described with reference to FIG.

1─a. Phosphor Synthesis Step The blue phosphor (BaMgAl ₁₀ O ₁₇ : Eu) is composed of barium carbonate (BaCO ₃ ), magnesium carbonate (MgCO ₃ ),
Aluminum oxide (α-Al ₂ O ₃ ) is converted to Ba, Mg, Al
Are mixed so that the atomic ratio becomes 1: 1: 10. next,
Adding a predetermined amount of europium oxide in the mixture (Eu ₂ 0 _3), an appropriate amount of flux (medium solvent, AlF ₂₎ are mixed in a ball mill with. And 1300 ° C-1800 ° C
At a predetermined time (for example, 0.5 hour), in a reducing atmosphere (H ₂ ,
Heated in N _2).

The red phosphor (Y_TwoO_Three: Eu) is hydroxylated
Thorium Y_Two(OH)_ThreeAnd boric acid (H _ThreeBO_Three) Of Y and B
It is blended so that the atomic ratio becomes 1: 1. Then this mixing
A certain amount of europium oxide (Eu)_TwoO_Three)
Mix with a ball mill with an appropriate amount of flux. And
1200 ° C to 1700 ° C in air for a predetermined time (for example,
Heat).

The green phosphor (Zn ₂ SiO ₄ : Mn) includes zinc oxide (ZnO) and silicon oxide (SiO 2) of Zn, S
It is blended so that the atomic ratio of i becomes 2: 1. Next, a predetermined amount of manganese oxide (Mn ₂ O ₃ ) is added to this mixture,
Mix with a ball mill. And 1000 ℃ ～ 15 in air
Heat at 00 ° C. for a predetermined time (for example, 0.5 hour). By the heating, the phosphor is synthesized. Since these synthesized phosphor particles are slightly aggregated, a crushing step 1 described later is used.
Prior to e, loosen (crush) with an ultrasonic generator or the like to such an extent that crystallinity is not impaired. Then, the phosphor in the coarse particle state shown in FIG. 3 is obtained.

It is known that the particle size of the primary particles in the phosphor obtained by the above synthesis can be adjusted by temperature conditions and heating time. Here, an example is shown in which the primary particles of each phosphor are set to have an average particle size of about 3 μm. For this reason, when using another phosphor material, it is necessary to adjust the particle size of the primary particles by appropriately changing the temperature conditions, the heating time, and the like.

1─b. Measurement of average particle size by air permeation method Next, the average particle size of the obtained phosphor in a coarse particle state is measured by an air permeation method. Here, it has been clarified by the inventors that the average particle size of the primary particles contained in the coarse particles can be measured by measuring the phosphor in the coarse particle state by the air permeation method. Specifically, since the air permeation method is a measurement method based on the specific surface area of particles to be measured, even when a coarse particle in which a plurality of particles having different particle diameters are aggregated is measured, the specific surface area ( Surface area / volume)
Is close to the average value of the specific surface area of each particle, and the particle size calculated from this is also close to the average particle size of the primary particles.

The measurement of the phosphor in the coarse particle state of each color of RGB was performed in this way, and it was confirmed that the average particle diameter of the primary particles contained in the coarse particles was about 3 μm. 1─c. Measurement of Average Particle Diameter by Coulter Counter Method Following the measurement of 1─b, the average particle diameter of the same phosphor in the coarse particle state is measured by the Coulter counter method. Here, it has been clarified by the inventors that the average particle size of the phosphor particles as the whole coarse particles can be measured by measuring the phosphor in the coarse particle state by the Coulter counter method. Specifically, since the Coulter Counter method is a measurement method based on the volume of particles to be measured, when measuring coarse particles in which a plurality of particles having different particle diameters are aggregated, the measured volume is It is the sum of the volumes of the primary particles, and the particle size calculated from this is a value close to the particle size of the coarse particles.

The average particle size of the phosphor in the coarse particle state of each of the RGB colors was measured in this way, and it was confirmed that the average particle size of the entire coarse particle of the phosphor was about 6 μm. 1─d. Measurement value comparison Next, the ratio of the average particle size of the primary particles and the average particle size of the coarse particles obtained in 1─b and 1─c is calculated, and the value of the ratio is compared with a reference value. . Here, as an example, a numerical value of 1.2 is used as a reference value, and the ratio of the average particle size of the coarse particles to the average particle size of the primary particles is used as a comparison value, which is approximately 1.2 times (rounded off the second decimal place. Is determined to be 1.2 times the value of The reason and purpose of making such a determination are as follows.

