The present invention relates to a method of manufacturing plasma display panels of plasma display devices to be used for displaying images in television receivers featuring a large screen, thin body and light-weight.
In recent years, computers and television receivers have employed a variety of color display devices. A plasma display panel (hereinafter simply referred to as “PDP”), among others, has drawn attention as a color display device that allows the display panel to be large-size, thin, and light weight.
A PDP includes the following elements:
The front and back plates are confronted each other and sealed, then neon (Ne) or xenon (Xe) is filled in the discharging space for discharging. Operating the foregoing PDP generates impurity gas because of the structure discussed above; thus, a degassing material is inserted into the PDP for absorbing and removing the impurity gas. In other words, the degassing treatment is provided. This instance is disclosed in Japanese Patent Application Non-Examined Publication No. 2000-311588. Further, providing the barrier ribs of the PDP with a degassing layer is proposed in Japanese Patent Application Non-Examined Publication No. 2002-531918.
However, the foregoing conventional degassing treatments are problematic.
On top of the foregoing problems, the conventional degassing material shown in
The present invention aims to provide a method of manufacturing PDPs in which impurity gas can be collected from overall the PDP without an activation treatment at a high temperature.
The method of manufacturing plasma display panels of the present invention comprises:
At least one of the above steps uses inorganic material that has undergone an impregnation process where solution including degassing material is impregnated into the inorganic material.
a) and 3(b) show schematic drawings illustrating interior structures of particles of inorganic material in accordance with the first exemplary embodiment of the present invention.
a) and 7(b) show a schematic sectional view and a schematic plan view of another PDP in accordance with an exemplary embodiment of the present invention.
Exemplary embodiments of the present invention are demonstrated hereinafter with reference to the accompanying drawings.
A method of manufacturing PDPs in accordance with the first exemplary embodiment of the present invention is demonstrated hereinafter with reference to the related drawings.
A structure of the PDP of the present invention is described with reference to
On the other hand, back plate 2 comprises the following elements:
The PDP is produced by air-tightly sealing front plate 1 and back plate 2 facing each other with address electrodes 11 intersecting with display electrodes 6 at right angles. Discharging space 15 formed by barrier ribs 13 is filled with a discharge-gas such as neon (Ne) or xenon (Xe) at a pressure of 400-600 Torrs. An application of a given voltage to display electrodes 6 and address electrodes 11 discharges discharge-gas, and the resultant ultraviolet ray excites phosphor layers 14 of the respective colors, so that the phosphor emits lights in red, green and blue. A color image is thus displayed.
In this first embodiment, barrier ribs 13 of the PDP discussed above are absorb and collect impurity gas.
First, in step 5, powder particles of inorganic material such as silica or aluminum oxide which is principal material of barrier ribs 13 are prepared. The purity of silica or aluminum oxide must be carefully selected from the standpoint of mechanical strength of barrier ribs 13. In the case of using aluminum oxide, θ or γ model crystal is preferably selected because of its greater specific surface area. This selection is useful in step 6 where metal salt is impregnated into inorganic material, and particularly, if it is necessary to impregnate a large amount of metal salt into aluminum oxide.
Next, in step 6, the metal salt of degassing material is impregnated into the inorganic material. The metal component of the metal salt (degassing material) can be any metals as long as they are in high activity state. For example, nickel (Ni), zirconium (Zr), iron (Fe), vanadium (V), chrome (Cr), or molybdenum (Mo) can be used. Among those metals, at least one metal can be used. A salt group of those metals can be, for example, an acetate group, a nitrate group, or a oxalate group. The metal salts are solved in pure water, and the inorganic material prepared in step 5 is added to the resultant solution of 1-4% density. This solution is agitated for approximately 2 hours for impregnating the metal salt solution into the inorganic material. Slurry is thus produced.
