JP2001229813A - Manufacturing method of plasma display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a plasma display panel overcoming the problem of the breakdown voltage of a dielectric glass layer. SOLUTION: As shown in figure 6 (c), the glass particles after receiving the surface melt-treatment become almost spheres as the edged parts of the glass particles roughly crushed by a crusher were smoothed down. As the use of such molten glass powders brings a uniform wetness on the glass particle surfaces, the binder 64 uniformly sticks to the surfaces of the glass particles 63 at a stage when glass powders are printed. As a result, it is also unlikely to cause that the combustion gas remains in the dielectric glass layer as air bubbles. As given in figure 6 (d) and compared with figure 6 (b), the number of air bubbles in the completed dielectric glass layer is considerably small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a plasma display panel used for a display device or the like, and more particularly to a method of manufacturing a plasma display panel capable of improving a dielectric glass layer.

[0002]

2. Description of the Related Art In recent years, expectations for high-definition and large-screen televisions including high-definition televisions have been increasing. Conventionally, CRTs, liquid crystals, and plasma display panels have been used as display devices for such televisions. Among them, the CRT is superior to the plasma display panel and the liquid crystal in terms of resolution and image quality, but is not suitable for a large screen of 40 inches or more in terms of depth and weight. Liquid crystals, on the other hand, have excellent performances such as low power consumption and low driving voltage, but have limitations in screen size and viewing angle. On the other hand, a plasma display panel is capable of realizing a large screen, and a 40-inch class product has already been developed (for example, “functional material” 19).
Vol. 16, No. 27 pages).

FIG. 8 is a perspective view of a main part of a conventional alternating current (AC) type plasma display panel. In FIG. 8, reference numeral 71 denotes a front glass substrate made of a sodium borosilicate glass by a float method.
A discharge electrode 72 is formed on the surface of the front glass substrate 71, and a dielectric glass layer 73 is formed so as to cover the discharge electrode 72.
Is formed, and the surface of the dielectric glass layer 73 is covered with a magnesium oxide (MgO) dielectric protection layer 74. The dielectric glass layer 73 functions as a capacitor,
It is formed using glass powder having an average particle diameter of 2 μm to 15 μm.

Reference numeral 75 denotes a rear glass substrate. On the surface of the rear glass substrate 75, address electrodes 76 are formed.
A dielectric glass layer 77 is provided so as to cover this, and a partition wall 78 and a phosphor layer 79 are further provided on the surface thereof. And between the partition walls 78 is a discharge space 80 for filling a discharge gas. The pixel level of full-spec high-definition televisions expected in recent years is 1 pixel.
920 × 1125, and the dot pitch is also 0.15 mm × 0.48 mm in the 42-inch class. Therefore, the area of one cell is as small as 0.072 mm ² .
The area of this one cell is the same as that of a conventional NTSC (640 × 480 pixels, dot pitch 0.43 mm × 1.
Compared to 29 mm, the area of one cell is 0.55 mm ² ), the fineness is 1/7 to 1/8.

[0005] Accordingly, in a full-spec high-definition television, the brightness of the panel is reduced (for example,
"Display and Imaging" 1997, Vo
l. 6, pp. 70). Further, not only the distance between the discharge electrodes becomes shorter, but also the discharge space becomes narrower. For this reason, in particular, the dielectric glass layers 73 and 77 need to have a smaller film thickness than before in order to ensure the same capacitance as a capacitor because the cell area is reduced.

[0006]

There are three main methods for forming a dielectric glass layer in the conventional method, which will be described below. In the first method, the average particle size of the glass powder is 2 to 15 μm, and the softening point of the glass is 550 ° C. to 60 ° C.
Using terpineol or butyl carbitol acetate containing glass powder at 0 ° C. and ethyl cellulose as a solvent, the mixture is pasted using a three-roll mill, and then screen-printed (50,000 to 10 pastes suitable for screen printing). This is a method in which a dielectric glass layer is formed by applying the composition on a front glass plate, drying it, and then sintering the glass near its softening point (550 ° C. to 600 ° C.).

In this method, the sintering is performed in the vicinity of the softening point where the glass does not flow so much that it is in an inactive state. Therefore, the molten glass is used as an electrode of Ag, ITO, Cr—Cu—C
It hardly reacts with r. Therefore, this method is characterized in that the resistance value of the electrode is not increased, the electrode component is not diffused in the glass to be colored, and the dielectric glass layer can be formed by one firing treatment. However, in this method, bubbles (pinholes) are generated in the dielectric, and the dielectric strength of the dielectric glass layer is reduced. Here, the withstand voltage means a limit of the insulating property when the insulating property is deteriorated due to physical breakdown of the dielectric glass layer when a voltage is applied.