That is, as described above, in order to obtain good panel luminance even in a PDP having a fine cell structure comparable to that of a high-definition television, one of the measures is to increase the filling rate of the phosphor particles used in the phosphor layer. Can be considered. This requires an adjustment process to suppress the variation in the particle size of the phosphor particles.However, if an excessive load is applied to the phosphor particles during this process, the crystallinity of the phosphor particles is impaired, and High luminous efficiency cannot be obtained.

In the first embodiment, in consideration of this problem, the disintegration process and the confirmation of the average particle size of the phosphor particles are repeated, and the phosphor having a coarse particle state at first is used to determine the average particle size of the primary particles. By making the average particle diameter equal to or close to a certain level, a phosphor having a uniform particle diameter while maintaining crystallinity is produced. In other words, the step of comparing the measured value of 1─d is based on how much the average particle diameter of the present phosphor in the coarse particle state deviates from the average particle diameter of the primary particles, and to what extent it is disintegrated. This is a step of determining whether to perform processing. Here, the numerical value of the “ratio of approximately 1.2 times” is
It is an example of a value found to be suitable from the experiment described below,
The value may be changed to another value as needed (in this case, a value is selected from a value range of 1.0 or more and 1.5 or less).

Since the average particle diameter of the primary particles is about 3 μm and the average particle diameter of the coarse particles is about 6 μm, the ratio of “average particle diameter of coarse particles / average particle diameter of primary particles” is 2. Therefore,
It is determined that it is necessary to perform the crushing process on the phosphor in the coarse particle state so that the value of this ratio becomes 1.2 by rounding off the second decimal place. 1─e. Crushing Step Next, according to the judgment of 1─d, a crushing step is performed on the phosphor in a coarse particle state. For this, a ball mill may be used, but it may be difficult to adjust the intensity.In order to maintain the crystallinity of the primary particles contained in the phosphor in a coarse particle state more appropriately, an ultrasonic generator or the like is used. Good to use.

Once the 1─e crushing process is completed,
As shown in the flow chart of FIG. 1, the process is returned to 1 ° C. again, and the average particle size of the phosphor is measured by the Coulter counter method. Then, 1─d is reached, the value of the ratio of the average particle size of the coarse particles to the average particle size of the primary particles (comparison value) is calculated and compared with the reference value (1.2 times). When the comparison value and the reference value become the same, the manufacturing process of the phosphor is terminated,
Otherwise, the cycle of 1─c → 1─d → 1─e → 1─c is repeated.

It is obvious that the average particle diameter of the primary particles is originally smaller than the average particle diameter of the coarse particles composed of the primary particles and the secondary particles. Gradually, phosphor particles having the same average particle diameter as the primary particles or close to a certain level thereof (here, the value of the ratio is finally 1.2 times) are obtained. The process for synthesizing the phosphor is not limited to the above-described method of 1a, and may be, for example, a synthesis process using a known sol-gel method or the like.

After the phosphor synthesizing step 1─a or 1 終了 d, after completion of the processing of the phosphor, heat treatment is carried out for a short time while keeping the temperature substantially the same as or slightly lower than that of 1─a. It is desirable that the defect level of the fine crystals existing on the surface of the phosphor particles be repaired by performing (the actual state of the surface of the phosphor particles can be confirmed by a TEM or the like).

<PDP Using Phosphor> Next, the structure of a PDP using the phosphor produced by the above method will be described. FIG. 2 is a partial cross-sectional perspective view showing a main configuration of the PDP. In the drawing, the z direction corresponds to the thickness direction of the PDP, and the xy plane corresponds to a plane parallel to the PDP surface. As shown in the figure, the present PDP is an AC surface discharge type PDP, and includes a front panel 10 and a back panel 20 which are arranged with their main surfaces facing each other.

A front panel glass 11 serving as a substrate of the front panel 10 has a pair of display electrodes 1 on one surface thereof.
2, 13 (the X electrode 12 and the Y electrode 13) are formed along the x direction, and perform a surface discharge between the pair of display electrodes 12 and 13. The front panel glass 21 provided with the display electrodes 12 and 13 is coated with a dielectric layer 14 over the entire surface of the glass 11, and the dielectric layer 14 is further coated with a protective layer 15.