Next, in step 7, filtrate the slurry undergone the impregnation is filtrated. Sucking filtration is preferable for removing water completely between particles. Next, in step 8, the slurry is dried and baked for drying moisture as well as decompositing and removing the salt group. For drying moisture, 150-300° C. is preferable, and oxygen atmosphere at 350-600° C. is preferable for decompositing and removing the salt group. Nitrogen atmosphere or reducing gas atmosphere such as hydrogen can be used depending on the situation. Steps 5 through 8 completes impregnation of the degassing material into silica or aluminum oxide, namely, principal material of barrier ribs 13. In other words, the process from step 5 to step 8 produces inorganic material into which the solution including the degassing material is impregnated. In step 8, acetate group, nitrate group, oxalate group are selected for decompositing and removing the salt group; however, the salt group may remain in some cases, so that a hydrochloric acid group, a phosphoric acid group or a formic acid group can be used. Further, an organic complex or an inorganic complex can also be used without question.
In step 9, an additional material of barrier rib 13 is added to the inorganic material to which the degassing material is impregnated, namely, glass component of low melting point is added, as shown
In step 3, barrier ribs 13 are patterned. Besides the foregoing photolitho method, a sand-blast method and lift-off method are available for the patterning. In the case of using the screen printing method, the paste produced in step 9 is directly printed on the pattern, so that step 2 is omitted. After the patterning, the pattern is baked at approx. 500° C. for removing the resin component from the paste and solidifying. Barrier ribs 13 in a given shape are thus produced.
In step 4, phosphor layer 14 are formed on both of lateral faces of barrier ribs 13 and back-plate dielectric layer 12. Phosphor layers 14 of three colors, i.e. red, green and blue, are formed by a method such as the screen printing method or the ink-jet method.
The steps discussed above form back plate 2, which is then bonded to front plate 1 which is produced separately, such that display electrode 6 of front plate 1 intersects with address electrode 11 of back plate 2 at right angles, and the bonded unit is sealed at its periphery. Then the bonded unit is heated and exhausted for removing the impurity gas generated and collected during the manufacturing process, and predetermined discharge gas is inserted into the unit before sealing. The PDP is thus completed.
In the foregoing PDP, impurity gas is generated at phosphor layer 14 and front plate 1 by the discharge of the PDP. The impurity gas is absorbed physically and chemically by fine particles of the degassing material in barrier ribs 13, which degassing material features high activity and is excellent in gas absorption performance. Since barrier ribs 13 are formed all over the display area of the PDP, the impurity gas all over the display area can be evenly absorbed. It is known that a large amount of the impurity gas occurs from phosphor layer 14, so a function of collecting impurity gas provided to barrier rib 13 adjacent to this gas source increases the effect of gas collection. Therefore, the PDP can maintain the discharge gas of given ingredients and at a given density, and the PDP can always discharge in a stable manner. A PDP excellent in discharging characteristics is thus obtainable.
Selection of γ model aluminum oxide or θ model aluminum oxide as the inorganic material for barrier rib 13 allows forming a barrier rib more excellent in collecting the impurity gas.
The second exemplary embodiment of the present invention refers to the case where phosphor layer 14 is equipped to absorb and collect the impurity gas.
In step 20, the blue phosphor (BAM:Eu) is prepared. The blue phosphor is compounded by, first, preparing the following materials in stoichiometrically adequate quantity: aluminum oxide, barium carbonate, and magnesium carbonate as the base material, europium as the activation agent, and a bit of aluminum fluoride as the flux agent that facilitates movement between the materials at partial melting on surface of each material as well as accelerates reactions. Then, the above materials are missed and baked at a high temperature. The baked materials are classified for obtaining powders of a given diameter.
In step 21, the degassing material is impregnated into the phosphor material or inorganic material separately added. In this embodiment, metal salt as the degassing material is impregnated into parts of the phosphor powders produced as discussed above. Metal components (degassing material) of the metal salt can be anything as long as they are high activation materials, e.g. at least one metal out of nickel (Ni), zirconium (Zr), iron (Fe), vanadium (V), chrome (Cr), and molybdenum (Mo). The salt group of those metal salts can be, for example, an acetate group, a nitrate group, or an oxalate group. The metal salts are solved in pure water, and the phosphor powders are added to the resultant solution of 1-4% density. This solution is agitated for approx. 2 hours for impregnating the metal salt solution into the phosphor powders. Slurry is thus produced.
Next, in step 22, the slurry undergone the impregnation is filtrated. Sucking filtration is preferable for removing water completely between molecules. Next, in step 23, the slurry is dried and baked for drying moisture as well as decompositing and removing the salt group. For drying moisture, 150-300° C. is preferable, and oxygen atmosphere at 350-600° C. is preferable for decompositing and removing the salt group. Nitrogen atmosphere or reducing gas atmosphere such as hydrogen can be used depending on the situation.