As a second method, similarly, the glass powder has an average particle diameter of 2 μm to 15 μm and a softening point of 450 to 50 μm.
After preparing a glass paste using a low melting point lead glass powder of about 0 ° C. (PbO is about 75%) (paste viscosity of 35,000)
1000 to 50,000 centipoise) Apply paste by screen printing method, and after drying, 550 which is about 100 ° C higher than softening point.
There is a method of sintering at ~ 600 ° C. The feature of this method is that since the firing temperature of the glass is sufficiently higher than the softening point and the flowability of the glass is good, a glass layer having a flat surface (surface roughness of about 2 μm) can be obtained. That is, a dielectric glass layer can be formed by the sintering process.

However, in this method, the molten glass is Ag,
It reacts with electrodes such as ITO and Cr-Cu-Cr to increase the resistance value, color the dielectric glass layer, and easily generate large bubbles due to the reaction with the electrodes. The third method is a method combining the first method and the second method (for example, JP-A-7-105855, JP-A-9-5).
No. 0769). That is, the average particle size of the glass is 2 μm to 15 μm and the softening point of the glass is 550 ° C. on the electrode.
After using a glass powder of up to 600 ° C. and pasting it in the same manner, it is printed and dried by a screen printing method and sintered near the softening point. Then, on this dielectric glass layer, the average particle diameter is also 2 μm to 15 μm, and the softening point of the glass is similarly pasted using glass powder having a temperature of 450 ° C. to 500 ° C., followed by printing and drying by screen printing. And sintering at 550 ° C. to 600 ° C., which is 100 ° C. higher than the softening point, to form a dielectric glass layer.

The feature of this method is that by adopting such a two-layer structure, it is possible to suppress the reaction between the electrode and the glass and to improve the withstand voltage. However, such a two-layer structure not only complicates the manufacturing process of the dielectric glass layer, but also makes it difficult to form a thin dielectric glass layer to achieve high luminance. Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a method of manufacturing a plasma display panel that overcomes the problem of withstand voltage of a dielectric glass layer.

[0011]

In order to solve the above-mentioned problems, the present invention provides a plasma display panel having a step of forming an electrode on a surface of a substrate body and a step of forming a dielectric glass layer on the electrode. In the manufacturing method, the step of forming the dielectric glass layer includes the steps of coarsely pulverizing the dielectric glass material, performing a spheroidizing process on the coarsely pulverized dielectric glass material, and performing the spheroidizing process. Disposing a mixture of the applied dielectric glass material and a binder in a layer on the substrate body on which the electrodes are formed, and then removing the binder from the layer containing the dielectric glass material and the binder while removing the binder from the dielectric glass material. Firing the material.

[0012] In the case of ordinary glass powder, the binder used for printing is difficult to adhere uniformly, and where a large amount of binder adheres, it is difficult to burn, so that the binder tends to remain even when the glass is melted and a film is formed. However, when the spheroidizing treatment is performed as described above, the shape of the glass particles approaches the sphere from the irregular shape after the coarse pulverization, so that the binder is used to form the dielectric glass layer using the glass powder. Will uniformly adhere to the surface of the glass, eliminating the difference in the binder burning rate between the glass particles, and when firing the glass powder, almost all the binder will burn out before the heating temperature reaches the softening point of the glass powder. .
Therefore, the combustion gas is not trapped in the dielectric glass layer, and the possibility that the trapped combustion gas remains as bubbles in the dielectric glass layer is low.
For this reason, the dielectric strength of the dielectric glass layer can be improved.

Here, the step of performing the spheroidizing treatment may be a treatment of melting the particle surface of the roughly pulverized dielectric glass material. By performing such a process of melting the particle surface, the glass particles can be made closer to a spherical shape. Here, the melting of the particle surface can be performed by a process of charging a roughly ground dielectric glass material into a plasma jet stream. Thereby, the particle surface of the glass material is melted by the action of the plasma giotto, and the glass particles can be made closer to a spherical shape.

[0014] The melting of the particle surface can be carried out by leaving the coarsely pulverized dielectric glass material in an atmosphere below its softening point. As a result, the particle surface of the glass material is melted, and the glass particles can be made closer to a spherical shape. The spheroidizing treatment may be performed by causing the dielectric glass material after the coarse pulverization to collide at high speed in an air current. Accordingly, the particles flowing in the high-speed air flow collide with each other to perform the particle pulverization. At the same time, the surface of the particles is polished so that the particle shape approaches a sphere.