A back panel glass 21 serving as a substrate of the back panel 20 has a plurality of address electrodes 23 on one surface thereof.
Are arranged side by side in a stripe pattern at regular intervals with the y direction as a longitudinal direction, and a dielectric film 22 is coated over the entire surface of the back panel glass 21 so as to include the address electrodes 23. Partition walls 24 are arranged on the dielectric film 22 so as to match the gaps between the adjacent address electrodes 23, and single-crystal grains are formed on the side walls of the adjacent partition walls 24 and on the surface of the dielectric film 22 therebetween. Average primary particle size is 3μ
m, red (R), green (G), blue (B) composed of phosphor particles of about 3.6 μm as a whole (that is, the ratio of the average particle size of the coarse particles to the average particle size of the primary particles is 1.2) The phosphor layers 25 to 27 corresponding to any of the above are formed.
As a feature of the present invention, since the phosphor particles are produced by avoiding an excessive pulverizing step, the crystallinity of the particle surface is improved as compared with the related art.

Front panel 10 and back panel 20
Are opposed to each other so that the longitudinal directions of the address electrode 23 and the display electrodes 12 and 13 are orthogonal to each other.
20 are adhered and sealed at the outer periphery. A discharge gas (filled gas) containing Xe is applied between the panels 10 and 20 at a predetermined pressure (conventionally, usually 300 to 500 Torr).
), And the space between adjacent partition walls 24 is discharged space 28
The area where the pair of adjacent display electrodes 12 and 13 and one address electrode 23 intersect with the discharge space 28 interposed therebetween is a cell (not shown) for image display. At the time of driving the PDP, in each cell, a discharge is started between the address electrode 23 and one of the display electrodes 12 and 13, and a short wavelength ultraviolet (Xe resonance line, wavelength) is generated by glow discharge between the pair of display electrodes 12 and 13. 147 nm), the phosphor layers 25 to 27 emit light, and an image is displayed.

The main feature of the present PDP lies in the phosphor layers 25 to 27. That is, since the variation in the particle size of the phosphor particles constituting the phosphor layers 25 to 27 is more uniform than in the past, the filling rate in the phosphor layers is improved. Further, since the particle size of the phosphor particles is adjusted based on the average particle size of the primary particles that are single crystal particles, the crystallinity is maintained without being impaired, and the phosphor layers 25 to 2 are maintained.
The luminous efficiency of No. 7 is improved higher than before.

According to the present PDP having the above-described structure, the phosphor layers 25 to 27 made of phosphor particles having an average particle diameter of about 3.6 μm as a whole emit fluorescent light upon receiving ultraviolet rays generated in the discharge space 28. I do. This fluorescent light is efficiently extracted from the front panel 10 side by the phosphor particles whose crystallinity on the particle surface is conventionally maintained. Therefore, panel luminance is improved, and good display performance is obtained.

Such a PDP is manufactured by the following manufacturing steps. 1. Fabrication of Front Panel 10 The front panel 10 has display electrodes 12 and 13 formed on a front panel glass 11, covered with a dielectric layer 14, and further formed with a protective layer 15 on the surface of the dielectric layer 14. It is produced by doing.

In the present embodiment, the display electrodes 12 and 13 are silver electrodes, and are formed by a method of screen-printing a paste for a silver electrode and then firing. Also, the dielectric layer 14
The composition of lead oxide (PbO) 70 wt%, boron oxide _{(B 2 O 3) 15wt%} , silicon oxide (SiO ₂₎ 15 w
t%, about 2% by screen printing and firing.
It is formed to a thickness of 0 μm. Next, a protective layer 15 of magnesium oxide (MgO) of 1.0 μm is formed on the dielectric layer 14 by a CVD method (chemical vapor deposition method).

2. Fabrication of Back Panel 20 An address electrode 23 is formed on the back panel glass 21 by screen printing a paste for a silver electrode, followed by baking. A dielectric film 2 made of TiO ₂ particles and dielectric glass is formed thereon by screen printing and firing.
2, the glass partition walls 24 obtained by repeating the same screen printing and then firing are formed at a predetermined pitch.

In each space sandwiched by these partition walls 24,
The phosphor layers 25 to 27 having a thickness of about 30 μm are formed by applying any one of the phosphor inks including the red phosphor, the green phosphor, and the blue phosphor described above. As a method of applying the phosphor ink, for example, there is a method of discharging the phosphor ink while forming a meniscus (crosslinking by surface tension) from an extremely fine nozzle called a meniscus method. This method is advantageous for uniformly applying the phosphor ink to a target area. An example of the meniscus method will be described below.