In step 24, the original phosphor powders and the phosphor powders undergone the impregnation are mixed together. Solvent is added to the resultant phosphor powders to form paste, and the paste is applied between barrier ribs 13 by the screen printing method or the inkjet method. In step 23, acetate group, nitrate group, oxalate group are selected for decompositing and removing the salt group; however, the salt group may remain in some cases, so that a hydrochloric acid group, a phosphoric acid group or a formic acid group can be used. Further, an organic complex or an inorganic complex can be used without question.
The phosphor powders prepared in step 20 have pores of several tens Å-several thousands Å across. Impregnation of the degassing material into these phosphor powders having the foregoing pores allows fine particles of several tens Å-several hundreds Å across of the degassing material to attach onto the inner wall of the pores or the outer surface around the pores. Such fine particles of the degassing material have high catalytic activity because of their small crystal diameters. On top of that, they have a structure similar to that can produce catalytic effect of several hundreds times that of the conventional degassing material, and they work as gas absorbing members. The small crystal diameter increases surface energy, so that not only physical adsorption but also chemical adsorption occurs. As a result, the degassing material can collect impurity gas without an activation treatment, which has been required with conventional degassing materials. The impregnation of the degassing material into only small parts of the original phosphor powders thus allows absorbing and collecting of the impurity gas. Therefore, the impurity gas can be collected free from degrading the characteristics of the phosphor.
In this embodiment, parts of the phosphor material are processed before mixing them with the unprocessed phosphor material. However, aluminum oxide or silica independent of the phosphor material can undergo the impregnation, and be mixed with the phosphor material. Further, a percentage of impregnation is adjusted for applying to the entire phosphor material instead of partial application.
In this embodiment, the blue phosphor undergoes the impregnation for absorbing and collecting the impurity gas; however, the impregnation can be applied to red or green phosphor.
The third exemplary embodiment of the present invention refers to a case where back-plate dielectric layer 12 is equipped to absorb and collect the impurity gas.
In step 1, shown in
With dielectric layer 8 of front plate 1 careful attention must be paid to the changes in permeability and dielectric constant due to the ingredients; however, back-plate dielectric layer 12 does not need such careful attention. Thus, selection of material, such as inorganic material, e.g. silica or aluminum oxide, impregnated with metal salt of degassing material, can be done with ease. The method of impregnation is similar to the method of impregnation to barrier ribs 13 in the first embodiment. The material undergone the impregnation is mixed with a glass component having a low melting point and being a principal material of back-plate dielectric layer 12. Then, resin and solvent are added to the resultant material to form paste.
The paste is applied onto back glass substrate 10 by the screen printing method or the die-coating method. The resultant glass substrate 10 is dried and baked to form back-plate dielectric layer 12. Layer 12 thus includes highly active fine particles similar to barrier ribs 13 or phosphor layer 14, and can absorb and collect the impurity gas well.
As discussed in the first embodiment through the third embodiment, the present invention allows the PDP to become excellent in collecting impurity gas by impregnating the materials of the barrier ribs, phosphor layer, or back-plate dielectric layer with the degassing material.
The PDP is filled with neon (Ne)-xenon (Xe; content is 5%) at a charged pressure of 500 Torrs. Discharging space 15, shown in
As shown in
In the first embodiment, barrier ribs 13 are equipped with the function of absorbing and collecting the impurity gas. However, dummy partitions independent of barrier ribs 13 can be prepared, and the same function can be provided to these dummy partitions.
In the embodiments previously discussed, the inorganic material impregnated with solution including the degassing material is used for building some elements of back plate 2 of the PDP. However, the effect of absorbing and collecting the impurity gas can be obtained by providing the face of front plate 1 exposed to the discharging space with a member formed of the foregoing inorganic material.
Number | Date | Country | Kind |
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2003-012252 | Jan 2003 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2004/000413 | 1/20/2004 | WO | 00 | 8/2/2004 |
Publishing Document | Publishing Date | Country | Kind |
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WO2004/066336 | 8/5/2004 | WO | A |
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20050093774 A1 | May 2005 | US |