Here, between the step of performing the spheroidizing treatment and the step of arranging the mixture of the dielectric glass material and the binder on the substrate body, the maximum particle diameter of the dielectric glass material is set to a value after the firing. The method may include a step of performing a classification process so as not to exceed 1/2 of the thickness. This makes it possible to make the dielectric glass layer thinner.

Here, the step of disposing the mixture of the dielectric glass material and the binder on the substrate body includes the step of forming the mixture of the dielectric glass material after the spheroidizing treatment and the thermoplastic resin into a sheet-like dielectric material. The glass sheet may be arranged on the substrate body. This makes it possible to make the dielectric glass layer thinner.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A configuration of a plasma display panel (hereinafter, referred to as "PDP") and a method of manufacturing the same according to an embodiment of the present invention will be described with reference to the drawings. The following embodiment is an example of the present invention in which a spheroidizing treatment is performed on a dielectric glass material after coarse pulverization, and a manufacturing method having the same function and effect falls within the scope of the technical idea of the present invention. Needless to say, it is included.

[First Embodiment] FIG. 1 is a perspective view of an essential part of an AC surface discharge type PDP according to the present embodiment. FIG. 2 is a vertical sectional view including the line XX of FIG. Is YY in FIG.
FIG. 4 is a vertical sectional view including a line. In these figures, only three cells are shown for convenience, but actually, red (R),
A PDP is formed by arranging a large number of cells that emit green (G) and blue (B) light.

In this PDP, a pulse-like voltage is applied to each electrode to generate a discharge inside the panel, and visible light of each color generated on the side of the back panel PA1 due to the discharge from the main surface of the front panel PA2. AC surface discharge type P to be transmitted
DP. The front panel PA1 has a dielectric glass layer 13 formed on a front glass substrate 11 on which discharge electrodes 12 are arranged in stripes so as to cover the discharge electrodes 12. The protective layer 14 is formed so as to cover. The discharge electrode 12 includes a transparent electrode 12a formed on the surface of the glass substrate 11, and a metal electrode 12b formed on the transparent electrode 12a.

On the other hand, the rear panel PA2 protects the address electrodes on the rear glass substrate 21 on which the address electrodes 22 are arranged in stripes so as to cover the address electrodes 22 and reflects visible light toward the front panel. An electrode protection layer 23 is formed, which acts in the same direction as the address electrodes 22 on the electrode protection layer 23.
Partition walls 24 are erected so as to sandwich the address electrode 22, and a phosphor layer 25 is further arranged between the partition walls 24.

Next, an outline of a method of manufacturing the PDP having the above configuration will be described. Fabrication of Front Panel PA1: The front panel PA1 has the discharge electrodes 12 formed in stripes on the surface of the front glass substrate 11 by a known chemical vapor deposition / photolithography method, and then covers the discharge electrodes 12. A dielectric glass layer 13 is formed using glass powder, and a protective layer 14 made of magnesium oxide (MgO) is formed on the surface of the dielectric glass layer 13 by an electron beam evaporation method. Production of back panel PA2: First, address electrodes 22 were formed on the surface of back glass substrate 21 by photolithography.
To form This address electrode is composed of only a metal electrode.

The electrode protection layer 2 is formed so as to cover the address electrodes 22 in the same manner as in the case of the front panel PA1.
Form 3 Next, glass partition walls 24 are provided on the electrode protection layer 23 at a predetermined pitch. And the partition 2
The phosphor layer 25 is formed by arranging a red (R) phosphor, a green (G) phosphor, and a blue (B) phosphor in each space between the four. As the phosphors of the respective colors R, G, and B, phosphors generally used in PDPs can be used. Here, the following phosphors are used.

Red phosphor: (Y _x Gd _(1-x) ) BO ₃ : Eu ³⁺ Green phosphor: Zn ₂ SiO ₄ : Mn Blue phosphor: BaMgAl ₁₀ O ₁₇ : Eu ²⁺ or Ba
Completion of PDP by MgAl ₁₄ O ₂₃ : Eu ²⁺ panel bonding: Next, the front panel PA1 and the rear panel PA2 are positioned such that the discharge electrodes 12 and the address electrodes 22 are orthogonal to each other, and both panels are bonded. Thereafter, discharge gas (for example, He-Xe-based, Ne-X
The PDP is completed by sealing e-type inert gas) at a predetermined pressure.