The phosphor ink used is a mixture of a phosphor, a binder (ethyl cellulose) and an organic solvent (α-terpineol) in a weight ratio of 45: 2: 53. This phosphor ink is put in a tank (not shown), and the tip of a nozzle (tip diameter 80 μm) connected to the tank is adjusted to the interval between the partition walls 24. Then, the phosphor ink is ejected at a pressure of 0.5 kgf / cm ² while scanning the nozzle at a speed of 50 mm / s along the longitudinal direction of the partition wall 24 while keeping a distance of about 100 μm from the dielectric film 22. Thus, the phosphor ink is applied while forming a meniscus between the nozzle and the partition wall 24 or between the nozzle and the surface of the dielectric film 22.

The same effect was obtained by applying a conventional printing method, a photo film method using a photosensitive resin, or a photo paste method as a method of applying the phosphor. After applying the phosphor ink, the phosphor layers 25 to 27 are formed by baking the profile at a maximum temperature of 520 ° C. for 2 hours. Here, the PDP may be manufactured according to the conventional NTSC specification. However, in order to match the size of a 40-inch class high-definition television, the height of the partition wall must be 0.1 mm.
To 0.15 mm, and the partition wall pitch needs to be 0.15 to 0.3 mm. Further, the thickness of the phosphor layers 25 to 27 is set to 5 to
It needs to be 50 μm.

3. Production of PDP by Laminating Panels Next, the front panel 10 and the back panel 20 are sealed with glass so that the display electrodes 12 and 13 of the front panel 10 and the address electrodes 23 of the back panel 20 are orthogonal to each other. Laminate using. After the inside of the discharge space 28 partitioned by the partition walls 24 is evacuated to a high vacuum, a discharge gas having a predetermined composition is sealed at a predetermined pressure to complete the PDP.

In this PDP, Ne in the discharge gas
Is 95% by volume, the content of Xe is 5% by volume,
The sealing pressure was set in the range of 500 to 800 Torr. (Experiment) In order to confirm the effects of the present invention, the above-mentioned blue phosphor (BaMgAl ₁₀ O ₁₇ : Eu), red phosphor ((Y, Gd) BO ₃ : Eu), green phosphor (Zn ₂ Si)
O ₄ : Mn) were synthesized by the manufacturing method of the first embodiment. Then, prepared were those in which the average particle size of the primary particles in each color phosphor in the obtained coarse particle state was different from the average particle size of the final phosphor adjusted by the crushing step. PDPs using these phosphors in the phosphor layer were named Examples 1 to 7.

Here, the blue phosphor (BaMgAl)
_{Although 10} O ₁₇ : Eu) is originally a particle composed of hexagonal plate-like crystals, it is produced as a spherical particle by the following production method.
Example 8 was a PDP using this as a blue phosphor layer.
The term “spherical particles” as used herein is defined, for example, as having a particle diameter ratio (major axis diameter / minor axis diameter) of 0.9 or more and 1.0 or less.

A blue phosphor (BaMg) based on a method described in JP-A-62-201989 will be described below.
A method for producing spherical particles of Al ₁₀ O ₁₇ : Eu) will be described. <Method for producing blue phosphor (BaMgAl ₁₀ O ₁₇ : Eu) spherical particles> 2─a. Phosphor material mixing step First, barium carbonate (BaCO ₃ ), magnesium carbonate (MgCO ₃ ), and aluminum oxide (α-Al ₂ O) ₃ ) is mixed so that the atomic ratio of Ba, Mg, and Al becomes 1: 1: 10. Then adding a predetermined amount of europium oxide in the mixture (Eu ₂ 0 _3), an appropriate amount of flux (medium solvent,
AlF ₂ ) and mix with a ball mill.

2─b. Plasma Evaporation Drying Process Using a plasma generator (Model 56 plasma torch manufactured by Tafar), carrier gas: N ₂ (3 kg / cm ² )
While setting the conditions of the phosphor discharge rate (100 g / min) and the plasma generation output at 200 kW, the mixture is allowed to evaporate to dryness while being freely dropped in a cylindrical reaction tube.

According to such a production method, a phosphor in the form of coarse particles comprising spherical particles and including secondary particles can be obtained. Regarding this phosphor, 1% to 1% of Embodiment 1
Is performed to obtain a spherical particle phosphor having an average particle diameter that is equal to or close to a certain level with respect to the average particle diameter of the primary particles contained in the coarse particle phosphor.
Here, the average particle size of the primary particles of the spherical particles was adjusted to 2.5 μm, and the final average particle size of the entire phosphor particles was adjusted to 2.7 μm by the crushing step.