The composition of the discharge gas to be filled is a conventionally used He-Xe type, Ne-Xe type or the like. In order to improve the light emission luminance of the cell, the content of Xe is reduced to 5% by volume. As described above, the sealing pressure is 0.67 × 10 ^{5 to} 1.01 ×
Set to 10 ⁵ Pa. The PDP having the above configuration is driven using the drive circuit shown in FIG. Address electrode drive unit 31
Is connected to the address electrode 22, and the scan electrode driving unit 3
2 is connected to an electrode on the scanning side of the discharge electrode 12, and the sustain electrode driving unit 33 is connected to an electrode on the sustain side of the discharge electrode 12. Then, wall charges are uniformly accumulated in all cells in the PDP so that discharge is easily generated in the setup period by such a driving circuit. Next, write discharge is performed on cells to be turned on in the address period. Further, the cells written in the address period are turned on in the sustain period to maintain the lighting, and the cell charges are stopped by erasing the wall charges in the erase period. These multiple operations are repeatedly performed to display an image of one TV field. * Regarding formation of dielectric glass layer The dielectric glass layer 13 is formed by screen printing, die coating, spin coating, spray coating, or the like using a glass powder having a predetermined average particle diameter and subjected to surface melting treatment. It is formed by printing on the surface of the front glass substrate 11 on which the discharge electrodes 12 are formed by a blade coating method, and then firing the printed film.

By using the glass powder subjected to such a surface melting treatment, a dielectric glass layer which is a sintered body of a metal oxide having a small number of bubbles and a dense structure can be obtained. The glass powder to be subjected to the surface melting treatment is a glass coarse material having a predetermined composition, and finally a dielectric glass layer is formed using a pulverizing device such as a ball mill or a wet jet mill (for example, HJP300-02 manufactured by Sugino Machine Co., Ltd.). It is roughly ground to near the particle size of the glass powder used for formation.
The particles of the glass powder after the crushing have a generally square and irregular shape as shown in FIG.

The glass coarse material includes, for example, components G1, G2,
When using glass consisting of G3, ..., GN,
The components G1, G2, G3,..., And GN were weighed at a ratio corresponding to the component ratio, and this was heated and melted, for example, in a furnace at 1300 ° C., and then poured into water. .
Specifically, as a glass coarse material, PbO—B ₂ O ₃ −
SiO ₂ -CaO-based _{glass, PbO-B 2 O 3 -SiO} 2 -
MgO based _{glass, PbO-B 2 O 3 -SiO} 2 -BaO -based _{glass, PbO-B 2 O 3 -SiO} 2 -MgO-Al 2 O 3
System _{glass, PbO-B 2 O 3 -SiO} 2 -BaO-Al 2 O
₃ based _{glass, PbO-B 2 O 3 -SiO} 2 -CaO-Al 2
O ₃ glass, Bi ₂ O ₃ —ZnO—B ₂ O ₃ —SiO ₂ —C
aO based _{glass, ZnO-B 2 O 3 -SiO} 2 -Al 2 O 3 -C
aO glass, can be used _{P 2 O 5 -ZnO-Al 2} O 3 -CaO based _{glass, Nb 2 O 5 -ZnO-B} 2 O 3 -SiO 2 -CaO -based glass alone or a mixture thereof.
In addition, glass generally used for a dielectric of a PDP can be similarly used.

The surface melting treatment of the glass powder can be performed by using a plasma torch 40 shown in FIG. The plasma torch 40 is used for the plasma spraying method, and has a cylindrical cathode 41 and a cylindrical anode 42, and a space 43 having a V-shaped cross section between the anode 42 and the cathode 41 has a plasma working gas. The arc discharge is generated by using the plasma working gas 44 in the space 43 when the DC power is supplied from the DC power supply 45 between the anode 42 and the cathode 41. The plasma working gas 44 into the space 43 is introduced from a gas port 46 provided on the upper part of the plasma torch, and is injected from a nozzle unit 47 at a pressure corresponding to the flow rate of the plasma working gas. As the plasma working gas 44, argon, helium, nitrogen,
Hydrogen or the like can be used. Although not shown, the cathode 41 and the anode 42 are configured to be water-cooled, and both electrodes are insulated by an insulating material 51.

A glass powder supply port 48 is opened in the cathode 41 in the vertical direction, and a glass powder 49 is supplied from the glass powder supply port 48 into the space 43.
The glass powder 49 supplied into the space 43 is heated and melted by being placed on a plasma working gas (carrier gas) 44 and exposed to the plasma jet 50, and is injected together with the plasma jet 50 from the nozzle part 47.

By subjecting the glass powder to a process of exposing the glass powder to a plasma jet using such a plasma torch 40, the surface of the glass
(Approximately 000 ° C.) and becomes close to a sphere as shown in FIG. In particular, with the above-described plasma torch configuration, the glass powder is surrounded by the plasma jet and stays in the plasma jet, so that the processing can be performed efficiently. This is because the glass powder is introduced from the region where the suction force by the plasma jet flow acts, so that the glass powder is efficiently taken into the plasma jet flow. On the other hand, in the extrapolation type in which the glass powder is supplied in the vicinity of the outlet side of the nozzle portion 47, a part of the glass powder is repelled by the plasma jet, so that it is difficult to make the glass powder stay in the plasma jet. Therefore, it is difficult to perform the processing efficiently.

However, it is necessary to set the output of the plasma jet so that the glass powder does not overmelt. The conditions for generating the plasma jet are as follows: the flow rate of the plasma working gas is 10 L / min, and the plasma current is
300A. Under these conditions, the surface of at least 90% (by weight) of the glass powder can be melted and brought closer to a sphere.

After performing the surface melting treatment, the particles are adjusted to a predetermined particle size distribution by a classifier. The classification is desirably performed so that the particle size distribution is as sharp as possible, that is, the particle diameters are made uniform. In particular, it is desirable to classify the dielectric glass material so that the maximum particle diameter of the dielectric glass material does not exceed 1/2 of the film thickness after firing, in order to reduce the thickness. Here, the method of performing the surface melting treatment of the glass particles is not limited to the method using the plasma torch as long as the method is to melt the surface of the glass particles. That is, it is possible to similarly melt the glass particle surface and spheroidize it by placing the coarsely ground glass powder in a heating furnace and heating at a temperature not exceeding the softening point. It is of course possible to do so.

Next, the glass powder subjected to the surface melting treatment as described above is kneaded well together with a binder and a solvent for dissolving the binder by a ball mill, a disper mill or a wet jet mill to produce a mixed glass paste.
As the binder used here, an acrylic resin, ethyl cellulose, ethylene oxide alone or a mixture thereof can be used. As a binder dissolving solvent,
Terpineol, butyl carbitol acetate, pentanediol alone, or a mixture thereof can be used. By adjusting the amount of the binder-dissolving solvent to be contained in the mixed paste, the viscosity of the mixed paste is set to a value suitable for a film forming method employing the mixed paste.

It is desirable to add a plasticizer or a surfactant (dispersant) to the mixed glass paste as needed. This is because if a plasticizer is added, the glass film after applying and drying the glass paste becomes flexible, and it is possible to prevent the film from cracking during sintering.
Further, when a surfactant is added, the surfactant is adsorbed around the glass particles, the dispersibility of the glass is improved, and uniform glass application can be performed. The addition of a surfactant is particularly effective in the case of a die coating method, a spray coating method, a spin coating method, and a blade coating method in which a film is formed using a glass paste having a low viscosity.

The composition of the mixed paste was as follows:
5% to 70% by weight, Binder 5% to 15% by weight
Is preferably 30% by weight to 65% by weight. The amount of the added plasticizer or surfactant (dispersant) is preferably 0.1% by weight to 3.0% by weight based on the binder component. As the surfactant (dispersant), an anionic surfactant can be used. Examples thereof include polycarboxylic acid, sodium salt of alkyl diphenyl ether sulfonate, alkyl phosphate, phosphate of higher alcohol, and polyoxyethylene. Ethylene diglycerin borate carboxylate, polyoxyethylene alkyl sulfate, naphthalenesulfonic acid formalin condensate, glycerol monooleate, sorbitan sesquiolate, or homogenol can be used. In addition, as a plasticizer, dibutyl phthalate,
Dioctyl phthalate or glycerin can be used. These may be used alone or in combination of two or more.

Next, using the mixed glass paste, a screen printing method, a die coating method, a spin coating method, a spray coating method, or a blade coating method is used to apply the mixed paste to the front glass substrate 11 on which the discharge electrodes 12 are formed.
After being coated on top and dried, a predetermined temperature (550 ° C. to 59
(0 ° C.) to sinter the glass powder in the glass paste.
Note that this sintering process is preferably performed near the softening point of the dielectric glass as much as possible. This is because, when sintering is performed at a temperature much higher than the softening point, the flowability of the molten glass increases, which causes a reaction with the discharge electrode to generate bubbles.

As the thickness of the dielectric glass layer becomes thinner, the effect of improving the panel brightness and reducing the discharge voltage becomes more remarkable. Therefore, it is desirable to set the thickness as thin as possible as long as the dielectric breakdown voltage is maintained. Hereinafter, a method of applying the mixed glass paste using the screen printing method in the printing method of the dielectric glass layer will be described.

In the screen printing method, the mixed glass paste (viscosity: about 50,000 centipoise) is placed on a stainless steel mesh having a predetermined mesh size (for example, 325 mesh), and printing is performed using a squeegee (printing step). . Next, through a step of drying and evaporating the organic solvent to dry the binder (drying step),
One film forming process is completed. When a predetermined film thickness is obtained by repeating this step a plurality of times, the glass powder is once fired at a temperature near the softening point (firing step). Next, after repeating the printing step and the drying step a plurality of times, a baking step is performed. By repeating such processing, the dielectric glass layer is finished.