Further, a PDP using a phosphor having an average particle diameter of 4 μm in a coarse particle state before the crushing step and an average particle diameter of primary particles of 2.5 μm as it is in a phosphor layer was used as a comparative example. In the PDPs of Examples 1 to 8 and Comparative Example, each PDP was measured at a discharge sustaining voltage of 150 V and a frequency of 30 k.
The operation was performed under a discharge condition of Hz. At this time, each PDP
Are set so that white balance can be obtained, and the entire surface is lit white.

For these Examples 1 to 8 and Comparative Example,
The relationship between the average particle size of the phosphor and the panel brightness was summarized.
The results are set forth in Table 1 below.

[0053]

[Table 1]

According to Table 1, first, the brightness of the PDPs of Examples 1 to 4 having the same average particle size of the primary particles (2.5 μm) and the comparative example was compared. It can be seen that the smaller the particle size (the average particle size of the entire phosphor particles after the final crushing step) / the average particle size (primary particle size) determined by the air permeation method is, the higher the luminance is. This suggests that by setting the degree of agglomeration of the secondary particles small, the packing ratio can be improved without impairing the crystallinity. In other words, it is considered that the disintegration step improves the filling rate of the phosphor layer by uniformizing the particle diameters of the phosphor particles, thereby improving the reflectance of the fluorescent light emitted from the phosphor layer. In addition, from the average particle diameter by the coulter counter method and the average particle diameter by the air permeation method (for example, Examples 1 to
4) Regardless of the particle size prior to the crushing step, it can be seen that the panel brightness is improved if the crushing step is performed on the phosphor particles by approaching the average particle size by the air permeation method.

When Examples 1 to 7 are compared as a whole,
It can be seen that the panel brightness is more remarkably improved as the average particle size ratio is closer to 1 and the average particle size of the primary particles is smaller (for example, the PDP of Example 4). This means that the smaller the particle size, the higher the number of phosphor particles in the phosphor layer and the higher the filling rate,
It is considered that the irregular reflection of unnecessary fluorescent light emission into the phosphor layer is suppressed, and the reflectance of the phosphor layer is improved accordingly.

From these Examples 1 to 7, it is considered that a certain effect of the present invention can be obtained if the average particle size ratio is in the range of about 1 to about 1.5, but more preferably, Examples 2 to 7 are more preferable. As in 4, the average particle size ratio is preferably about 1 or more and about 1.2 times or less. From the results of this experiment, as in Example 4, it is most preferable that the average particle size ratio be 1 or more and about 1.1, or the average particle size ratio is about 1 (1 or more and less than 1.1). It can be said.

On the other hand, from the experimental results summarized in Table 1, the effects of the present invention can be summarized as follows from the viewpoint of the average particle size (average particle size of primary particles) by the air permeation method. That is, as in Example 5, if the average particle diameter of the primary particles is around 5 μm, which has been conventionally regarded as the average particle diameter of the phosphor, the primal effect of the present invention can be analogized. The more preferable value is on the order of 3 μm (Example 6), and the effect is more remarkable when it is on the order of 2 μm (Examples 1-4, 7, 8). The average particle size of the primary particles is 1.5 μm
When it is reduced to the extent, the most excellent panel luminance can be obtained (Example 7).

Subsequently, when comparing Examples 3 and 8 which differ only in the property that the blue phosphor particles have the same hexagonal plate shape and spherical shape with the same average particle size ratio (2.5), the spherical particles (Example 8) It can be seen that ()) is superior in panel luminance. Thus, the present invention, in which the average particle diameter of the entire phosphor particles is adjusted based on the average particle diameter of the primary particles, is further improved by adding a device for forming the phosphor into spherical particles. It has been found that the effect of improving the brightness can be enhanced.

Although the embodiment and the example show the example of the AC surface discharge type PDP, the present invention is not limited to this, and can be applied to other PDPs such as a counter discharge type. Further, the phosphor is not limited to the phosphor layer of the PDP, but may be applied to a fluorescent lamp or a light table which emits ultraviolet rays by applying the phosphor over the entire surface of a transparent plate.

Further, in the first embodiment, an example in which the cycle of 1─c → 1─d... Is performed based on the flow chart of FIG. 1 has been described. Then, this may be performed once. However, also in this case, it is desirable to inspect later whether the crushing process has been performed as set.