Next, the formation of the electrode protection layer 23 will be described. The electrode protection layer 23 on the address electrode is formed by adding 5% by weight of TiO ₂ to the glass powder used for forming the dielectric glass layer 13.
The dielectric glass layer 13 is formed by using
Are formed in the same manner as when forming. Thus, Ti
By adding O ₂ , the dielectric glass layer on the back glass substrate plays a role of reflecting light emitted from the phosphor toward the front panel. It should be noted that the greater the amount of TiO ₂ added, the higher the reflectivity.
On the other hand, if the amount is too large, the withstand voltage is reduced, so that 30% by weight with respect to the dielectric glass powder seems to be the limit.

The glass powder to which TiO ₂ has been added is also subjected to the surface melting treatment (sphering treatment) as described above and classified into a predetermined particle size distribution. When the dielectric glass layer is formed using the glass powder subjected to the surface melting treatment described above, the following actions and effects can be obtained, and the PD having excellent withstand voltage property can be obtained.
P can be realized. FIG. 6 is a schematic diagram (cross-sectional view) for explaining the operation and effect.

First, the case where a glass powder not subjected to a surface melting treatment (spheroidizing treatment) is used will be described. FIG.
As shown in (a), the glass particles that are not subjected to the surface melting treatment (spheroidizing treatment) are obtained by simply grinding the glass coarse material using a grinding device, and thus the shape of the glass particles is irregular and angular. There are many things. Therefore, the wettability of the particle surface is non-uniform, and at the stage of printing the glass powder, the binder 62 is non-uniformly adhered to the surface of the glass particle 61, not uniformly. Therefore, a difference is generated in the burning rate of the binder 62 between the glass particles at the time of firing, so that before the heating temperature reaches the softening point of the glass powder,
Not all the binder burns out, and there is a part that burns out after the glass powder starts to soften. When the glass powder begins to soften, the combustion gas flow path resulting from the burning of the binder disappears, and the combustion gas is confined in the dielectric glass layer. The combustion gas confined in this manner remains in the dielectric glass layer as bubbles AH as shown in FIG. 6B.

On the other hand, as shown in FIG.
In the glass particles subjected to the surface melting treatment (spheroidizing treatment), the angular portions of the glass particles after pulverization by the pulverizer are tanned and approach the sphere. In particular, when melting is performed using a plasma jet as described above, it can be made closer to a sphere by surface tension. When the glass powder subjected to the surface melting treatment is used, since the wettability of the particle surface is uniform, the binder 64 is uniformly attached to the surface of the glass particle 63 at the stage of printing the glass powder. . For this reason, there is little difference in the burning rate of the binder 64 between the glass particles, and almost all the binder is burned out before the heating temperature reaches the softening point of the glass powder. Therefore, the possibility that the combustion gas is confined in the dielectric glass layer is low, and the possibility that the combustion gas confined in this way remains as bubbles in the dielectric glass layer is low.
In the completed dielectric glass layer, FIG.
As shown in (d), compared to the case shown in FIG.
The bubble AH number is decreasing.

This effect also depends on the particle size distribution of the glass powder. The sharper the particle size distribution, the smaller the number of bubbles. This is based on the following reasons. Glass particles having a relatively small particle diameter melt faster than glass particles having a relatively large particle diameter.
Therefore, if the glass particles having a large particle diameter and the glass particles having a small particle diameter are mixed in the applied layer, the glass particles having a small particle diameter are melted first by the time when the firing treatment is completed, The fluidized glass component agglomerates due to its fluidity, and there is no gas escape path. At this time, if the glass particles having a large particle diameter are not melted, the gas remains in the gap. Therefore, due to such a difference in the melting rate of the glass particles, the gap between the glass particles having a relatively large particle diameter, which is not completely melted, becomes bubbles and remains after firing. As described above, there is a strong correlation between the particle size and the factor that determines the degree of bubble generation, that is, the particle size of glass powder and the size of generated bubbles.

<Example> Based on the above embodiment, the PD
P was prepared, and the characteristics of the dielectric glass layer were examined. Specifically, a glass powder obtained by subjecting a glass powder having a composition of PbO-Al ₂ O ₃ —SiO _{2 to} a surface melting treatment under the following conditions, and classifying the glass powder so as to remove particles having a particle diameter exceeding 5 μm. A dielectric glass layer on the front panel was made using the powder.

Plasma working gas; Argon Flow rate of plasma working gas; 10 L / min Current applied between anode and cathode; 300 A Ethyl cellulose as binder for printing dielectric glass layer, α-terpineol as solvent The mixing ratio of glass powder, binder and solvent used is about 65% glass powder, resin about 3%, solvent about 32% (weight ratio),
The firing was performed twice, and the final film thickness was set to 40 μm.

As a comparative example, a panel in which a dielectric glass layer of a front panel was formed using the same glass powder but not subjected to surface melting treatment was manufactured. In the panel manufactured in this manner, 300c of the dielectric glass layer of the front panel was used.
It was counted the number of bubbles per m ^2. The counting of air bubbles was performed by observing with an optical microscope at a magnification of 100 times. Further, a withstand voltage test of the dielectric glass layer was performed as follows. That is, the front panel was removed, the discharge electrode was made positive, a silver paste was printed on the dielectric glass layer, and after drying, the silver paste was made negative, and a DC voltage was applied. The voltage at which physical insulation breakdown occurred was defined as the withstand voltage.

The results are shown in Table 1 below.

[0047]

[Table 1]

As can be seen from this table, the number of bubbles is as small as 2 in the PDP according to the example (as opposed to 10 in the PDP according to the comparative example), and as a result, the breakdown voltage is as high as 170 V / μm. (On the other hand, the PDP according to the comparative example is as low as 130 V / μm.) [Embodiment 2] The PDP according to the present embodiment has the same configuration as that of the above-described embodiment, but the method of spheroidizing the dielectric glass material used for forming the dielectric glass layer is the same as that of the above-described embodiment. Unlike this, there is a characteristic in that point. That is, here, the spheroidization after the coarse pulverization is further pulverized into finer particles by a dry-type jott mill pulverizer (for example, a counter jet mill AGF type (manufactured by Alpine)), thereby simultaneously bringing the particle shape closer to a spherical shape. (Spheroidizing treatment).

More specifically, the dry jott mill crusher used here mixes a dielectric glass material into two high-speed air streams, and pulverizes the powder by utilizing the collision force of the high-speed air streams. When the two air streams collide with each other, the glass particles also collide with each other, so that the particle size is reduced, and at the same time, the particle size is uniform and the particle size distribution becomes sharp.

Further, since the particles flowing in such a high-speed airflow collide with each other at a high speed, the particles are crushed. At the same time, when the particle surface is polished, the particle shape approaches a sphere. In addition, it was confirmed by microscopic observation that the shape of the particles approached a sphere with the pulverization. In addition, it has been confirmed that the wet-type jet mill generally has a limit in pulverization, and that the pulverization is not performed until the particle shape approaches a sphere as in the present embodiment. Therefore, it is meaningful to use a dry type in which the particles can be made to collide at high speed to the extent that the particles are spheroidized even with the same jet mill pulverizer.

When a dielectric glass layer is formed using a dielectric glass material subjected to such a spheroidizing treatment, as described above, a difference is hardly generated in the binder burning speed between the glass particles, and the heating temperature is reduced. Almost all the binder is burned out before the softening point of the powder is reached. Therefore, the possibility that the combustion gas is confined in the dielectric glass layer is low,
The possibility that the combustion gas confined in this way remains as bubbles in the dielectric glass layer is low. Then, in the completed dielectric glass layer, the number of bubbles is reduced.

Further, by pulverizing as described above, the particle size of the dielectric glass material becomes small and the particle size distribution becomes sharp, so that the number of residual bubbles in the dielectric glass layer is further reduced. Becomes possible. The reason for this is that if the particle size of the glass particles is smaller, the gap between the glass particles is smaller because the glass particles are more densely packed than when the particle size is larger, and if the particle size distribution of the glass powder becomes sharper, There are two reasons why the melting rates of the glass materials are matched. However, if the particle size is too small, the glass particles will aggregate in the paste, resulting in an increase in the number of bubbles. [Modification] In the above description, a dielectric glass layer is formed by printing a paste containing a dielectric glass material and a binder and baking the paste, but a method of arranging the dielectric glass material on a substrate on which electrodes are formed is used. For example, a dielectric glass sheet that has been processed in advance may be used.

This dielectric glass sheet is formed by processing a mixture of a dielectric glass material, a thermoplastic resin, and an organic solvent into a sheet by a known method such as a blade method. If such a dielectric glass sheet is used, the dielectric glass layer can be made thinner.

[0054]

As described above, according to the method of manufacturing a plasma display panel of the present invention, a dielectric glass layer is formed using a dielectric glass material that has been subjected to spheroidizing treatment after coarse pulverization. The number of remaining bubbles can be reduced, and the withstand voltage can be improved. In particular, when the film is made thin, the effect is more remarkable than when the conventional spheroidizing treatment is not performed.