[0061]

As described above, in the method for producing a phosphor of the present invention, the synthesis step of synthesizing the phosphor in the coarse particle state, and the average particle diameter of the synthesized phosphor in the coarse particle state are performed by the air permeation method. A first measurement step of measuring, a second measurement step of measuring the average particle diameter of the synthesized phosphor in a coarse particle state by a Coulter counter method, and a measurement value in the second measurement step is the second measurement step. If the measured value in one measurement step does not fall within the same value or more than 1.5 times,
After the second measurement step, a crushing step of crushing the phosphor in a coarse particle state so as to fall within the above range is performed. As a result, the present invention makes it possible to produce a phosphor having a more uniform particle size and better crystallinity than conventional phosphors and having excellent luminous efficiency.

Since the average particle size of the phosphor of the present invention is adjusted on the basis of primary particles (single crystal particles), the crystallinity is maintained even if the particles are reduced, and the phosphor has good emission intensity. Therefore, if this phosphor is used as a phosphor film in a phosphor layer such as a PDP, the filling rate can be improved and the reflection efficiency can be improved. Also, a PDP with excellent luminance and luminous efficiency can be realized.

[Brief description of the drawings]

FIG. 1 is a flowchart of a manufacturing process of a phosphor according to a first embodiment.

FIG. 2 is a partial sectional perspective view showing a configuration of an AC surface discharge type PDP which is an application example of the present invention.

FIG. 3 is a diagram illustrating a state of a phosphor in a coarse particle state including aggregated particles (secondary particles).

FIG. 4 is a diagram showing a state of a phosphor after agglomerated particles (secondary particles) are crushed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Front panel 11 Front panel glass 12, 13 Display electrode 14 Dielectric protective layer (MgO) 15 Protective layer 20 Back panel 21 Back panel glass 22 Dielectric film 23 Address electrode 24 Partition 25-27 Phosphor layer 28 Discharge space

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01J 11/02 H01J 11/02 B F term (Reference) 4H001 XA05 XA08 XA12 XA13 XA14 XA30 XA39 XA56 XA64 YA25 YA63 5C028 FF16 HH14 5C040 FA01 GA03 GB02 GG07 GG09 JA40 MA03 MA24

Claims (14)

[Claims] 1. A synthesis step of synthesizing a phosphor in a coarse particle state, a first measuring step of measuring an average particle diameter of the synthesized phosphor in a coarse particle state by an air permeation method, A second measurement step of measuring the average particle diameter of the phosphor by the Coulter counter method, the measured value in the second measurement step is equal to or greater than the measured value in the first measurement step 1. A step of disintegrating the coarse-particle phosphor so as to fall within the range after the second measurement step, if the range does not fall within the range of 5 times or less. 2. The method for manufacturing a phosphor according to claim 1, wherein an annealing step is performed after the crushing step. 3. A phosphor comprising phosphor particles, wherein an average particle diameter measured by a Coulter counter method is equal to or more than 1.5 times an average particle diameter measured by an air permeation method. . 4. A phosphor comprising phosphor particles, wherein an average particle diameter measured by a coulter counter method is equal to or more than 1.2 times an average particle diameter measured by an air permeation method. . 5. A phosphor comprising phosphor particles, wherein the average particle diameter measured by the Coulter counter method is equal to or more than 1.1 times the average particle diameter measured by the air permeation method. . 6. A phosphor comprising phosphor particles, wherein the average particle diameter measured by the Coulter counter method is equal to or more than 1.1 times the average particle diameter measured by the air permeation method. . 7. The phosphor according to claim 3, wherein a measured value of an average particle diameter by the air permeation method is 5 μm or less. 8. The phosphor according to claim 3, wherein a measured value of an average particle diameter by the air permeation method is 3 μm or less. 9. The phosphor according to claim 3, wherein the measured value of the average particle diameter by the air permeation method is 2 μm or less. 10. The phosphor according to claim 3, wherein the phosphor is excited by vacuum ultraviolet light and emits fluorescent light at a wavelength of visible light. 11. The phosphor is made of BaMgAl._TenO₁₇: E
u, (Y, Gd) BO _Three: Eu, Zn_TwoSiO_Four: Mn
The firefly according to claim 10, which is any one of the above.
Light body. 12. The phosphor according to claim 10, wherein the phosphor has a shape of a spherical particle. 13. A phosphor film obtained by molding the phosphor according to claim 10 into a film and firing the film. 14. A plasma display panel in which an electrode and phosphor layers of a plurality of colors are disposed between a pair of parallelly disposed plates, and a discharge space in which a discharge gas is sealed is formed. A plasma display panel comprising a phosphor layer according to claim 13.