The reason is that the binder can be uniformly attached to the surface of the glass particles so that the burnout speed of the binder can be matched.

[Brief description of the drawings]

FIG. 1 is an AC surface discharge type PD according to an embodiment of the present invention.
It is a principal part perspective view of P.

FIG. 2 is a vertical sectional view including the line XX of FIG. 1;

FIG. 3 is a vertical sectional view including a line YY of FIG. 1;

FIGS. 4A and 4B are diagrams (cross-sectional views) showing the shape of particles of glass powder used for forming a dielectric glass layer, where FIG. 4A shows the particle shape before surface melting treatment is performed, and FIG. The shape of the particles after the surface melting treatment is shown.

FIG. 5 is a cross-sectional view showing a configuration of a plasma torch for adjusting glass powder used for forming a dielectric glass layer.

FIG. 6 is a schematic diagram (cross-sectional view) for explaining the operation and effect of the present invention. (A) is a figure which shows a mode when the dielectric glass layer is printed using the glass powder which does not perform a surface melting process. (B) is a figure which shows a mode that a bubble exists in the dielectric glass layer produced using the glass powder which does not perform a surface melting process. (C) is a diagram showing a state when a dielectric glass layer is printed using glass powder subjected to a surface melting treatment. (D) is a diagram illustrating a state in which bubbles are present in a dielectric glass layer manufactured using a glass powder subjected to a surface melting treatment.

FIG. 7 is a block diagram showing a driving circuit of the PDP.

FIG. 8 is a perspective view of a main part of an AC surface discharge type PDP according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Front glass substrate 12 Discharge electrode 12a Transparent electrode 12b Metal electrode 13 Dielectric glass layer 14 Protective layer 21 Back glass substrate 22 Address electrode 23 Electrode protective layer 24 Partition wall 25 Phosphor layer 30 Discharge space 31 Address electrode drive part 32 Scan electrode drive Unit 33 sustain electrode driving unit 40 plasma torch 41 cathode 42 anode 43 space (space where arc discharge is generated) 44 plasma working gas 45 DC power supply 46 gas port 47 nozzle unit 48 glass powder supply port 49 glass powder 50 plasma jet 51 insulation Materials 61,63 Glass particles 62,64 Binder PA1 Front panel PA2 Back panel AH Air bubbles

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shigeo Suzuki 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F-term (reference) 5C027 AA05 5C040 FA01 FA04 GD09 KA07 MA30

Claims (8)

[Claims] 1. A method for manufacturing a plasma display panel, comprising: forming an electrode on a surface of a substrate body; and forming a dielectric glass layer on the electrode, wherein the step of forming the dielectric glass layer comprises the steps of: A step of coarsely pulverizing the body glass material, a step of performing spheroidization on the dielectric glass material after the coarse pulverization, and forming an electrode by mixing the dielectric glass material subjected to the spheroidization with a binder A plasma display, comprising the steps of: disposing in a layered form on a substrate body that has been formed, and then firing the dielectric glass material while eliminating the binder from the layer containing the dielectric glass material and the binder. Panel manufacturing method. 2. The method of manufacturing a plasma display panel according to claim 1, wherein the step of performing the spheroidizing process comprises a process of melting the surface of the particles of the dielectric glass material after the coarse pulverization. 3. The method of manufacturing a plasma display panel according to claim 2, wherein the melting of the particle surface is performed by a process of charging a roughly ground dielectric glass material into a plasma jet flow. 4. The method for manufacturing a plasma play panel according to claim 2, wherein the surface melting of the particles is performed by leaving the coarsely pulverized dielectric glass material in an atmosphere having a softening point or lower. 5. The method of manufacturing a plasma display panel according to claim 1, wherein the step of performing the spheroidizing process comprises a process of colliding the coarsely pulverized dielectric glass material in an air current at a high speed. . 6. The method according to claim 1, wherein the step of applying a spheroidizing treatment and the step of disposing a mixture of the dielectric glass material and the binder on the substrate body have a maximum particle diameter of the dielectric glass material after firing. The method of manufacturing a plasma display panel according to any one of claims 1 to 5, further comprising a step of performing a classification process so as not to exceed 1/2 of the following. 7. The step of arranging a mixture of a dielectric glass material and a binder on a substrate body includes the step of forming a mixture of a dielectric glass material after spheroidization treatment and a thermoplastic resin into a sheet-like dielectric glass. The method for manufacturing a plasma display panel according to any one of claims 1 to 6, comprising arranging a sheet on a substrate main body. 8. An image display device comprising: a plasma display panel manufactured by the manufacturing method according to claim 1; and a drive circuit for driving the plasma display panel.